Merge tag 'drm/tegra/for-4.9-rc1' of git://anongit.freedesktop.org/tegra/linux into...

[cascardo/linux.git] / drivers / gpu / drm / i915 / i915_gem.c

/*
 * Copyright © 2008-2015 Intel Corporation
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice (including the next
 * paragraph) shall be included in all copies or substantial portions of the
 * Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
 * IN THE SOFTWARE.
 *
 * Authors:
 *    Eric Anholt <eric@anholt.net>
 *
 */

#include <drm/drmP.h>
#include <drm/drm_vma_manager.h>
#include <drm/i915_drm.h>
#include "i915_drv.h"
#include "i915_gem_dmabuf.h"
#include "i915_vgpu.h"
#include "i915_trace.h"
#include "intel_drv.h"
#include "intel_frontbuffer.h"
#include "intel_mocs.h"
#include <linux/reservation.h>
#include <linux/shmem_fs.h>
#include <linux/slab.h>
#include <linux/swap.h>
#include <linux/pci.h>
#include <linux/dma-buf.h>

static void i915_gem_object_flush_gtt_write_domain(struct drm_i915_gem_object *obj);
static void i915_gem_object_flush_cpu_write_domain(struct drm_i915_gem_object *obj);

static bool cpu_cache_is_coherent(struct drm_device *dev,
                                  enum i915_cache_level level)
{
        return HAS_LLC(dev) || level != I915_CACHE_NONE;
}

static bool cpu_write_needs_clflush(struct drm_i915_gem_object *obj)
{
        if (obj->base.write_domain == I915_GEM_DOMAIN_CPU)
                return false;

        if (!cpu_cache_is_coherent(obj->base.dev, obj->cache_level))
                return true;

        return obj->pin_display;
}

static int
insert_mappable_node(struct drm_i915_private *i915,
                     struct drm_mm_node *node, u32 size)
{
        memset(node, 0, sizeof(*node));
        return drm_mm_insert_node_in_range_generic(&i915->ggtt.base.mm, node,
                                                   size, 0, 0, 0,
                                                   i915->ggtt.mappable_end,
                                                   DRM_MM_SEARCH_DEFAULT,
                                                   DRM_MM_CREATE_DEFAULT);
}

static void
remove_mappable_node(struct drm_mm_node *node)
{
        drm_mm_remove_node(node);
}

/* some bookkeeping */
static void i915_gem_info_add_obj(struct drm_i915_private *dev_priv,
                                  size_t size)
{
        spin_lock(&dev_priv->mm.object_stat_lock);
        dev_priv->mm.object_count++;
        dev_priv->mm.object_memory += size;
        spin_unlock(&dev_priv->mm.object_stat_lock);
}

static void i915_gem_info_remove_obj(struct drm_i915_private *dev_priv,
                                     size_t size)
{
        spin_lock(&dev_priv->mm.object_stat_lock);
        dev_priv->mm.object_count--;
        dev_priv->mm.object_memory -= size;
        spin_unlock(&dev_priv->mm.object_stat_lock);
}

static int
i915_gem_wait_for_error(struct i915_gpu_error *error)
{
        int ret;

        if (!i915_reset_in_progress(error))
                return 0;

        /*
         * Only wait 10 seconds for the gpu reset to complete to avoid hanging
         * userspace. If it takes that long something really bad is going on and
         * we should simply try to bail out and fail as gracefully as possible.
         */
        ret = wait_event_interruptible_timeout(error->reset_queue,
                                               !i915_reset_in_progress(error),
                                               10*HZ);
        if (ret == 0) {
                DRM_ERROR("Timed out waiting for the gpu reset to complete\n");
                return -EIO;
        } else if (ret < 0) {
                return ret;
        } else {
                return 0;
        }
}

int i915_mutex_lock_interruptible(struct drm_device *dev)
{
        struct drm_i915_private *dev_priv = to_i915(dev);
        int ret;

        ret = i915_gem_wait_for_error(&dev_priv->gpu_error);
        if (ret)
                return ret;

        ret = mutex_lock_interruptible(&dev->struct_mutex);
        if (ret)
                return ret;

        return 0;
}

int
i915_gem_get_aperture_ioctl(struct drm_device *dev, void *data,
                            struct drm_file *file)
{
        struct drm_i915_private *dev_priv = to_i915(dev);
        struct i915_ggtt *ggtt = &dev_priv->ggtt;
        struct drm_i915_gem_get_aperture *args = data;
        struct i915_vma *vma;
        size_t pinned;

        pinned = 0;
        mutex_lock(&dev->struct_mutex);
        list_for_each_entry(vma, &ggtt->base.active_list, vm_link)
                if (i915_vma_is_pinned(vma))
                        pinned += vma->node.size;
        list_for_each_entry(vma, &ggtt->base.inactive_list, vm_link)
                if (i915_vma_is_pinned(vma))
                        pinned += vma->node.size;
        mutex_unlock(&dev->struct_mutex);

        args->aper_size = ggtt->base.total;
        args->aper_available_size = args->aper_size - pinned;

        return 0;
}

static int
i915_gem_object_get_pages_phys(struct drm_i915_gem_object *obj)
{
        struct address_space *mapping = obj->base.filp->f_mapping;
        char *vaddr = obj->phys_handle->vaddr;
        struct sg_table *st;
        struct scatterlist *sg;
        int i;

        if (WARN_ON(i915_gem_object_needs_bit17_swizzle(obj)))
                return -EINVAL;

        for (i = 0; i < obj->base.size / PAGE_SIZE; i++) {
                struct page *page;
                char *src;

                page = shmem_read_mapping_page(mapping, i);
                if (IS_ERR(page))
                        return PTR_ERR(page);

                src = kmap_atomic(page);
                memcpy(vaddr, src, PAGE_SIZE);
                drm_clflush_virt_range(vaddr, PAGE_SIZE);
                kunmap_atomic(src);

                put_page(page);
                vaddr += PAGE_SIZE;
        }

        i915_gem_chipset_flush(to_i915(obj->base.dev));

        st = kmalloc(sizeof(*st), GFP_KERNEL);
        if (st == NULL)
                return -ENOMEM;

        if (sg_alloc_table(st, 1, GFP_KERNEL)) {
                kfree(st);
                return -ENOMEM;
        }

        sg = st->sgl;
        sg->offset = 0;
        sg->length = obj->base.size;

        sg_dma_address(sg) = obj->phys_handle->busaddr;
        sg_dma_len(sg) = obj->base.size;

        obj->pages = st;
        return 0;
}

static void
i915_gem_object_put_pages_phys(struct drm_i915_gem_object *obj)
{
        int ret;

        BUG_ON(obj->madv == __I915_MADV_PURGED);

        ret = i915_gem_object_set_to_cpu_domain(obj, true);
        if (WARN_ON(ret)) {
                /* In the event of a disaster, abandon all caches and
                 * hope for the best.
                 */
                obj->base.read_domains = obj->base.write_domain = I915_GEM_DOMAIN_CPU;
        }

        if (obj->madv == I915_MADV_DONTNEED)
                obj->dirty = 0;

        if (obj->dirty) {
                struct address_space *mapping = obj->base.filp->f_mapping;
                char *vaddr = obj->phys_handle->vaddr;
                int i;

                for (i = 0; i < obj->base.size / PAGE_SIZE; i++) {
                        struct page *page;
                        char *dst;

                        page = shmem_read_mapping_page(mapping, i);
                        if (IS_ERR(page))
                                continue;

                        dst = kmap_atomic(page);
                        drm_clflush_virt_range(vaddr, PAGE_SIZE);
                        memcpy(dst, vaddr, PAGE_SIZE);
                        kunmap_atomic(dst);

                        set_page_dirty(page);
                        if (obj->madv == I915_MADV_WILLNEED)
                                mark_page_accessed(page);
                        put_page(page);
                        vaddr += PAGE_SIZE;
                }
                obj->dirty = 0;
        }

        sg_free_table(obj->pages);
        kfree(obj->pages);
}

static void
i915_gem_object_release_phys(struct drm_i915_gem_object *obj)
{
        drm_pci_free(obj->base.dev, obj->phys_handle);
}

static const struct drm_i915_gem_object_ops i915_gem_phys_ops = {
        .get_pages = i915_gem_object_get_pages_phys,
        .put_pages = i915_gem_object_put_pages_phys,
        .release = i915_gem_object_release_phys,
};

int i915_gem_object_unbind(struct drm_i915_gem_object *obj)
{
        struct i915_vma *vma;
        LIST_HEAD(still_in_list);
        int ret;

        lockdep_assert_held(&obj->base.dev->struct_mutex);

        /* Closed vma are removed from the obj->vma_list - but they may
         * still have an active binding on the object. To remove those we
         * must wait for all rendering to complete to the object (as unbinding
         * must anyway), and retire the requests.
         */
        ret = i915_gem_object_wait_rendering(obj, false);
        if (ret)
                return ret;

        i915_gem_retire_requests(to_i915(obj->base.dev));

        while ((vma = list_first_entry_or_null(&obj->vma_list,
                                               struct i915_vma,
                                               obj_link))) {
                list_move_tail(&vma->obj_link, &still_in_list);
                ret = i915_vma_unbind(vma);
                if (ret)
                        break;
        }
        list_splice(&still_in_list, &obj->vma_list);

        return ret;
}

/**
 * Ensures that all rendering to the object has completed and the object is
 * safe to unbind from the GTT or access from the CPU.
 * @obj: i915 gem object
 * @readonly: waiting for just read access or read-write access
 */
int
i915_gem_object_wait_rendering(struct drm_i915_gem_object *obj,
                               bool readonly)
{
        struct reservation_object *resv;
        struct i915_gem_active *active;
        unsigned long active_mask;
        int idx;

        lockdep_assert_held(&obj->base.dev->struct_mutex);

        if (!readonly) {
                active = obj->last_read;
                active_mask = i915_gem_object_get_active(obj);
        } else {
                active_mask = 1;
                active = &obj->last_write;
        }

        for_each_active(active_mask, idx) {
                int ret;

                ret = i915_gem_active_wait(&active[idx],
                                           &obj->base.dev->struct_mutex);
                if (ret)
                        return ret;
        }

        resv = i915_gem_object_get_dmabuf_resv(obj);
        if (resv) {
                long err;

                err = reservation_object_wait_timeout_rcu(resv, !readonly, true,
                                                          MAX_SCHEDULE_TIMEOUT);
                if (err < 0)
                        return err;
        }

        return 0;
}

/* A nonblocking variant of the above wait. Must be called prior to
 * acquiring the mutex for the object, as the object state may change
 * during this call. A reference must be held by the caller for the object.
 */
static __must_check int
__unsafe_wait_rendering(struct drm_i915_gem_object *obj,
                        struct intel_rps_client *rps,
                        bool readonly)
{
        struct i915_gem_active *active;
        unsigned long active_mask;
        int idx;

        active_mask = __I915_BO_ACTIVE(obj);
        if (!active_mask)
                return 0;

        if (!readonly) {
                active = obj->last_read;
        } else {
                active_mask = 1;
                active = &obj->last_write;
        }

        for_each_active(active_mask, idx) {
                int ret;

                ret = i915_gem_active_wait_unlocked(&active[idx],
                                                    I915_WAIT_INTERRUPTIBLE,
                                                    NULL, rps);
                if (ret)
                        return ret;
        }

        return 0;
}

static struct intel_rps_client *to_rps_client(struct drm_file *file)
{
        struct drm_i915_file_private *fpriv = file->driver_priv;

        return &fpriv->rps;
}

int
i915_gem_object_attach_phys(struct drm_i915_gem_object *obj,
                            int align)
{
        drm_dma_handle_t *phys;
        int ret;

        if (obj->phys_handle) {
                if ((unsigned long)obj->phys_handle->vaddr & (align -1))
                        return -EBUSY;

                return 0;
        }

        if (obj->madv != I915_MADV_WILLNEED)
                return -EFAULT;

        if (obj->base.filp == NULL)
                return -EINVAL;

        ret = i915_gem_object_unbind(obj);
        if (ret)
                return ret;

        ret = i915_gem_object_put_pages(obj);
        if (ret)
                return ret;

        /* create a new object */
        phys = drm_pci_alloc(obj->base.dev, obj->base.size, align);
        if (!phys)
                return -ENOMEM;

        obj->phys_handle = phys;
        obj->ops = &i915_gem_phys_ops;

        return i915_gem_object_get_pages(obj);
}

static int
i915_gem_phys_pwrite(struct drm_i915_gem_object *obj,
                     struct drm_i915_gem_pwrite *args,
                     struct drm_file *file_priv)
{
        struct drm_device *dev = obj->base.dev;
        void *vaddr = obj->phys_handle->vaddr + args->offset;
        char __user *user_data = u64_to_user_ptr(args->data_ptr);
        int ret = 0;

        /* We manually control the domain here and pretend that it
         * remains coherent i.e. in the GTT domain, like shmem_pwrite.
         */
        ret = i915_gem_object_wait_rendering(obj, false);
        if (ret)
                return ret;

        intel_fb_obj_invalidate(obj, ORIGIN_CPU);
        if (__copy_from_user_inatomic_nocache(vaddr, user_data, args->size)) {
                unsigned long unwritten;

                /* The physical object once assigned is fixed for the lifetime
                 * of the obj, so we can safely drop the lock and continue
                 * to access vaddr.
                 */
                mutex_unlock(&dev->struct_mutex);
                unwritten = copy_from_user(vaddr, user_data, args->size);
                mutex_lock(&dev->struct_mutex);
                if (unwritten) {
                        ret = -EFAULT;
                        goto out;
                }
        }

        drm_clflush_virt_range(vaddr, args->size);
        i915_gem_chipset_flush(to_i915(dev));

out:
        intel_fb_obj_flush(obj, false, ORIGIN_CPU);
        return ret;
}

void *i915_gem_object_alloc(struct drm_device *dev)
{
        struct drm_i915_private *dev_priv = to_i915(dev);
        return kmem_cache_zalloc(dev_priv->objects, GFP_KERNEL);
}

void i915_gem_object_free(struct drm_i915_gem_object *obj)
{
        struct drm_i915_private *dev_priv = to_i915(obj->base.dev);
        kmem_cache_free(dev_priv->objects, obj);
}

static int
i915_gem_create(struct drm_file *file,
                struct drm_device *dev,
                uint64_t size,
                uint32_t *handle_p)
{
        struct drm_i915_gem_object *obj;
        int ret;
        u32 handle;

        size = roundup(size, PAGE_SIZE);
        if (size == 0)
                return -EINVAL;

        /* Allocate the new object */
        obj = i915_gem_object_create(dev, size);
        if (IS_ERR(obj))
                return PTR_ERR(obj);

        ret = drm_gem_handle_create(file, &obj->base, &handle);
        /* drop reference from allocate - handle holds it now */
        i915_gem_object_put_unlocked(obj);
        if (ret)
                return ret;

        *handle_p = handle;
        return 0;
}

int
i915_gem_dumb_create(struct drm_file *file,
                     struct drm_device *dev,
                     struct drm_mode_create_dumb *args)
{
        /* have to work out size/pitch and return them */
        args->pitch = ALIGN(args->width * DIV_ROUND_UP(args->bpp, 8), 64);
        args->size = args->pitch * args->height;
        return i915_gem_create(file, dev,
                               args->size, &args->handle);
}

/**
 * Creates a new mm object and returns a handle to it.
 * @dev: drm device pointer
 * @data: ioctl data blob
 * @file: drm file pointer
 */
int
i915_gem_create_ioctl(struct drm_device *dev, void *data,
                      struct drm_file *file)
{
        struct drm_i915_gem_create *args = data;

        return i915_gem_create(file, dev,
                               args->size, &args->handle);
}

static inline int
__copy_to_user_swizzled(char __user *cpu_vaddr,
                        const char *gpu_vaddr, int gpu_offset,
                        int length)
{
        int ret, cpu_offset = 0;

        while (length > 0) {
                int cacheline_end = ALIGN(gpu_offset + 1, 64);
                int this_length = min(cacheline_end - gpu_offset, length);
                int swizzled_gpu_offset = gpu_offset ^ 64;

                ret = __copy_to_user(cpu_vaddr + cpu_offset,
                                     gpu_vaddr + swizzled_gpu_offset,
                                     this_length);
                if (ret)
                        return ret + length;

                cpu_offset += this_length;
                gpu_offset += this_length;
                length -= this_length;
        }

        return 0;
}

static inline int
__copy_from_user_swizzled(char *gpu_vaddr, int gpu_offset,
                          const char __user *cpu_vaddr,
                          int length)
{
        int ret, cpu_offset = 0;

        while (length > 0) {
                int cacheline_end = ALIGN(gpu_offset + 1, 64);
                int this_length = min(cacheline_end - gpu_offset, length);
                int swizzled_gpu_offset = gpu_offset ^ 64;

                ret = __copy_from_user(gpu_vaddr + swizzled_gpu_offset,
                                       cpu_vaddr + cpu_offset,
                                       this_length);
                if (ret)
                        return ret + length;

                cpu_offset += this_length;
                gpu_offset += this_length;
                length -= this_length;
        }

        return 0;
}

/*
 * Pins the specified object's pages and synchronizes the object with
 * GPU accesses. Sets needs_clflush to non-zero if the caller should
 * flush the object from the CPU cache.
 */
int i915_gem_obj_prepare_shmem_read(struct drm_i915_gem_object *obj,
                                    unsigned int *needs_clflush)
{
        int ret;

        *needs_clflush = 0;

        if (!i915_gem_object_has_struct_page(obj))
                return -ENODEV;

        ret = i915_gem_object_wait_rendering(obj, true);
        if (ret)
                return ret;

        ret = i915_gem_object_get_pages(obj);
        if (ret)
                return ret;

        i915_gem_object_pin_pages(obj);

        i915_gem_object_flush_gtt_write_domain(obj);

        /* If we're not in the cpu read domain, set ourself into the gtt
         * read domain and manually flush cachelines (if required). This
         * optimizes for the case when the gpu will dirty the data
         * anyway again before the next pread happens.
         */
        if (!(obj->base.read_domains & I915_GEM_DOMAIN_CPU))
                *needs_clflush = !cpu_cache_is_coherent(obj->base.dev,
                                                        obj->cache_level);

        if (*needs_clflush && !static_cpu_has(X86_FEATURE_CLFLUSH)) {
                ret = i915_gem_object_set_to_cpu_domain(obj, false);
                if (ret)
                        goto err_unpin;

                *needs_clflush = 0;
        }

        /* return with the pages pinned */
        return 0;

err_unpin:
        i915_gem_object_unpin_pages(obj);
        return ret;
}

int i915_gem_obj_prepare_shmem_write(struct drm_i915_gem_object *obj,
                                     unsigned int *needs_clflush)
{
        int ret;

        *needs_clflush = 0;
        if (!i915_gem_object_has_struct_page(obj))
                return -ENODEV;

        ret = i915_gem_object_wait_rendering(obj, false);
        if (ret)
                return ret;

        ret = i915_gem_object_get_pages(obj);
        if (ret)
                return ret;

        i915_gem_object_pin_pages(obj);

        i915_gem_object_flush_gtt_write_domain(obj);

        /* If we're not in the cpu write domain, set ourself into the
         * gtt write domain and manually flush cachelines (as required).
         * This optimizes for the case when the gpu will use the data
         * right away and we therefore have to clflush anyway.
         */
        if (obj->base.write_domain != I915_GEM_DOMAIN_CPU)
                *needs_clflush |= cpu_write_needs_clflush(obj) << 1;

        /* Same trick applies to invalidate partially written cachelines read
         * before writing.
         */
        if (!(obj->base.read_domains & I915_GEM_DOMAIN_CPU))
                *needs_clflush |= !cpu_cache_is_coherent(obj->base.dev,
                                                         obj->cache_level);

        if (*needs_clflush && !static_cpu_has(X86_FEATURE_CLFLUSH)) {
                ret = i915_gem_object_set_to_cpu_domain(obj, true);
                if (ret)
                        goto err_unpin;

                *needs_clflush = 0;
        }

        if ((*needs_clflush & CLFLUSH_AFTER) == 0)
                obj->cache_dirty = true;

        intel_fb_obj_invalidate(obj, ORIGIN_CPU);
        obj->dirty = 1;
        /* return with the pages pinned */
        return 0;

err_unpin:
        i915_gem_object_unpin_pages(obj);
        return ret;
}

/* Per-page copy function for the shmem pread fastpath.
 * Flushes invalid cachelines before reading the target if
 * needs_clflush is set. */
static int
shmem_pread_fast(struct page *page, int shmem_page_offset, int page_length,
                 char __user *user_data,
                 bool page_do_bit17_swizzling, bool needs_clflush)
{
        char *vaddr;
        int ret;

        if (unlikely(page_do_bit17_swizzling))
                return -EINVAL;

        vaddr = kmap_atomic(page);
        if (needs_clflush)
                drm_clflush_virt_range(vaddr + shmem_page_offset,
                                       page_length);
        ret = __copy_to_user_inatomic(user_data,
                                      vaddr + shmem_page_offset,
                                      page_length);
        kunmap_atomic(vaddr);

        return ret ? -EFAULT : 0;
}

static void
shmem_clflush_swizzled_range(char *addr, unsigned long length,
                             bool swizzled)
{
        if (unlikely(swizzled)) {
                unsigned long start = (unsigned long) addr;
                unsigned long end = (unsigned long) addr + length;

                /* For swizzling simply ensure that we always flush both
                 * channels. Lame, but simple and it works. Swizzled
                 * pwrite/pread is far from a hotpath - current userspace
                 * doesn't use it at all. */
                start = round_down(start, 128);
                end = round_up(end, 128);

                drm_clflush_virt_range((void *)start, end - start);
        } else {
                drm_clflush_virt_range(addr, length);
        }

}

/* Only difference to the fast-path function is that this can handle bit17
 * and uses non-atomic copy and kmap functions. */
static int
shmem_pread_slow(struct page *page, int shmem_page_offset, int page_length,
                 char __user *user_data,
                 bool page_do_bit17_swizzling, bool needs_clflush)
{
        char *vaddr;
        int ret;

        vaddr = kmap(page);
        if (needs_clflush)
                shmem_clflush_swizzled_range(vaddr + shmem_page_offset,
                                             page_length,
                                             page_do_bit17_swizzling);

        if (page_do_bit17_swizzling)
                ret = __copy_to_user_swizzled(user_data,
                                              vaddr, shmem_page_offset,
                                              page_length);
        else
                ret = __copy_to_user(user_data,
                                     vaddr + shmem_page_offset,
                                     page_length);
        kunmap(page);

        return ret ? - EFAULT : 0;
}

static inline unsigned long
slow_user_access(struct io_mapping *mapping,
                 uint64_t page_base, int page_offset,
                 char __user *user_data,
                 unsigned long length, bool pwrite)
{
        void __iomem *ioaddr;
        void *vaddr;
        uint64_t unwritten;

        ioaddr = io_mapping_map_wc(mapping, page_base, PAGE_SIZE);
        /* We can use the cpu mem copy function because this is X86. */
        vaddr = (void __force *)ioaddr + page_offset;
        if (pwrite)
                unwritten = __copy_from_user(vaddr, user_data, length);
        else
                unwritten = __copy_to_user(user_data, vaddr, length);

        io_mapping_unmap(ioaddr);
        return unwritten;
}

static int
i915_gem_gtt_pread(struct drm_device *dev,
                   struct drm_i915_gem_object *obj, uint64_t size,
                   uint64_t data_offset, uint64_t data_ptr)
{
        struct drm_i915_private *dev_priv = to_i915(dev);
        struct i915_ggtt *ggtt = &dev_priv->ggtt;
        struct i915_vma *vma;
        struct drm_mm_node node;
        char __user *user_data;
        uint64_t remain;
        uint64_t offset;
        int ret;

        vma = i915_gem_object_ggtt_pin(obj, NULL, 0, 0, PIN_MAPPABLE);
        if (!IS_ERR(vma)) {
                node.start = i915_ggtt_offset(vma);
                node.allocated = false;
                ret = i915_vma_put_fence(vma);
                if (ret) {
                        i915_vma_unpin(vma);
                        vma = ERR_PTR(ret);
                }
        }
        if (IS_ERR(vma)) {
                ret = insert_mappable_node(dev_priv, &node, PAGE_SIZE);
                if (ret)
                        goto out;

                ret = i915_gem_object_get_pages(obj);
                if (ret) {
                        remove_mappable_node(&node);
                        goto out;
                }

                i915_gem_object_pin_pages(obj);
        }

        ret = i915_gem_object_set_to_gtt_domain(obj, false);
        if (ret)
                goto out_unpin;

        user_data = u64_to_user_ptr(data_ptr);
        remain = size;
        offset = data_offset;

        mutex_unlock(&dev->struct_mutex);
        if (likely(!i915.prefault_disable)) {
                ret = fault_in_multipages_writeable(user_data, remain);
                if (ret) {
                        mutex_lock(&dev->struct_mutex);
                        goto out_unpin;
                }
        }

        while (remain > 0) {
                /* Operation in this page
                 *
                 * page_base = page offset within aperture
                 * page_offset = offset within page
                 * page_length = bytes to copy for this page
                 */
                u32 page_base = node.start;
                unsigned page_offset = offset_in_page(offset);
                unsigned page_length = PAGE_SIZE - page_offset;
                page_length = remain < page_length ? remain : page_length;
                if (node.allocated) {
                        wmb();
                        ggtt->base.insert_page(&ggtt->base,
                                               i915_gem_object_get_dma_address(obj, offset >> PAGE_SHIFT),
                                               node.start,
                                               I915_CACHE_NONE, 0);
                        wmb();
                } else {
                        page_base += offset & PAGE_MASK;
                }
                /* This is a slow read/write as it tries to read from
                 * and write to user memory which may result into page
                 * faults, and so we cannot perform this under struct_mutex.
                 */
                if (slow_user_access(&ggtt->mappable, page_base,
                                     page_offset, user_data,
                                     page_length, false)) {
                        ret = -EFAULT;
                        break;
                }

                remain -= page_length;
                user_data += page_length;
                offset += page_length;
        }

        mutex_lock(&dev->struct_mutex);
        if (ret == 0 && (obj->base.read_domains & I915_GEM_DOMAIN_GTT) == 0) {
                /* The user has modified the object whilst we tried
                 * reading from it, and we now have no idea what domain
                 * the pages should be in. As we have just been touching
                 * them directly, flush everything back to the GTT
                 * domain.
                 */
                ret = i915_gem_object_set_to_gtt_domain(obj, false);
        }

out_unpin:
        if (node.allocated) {
                wmb();
                ggtt->base.clear_range(&ggtt->base,
                                       node.start, node.size,
                                       true);
                i915_gem_object_unpin_pages(obj);
                remove_mappable_node(&node);
        } else {
                i915_vma_unpin(vma);
        }
out:
        return ret;
}

static int
i915_gem_shmem_pread(struct drm_device *dev,
                     struct drm_i915_gem_object *obj,
                     struct drm_i915_gem_pread *args,
                     struct drm_file *file)
{
        char __user *user_data;
        ssize_t remain;
        loff_t offset;
        int shmem_page_offset, page_length, ret = 0;
        int obj_do_bit17_swizzling, page_do_bit17_swizzling;
        int prefaulted = 0;
        int needs_clflush = 0;
        struct sg_page_iter sg_iter;

        ret = i915_gem_obj_prepare_shmem_read(obj, &needs_clflush);
        if (ret)
                return ret;

        obj_do_bit17_swizzling = i915_gem_object_needs_bit17_swizzle(obj);
        user_data = u64_to_user_ptr(args->data_ptr);
        offset = args->offset;
        remain = args->size;

        for_each_sg_page(obj->pages->sgl, &sg_iter, obj->pages->nents,
                         offset >> PAGE_SHIFT) {
                struct page *page = sg_page_iter_page(&sg_iter);

                if (remain <= 0)
                        break;

                /* Operation in this page
                 *
                 * shmem_page_offset = offset within page in shmem file
                 * page_length = bytes to copy for this page
                 */
                shmem_page_offset = offset_in_page(offset);
                page_length = remain;
                if ((shmem_page_offset + page_length) > PAGE_SIZE)
                        page_length = PAGE_SIZE - shmem_page_offset;

                page_do_bit17_swizzling = obj_do_bit17_swizzling &&
                        (page_to_phys(page) & (1 << 17)) != 0;

                ret = shmem_pread_fast(page, shmem_page_offset, page_length,
                                       user_data, page_do_bit17_swizzling,
                                       needs_clflush);
                if (ret == 0)
                        goto next_page;

                mutex_unlock(&dev->struct_mutex);

                if (likely(!i915.prefault_disable) && !prefaulted) {
                        ret = fault_in_multipages_writeable(user_data, remain);
                        /* Userspace is tricking us, but we've already clobbered
                         * its pages with the prefault and promised to write the
                         * data up to the first fault. Hence ignore any errors
                         * and just continue. */
                        (void)ret;
                        prefaulted = 1;
                }

                ret = shmem_pread_slow(page, shmem_page_offset, page_length,
                                       user_data, page_do_bit17_swizzling,
                                       needs_clflush);

                mutex_lock(&dev->struct_mutex);

                if (ret)
                        goto out;

next_page:
                remain -= page_length;
                user_data += page_length;
                offset += page_length;
        }

out:
        i915_gem_obj_finish_shmem_access(obj);

        return ret;
}

/**
 * Reads data from the object referenced by handle.
 * @dev: drm device pointer
 * @data: ioctl data blob
 * @file: drm file pointer
 *
 * On error, the contents of *data are undefined.
 */
int
i915_gem_pread_ioctl(struct drm_device *dev, void *data,
                     struct drm_file *file)
{
        struct drm_i915_gem_pread *args = data;
        struct drm_i915_gem_object *obj;
        int ret = 0;

        if (args->size == 0)
                return 0;

        if (!access_ok(VERIFY_WRITE,
                       u64_to_user_ptr(args->data_ptr),
                       args->size))
                return -EFAULT;

        obj = i915_gem_object_lookup(file, args->handle);
        if (!obj)
                return -ENOENT;

        /* Bounds check source.  */
        if (args->offset > obj->base.size ||
            args->size > obj->base.size - args->offset) {
                ret = -EINVAL;
                goto err;
        }

        trace_i915_gem_object_pread(obj, args->offset, args->size);

        ret = __unsafe_wait_rendering(obj, to_rps_client(file), true);
        if (ret)
                goto err;

        ret = i915_mutex_lock_interruptible(dev);
        if (ret)
                goto err;

        ret = i915_gem_shmem_pread(dev, obj, args, file);

        /* pread for non shmem backed objects */
        if (ret == -EFAULT || ret == -ENODEV) {
                intel_runtime_pm_get(to_i915(dev));
                ret = i915_gem_gtt_pread(dev, obj, args->size,
                                        args->offset, args->data_ptr);
                intel_runtime_pm_put(to_i915(dev));
        }

        i915_gem_object_put(obj);
        mutex_unlock(&dev->struct_mutex);

        return ret;

err:
        i915_gem_object_put_unlocked(obj);
        return ret;
}

/* This is the fast write path which cannot handle
 * page faults in the source data
 */

static inline int
fast_user_write(struct io_mapping *mapping,
                loff_t page_base, int page_offset,
                char __user *user_data,
                int length)
{
        void __iomem *vaddr_atomic;
        void *vaddr;
        unsigned long unwritten;

        vaddr_atomic = io_mapping_map_atomic_wc(mapping, page_base);
        /* We can use the cpu mem copy function because this is X86. */
        vaddr = (void __force*)vaddr_atomic + page_offset;
        unwritten = __copy_from_user_inatomic_nocache(vaddr,
                                                      user_data, length);
        io_mapping_unmap_atomic(vaddr_atomic);
        return unwritten;
}

/**
 * This is the fast pwrite path, where we copy the data directly from the
 * user into the GTT, uncached.
 * @i915: i915 device private data
 * @obj: i915 gem object
 * @args: pwrite arguments structure
 * @file: drm file pointer
 */
static int
i915_gem_gtt_pwrite_fast(struct drm_i915_private *i915,
                         struct drm_i915_gem_object *obj,
                         struct drm_i915_gem_pwrite *args,
                         struct drm_file *file)
{
        struct i915_ggtt *ggtt = &i915->ggtt;
        struct drm_device *dev = obj->base.dev;
        struct i915_vma *vma;
        struct drm_mm_node node;
        uint64_t remain, offset;
        char __user *user_data;
        int ret;
        bool hit_slow_path = false;

        if (i915_gem_object_is_tiled(obj))
                return -EFAULT;

        vma = i915_gem_object_ggtt_pin(obj, NULL, 0, 0,
                                       PIN_MAPPABLE | PIN_NONBLOCK);
        if (!IS_ERR(vma)) {
                node.start = i915_ggtt_offset(vma);
                node.allocated = false;
                ret = i915_vma_put_fence(vma);
                if (ret) {
                        i915_vma_unpin(vma);
                        vma = ERR_PTR(ret);
                }
        }
        if (IS_ERR(vma)) {
                ret = insert_mappable_node(i915, &node, PAGE_SIZE);
                if (ret)
                        goto out;

                ret = i915_gem_object_get_pages(obj);
                if (ret) {
                        remove_mappable_node(&node);
                        goto out;
                }

                i915_gem_object_pin_pages(obj);
        }

        ret = i915_gem_object_set_to_gtt_domain(obj, true);
        if (ret)
                goto out_unpin;

        intel_fb_obj_invalidate(obj, ORIGIN_CPU);
        obj->dirty = true;

        user_data = u64_to_user_ptr(args->data_ptr);
        offset = args->offset;
        remain = args->size;
        while (remain) {
                /* Operation in this page
                 *
                 * page_base = page offset within aperture
                 * page_offset = offset within page
                 * page_length = bytes to copy for this page
                 */
                u32 page_base = node.start;
                unsigned page_offset = offset_in_page(offset);
                unsigned page_length = PAGE_SIZE - page_offset;
                page_length = remain < page_length ? remain : page_length;
                if (node.allocated) {
                        wmb(); /* flush the write before we modify the GGTT */
                        ggtt->base.insert_page(&ggtt->base,
                                               i915_gem_object_get_dma_address(obj, offset >> PAGE_SHIFT),
                                               node.start, I915_CACHE_NONE, 0);
                        wmb(); /* flush modifications to the GGTT (insert_page) */
                } else {
                        page_base += offset & PAGE_MASK;
                }
                /* If we get a fault while copying data, then (presumably) our
                 * source page isn't available.  Return the error and we'll
                 * retry in the slow path.
                 * If the object is non-shmem backed, we retry again with the
                 * path that handles page fault.
                 */
                if (fast_user_write(&ggtt->mappable, page_base,
                                    page_offset, user_data, page_length)) {
                        hit_slow_path = true;
                        mutex_unlock(&dev->struct_mutex);
                        if (slow_user_access(&ggtt->mappable,
                                             page_base,
                                             page_offset, user_data,
                                             page_length, true)) {
                                ret = -EFAULT;
                                mutex_lock(&dev->struct_mutex);
                                goto out_flush;
                        }

                        mutex_lock(&dev->struct_mutex);
                }

                remain -= page_length;
                user_data += page_length;
                offset += page_length;
        }

out_flush:
        if (hit_slow_path) {
                if (ret == 0 &&
                    (obj->base.read_domains & I915_GEM_DOMAIN_GTT) == 0) {
                        /* The user has modified the object whilst we tried
                         * reading from it, and we now have no idea what domain
                         * the pages should be in. As we have just been touching
                         * them directly, flush everything back to the GTT
                         * domain.
                         */
                        ret = i915_gem_object_set_to_gtt_domain(obj, false);
                }
        }

        intel_fb_obj_flush(obj, false, ORIGIN_CPU);
out_unpin:
        if (node.allocated) {
                wmb();
                ggtt->base.clear_range(&ggtt->base,
                                       node.start, node.size,
                                       true);
                i915_gem_object_unpin_pages(obj);
                remove_mappable_node(&node);
        } else {
                i915_vma_unpin(vma);
        }
out:
        return ret;
}

/* Per-page copy function for the shmem pwrite fastpath.
 * Flushes invalid cachelines before writing to the target if
 * needs_clflush_before is set and flushes out any written cachelines after
 * writing if needs_clflush is set. */
static int
shmem_pwrite_fast(struct page *page, int shmem_page_offset, int page_length,
                  char __user *user_data,
                  bool page_do_bit17_swizzling,
                  bool needs_clflush_before,
                  bool needs_clflush_after)
{
        char *vaddr;
        int ret;

        if (unlikely(page_do_bit17_swizzling))
                return -EINVAL;

        vaddr = kmap_atomic(page);
        if (needs_clflush_before)
                drm_clflush_virt_range(vaddr + shmem_page_offset,
                                       page_length);
        ret = __copy_from_user_inatomic(vaddr + shmem_page_offset,
                                        user_data, page_length);
        if (needs_clflush_after)
                drm_clflush_virt_range(vaddr + shmem_page_offset,
                                       page_length);
        kunmap_atomic(vaddr);

        return ret ? -EFAULT : 0;
}

/* Only difference to the fast-path function is that this can handle bit17
 * and uses non-atomic copy and kmap functions. */
static int
shmem_pwrite_slow(struct page *page, int shmem_page_offset, int page_length,
                  char __user *user_data,
                  bool page_do_bit17_swizzling,
                  bool needs_clflush_before,
                  bool needs_clflush_after)
{
        char *vaddr;
        int ret;

        vaddr = kmap(page);
        if (unlikely(needs_clflush_before || page_do_bit17_swizzling))
                shmem_clflush_swizzled_range(vaddr + shmem_page_offset,
                                             page_length,
                                             page_do_bit17_swizzling);
        if (page_do_bit17_swizzling)
                ret = __copy_from_user_swizzled(vaddr, shmem_page_offset,
                                                user_data,
                                                page_length);
        else
                ret = __copy_from_user(vaddr + shmem_page_offset,
                                       user_data,
                                       page_length);
        if (needs_clflush_after)
                shmem_clflush_swizzled_range(vaddr + shmem_page_offset,
                                             page_length,
                                             page_do_bit17_swizzling);
        kunmap(page);

        return ret ? -EFAULT : 0;
}

static int
i915_gem_shmem_pwrite(struct drm_device *dev,
                      struct drm_i915_gem_object *obj,
                      struct drm_i915_gem_pwrite *args,
                      struct drm_file *file)
{
        ssize_t remain;
        loff_t offset;
        char __user *user_data;
        int shmem_page_offset, page_length, ret = 0;
        int obj_do_bit17_swizzling, page_do_bit17_swizzling;
        int hit_slowpath = 0;
        unsigned int needs_clflush;
        struct sg_page_iter sg_iter;

        ret = i915_gem_obj_prepare_shmem_write(obj, &needs_clflush);
        if (ret)
                return ret;

        obj_do_bit17_swizzling = i915_gem_object_needs_bit17_swizzle(obj);
        user_data = u64_to_user_ptr(args->data_ptr);
        offset = args->offset;
        remain = args->size;

        for_each_sg_page(obj->pages->sgl, &sg_iter, obj->pages->nents,
                         offset >> PAGE_SHIFT) {
                struct page *page = sg_page_iter_page(&sg_iter);
                int partial_cacheline_write;

                if (remain <= 0)
                        break;

                /* Operation in this page
                 *
                 * shmem_page_offset = offset within page in shmem file
                 * page_length = bytes to copy for this page
                 */
                shmem_page_offset = offset_in_page(offset);

                page_length = remain;
                if ((shmem_page_offset + page_length) > PAGE_SIZE)
                        page_length = PAGE_SIZE - shmem_page_offset;

                /* If we don't overwrite a cacheline completely we need to be
                 * careful to have up-to-date data by first clflushing. Don't
                 * overcomplicate things and flush the entire patch. */
                partial_cacheline_write = needs_clflush & CLFLUSH_BEFORE &&
                        ((shmem_page_offset | page_length)
                                & (boot_cpu_data.x86_clflush_size - 1));

                page_do_bit17_swizzling = obj_do_bit17_swizzling &&
                        (page_to_phys(page) & (1 << 17)) != 0;

                ret = shmem_pwrite_fast(page, shmem_page_offset, page_length,
                                        user_data, page_do_bit17_swizzling,
                                        partial_cacheline_write,
                                        needs_clflush & CLFLUSH_AFTER);
                if (ret == 0)
                        goto next_page;

                hit_slowpath = 1;
                mutex_unlock(&dev->struct_mutex);
                ret = shmem_pwrite_slow(page, shmem_page_offset, page_length,
                                        user_data, page_do_bit17_swizzling,
                                        partial_cacheline_write,
                                        needs_clflush & CLFLUSH_AFTER);

                mutex_lock(&dev->struct_mutex);

                if (ret)
                        goto out;

next_page:
                remain -= page_length;
                user_data += page_length;
                offset += page_length;
        }

out:
        i915_gem_obj_finish_shmem_access(obj);

        if (hit_slowpath) {
                /*
                 * Fixup: Flush cpu caches in case we didn't flush the dirty
                 * cachelines in-line while writing and the object moved
                 * out of the cpu write domain while we've dropped the lock.
                 */
                if (!(needs_clflush & CLFLUSH_AFTER) &&
                    obj->base.write_domain != I915_GEM_DOMAIN_CPU) {
                        if (i915_gem_clflush_object(obj, obj->pin_display))
                                needs_clflush |= CLFLUSH_AFTER;
                }
        }

        if (needs_clflush & CLFLUSH_AFTER)
                i915_gem_chipset_flush(to_i915(dev));

        intel_fb_obj_flush(obj, false, ORIGIN_CPU);
        return ret;
}

/**
 * Writes data to the object referenced by handle.
 * @dev: drm device
 * @data: ioctl data blob
 * @file: drm file
 *
 * On error, the contents of the buffer that were to be modified are undefined.
 */
int
i915_gem_pwrite_ioctl(struct drm_device *dev, void *data,
                      struct drm_file *file)
{
        struct drm_i915_private *dev_priv = to_i915(dev);
        struct drm_i915_gem_pwrite *args = data;
        struct drm_i915_gem_object *obj;
        int ret;

        if (args->size == 0)
                return 0;

        if (!access_ok(VERIFY_READ,
                       u64_to_user_ptr(args->data_ptr),
                       args->size))
                return -EFAULT;

        if (likely(!i915.prefault_disable)) {
                ret = fault_in_multipages_readable(u64_to_user_ptr(args->data_ptr),
                                                   args->size);
                if (ret)
                        return -EFAULT;
        }

        obj = i915_gem_object_lookup(file, args->handle);
        if (!obj)
                return -ENOENT;

        /* Bounds check destination. */
        if (args->offset > obj->base.size ||
            args->size > obj->base.size - args->offset) {
                ret = -EINVAL;
                goto err;
        }

        trace_i915_gem_object_pwrite(obj, args->offset, args->size);

        ret = __unsafe_wait_rendering(obj, to_rps_client(file), false);
        if (ret)
                goto err;

        intel_runtime_pm_get(dev_priv);

        ret = i915_mutex_lock_interruptible(dev);
        if (ret)
                goto err_rpm;

        ret = -EFAULT;
        /* We can only do the GTT pwrite on untiled buffers, as otherwise
         * it would end up going through the fenced access, and we'll get
         * different detiling behavior between reading and writing.
         * pread/pwrite currently are reading and writing from the CPU
         * perspective, requiring manual detiling by the client.
         */
        if (!i915_gem_object_has_struct_page(obj) ||
            cpu_write_needs_clflush(obj)) {
                ret = i915_gem_gtt_pwrite_fast(dev_priv, obj, args, file);
                /* Note that the gtt paths might fail with non-page-backed user
                 * pointers (e.g. gtt mappings when moving data between
                 * textures). Fallback to the shmem path in that case. */
        }

        if (ret == -EFAULT || ret == -ENOSPC) {
                if (obj->phys_handle)
                        ret = i915_gem_phys_pwrite(obj, args, file);
                else
                        ret = i915_gem_shmem_pwrite(dev, obj, args, file);
        }

        i915_gem_object_put(obj);
        mutex_unlock(&dev->struct_mutex);
        intel_runtime_pm_put(dev_priv);

        return ret;

err_rpm:
        intel_runtime_pm_put(dev_priv);
err:
        i915_gem_object_put_unlocked(obj);
        return ret;
}

static inline enum fb_op_origin
write_origin(struct drm_i915_gem_object *obj, unsigned domain)
{
        return (domain == I915_GEM_DOMAIN_GTT ?
                obj->frontbuffer_ggtt_origin : ORIGIN_CPU);
}

/**
 * Called when user space prepares to use an object with the CPU, either
 * through the mmap ioctl's mapping or a GTT mapping.
 * @dev: drm device
 * @data: ioctl data blob
 * @file: drm file
 */
int
i915_gem_set_domain_ioctl(struct drm_device *dev, void *data,
                          struct drm_file *file)
{
        struct drm_i915_gem_set_domain *args = data;
        struct drm_i915_gem_object *obj;
        uint32_t read_domains = args->read_domains;
        uint32_t write_domain = args->write_domain;
        int ret;

        /* Only handle setting domains to types used by the CPU. */
        if ((write_domain | read_domains) & I915_GEM_GPU_DOMAINS)
                return -EINVAL;

        /* Having something in the write domain implies it's in the read
         * domain, and only that read domain.  Enforce that in the request.
         */
        if (write_domain != 0 && read_domains != write_domain)
                return -EINVAL;

        obj = i915_gem_object_lookup(file, args->handle);
        if (!obj)
                return -ENOENT;

        /* Try to flush the object off the GPU without holding the lock.
         * We will repeat the flush holding the lock in the normal manner
         * to catch cases where we are gazumped.
         */
        ret = __unsafe_wait_rendering(obj, to_rps_client(file), !write_domain);
        if (ret)
                goto err;

        ret = i915_mutex_lock_interruptible(dev);
        if (ret)
                goto err;

        if (read_domains & I915_GEM_DOMAIN_GTT)
                ret = i915_gem_object_set_to_gtt_domain(obj, write_domain != 0);
        else
                ret = i915_gem_object_set_to_cpu_domain(obj, write_domain != 0);

        if (write_domain != 0)
                intel_fb_obj_invalidate(obj, write_origin(obj, write_domain));

        i915_gem_object_put(obj);
        mutex_unlock(&dev->struct_mutex);
        return ret;

err:
        i915_gem_object_put_unlocked(obj);
        return ret;
}

/**
 * Called when user space has done writes to this buffer
 * @dev: drm device
 * @data: ioctl data blob
 * @file: drm file
 */
int
i915_gem_sw_finish_ioctl(struct drm_device *dev, void *data,
                         struct drm_file *file)
{
        struct drm_i915_gem_sw_finish *args = data;
        struct drm_i915_gem_object *obj;
        int err = 0;

        obj = i915_gem_object_lookup(file, args->handle);
        if (!obj)
                return -ENOENT;

        /* Pinned buffers may be scanout, so flush the cache */
        if (READ_ONCE(obj->pin_display)) {
                err = i915_mutex_lock_interruptible(dev);
                if (!err) {
                        i915_gem_object_flush_cpu_write_domain(obj);
                        mutex_unlock(&dev->struct_mutex);
                }
        }

        i915_gem_object_put_unlocked(obj);
        return err;
}

/**
 * i915_gem_mmap_ioctl - Maps the contents of an object, returning the address
 *                       it is mapped to.
 * @dev: drm device
 * @data: ioctl data blob
 * @file: drm file
 *
 * While the mapping holds a reference on the contents of the object, it doesn't
 * imply a ref on the object itself.
 *
 * IMPORTANT:
 *
 * DRM driver writers who look a this function as an example for how to do GEM
 * mmap support, please don't implement mmap support like here. The modern way
 * to implement DRM mmap support is with an mmap offset ioctl (like
 * i915_gem_mmap_gtt) and then using the mmap syscall on the DRM fd directly.
 * That way debug tooling like valgrind will understand what's going on, hiding
 * the mmap call in a driver private ioctl will break that. The i915 driver only
 * does cpu mmaps this way because we didn't know better.
 */
int
i915_gem_mmap_ioctl(struct drm_device *dev, void *data,
                    struct drm_file *file)
{
        struct drm_i915_gem_mmap *args = data;
        struct drm_i915_gem_object *obj;
        unsigned long addr;

        if (args->flags & ~(I915_MMAP_WC))
                return -EINVAL;

        if (args->flags & I915_MMAP_WC && !boot_cpu_has(X86_FEATURE_PAT))
                return -ENODEV;

        obj = i915_gem_object_lookup(file, args->handle);
        if (!obj)
                return -ENOENT;

        /* prime objects have no backing filp to GEM mmap
         * pages from.
         */
        if (!obj->base.filp) {
                i915_gem_object_put_unlocked(obj);
                return -EINVAL;
        }

        addr = vm_mmap(obj->base.filp, 0, args->size,
                       PROT_READ | PROT_WRITE, MAP_SHARED,
                       args->offset);
        if (args->flags & I915_MMAP_WC) {
                struct mm_struct *mm = current->mm;
                struct vm_area_struct *vma;

                if (down_write_killable(&mm->mmap_sem)) {
                        i915_gem_object_put_unlocked(obj);
                        return -EINTR;
                }
                vma = find_vma(mm, addr);
                if (vma)
                        vma->vm_page_prot =
                                pgprot_writecombine(vm_get_page_prot(vma->vm_flags));
                else
                        addr = -ENOMEM;
                up_write(&mm->mmap_sem);

                /* This may race, but that's ok, it only gets set */
                WRITE_ONCE(obj->frontbuffer_ggtt_origin, ORIGIN_CPU);
        }
        i915_gem_object_put_unlocked(obj);
        if (IS_ERR((void *)addr))
                return addr;

        args->addr_ptr = (uint64_t) addr;

        return 0;
}

static unsigned int tile_row_pages(struct drm_i915_gem_object *obj)
{
        u64 size;

        size = i915_gem_object_get_stride(obj);
        size *= i915_gem_object_get_tiling(obj) == I915_TILING_Y ? 32 : 8;

        return size >> PAGE_SHIFT;
}

/**
 * i915_gem_mmap_gtt_version - report the current feature set for GTT mmaps
 *
 * A history of the GTT mmap interface:
 *
 * 0 - Everything had to fit into the GTT. Both parties of a memcpy had to
 *     aligned and suitable for fencing, and still fit into the available
 *     mappable space left by the pinned display objects. A classic problem
 *     we called the page-fault-of-doom where we would ping-pong between
 *     two objects that could not fit inside the GTT and so the memcpy
 *     would page one object in at the expense of the other between every
 *     single byte.
 *
 * 1 - Objects can be any size, and have any compatible fencing (X Y, or none
 *     as set via i915_gem_set_tiling() [DRM_I915_GEM_SET_TILING]). If the
 *     object is too large for the available space (or simply too large
 *     for the mappable aperture!), a view is created instead and faulted
 *     into userspace. (This view is aligned and sized appropriately for
 *     fenced access.)
 *
 * Restrictions:
 *
 *  * snoopable objects cannot be accessed via the GTT. It can cause machine
 *    hangs on some architectures, corruption on others. An attempt to service
 *    a GTT page fault from a snoopable object will generate a SIGBUS.
 *
 *  * the object must be able to fit into RAM (physical memory, though no
 *    limited to the mappable aperture).
 *
 *
 * Caveats:
 *
 *  * a new GTT page fault will synchronize rendering from the GPU and flush
 *    all data to system memory. Subsequent access will not be synchronized.
 *
 *  * all mappings are revoked on runtime device suspend.
 *
 *  * there are only 8, 16 or 32 fence registers to share between all users
 *    (older machines require fence register for display and blitter access
 *    as well). Contention of the fence registers will cause the previous users
 *    to be unmapped and any new access will generate new page faults.
 *
 *  * running out of memory while servicing a fault may generate a SIGBUS,
 *    rather than the expected SIGSEGV.
 */
int i915_gem_mmap_gtt_version(void)
{
        return 1;
}

/**
 * i915_gem_fault - fault a page into the GTT
 * @area: CPU VMA in question
 * @vmf: fault info
 *
 * The fault handler is set up by drm_gem_mmap() when a object is GTT mapped
 * from userspace.  The fault handler takes care of binding the object to
 * the GTT (if needed), allocating and programming a fence register (again,
 * only if needed based on whether the old reg is still valid or the object
 * is tiled) and inserting a new PTE into the faulting process.
 *
 * Note that the faulting process may involve evicting existing objects
 * from the GTT and/or fence registers to make room.  So performance may
 * suffer if the GTT working set is large or there are few fence registers
 * left.
 *
 * The current feature set supported by i915_gem_fault() and thus GTT mmaps
 * is exposed via I915_PARAM_MMAP_GTT_VERSION (see i915_gem_mmap_gtt_version).
 */
int i915_gem_fault(struct vm_area_struct *area, struct vm_fault *vmf)
{
#define MIN_CHUNK_PAGES ((1 << 20) >> PAGE_SHIFT) /* 1 MiB */
        struct drm_i915_gem_object *obj = to_intel_bo(area->vm_private_data);
        struct drm_device *dev = obj->base.dev;
        struct drm_i915_private *dev_priv = to_i915(dev);
        struct i915_ggtt *ggtt = &dev_priv->ggtt;
        bool write = !!(vmf->flags & FAULT_FLAG_WRITE);
        struct i915_vma *vma;
        pgoff_t page_offset;
        unsigned int flags;
        int ret;

        /* We don't use vmf->pgoff since that has the fake offset */
        page_offset = ((unsigned long)vmf->virtual_address - area->vm_start) >>
                PAGE_SHIFT;

        trace_i915_gem_object_fault(obj, page_offset, true, write);

        /* Try to flush the object off the GPU first without holding the lock.
         * Upon acquiring the lock, we will perform our sanity checks and then
         * repeat the flush holding the lock in the normal manner to catch cases
         * where we are gazumped.
         */
        ret = __unsafe_wait_rendering(obj, NULL, !write);
        if (ret)
                goto err;

        intel_runtime_pm_get(dev_priv);

        ret = i915_mutex_lock_interruptible(dev);
        if (ret)
                goto err_rpm;

        /* Access to snoopable pages through the GTT is incoherent. */
        if (obj->cache_level != I915_CACHE_NONE && !HAS_LLC(dev)) {
                ret = -EFAULT;
                goto err_unlock;
        }

        /* If the object is smaller than a couple of partial vma, it is
         * not worth only creating a single partial vma - we may as well
         * clear enough space for the full object.
         */
        flags = PIN_MAPPABLE;
        if (obj->base.size > 2 * MIN_CHUNK_PAGES << PAGE_SHIFT)
                flags |= PIN_NONBLOCK | PIN_NONFAULT;

        /* Now pin it into the GTT as needed */
        vma = i915_gem_object_ggtt_pin(obj, NULL, 0, 0, flags);
        if (IS_ERR(vma)) {
                struct i915_ggtt_view view;
                unsigned int chunk_size;

                /* Use a partial view if it is bigger than available space */
                chunk_size = MIN_CHUNK_PAGES;
                if (i915_gem_object_is_tiled(obj))
                        chunk_size = max(chunk_size, tile_row_pages(obj));

                memset(&view, 0, sizeof(view));
                view.type = I915_GGTT_VIEW_PARTIAL;
                view.params.partial.offset = rounddown(page_offset, chunk_size);
                view.params.partial.size =
                        min_t(unsigned int, chunk_size,
                              (area->vm_end - area->vm_start) / PAGE_SIZE -
                              view.params.partial.offset);

                /* If the partial covers the entire object, just create a
                 * normal VMA.
                 */
                if (chunk_size >= obj->base.size >> PAGE_SHIFT)
                        view.type = I915_GGTT_VIEW_NORMAL;

                /* Userspace is now writing through an untracked VMA, abandon
                 * all hope that the hardware is able to track future writes.
                 */
                obj->frontbuffer_ggtt_origin = ORIGIN_CPU;

                vma = i915_gem_object_ggtt_pin(obj, &view, 0, 0, PIN_MAPPABLE);
        }
        if (IS_ERR(vma)) {
                ret = PTR_ERR(vma);
                goto err_unlock;
        }

        ret = i915_gem_object_set_to_gtt_domain(obj, write);
        if (ret)
                goto err_unpin;

        ret = i915_vma_get_fence(vma);
        if (ret)
                goto err_unpin;

        /* Finally, remap it using the new GTT offset */
        ret = remap_io_mapping(area,
                               area->vm_start + (vma->ggtt_view.params.partial.offset << PAGE_SHIFT),
                               (ggtt->mappable_base + vma->node.start) >> PAGE_SHIFT,
                               min_t(u64, vma->size, area->vm_end - area->vm_start),
                               &ggtt->mappable);
        if (ret)
                goto err_unpin;

        obj->fault_mappable = true;
err_unpin:
        __i915_vma_unpin(vma);
err_unlock:
        mutex_unlock(&dev->struct_mutex);
err_rpm:
        intel_runtime_pm_put(dev_priv);
err:
        switch (ret) {
        case -EIO:
                /*
                 * We eat errors when the gpu is terminally wedged to avoid
                 * userspace unduly crashing (gl has no provisions for mmaps to
                 * fail). But any other -EIO isn't ours (e.g. swap in failure)
                 * and so needs to be reported.
                 */
                if (!i915_terminally_wedged(&dev_priv->gpu_error)) {
                        ret = VM_FAULT_SIGBUS;
                        break;
                }
        case -EAGAIN:
                /*
                 * EAGAIN means the gpu is hung and we'll wait for the error
                 * handler to reset everything when re-faulting in
                 * i915_mutex_lock_interruptible.
                 */
        case 0:
        case -ERESTARTSYS:
        case -EINTR:
        case -EBUSY:
                /*
                 * EBUSY is ok: this just means that another thread
                 * already did the job.
                 */
                ret = VM_FAULT_NOPAGE;
                break;
        case -ENOMEM:
                ret = VM_FAULT_OOM;
                break;
        case -ENOSPC:
        case -EFAULT:
                ret = VM_FAULT_SIGBUS;
                break;
        default:
                WARN_ONCE(ret, "unhandled error in i915_gem_fault: %i\n", ret);
                ret = VM_FAULT_SIGBUS;
                break;
        }
        return ret;
}

/**
 * i915_gem_release_mmap - remove physical page mappings
 * @obj: obj in question
 *
 * Preserve the reservation of the mmapping with the DRM core code, but
 * relinquish ownership of the pages back to the system.
 *
 * It is vital that we remove the page mapping if we have mapped a tiled
 * object through the GTT and then lose the fence register due to
 * resource pressure. Similarly if the object has been moved out of the
 * aperture, than pages mapped into userspace must be revoked. Removing the
 * mapping will then trigger a page fault on the next user access, allowing
 * fixup by i915_gem_fault().
 */
void
i915_gem_release_mmap(struct drm_i915_gem_object *obj)
{
        /* Serialisation between user GTT access and our code depends upon
         * revoking the CPU's PTE whilst the mutex is held. The next user
         * pagefault then has to wait until we release the mutex.
         */
        lockdep_assert_held(&obj->base.dev->struct_mutex);

        if (!obj->fault_mappable)
                return;

        drm_vma_node_unmap(&obj->base.vma_node,
                           obj->base.dev->anon_inode->i_mapping);

        /* Ensure that the CPU's PTE are revoked and there are not outstanding
         * memory transactions from userspace before we return. The TLB
         * flushing implied above by changing the PTE above *should* be
         * sufficient, an extra barrier here just provides us with a bit
         * of paranoid documentation about our requirement to serialise
         * memory writes before touching registers / GSM.
         */
        wmb();

        obj->fault_mappable = false;
}

void
i915_gem_release_all_mmaps(struct drm_i915_private *dev_priv)
{
        struct drm_i915_gem_object *obj;

        list_for_each_entry(obj, &dev_priv->mm.bound_list, global_list)
                i915_gem_release_mmap(obj);
}

/**
 * i915_gem_get_ggtt_size - return required global GTT size for an object
 * @dev_priv: i915 device
 * @size: object size
 * @tiling_mode: tiling mode
 *
 * Return the required global GTT size for an object, taking into account
 * potential fence register mapping.
 */
u64 i915_gem_get_ggtt_size(struct drm_i915_private *dev_priv,
                           u64 size, int tiling_mode)
{
        u64 ggtt_size;

        GEM_BUG_ON(size == 0);

        if (INTEL_GEN(dev_priv) >= 4 ||
            tiling_mode == I915_TILING_NONE)
                return size;

        /* Previous chips need a power-of-two fence region when tiling */
        if (IS_GEN3(dev_priv))
                ggtt_size = 1024*1024;
        else
                ggtt_size = 512*1024;

        while (ggtt_size < size)
                ggtt_size <<= 1;

        return ggtt_size;
}

/**
 * i915_gem_get_ggtt_alignment - return required global GTT alignment
 * @dev_priv: i915 device
 * @size: object size
 * @tiling_mode: tiling mode
 * @fenced: is fenced alignment required or not
 *
 * Return the required global GTT alignment for an object, taking into account
 * potential fence register mapping.
 */
u64 i915_gem_get_ggtt_alignment(struct drm_i915_private *dev_priv, u64 size,
                                int tiling_mode, bool fenced)
{
        GEM_BUG_ON(size == 0);

        /*
         * Minimum alignment is 4k (GTT page size), but might be greater
         * if a fence register is needed for the object.
         */
        if (INTEL_GEN(dev_priv) >= 4 || (!fenced && IS_G33(dev_priv)) ||
            tiling_mode == I915_TILING_NONE)
                return 4096;

        /*
         * Previous chips need to be aligned to the size of the smallest
         * fence register that can contain the object.
         */
        return i915_gem_get_ggtt_size(dev_priv, size, tiling_mode);
}

static int i915_gem_object_create_mmap_offset(struct drm_i915_gem_object *obj)
{
        struct drm_i915_private *dev_priv = to_i915(obj->base.dev);
        int err;

        err = drm_gem_create_mmap_offset(&obj->base);
        if (!err)
                return 0;

        /* We can idle the GPU locklessly to flush stale objects, but in order
         * to claim that space for ourselves, we need to take the big
         * struct_mutex to free the requests+objects and allocate our slot.
         */
        err = i915_gem_wait_for_idle(dev_priv, I915_WAIT_INTERRUPTIBLE);
        if (err)
                return err;

        err = i915_mutex_lock_interruptible(&dev_priv->drm);
        if (!err) {
                i915_gem_retire_requests(dev_priv);
                err = drm_gem_create_mmap_offset(&obj->base);
                mutex_unlock(&dev_priv->drm.struct_mutex);
        }

        return err;
}

static void i915_gem_object_free_mmap_offset(struct drm_i915_gem_object *obj)
{
        drm_gem_free_mmap_offset(&obj->base);
}

int
i915_gem_mmap_gtt(struct drm_file *file,
                  struct drm_device *dev,
                  uint32_t handle,
                  uint64_t *offset)
{
        struct drm_i915_gem_object *obj;
        int ret;

        obj = i915_gem_object_lookup(file, handle);
        if (!obj)
                return -ENOENT;

        ret = i915_gem_object_create_mmap_offset(obj);
        if (ret == 0)
                *offset = drm_vma_node_offset_addr(&obj->base.vma_node);

        i915_gem_object_put_unlocked(obj);
        return ret;
}

/**
 * i915_gem_mmap_gtt_ioctl - prepare an object for GTT mmap'ing
 * @dev: DRM device
 * @data: GTT mapping ioctl data
 * @file: GEM object info
 *
 * Simply returns the fake offset to userspace so it can mmap it.
 * The mmap call will end up in drm_gem_mmap(), which will set things
 * up so we can get faults in the handler above.
 *
 * The fault handler will take care of binding the object into the GTT
 * (since it may have been evicted to make room for something), allocating
 * a fence register, and mapping the appropriate aperture address into
 * userspace.
 */
int
i915_gem_mmap_gtt_ioctl(struct drm_device *dev, void *data,
                        struct drm_file *file)
{
        struct drm_i915_gem_mmap_gtt *args = data;

        return i915_gem_mmap_gtt(file, dev, args->handle, &args->offset);
}

/* Immediately discard the backing storage */
static void
i915_gem_object_truncate(struct drm_i915_gem_object *obj)
{
        i915_gem_object_free_mmap_offset(obj);

        if (obj->base.filp == NULL)
                return;

        /* Our goal here is to return as much of the memory as
         * is possible back to the system as we are called from OOM.
         * To do this we must instruct the shmfs to drop all of its
         * backing pages, *now*.
         */
        shmem_truncate_range(file_inode(obj->base.filp), 0, (loff_t)-1);
        obj->madv = __I915_MADV_PURGED;
}

/* Try to discard unwanted pages */
static void
i915_gem_object_invalidate(struct drm_i915_gem_object *obj)
{
        struct address_space *mapping;

        switch (obj->madv) {
        case I915_MADV_DONTNEED:
                i915_gem_object_truncate(obj);
        case __I915_MADV_PURGED:
                return;
        }

        if (obj->base.filp == NULL)
                return;

        mapping = obj->base.filp->f_mapping,
        invalidate_mapping_pages(mapping, 0, (loff_t)-1);
}

static void
i915_gem_object_put_pages_gtt(struct drm_i915_gem_object *obj)
{
        struct sgt_iter sgt_iter;
        struct page *page;
        int ret;

        BUG_ON(obj->madv == __I915_MADV_PURGED);

        ret = i915_gem_object_set_to_cpu_domain(obj, true);
        if (WARN_ON(ret)) {
                /* In the event of a disaster, abandon all caches and
                 * hope for the best.
                 */
                i915_gem_clflush_object(obj, true);
                obj->base.read_domains = obj->base.write_domain = I915_GEM_DOMAIN_CPU;
        }

        i915_gem_gtt_finish_object(obj);

        if (i915_gem_object_needs_bit17_swizzle(obj))
                i915_gem_object_save_bit_17_swizzle(obj);

        if (obj->madv == I915_MADV_DONTNEED)
                obj->dirty = 0;

        for_each_sgt_page(page, sgt_iter, obj->pages) {
                if (obj->dirty)
                        set_page_dirty(page);

                if (obj->madv == I915_MADV_WILLNEED)
                        mark_page_accessed(page);

                put_page(page);
        }
        obj->dirty = 0;

        sg_free_table(obj->pages);
        kfree(obj->pages);
}

int
i915_gem_object_put_pages(struct drm_i915_gem_object *obj)
{
        const struct drm_i915_gem_object_ops *ops = obj->ops;

        if (obj->pages == NULL)
                return 0;

        if (obj->pages_pin_count)
                return -EBUSY;

        GEM_BUG_ON(obj->bind_count);

        /* ->put_pages might need to allocate memory for the bit17 swizzle
         * array, hence protect them from being reaped by removing them from gtt
         * lists early. */
        list_del(&obj->global_list);

        if (obj->mapping) {
                void *ptr;

                ptr = ptr_mask_bits(obj->mapping);
                if (is_vmalloc_addr(ptr))
                        vunmap(ptr);
                else
                        kunmap(kmap_to_page(ptr));

                obj->mapping = NULL;
        }

        ops->put_pages(obj);
        obj->pages = NULL;

        i915_gem_object_invalidate(obj);

        return 0;
}

static int
i915_gem_object_get_pages_gtt(struct drm_i915_gem_object *obj)
{
        struct drm_i915_private *dev_priv = to_i915(obj->base.dev);
        int page_count, i;
        struct address_space *mapping;
        struct sg_table *st;
        struct scatterlist *sg;
        struct sgt_iter sgt_iter;
        struct page *page;
        unsigned long last_pfn = 0;     /* suppress gcc warning */
        int ret;
        gfp_t gfp;

        /* Assert that the object is not currently in any GPU domain. As it
         * wasn't in the GTT, there shouldn't be any way it could have been in
         * a GPU cache
         */
        BUG_ON(obj->base.read_domains & I915_GEM_GPU_DOMAINS);
        BUG_ON(obj->base.write_domain & I915_GEM_GPU_DOMAINS);

        st = kmalloc(sizeof(*st), GFP_KERNEL);
        if (st == NULL)
                return -ENOMEM;

        page_count = obj->base.size / PAGE_SIZE;
        if (sg_alloc_table(st, page_count, GFP_KERNEL)) {
                kfree(st);
                return -ENOMEM;
        }

        /* Get the list of pages out of our struct file.  They'll be pinned
         * at this point until we release them.
         *
         * Fail silently without starting the shrinker
         */
        mapping = obj->base.filp->f_mapping;
        gfp = mapping_gfp_constraint(mapping, ~(__GFP_IO | __GFP_RECLAIM));
        gfp |= __GFP_NORETRY | __GFP_NOWARN;
        sg = st->sgl;
        st->nents = 0;
        for (i = 0; i < page_count; i++) {
                page = shmem_read_mapping_page_gfp(mapping, i, gfp);
                if (IS_ERR(page)) {
                        i915_gem_shrink(dev_priv,
                                        page_count,
                                        I915_SHRINK_BOUND |
                                        I915_SHRINK_UNBOUND |
                                        I915_SHRINK_PURGEABLE);
                        page = shmem_read_mapping_page_gfp(mapping, i, gfp);
                }
                if (IS_ERR(page)) {
                        /* We've tried hard to allocate the memory by reaping
                         * our own buffer, now let the real VM do its job and
                         * go down in flames if truly OOM.
                         */
                        i915_gem_shrink_all(dev_priv);
                        page = shmem_read_mapping_page(mapping, i);
                        if (IS_ERR(page)) {
                                ret = PTR_ERR(page);
                                goto err_pages;
                        }
                }
#ifdef CONFIG_SWIOTLB
                if (swiotlb_nr_tbl()) {
                        st->nents++;
                        sg_set_page(sg, page, PAGE_SIZE, 0);
                        sg = sg_next(sg);
                        continue;
                }
#endif
                if (!i || page_to_pfn(page) != last_pfn + 1) {
                        if (i)
                                sg = sg_next(sg);
                        st->nents++;
                        sg_set_page(sg, page, PAGE_SIZE, 0);
                } else {
                        sg->length += PAGE_SIZE;
                }
                last_pfn = page_to_pfn(page);

                /* Check that the i965g/gm workaround works. */
                WARN_ON((gfp & __GFP_DMA32) && (last_pfn >= 0x00100000UL));
        }
#ifdef CONFIG_SWIOTLB
        if (!swiotlb_nr_tbl())
#endif
                sg_mark_end(sg);
        obj->pages = st;

        ret = i915_gem_gtt_prepare_object(obj);
        if (ret)
                goto err_pages;

        if (i915_gem_object_needs_bit17_swizzle(obj))
                i915_gem_object_do_bit_17_swizzle(obj);

        if (i915_gem_object_is_tiled(obj) &&
            dev_priv->quirks & QUIRK_PIN_SWIZZLED_PAGES)
                i915_gem_object_pin_pages(obj);

        return 0;

err_pages:
        sg_mark_end(sg);
        for_each_sgt_page(page, sgt_iter, st)
                put_page(page);
        sg_free_table(st);
        kfree(st);

        /* shmemfs first checks if there is enough memory to allocate the page
         * and reports ENOSPC should there be insufficient, along with the usual
         * ENOMEM for a genuine allocation failure.
         *
         * We use ENOSPC in our driver to mean that we have run out of aperture
         * space and so want to translate the error from shmemfs back to our
         * usual understanding of ENOMEM.
         */
        if (ret == -ENOSPC)
                ret = -ENOMEM;

        return ret;
}

/* Ensure that the associated pages are gathered from the backing storage
 * and pinned into our object. i915_gem_object_get_pages() may be called
 * multiple times before they are released by a single call to
 * i915_gem_object_put_pages() - once the pages are no longer referenced
 * either as a result of memory pressure (reaping pages under the shrinker)
 * or as the object is itself released.
 */
int
i915_gem_object_get_pages(struct drm_i915_gem_object *obj)
{
        struct drm_i915_private *dev_priv = to_i915(obj->base.dev);
        const struct drm_i915_gem_object_ops *ops = obj->ops;
        int ret;

        if (obj->pages)
                return 0;

        if (obj->madv != I915_MADV_WILLNEED) {
                DRM_DEBUG("Attempting to obtain a purgeable object\n");
                return -EFAULT;
        }

        BUG_ON(obj->pages_pin_count);

        ret = ops->get_pages(obj);
        if (ret)
                return ret;

        list_add_tail(&obj->global_list, &dev_priv->mm.unbound_list);

        obj->get_page.sg = obj->pages->sgl;
        obj->get_page.last = 0;

        return 0;
}

/* The 'mapping' part of i915_gem_object_pin_map() below */
static void *i915_gem_object_map(const struct drm_i915_gem_object *obj,
                                 enum i915_map_type type)
{
        unsigned long n_pages = obj->base.size >> PAGE_SHIFT;
        struct sg_table *sgt = obj->pages;
        struct sgt_iter sgt_iter;
        struct page *page;
        struct page *stack_pages[32];
        struct page **pages = stack_pages;
        unsigned long i = 0;
        pgprot_t pgprot;
        void *addr;

        /* A single page can always be kmapped */
        if (n_pages == 1 && type == I915_MAP_WB)
                return kmap(sg_page(sgt->sgl));

        if (n_pages > ARRAY_SIZE(stack_pages)) {
                /* Too big for stack -- allocate temporary array instead */
                pages = drm_malloc_gfp(n_pages, sizeof(*pages), GFP_TEMPORARY);
                if (!pages)
                        return NULL;
        }

        for_each_sgt_page(page, sgt_iter, sgt)
                pages[i++] = page;

        /* Check that we have the expected number of pages */
        GEM_BUG_ON(i != n_pages);

        switch (type) {
        case I915_MAP_WB:
                pgprot = PAGE_KERNEL;
                break;
        case I915_MAP_WC:
                pgprot = pgprot_writecombine(PAGE_KERNEL_IO);
                break;
        }
        addr = vmap(pages, n_pages, 0, pgprot);

        if (pages != stack_pages)
                drm_free_large(pages);

        return addr;
}

/* get, pin, and map the pages of the object into kernel space */
void *i915_gem_object_pin_map(struct drm_i915_gem_object *obj,
                              enum i915_map_type type)
{
        enum i915_map_type has_type;
        bool pinned;
        void *ptr;
        int ret;

        lockdep_assert_held(&obj->base.dev->struct_mutex);
        GEM_BUG_ON(!i915_gem_object_has_struct_page(obj));

        ret = i915_gem_object_get_pages(obj);
        if (ret)
                return ERR_PTR(ret);

        i915_gem_object_pin_pages(obj);
        pinned = obj->pages_pin_count > 1;

        ptr = ptr_unpack_bits(obj->mapping, has_type);
        if (ptr && has_type != type) {
                if (pinned) {
                        ret = -EBUSY;
                        goto err;
                }

                if (is_vmalloc_addr(ptr))
                        vunmap(ptr);
                else
                        kunmap(kmap_to_page(ptr));

                ptr = obj->mapping = NULL;
        }

        if (!ptr) {
                ptr = i915_gem_object_map(obj, type);
                if (!ptr) {
                        ret = -ENOMEM;
                        goto err;
                }

                obj->mapping = ptr_pack_bits(ptr, type);
        }

        return ptr;

err:
        i915_gem_object_unpin_pages(obj);
        return ERR_PTR(ret);
}

static void
i915_gem_object_retire__write(struct i915_gem_active *active,
                              struct drm_i915_gem_request *request)
{
        struct drm_i915_gem_object *obj =
                container_of(active, struct drm_i915_gem_object, last_write);

        intel_fb_obj_flush(obj, true, ORIGIN_CS);
}

static void
i915_gem_object_retire__read(struct i915_gem_active *active,
                             struct drm_i915_gem_request *request)
{
        int idx = request->engine->id;
        struct drm_i915_gem_object *obj =
                container_of(active, struct drm_i915_gem_object, last_read[idx]);

        GEM_BUG_ON(!i915_gem_object_has_active_engine(obj, idx));

        i915_gem_object_clear_active(obj, idx);
        if (i915_gem_object_is_active(obj))
                return;

        /* Bump our place on the bound list to keep it roughly in LRU order
         * so that we don't steal from recently used but inactive objects
         * (unless we are forced to ofc!)
         */
        if (obj->bind_count)
                list_move_tail(&obj->global_list,
                               &request->i915->mm.bound_list);

        i915_gem_object_put(obj);
}

static bool i915_context_is_banned(const struct i915_gem_context *ctx)
{
        unsigned long elapsed;

        if (ctx->hang_stats.banned)
                return true;

        elapsed = get_seconds() - ctx->hang_stats.guilty_ts;
        if (ctx->hang_stats.ban_period_seconds &&
            elapsed <= ctx->hang_stats.ban_period_seconds) {
                DRM_DEBUG("context hanging too fast, banning!\n");
                return true;
        }

        return false;
}

static void i915_set_reset_status(struct i915_gem_context *ctx,
                                  const bool guilty)
{
        struct i915_ctx_hang_stats *hs = &ctx->hang_stats;

        if (guilty) {
                hs->banned = i915_context_is_banned(ctx);
                hs->batch_active++;
                hs->guilty_ts = get_seconds();
        } else {
                hs->batch_pending++;
        }
}

struct drm_i915_gem_request *
i915_gem_find_active_request(struct intel_engine_cs *engine)
{
        struct drm_i915_gem_request *request;

        /* We are called by the error capture and reset at a random
         * point in time. In particular, note that neither is crucially
         * ordered with an interrupt. After a hang, the GPU is dead and we
         * assume that no more writes can happen (we waited long enough for
         * all writes that were in transaction to be flushed) - adding an
         * extra delay for a recent interrupt is pointless. Hence, we do
         * not need an engine->irq_seqno_barrier() before the seqno reads.
         */
        list_for_each_entry(request, &engine->request_list, link) {
                if (i915_gem_request_completed(request))
                        continue;

                if (!i915_sw_fence_done(&request->submit))
                        break;

                return request;
        }

        return NULL;
}

static void reset_request(struct drm_i915_gem_request *request)
{
        void *vaddr = request->ring->vaddr;
        u32 head;

        /* As this request likely depends on state from the lost
         * context, clear out all the user operations leaving the
         * breadcrumb at the end (so we get the fence notifications).
         */
        head = request->head;
        if (request->postfix < head) {
                memset(vaddr + head, 0, request->ring->size - head);
                head = 0;
        }
        memset(vaddr + head, 0, request->postfix - head);
}

static void i915_gem_reset_engine(struct intel_engine_cs *engine)
{
        struct drm_i915_gem_request *request;
        struct i915_gem_context *incomplete_ctx;
        bool ring_hung;

        /* Ensure irq handler finishes, and not run again. */
        tasklet_kill(&engine->irq_tasklet);
        if (engine->irq_seqno_barrier)
                engine->irq_seqno_barrier(engine);

        request = i915_gem_find_active_request(engine);
        if (!request)
                return;

        ring_hung = engine->hangcheck.score >= HANGCHECK_SCORE_RING_HUNG;
        i915_set_reset_status(request->ctx, ring_hung);
        if (!ring_hung)
                return;

        DRM_DEBUG_DRIVER("resetting %s to restart from tail of request 0x%x\n",
                         engine->name, request->fence.seqno);

        /* Setup the CS to resume from the breadcrumb of the hung request */
        engine->reset_hw(engine, request);

        /* Users of the default context do not rely on logical state
         * preserved between batches. They have to emit full state on
         * every batch and so it is safe to execute queued requests following
         * the hang.
         *
         * Other contexts preserve state, now corrupt. We want to skip all
         * queued requests that reference the corrupt context.
         */
        incomplete_ctx = request->ctx;
        if (i915_gem_context_is_default(incomplete_ctx))
                return;

        list_for_each_entry_continue(request, &engine->request_list, link)
                if (request->ctx == incomplete_ctx)
                        reset_request(request);

        engine->i915->gt.active_engines &= ~intel_engine_flag(engine);
}

void i915_gem_reset(struct drm_i915_private *dev_priv)
{
        struct intel_engine_cs *engine;

        i915_gem_retire_requests(dev_priv);

        for_each_engine(engine, dev_priv)
                i915_gem_reset_engine(engine);
        mod_delayed_work(dev_priv->wq, &dev_priv->gt.idle_work, 0);

        i915_gem_restore_fences(&dev_priv->drm);
}

static void nop_submit_request(struct drm_i915_gem_request *request)
{
}

static void i915_gem_cleanup_engine(struct intel_engine_cs *engine)
{
        engine->submit_request = nop_submit_request;

        /* Mark all pending requests as complete so that any concurrent
         * (lockless) lookup doesn't try and wait upon the request as we
         * reset it.
         */
        intel_engine_init_seqno(engine, engine->last_submitted_seqno);

        /*
         * Clear the execlists queue up before freeing the requests, as those
         * are the ones that keep the context and ringbuffer backing objects
         * pinned in place.
         */

        if (i915.enable_execlists) {
                spin_lock(&engine->execlist_lock);
                INIT_LIST_HEAD(&engine->execlist_queue);
                i915_gem_request_put(engine->execlist_port[0].request);
                i915_gem_request_put(engine->execlist_port[1].request);
                memset(engine->execlist_port, 0, sizeof(engine->execlist_port));
                spin_unlock(&engine->execlist_lock);
        }

        engine->i915->gt.active_engines &= ~intel_engine_flag(engine);
}

void i915_gem_set_wedged(struct drm_i915_private *dev_priv)
{
        struct intel_engine_cs *engine;

        lockdep_assert_held(&dev_priv->drm.struct_mutex);
        set_bit(I915_WEDGED, &dev_priv->gpu_error.flags);

        i915_gem_context_lost(dev_priv);
        for_each_engine(engine, dev_priv)
                i915_gem_cleanup_engine(engine);
        mod_delayed_work(dev_priv->wq, &dev_priv->gt.idle_work, 0);

        i915_gem_retire_requests(dev_priv);
}

static void
i915_gem_retire_work_handler(struct work_struct *work)
{
        struct drm_i915_private *dev_priv =
                container_of(work, typeof(*dev_priv), gt.retire_work.work);
        struct drm_device *dev = &dev_priv->drm;

        /* Come back later if the device is busy... */
        if (mutex_trylock(&dev->struct_mutex)) {
                i915_gem_retire_requests(dev_priv);
                mutex_unlock(&dev->struct_mutex);
        }

        /* Keep the retire handler running until we are finally idle.
         * We do not need to do this test under locking as in the worst-case
         * we queue the retire worker once too often.
         */
        if (READ_ONCE(dev_priv->gt.awake)) {
                i915_queue_hangcheck(dev_priv);
                queue_delayed_work(dev_priv->wq,
                                   &dev_priv->gt.retire_work,
                                   round_jiffies_up_relative(HZ));
        }
}

static void
i915_gem_idle_work_handler(struct work_struct *work)
{
        struct drm_i915_private *dev_priv =
                container_of(work, typeof(*dev_priv), gt.idle_work.work);
        struct drm_device *dev = &dev_priv->drm;
        struct intel_engine_cs *engine;
        bool rearm_hangcheck;

        if (!READ_ONCE(dev_priv->gt.awake))
                return;

        if (READ_ONCE(dev_priv->gt.active_engines))
                return;

        rearm_hangcheck =
                cancel_delayed_work_sync(&dev_priv->gpu_error.hangcheck_work);

        if (!mutex_trylock(&dev->struct_mutex)) {
                /* Currently busy, come back later */
                mod_delayed_work(dev_priv->wq,
                                 &dev_priv->gt.idle_work,
                                 msecs_to_jiffies(50));
                goto out_rearm;
        }

        if (dev_priv->gt.active_engines)
                goto out_unlock;

        for_each_engine(engine, dev_priv)
                i915_gem_batch_pool_fini(&engine->batch_pool);

        GEM_BUG_ON(!dev_priv->gt.awake);
        dev_priv->gt.awake = false;
        rearm_hangcheck = false;

        if (INTEL_GEN(dev_priv) >= 6)
                gen6_rps_idle(dev_priv);
        intel_runtime_pm_put(dev_priv);
out_unlock:
        mutex_unlock(&dev->struct_mutex);

out_rearm:
        if (rearm_hangcheck) {
                GEM_BUG_ON(!dev_priv->gt.awake);
                i915_queue_hangcheck(dev_priv);
        }
}

void i915_gem_close_object(struct drm_gem_object *gem, struct drm_file *file)
{
        struct drm_i915_gem_object *obj = to_intel_bo(gem);
        struct drm_i915_file_private *fpriv = file->driver_priv;
        struct i915_vma *vma, *vn;

        mutex_lock(&obj->base.dev->struct_mutex);
        list_for_each_entry_safe(vma, vn, &obj->vma_list, obj_link)
                if (vma->vm->file == fpriv)
                        i915_vma_close(vma);
        mutex_unlock(&obj->base.dev->struct_mutex);
}

/**
 * i915_gem_wait_ioctl - implements DRM_IOCTL_I915_GEM_WAIT
 * @dev: drm device pointer
 * @data: ioctl data blob
 * @file: drm file pointer
 *
 * Returns 0 if successful, else an error is returned with the remaining time in
 * the timeout parameter.
 *  -ETIME: object is still busy after timeout
 *  -ERESTARTSYS: signal interrupted the wait
 *  -ENONENT: object doesn't exist
 * Also possible, but rare:
 *  -EAGAIN: GPU wedged
 *  -ENOMEM: damn
 *  -ENODEV: Internal IRQ fail
 *  -E?: The add request failed
 *
 * The wait ioctl with a timeout of 0 reimplements the busy ioctl. With any
 * non-zero timeout parameter the wait ioctl will wait for the given number of
 * nanoseconds on an object becoming unbusy. Since the wait itself does so
 * without holding struct_mutex the object may become re-busied before this
 * function completes. A similar but shorter * race condition exists in the busy
 * ioctl
 */
int
i915_gem_wait_ioctl(struct drm_device *dev, void *data, struct drm_file *file)
{
        struct drm_i915_gem_wait *args = data;
        struct intel_rps_client *rps = to_rps_client(file);
        struct drm_i915_gem_object *obj;
        unsigned long active;
        int idx, ret = 0;

        if (args->flags != 0)
                return -EINVAL;

        obj = i915_gem_object_lookup(file, args->bo_handle);
        if (!obj)
                return -ENOENT;

        active = __I915_BO_ACTIVE(obj);
        for_each_active(active, idx) {
                s64 *timeout = args->timeout_ns >= 0 ? &args->timeout_ns : NULL;
                ret = i915_gem_active_wait_unlocked(&obj->last_read[idx],
                                                    I915_WAIT_INTERRUPTIBLE,
                                                    timeout, rps);
                if (ret)
                        break;
        }

        i915_gem_object_put_unlocked(obj);
        return ret;
}

static void __i915_vma_iounmap(struct i915_vma *vma)
{
        GEM_BUG_ON(i915_vma_is_pinned(vma));

        if (vma->iomap == NULL)
                return;

        io_mapping_unmap(vma->iomap);
        vma->iomap = NULL;
}

int i915_vma_unbind(struct i915_vma *vma)
{
        struct drm_i915_gem_object *obj = vma->obj;
        unsigned long active;
        int ret;

        /* First wait upon any activity as retiring the request may
         * have side-effects such as unpinning or even unbinding this vma.
         */
        active = i915_vma_get_active(vma);
        if (active) {
                int idx;

                /* When a closed VMA is retired, it is unbound - eek.
                 * In order to prevent it from being recursively closed,
                 * take a pin on the vma so that the second unbind is
                 * aborted.
                 */
                __i915_vma_pin(vma);

                for_each_active(active, idx) {
                        ret = i915_gem_active_retire(&vma->last_read[idx],
                                                   &vma->vm->dev->struct_mutex);
                        if (ret)
                                break;
                }

                __i915_vma_unpin(vma);
                if (ret)
                        return ret;

                GEM_BUG_ON(i915_vma_is_active(vma));
        }

        if (i915_vma_is_pinned(vma))
                return -EBUSY;

        if (!drm_mm_node_allocated(&vma->node))
                goto destroy;

        GEM_BUG_ON(obj->bind_count == 0);
        GEM_BUG_ON(!obj->pages);

        if (i915_vma_is_map_and_fenceable(vma)) {
                /* release the fence reg _after_ flushing */
                ret = i915_vma_put_fence(vma);
                if (ret)
                        return ret;

                /* Force a pagefault for domain tracking on next user access */
                i915_gem_release_mmap(obj);

                __i915_vma_iounmap(vma);
                vma->flags &= ~I915_VMA_CAN_FENCE;
        }

        if (likely(!vma->vm->closed)) {
                trace_i915_vma_unbind(vma);
                vma->vm->unbind_vma(vma);
        }
        vma->flags &= ~(I915_VMA_GLOBAL_BIND | I915_VMA_LOCAL_BIND);

        drm_mm_remove_node(&vma->node);
        list_move_tail(&vma->vm_link, &vma->vm->unbound_list);

        if (vma->pages != obj->pages) {
                GEM_BUG_ON(!vma->pages);
                sg_free_table(vma->pages);
                kfree(vma->pages);
        }
        vma->pages = NULL;

        /* Since the unbound list is global, only move to that list if
         * no more VMAs exist. */
        if (--obj->bind_count == 0)
                list_move_tail(&obj->global_list,
                               &to_i915(obj->base.dev)->mm.unbound_list);

        /* And finally now the object is completely decoupled from this vma,
         * we can drop its hold on the backing storage and allow it to be
         * reaped by the shrinker.
         */
        i915_gem_object_unpin_pages(obj);

destroy:
        if (unlikely(i915_vma_is_closed(vma)))
                i915_vma_destroy(vma);

        return 0;
}

int i915_gem_wait_for_idle(struct drm_i915_private *dev_priv,
                           unsigned int flags)
{
        struct intel_engine_cs *engine;
        int ret;

        for_each_engine(engine, dev_priv) {
                if (engine->last_context == NULL)
                        continue;

                ret = intel_engine_idle(engine, flags);
                if (ret)
                        return ret;
        }

        return 0;
}

static bool i915_gem_valid_gtt_space(struct i915_vma *vma,
                                     unsigned long cache_level)
{
        struct drm_mm_node *gtt_space = &vma->node;
        struct drm_mm_node *other;

        /*
         * On some machines we have to be careful when putting differing types
         * of snoopable memory together to avoid the prefetcher crossing memory
         * domains and dying. During vm initialisation, we decide whether or not
         * these constraints apply and set the drm_mm.color_adjust
         * appropriately.
         */
        if (vma->vm->mm.color_adjust == NULL)
                return true;

        if (!drm_mm_node_allocated(gtt_space))
                return true;

        if (list_empty(&gtt_space->node_list))
                return true;

        other = list_entry(gtt_space->node_list.prev, struct drm_mm_node, node_list);
        if (other->allocated && !other->hole_follows && other->color != cache_level)
                return false;

        other = list_entry(gtt_space->node_list.next, struct drm_mm_node, node_list);
        if (other->allocated && !gtt_space->hole_follows && other->color != cache_level)
                return false;

        return true;
}

/**
 * i915_vma_insert - finds a slot for the vma in its address space
 * @vma: the vma
 * @size: requested size in bytes (can be larger than the VMA)
 * @alignment: required alignment
 * @flags: mask of PIN_* flags to use
 *
 * First we try to allocate some free space that meets the requirements for
 * the VMA. Failiing that, if the flags permit, it will evict an old VMA,
 * preferrably the oldest idle entry to make room for the new VMA.
 *
 * Returns:
 * 0 on success, negative error code otherwise.
 */
static int
i915_vma_insert(struct i915_vma *vma, u64 size, u64 alignment, u64 flags)
{
        struct drm_i915_private *dev_priv = to_i915(vma->vm->dev);
        struct drm_i915_gem_object *obj = vma->obj;
        u64 start, end;
        int ret;

        GEM_BUG_ON(vma->flags & (I915_VMA_GLOBAL_BIND | I915_VMA_LOCAL_BIND));
        GEM_BUG_ON(drm_mm_node_allocated(&vma->node));

        size = max(size, vma->size);
        if (flags & PIN_MAPPABLE)
                size = i915_gem_get_ggtt_size(dev_priv, size,
                                              i915_gem_object_get_tiling(obj));

        alignment = max(max(alignment, vma->display_alignment),
                        i915_gem_get_ggtt_alignment(dev_priv, size,
                                                    i915_gem_object_get_tiling(obj),
                                                    flags & PIN_MAPPABLE));

        start = flags & PIN_OFFSET_BIAS ? flags & PIN_OFFSET_MASK : 0;

        end = vma->vm->total;
        if (flags & PIN_MAPPABLE)
                end = min_t(u64, end, dev_priv->ggtt.mappable_end);
        if (flags & PIN_ZONE_4G)
                end = min_t(u64, end, (1ULL << 32) - PAGE_SIZE);

        /* If binding the object/GGTT view requires more space than the entire
         * aperture has, reject it early before evicting everything in a vain
         * attempt to find space.
         */
        if (size > end) {
                DRM_DEBUG("Attempting to bind an object larger than the aperture: request=%llu [object=%zd] > %s aperture=%llu\n",
                          size, obj->base.size,
                          flags & PIN_MAPPABLE ? "mappable" : "total",
                          end);
                return -E2BIG;
        }

        ret = i915_gem_object_get_pages(obj);
        if (ret)
                return ret;

        i915_gem_object_pin_pages(obj);

        if (flags & PIN_OFFSET_FIXED) {
                u64 offset = flags & PIN_OFFSET_MASK;
                if (offset & (alignment - 1) || offset > end - size) {
                        ret = -EINVAL;
                        goto err_unpin;
                }

                vma->node.start = offset;
                vma->node.size = size;
                vma->node.color = obj->cache_level;
                ret = drm_mm_reserve_node(&vma->vm->mm, &vma->node);
                if (ret) {
                        ret = i915_gem_evict_for_vma(vma);
                        if (ret == 0)
                                ret = drm_mm_reserve_node(&vma->vm->mm, &vma->node);
                        if (ret)
                                goto err_unpin;
                }
        } else {
                u32 search_flag, alloc_flag;

                if (flags & PIN_HIGH) {
                        search_flag = DRM_MM_SEARCH_BELOW;
                        alloc_flag = DRM_MM_CREATE_TOP;
                } else {
                        search_flag = DRM_MM_SEARCH_DEFAULT;
                        alloc_flag = DRM_MM_CREATE_DEFAULT;
                }

                /* We only allocate in PAGE_SIZE/GTT_PAGE_SIZE (4096) chunks,
                 * so we know that we always have a minimum alignment of 4096.
                 * The drm_mm range manager is optimised to return results
                 * with zero alignment, so where possible use the optimal
                 * path.
                 */
                if (alignment <= 4096)
                        alignment = 0;

search_free:
                ret = drm_mm_insert_node_in_range_generic(&vma->vm->mm,
                                                          &vma->node,
                                                          size, alignment,
                                                          obj->cache_level,
                                                          start, end,
                                                          search_flag,
                                                          alloc_flag);
                if (ret) {
                        ret = i915_gem_evict_something(vma->vm, size, alignment,
                                                       obj->cache_level,
                                                       start, end,
                                                       flags);
                        if (ret == 0)
                                goto search_free;

                        goto err_unpin;
                }
        }
        GEM_BUG_ON(!i915_gem_valid_gtt_space(vma, obj->cache_level));

        list_move_tail(&obj->global_list, &dev_priv->mm.bound_list);
        list_move_tail(&vma->vm_link, &vma->vm->inactive_list);
        obj->bind_count++;

        return 0;

err_unpin:
        i915_gem_object_unpin_pages(obj);
        return ret;
}

bool
i915_gem_clflush_object(struct drm_i915_gem_object *obj,
                        bool force)
{
        /* If we don't have a page list set up, then we're not pinned
         * to GPU, and we can ignore the cache flush because it'll happen
         * again at bind time.
         */
        if (obj->pages == NULL)
                return false;

        /*
         * Stolen memory is always coherent with the GPU as it is explicitly
         * marked as wc by the system, or the system is cache-coherent.
         */
        if (obj->stolen || obj->phys_handle)
                return false;

        /* If the GPU is snooping the contents of the CPU cache,
         * we do not need to manually clear the CPU cache lines.  However,
         * the caches are only snooped when the render cache is
         * flushed/invalidated.  As we always have to emit invalidations
         * and flushes when moving into and out of the RENDER domain, correct
         * snooping behaviour occurs naturally as the result of our domain
         * tracking.
         */
        if (!force && cpu_cache_is_coherent(obj->base.dev, obj->cache_level)) {
                obj->cache_dirty = true;
                return false;
        }

        trace_i915_gem_object_clflush(obj);
        drm_clflush_sg(obj->pages);
        obj->cache_dirty = false;

        return true;
}

/** Flushes the GTT write domain for the object if it's dirty. */
static void
i915_gem_object_flush_gtt_write_domain(struct drm_i915_gem_object *obj)
{
        struct drm_i915_private *dev_priv = to_i915(obj->base.dev);

        if (obj->base.write_domain != I915_GEM_DOMAIN_GTT)
                return;

        /* No actual flushing is required for the GTT write domain.  Writes
         * to it "immediately" go to main memory as far as we know, so there's
         * no chipset flush.  It also doesn't land in render cache.
         *
         * However, we do have to enforce the order so that all writes through
         * the GTT land before any writes to the device, such as updates to
         * the GATT itself.
         *
         * We also have to wait a bit for the writes to land from the GTT.
         * An uncached read (i.e. mmio) seems to be ideal for the round-trip
         * timing. This issue has only been observed when switching quickly
         * between GTT writes and CPU reads from inside the kernel on recent hw,
         * and it appears to only affect discrete GTT blocks (i.e. on LLC
         * system agents we cannot reproduce this behaviour).
         */
        wmb();
        if (INTEL_GEN(dev_priv) >= 6 && !HAS_LLC(dev_priv))
                POSTING_READ(RING_ACTHD(dev_priv->engine[RCS].mmio_base));

        intel_fb_obj_flush(obj, false, write_origin(obj, I915_GEM_DOMAIN_GTT));

        obj->base.write_domain = 0;
        trace_i915_gem_object_change_domain(obj,
                                            obj->base.read_domains,
                                            I915_GEM_DOMAIN_GTT);
}

/** Flushes the CPU write domain for the object if it's dirty. */
static void
i915_gem_object_flush_cpu_write_domain(struct drm_i915_gem_object *obj)
{
        if (obj->base.write_domain != I915_GEM_DOMAIN_CPU)
                return;

        if (i915_gem_clflush_object(obj, obj->pin_display))
                i915_gem_chipset_flush(to_i915(obj->base.dev));

        intel_fb_obj_flush(obj, false, ORIGIN_CPU);

        obj->base.write_domain = 0;
        trace_i915_gem_object_change_domain(obj,
                                            obj->base.read_domains,
                                            I915_GEM_DOMAIN_CPU);
}

static void i915_gem_object_bump_inactive_ggtt(struct drm_i915_gem_object *obj)
{
        struct i915_vma *vma;

        list_for_each_entry(vma, &obj->vma_list, obj_link) {
                if (!i915_vma_is_ggtt(vma))
                        continue;

                if (i915_vma_is_active(vma))
                        continue;

                if (!drm_mm_node_allocated(&vma->node))
                        continue;

                list_move_tail(&vma->vm_link, &vma->vm->inactive_list);
        }
}

/**
 * Moves a single object to the GTT read, and possibly write domain.
 * @obj: object to act on
 * @write: ask for write access or read only
 *
 * This function returns when the move is complete, including waiting on
 * flushes to occur.
 */
int
i915_gem_object_set_to_gtt_domain(struct drm_i915_gem_object *obj, bool write)
{
        uint32_t old_write_domain, old_read_domains;
        int ret;

        ret = i915_gem_object_wait_rendering(obj, !write);
        if (ret)
                return ret;

        if (obj->base.write_domain == I915_GEM_DOMAIN_GTT)
                return 0;

        /* Flush and acquire obj->pages so that we are coherent through
         * direct access in memory with previous cached writes through
         * shmemfs and that our cache domain tracking remains valid.
         * For example, if the obj->filp was moved to swap without us
         * being notified and releasing the pages, we would mistakenly
         * continue to assume that the obj remained out of the CPU cached
         * domain.
         */
        ret = i915_gem_object_get_pages(obj);
        if (ret)
                return ret;

        i915_gem_object_flush_cpu_write_domain(obj);

        /* Serialise direct access to this object with the barriers for
         * coherent writes from the GPU, by effectively invalidating the
         * GTT domain upon first access.
         */
        if ((obj->base.read_domains & I915_GEM_DOMAIN_GTT) == 0)
                mb();

        old_write_domain = obj->base.write_domain;
        old_read_domains = obj->base.read_domains;

        /* It should now be out of any other write domains, and we can update
         * the domain values for our changes.
         */
        BUG_ON((obj->base.write_domain & ~I915_GEM_DOMAIN_GTT) != 0);
        obj->base.read_domains |= I915_GEM_DOMAIN_GTT;
        if (write) {
                obj->base.read_domains = I915_GEM_DOMAIN_GTT;
                obj->base.write_domain = I915_GEM_DOMAIN_GTT;
                obj->dirty = 1;
        }

        trace_i915_gem_object_change_domain(obj,
                                            old_read_domains,
                                            old_write_domain);

        /* And bump the LRU for this access */
        i915_gem_object_bump_inactive_ggtt(obj);

        return 0;
}

/**
 * Changes the cache-level of an object across all VMA.
 * @obj: object to act on
 * @cache_level: new cache level to set for the object
 *
 * After this function returns, the object will be in the new cache-level
 * across all GTT and the contents of the backing storage will be coherent,
 * with respect to the new cache-level. In order to keep the backing storage
 * coherent for all users, we only allow a single cache level to be set
 * globally on the object and prevent it from being changed whilst the
 * hardware is reading from the object. That is if the object is currently
 * on the scanout it will be set to uncached (or equivalent display
 * cache coherency) and all non-MOCS GPU access will also be uncached so
 * that all direct access to the scanout remains coherent.
 */
int i915_gem_object_set_cache_level(struct drm_i915_gem_object *obj,
                                    enum i915_cache_level cache_level)
{
        struct i915_vma *vma;
        int ret = 0;

        if (obj->cache_level == cache_level)
                goto out;

        /* Inspect the list of currently bound VMA and unbind any that would
         * be invalid given the new cache-level. This is principally to
         * catch the issue of the CS prefetch crossing page boundaries and
         * reading an invalid PTE on older architectures.
         */
restart:
        list_for_each_entry(vma, &obj->vma_list, obj_link) {
                if (!drm_mm_node_allocated(&vma->node))
                        continue;

                if (i915_vma_is_pinned(vma)) {
                        DRM_DEBUG("can not change the cache level of pinned objects\n");
                        return -EBUSY;
                }

                if (i915_gem_valid_gtt_space(vma, cache_level))
                        continue;

                ret = i915_vma_unbind(vma);
                if (ret)
                        return ret;

                /* As unbinding may affect other elements in the
                 * obj->vma_list (due to side-effects from retiring
                 * an active vma), play safe and restart the iterator.
                 */
                goto restart;
        }

        /* We can reuse the existing drm_mm nodes but need to change the
         * cache-level on the PTE. We could simply unbind them all and
         * rebind with the correct cache-level on next use. However since
         * we already have a valid slot, dma mapping, pages etc, we may as
         * rewrite the PTE in the belief that doing so tramples upon less
         * state and so involves less work.
         */
        if (obj->bind_count) {
                /* Before we change the PTE, the GPU must not be accessing it.
                 * If we wait upon the object, we know that all the bound
                 * VMA are no longer active.
                 */
                ret = i915_gem_object_wait_rendering(obj, false);
                if (ret)
                        return ret;

                if (!HAS_LLC(obj->base.dev) && cache_level != I915_CACHE_NONE) {
                        /* Access to snoopable pages through the GTT is
                         * incoherent and on some machines causes a hard
                         * lockup. Relinquish the CPU mmaping to force
                         * userspace to refault in the pages and we can
                         * then double check if the GTT mapping is still
                         * valid for that pointer access.
                         */
                        i915_gem_release_mmap(obj);

                        /* As we no longer need a fence for GTT access,
                         * we can relinquish it now (and so prevent having
                         * to steal a fence from someone else on the next
                         * fence request). Note GPU activity would have
                         * dropped the fence as all snoopable access is
                         * supposed to be linear.
                         */
                        list_for_each_entry(vma, &obj->vma_list, obj_link) {
                                ret = i915_vma_put_fence(vma);
                                if (ret)
                                        return ret;
                        }
                } else {
                        /* We either have incoherent backing store and
                         * so no GTT access or the architecture is fully
                         * coherent. In such cases, existing GTT mmaps
                         * ignore the cache bit in the PTE and we can
                         * rewrite it without confusing the GPU or having
                         * to force userspace to fault back in its mmaps.
                         */
                }

                list_for_each_entry(vma, &obj->vma_list, obj_link) {
                        if (!drm_mm_node_allocated(&vma->node))
                                continue;

                        ret = i915_vma_bind(vma, cache_level, PIN_UPDATE);
                        if (ret)
                                return ret;
                }
        }

        list_for_each_entry(vma, &obj->vma_list, obj_link)
                vma->node.color = cache_level;
        obj->cache_level = cache_level;

out:
        /* Flush the dirty CPU caches to the backing storage so that the
         * object is now coherent at its new cache level (with respect
         * to the access domain).
         */
        if (obj->cache_dirty && cpu_write_needs_clflush(obj)) {
                if (i915_gem_clflush_object(obj, true))
                        i915_gem_chipset_flush(to_i915(obj->base.dev));
        }

        return 0;
}

int i915_gem_get_caching_ioctl(struct drm_device *dev, void *data,
                               struct drm_file *file)
{
        struct drm_i915_gem_caching *args = data;
        struct drm_i915_gem_object *obj;

        obj = i915_gem_object_lookup(file, args->handle);
        if (!obj)
                return -ENOENT;

        switch (obj->cache_level) {
        case I915_CACHE_LLC:
        case I915_CACHE_L3_LLC:
                args->caching = I915_CACHING_CACHED;
                break;

        case I915_CACHE_WT:
                args->caching = I915_CACHING_DISPLAY;
                break;

        default:
                args->caching = I915_CACHING_NONE;
                break;
        }

        i915_gem_object_put_unlocked(obj);
        return 0;
}

int i915_gem_set_caching_ioctl(struct drm_device *dev, void *data,
                               struct drm_file *file)
{
        struct drm_i915_private *dev_priv = to_i915(dev);
        struct drm_i915_gem_caching *args = data;
        struct drm_i915_gem_object *obj;
        enum i915_cache_level level;
        int ret;

        switch (args->caching) {
        case I915_CACHING_NONE:
                level = I915_CACHE_NONE;
                break;
        case I915_CACHING_CACHED:
                /*
                 * Due to a HW issue on BXT A stepping, GPU stores via a
                 * snooped mapping may leave stale data in a corresponding CPU
                 * cacheline, whereas normally such cachelines would get
                 * invalidated.
                 */
                if (!HAS_LLC(dev) && !HAS_SNOOP(dev))
                        return -ENODEV;

                level = I915_CACHE_LLC;
                break;
        case I915_CACHING_DISPLAY:
                level = HAS_WT(dev) ? I915_CACHE_WT : I915_CACHE_NONE;
                break;
        default:
                return -EINVAL;
        }

        intel_runtime_pm_get(dev_priv);

        ret = i915_mutex_lock_interruptible(dev);
        if (ret)
                goto rpm_put;

        obj = i915_gem_object_lookup(file, args->handle);
        if (!obj) {
                ret = -ENOENT;
                goto unlock;
        }

        ret = i915_gem_object_set_cache_level(obj, level);

        i915_gem_object_put(obj);
unlock:
        mutex_unlock(&dev->struct_mutex);
rpm_put:
        intel_runtime_pm_put(dev_priv);

        return ret;
}

/*
 * Prepare buffer for display plane (scanout, cursors, etc).
 * Can be called from an uninterruptible phase (modesetting) and allows
 * any flushes to be pipelined (for pageflips).
 */
struct i915_vma *
i915_gem_object_pin_to_display_plane(struct drm_i915_gem_object *obj,
                                     u32 alignment,
                                     const struct i915_ggtt_view *view)
{
        struct i915_vma *vma;
        u32 old_read_domains, old_write_domain;
        int ret;

        /* Mark the pin_display early so that we account for the
         * display coherency whilst setting up the cache domains.
         */
        obj->pin_display++;

        /* The display engine is not coherent with the LLC cache on gen6.  As
         * a result, we make sure that the pinning that is about to occur is
         * done with uncached PTEs. This is lowest common denominator for all
         * chipsets.
         *
         * However for gen6+, we could do better by using the GFDT bit instead
         * of uncaching, which would allow us to flush all the LLC-cached data
         * with that bit in the PTE to main memory with just one PIPE_CONTROL.
         */
        ret = i915_gem_object_set_cache_level(obj,
                                              HAS_WT(obj->base.dev) ? I915_CACHE_WT : I915_CACHE_NONE);
        if (ret) {
                vma = ERR_PTR(ret);
                goto err_unpin_display;
        }

        /* As the user may map the buffer once pinned in the display plane
         * (e.g. libkms for the bootup splash), we have to ensure that we
         * always use map_and_fenceable for all scanout buffers. However,
         * it may simply be too big to fit into mappable, in which case
         * put it anyway and hope that userspace can cope (but always first
         * try to preserve the existing ABI).
         */
        vma = ERR_PTR(-ENOSPC);
        if (view->type == I915_GGTT_VIEW_NORMAL)
                vma = i915_gem_object_ggtt_pin(obj, view, 0, alignment,
                                               PIN_MAPPABLE | PIN_NONBLOCK);
        if (IS_ERR(vma))
                vma = i915_gem_object_ggtt_pin(obj, view, 0, alignment, 0);
        if (IS_ERR(vma))
                goto err_unpin_display;

        vma->display_alignment = max_t(u64, vma->display_alignment, alignment);

        WARN_ON(obj->pin_display > i915_vma_pin_count(vma));

        i915_gem_object_flush_cpu_write_domain(obj);

        old_write_domain = obj->base.write_domain;
        old_read_domains = obj->base.read_domains;

        /* It should now be out of any other write domains, and we can update
         * the domain values for our changes.
         */
        obj->base.write_domain = 0;
        obj->base.read_domains |= I915_GEM_DOMAIN_GTT;

        trace_i915_gem_object_change_domain(obj,
                                            old_read_domains,
                                            old_write_domain);

        return vma;

err_unpin_display:
        obj->pin_display--;
        return vma;
}

void
i915_gem_object_unpin_from_display_plane(struct i915_vma *vma)
{
        if (WARN_ON(vma->obj->pin_display == 0))
                return;

        if (--vma->obj->pin_display == 0)
                vma->display_alignment = 0;

        /* Bump the LRU to try and avoid premature eviction whilst flipping  */
        if (!i915_vma_is_active(vma))
                list_move_tail(&vma->vm_link, &vma->vm->inactive_list);

        i915_vma_unpin(vma);
        WARN_ON(vma->obj->pin_display > i915_vma_pin_count(vma));
}

/**
 * Moves a single object to the CPU read, and possibly write domain.
 * @obj: object to act on
 * @write: requesting write or read-only access
 *
 * This function returns when the move is complete, including waiting on
 * flushes to occur.
 */
int
i915_gem_object_set_to_cpu_domain(struct drm_i915_gem_object *obj, bool write)
{
        uint32_t old_write_domain, old_read_domains;
        int ret;

        ret = i915_gem_object_wait_rendering(obj, !write);
        if (ret)
                return ret;

        if (obj->base.write_domain == I915_GEM_DOMAIN_CPU)
                return 0;

        i915_gem_object_flush_gtt_write_domain(obj);

        old_write_domain = obj->base.write_domain;
        old_read_domains = obj->base.read_domains;

        /* Flush the CPU cache if it's still invalid. */
        if ((obj->base.read_domains & I915_GEM_DOMAIN_CPU) == 0) {
                i915_gem_clflush_object(obj, false);

                obj->base.read_domains |= I915_GEM_DOMAIN_CPU;
        }

        /* It should now be out of any other write domains, and we can update
         * the domain values for our changes.
         */
        BUG_ON((obj->base.write_domain & ~I915_GEM_DOMAIN_CPU) != 0);

        /* If we're writing through the CPU, then the GPU read domains will
         * need to be invalidated at next use.
         */
        if (write) {
                obj->base.read_domains = I915_GEM_DOMAIN_CPU;
                obj->base.write_domain = I915_GEM_DOMAIN_CPU;
        }

        trace_i915_gem_object_change_domain(obj,
                                            old_read_domains,
                                            old_write_domain);

        return 0;
}

/* Throttle our rendering by waiting until the ring has completed our requests
 * emitted over 20 msec ago.
 *
 * Note that if we were to use the current jiffies each time around the loop,
 * we wouldn't escape the function with any frames outstanding if the time to
 * render a frame was over 20ms.
 *
 * This should get us reasonable parallelism between CPU and GPU but also
 * relatively low latency when blocking on a particular request to finish.
 */
static int
i915_gem_ring_throttle(struct drm_device *dev, struct drm_file *file)
{
        struct drm_i915_private *dev_priv = to_i915(dev);
        struct drm_i915_file_private *file_priv = file->driver_priv;
        unsigned long recent_enough = jiffies - DRM_I915_THROTTLE_JIFFIES;
        struct drm_i915_gem_request *request, *target = NULL;
        int ret;

        ret = i915_gem_wait_for_error(&dev_priv->gpu_error);
        if (ret)
                return ret;

        /* ABI: return -EIO if already wedged */
        if (i915_terminally_wedged(&dev_priv->gpu_error))
                return -EIO;

        spin_lock(&file_priv->mm.lock);
        list_for_each_entry(request, &file_priv->mm.request_list, client_list) {
                if (time_after_eq(request->emitted_jiffies, recent_enough))
                        break;

                /*
                 * Note that the request might not have been submitted yet.
                 * In which case emitted_jiffies will be zero.
                 */
                if (!request->emitted_jiffies)
                        continue;

                target = request;
        }
        if (target)
                i915_gem_request_get(target);
        spin_unlock(&file_priv->mm.lock);

        if (target == NULL)
                return 0;

        ret = i915_wait_request(target, I915_WAIT_INTERRUPTIBLE, NULL, NULL);
        i915_gem_request_put(target);

        return ret;
}

static bool
i915_vma_misplaced(struct i915_vma *vma, u64 size, u64 alignment, u64 flags)
{
        if (!drm_mm_node_allocated(&vma->node))
                return false;

        if (vma->node.size < size)
                return true;

        if (alignment && vma->node.start & (alignment - 1))
                return true;

        if (flags & PIN_MAPPABLE && !i915_vma_is_map_and_fenceable(vma))
                return true;

        if (flags & PIN_OFFSET_BIAS &&
            vma->node.start < (flags & PIN_OFFSET_MASK))
                return true;

        if (flags & PIN_OFFSET_FIXED &&
            vma->node.start != (flags & PIN_OFFSET_MASK))
                return true;

        return false;
}

void __i915_vma_set_map_and_fenceable(struct i915_vma *vma)
{
        struct drm_i915_gem_object *obj = vma->obj;
        struct drm_i915_private *dev_priv = to_i915(obj->base.dev);
        bool mappable, fenceable;
        u32 fence_size, fence_alignment;

        fence_size = i915_gem_get_ggtt_size(dev_priv,
                                            vma->size,
                                            i915_gem_object_get_tiling(obj));
        fence_alignment = i915_gem_get_ggtt_alignment(dev_priv,
                                                      vma->size,
                                                      i915_gem_object_get_tiling(obj),
                                                      true);

        fenceable = (vma->node.size == fence_size &&
                     (vma->node.start & (fence_alignment - 1)) == 0);

        mappable = (vma->node.start + fence_size <=
                    dev_priv->ggtt.mappable_end);

        if (mappable && fenceable)
                vma->flags |= I915_VMA_CAN_FENCE;
        else
                vma->flags &= ~I915_VMA_CAN_FENCE;
}

int __i915_vma_do_pin(struct i915_vma *vma,
                      u64 size, u64 alignment, u64 flags)
{
        unsigned int bound = vma->flags;
        int ret;

        GEM_BUG_ON((flags & (PIN_GLOBAL | PIN_USER)) == 0);
        GEM_BUG_ON((flags & PIN_GLOBAL) && !i915_vma_is_ggtt(vma));

        if (WARN_ON(bound & I915_VMA_PIN_OVERFLOW)) {
                ret = -EBUSY;
                goto err;
        }

        if ((bound & I915_VMA_BIND_MASK) == 0) {
                ret = i915_vma_insert(vma, size, alignment, flags);
                if (ret)
                        goto err;
        }

        ret = i915_vma_bind(vma, vma->obj->cache_level, flags);
        if (ret)
                goto err;

        if ((bound ^ vma->flags) & I915_VMA_GLOBAL_BIND)
                __i915_vma_set_map_and_fenceable(vma);

        GEM_BUG_ON(i915_vma_misplaced(vma, size, alignment, flags));
        return 0;

err:
        __i915_vma_unpin(vma);
        return ret;
}

struct i915_vma *
i915_gem_object_ggtt_pin(struct drm_i915_gem_object *obj,
                         const struct i915_ggtt_view *view,
                         u64 size,
                         u64 alignment,
                         u64 flags)
{
        struct i915_address_space *vm = &to_i915(obj->base.dev)->ggtt.base;
        struct i915_vma *vma;
        int ret;

        vma = i915_gem_obj_lookup_or_create_vma(obj, vm, view);
        if (IS_ERR(vma))
                return vma;

        if (i915_vma_misplaced(vma, size, alignment, flags)) {
                if (flags & PIN_NONBLOCK &&
                    (i915_vma_is_pinned(vma) || i915_vma_is_active(vma)))
                        return ERR_PTR(-ENOSPC);

                WARN(i915_vma_is_pinned(vma),
                     "bo is already pinned in ggtt with incorrect alignment:"
                     " offset=%08x, req.alignment=%llx,"
                     " req.map_and_fenceable=%d, vma->map_and_fenceable=%d\n",
                     i915_ggtt_offset(vma), alignment,
                     !!(flags & PIN_MAPPABLE),
                     i915_vma_is_map_and_fenceable(vma));
                ret = i915_vma_unbind(vma);
                if (ret)
                        return ERR_PTR(ret);
        }

        ret = i915_vma_pin(vma, size, alignment, flags | PIN_GLOBAL);
        if (ret)
                return ERR_PTR(ret);

        return vma;
}

static __always_inline unsigned int __busy_read_flag(unsigned int id)
{
        /* Note that we could alias engines in the execbuf API, but
         * that would be very unwise as it prevents userspace from
         * fine control over engine selection. Ahem.
         *
         * This should be something like EXEC_MAX_ENGINE instead of
         * I915_NUM_ENGINES.
         */
        BUILD_BUG_ON(I915_NUM_ENGINES > 16);
        return 0x10000 << id;
}

static __always_inline unsigned int __busy_write_id(unsigned int id)
{
        /* The uABI guarantees an active writer is also amongst the read
         * engines. This would be true if we accessed the activity tracking
         * under the lock, but as we perform the lookup of the object and
         * its activity locklessly we can not guarantee that the last_write
         * being active implies that we have set the same engine flag from
         * last_read - hence we always set both read and write busy for
         * last_write.
         */
        return id | __busy_read_flag(id);
}

static __always_inline unsigned int
__busy_set_if_active(const struct i915_gem_active *active,
                     unsigned int (*flag)(unsigned int id))
{
        struct drm_i915_gem_request *request;

        request = rcu_dereference(active->request);
        if (!request || i915_gem_request_completed(request))
                return 0;

        /* This is racy. See __i915_gem_active_get_rcu() for an in detail
         * discussion of how to handle the race correctly, but for reporting
         * the busy state we err on the side of potentially reporting the
         * wrong engine as being busy (but we guarantee that the result
         * is at least self-consistent).
         *
         * As we use SLAB_DESTROY_BY_RCU, the request may be reallocated
         * whilst we are inspecting it, even under the RCU read lock as we are.
         * This means that there is a small window for the engine and/or the
         * seqno to have been overwritten. The seqno will always be in the
         * future compared to the intended, and so we know that if that
         * seqno is idle (on whatever engine) our request is idle and the
         * return 0 above is correct.
         *
         * The issue is that if the engine is switched, it is just as likely
         * to report that it is busy (but since the switch happened, we know
         * the request should be idle). So there is a small chance that a busy
         * result is actually the wrong engine.
         *
         * So why don't we care?
         *
         * For starters, the busy ioctl is a heuristic that is by definition
         * racy. Even with perfect serialisation in the driver, the hardware
         * state is constantly advancing - the state we report to the user
         * is stale.
         *
         * The critical information for the busy-ioctl is whether the object
         * is idle as userspace relies on that to detect whether its next
         * access will stall, or if it has missed submitting commands to
         * the hardware allowing the GPU to stall. We never generate a
         * false-positive for idleness, thus busy-ioctl is reliable at the
         * most fundamental level, and we maintain the guarantee that a
         * busy object left to itself will eventually become idle (and stay
         * idle!).
         *
         * We allow ourselves the leeway of potentially misreporting the busy
         * state because that is an optimisation heuristic that is constantly
         * in flux. Being quickly able to detect the busy/idle state is much
         * more important than accurate logging of exactly which engines were
         * busy.
         *
         * For accuracy in reporting the engine, we could use
         *
         *      result = 0;
         *      request = __i915_gem_active_get_rcu(active);
         *      if (request) {
         *              if (!i915_gem_request_completed(request))
         *                      result = flag(request->engine->exec_id);
         *              i915_gem_request_put(request);
         *      }
         *
         * but that still remains susceptible to both hardware and userspace
         * races. So we accept making the result of that race slightly worse,
         * given the rarity of the race and its low impact on the result.
         */
        return flag(READ_ONCE(request->engine->exec_id));
}

static __always_inline unsigned int
busy_check_reader(const struct i915_gem_active *active)
{
        return __busy_set_if_active(active, __busy_read_flag);
}

static __always_inline unsigned int
busy_check_writer(const struct i915_gem_active *active)
{
        return __busy_set_if_active(active, __busy_write_id);
}

int
i915_gem_busy_ioctl(struct drm_device *dev, void *data,
                    struct drm_file *file)
{
        struct drm_i915_gem_busy *args = data;
        struct drm_i915_gem_object *obj;
        unsigned long active;

        obj = i915_gem_object_lookup(file, args->handle);
        if (!obj)
                return -ENOENT;

        args->busy = 0;
        active = __I915_BO_ACTIVE(obj);
        if (active) {
                int idx;

                /* Yes, the lookups are intentionally racy.
                 *
                 * First, we cannot simply rely on __I915_BO_ACTIVE. We have
                 * to regard the value as stale and as our ABI guarantees
                 * forward progress, we confirm the status of each active
                 * request with the hardware.
                 *
                 * Even though we guard the pointer lookup by RCU, that only
                 * guarantees that the pointer and its contents remain
                 * dereferencable and does *not* mean that the request we
                 * have is the same as the one being tracked by the object.
                 *
                 * Consider that we lookup the request just as it is being
                 * retired and freed. We take a local copy of the pointer,
                 * but before we add its engine into the busy set, the other
                 * thread reallocates it and assigns it to a task on another
                 * engine with a fresh and incomplete seqno. Guarding against
                 * that requires careful serialisation and reference counting,
                 * i.e. using __i915_gem_active_get_request_rcu(). We don't,
                 * instead we expect that if the result is busy, which engines
                 * are busy is not completely reliable - we only guarantee
                 * that the object was busy.
                 */
                rcu_read_lock();

                for_each_active(active, idx)
                        args->busy |= busy_check_reader(&obj->last_read[idx]);

                /* For ABI sanity, we only care that the write engine is in
                 * the set of read engines. This should be ensured by the
                 * ordering of setting last_read/last_write in
                 * i915_vma_move_to_active(), and then in reverse in retire.
                 * However, for good measure, we always report the last_write
                 * request as a busy read as well as being a busy write.
                 *
                 * We don't care that the set of active read/write engines
                 * may change during construction of the result, as it is
                 * equally liable to change before userspace can inspect
                 * the result.
                 */
                args->busy |= busy_check_writer(&obj->last_write);

                rcu_read_unlock();
        }

        i915_gem_object_put_unlocked(obj);
        return 0;
}

int
i915_gem_throttle_ioctl(struct drm_device *dev, void *data,
                        struct drm_file *file_priv)
{
        return i915_gem_ring_throttle(dev, file_priv);
}

int
i915_gem_madvise_ioctl(struct drm_device *dev, void *data,
                       struct drm_file *file_priv)
{
        struct drm_i915_private *dev_priv = to_i915(dev);
        struct drm_i915_gem_madvise *args = data;
        struct drm_i915_gem_object *obj;
        int ret;

        switch (args->madv) {
        case I915_MADV_DONTNEED:
        case I915_MADV_WILLNEED:
            break;
        default:
            return -EINVAL;
        }

        ret = i915_mutex_lock_interruptible(dev);
        if (ret)
                return ret;

        obj = i915_gem_object_lookup(file_priv, args->handle);
        if (!obj) {
                ret = -ENOENT;
                goto unlock;
        }

        if (obj->pages &&
            i915_gem_object_is_tiled(obj) &&
            dev_priv->quirks & QUIRK_PIN_SWIZZLED_PAGES) {
                if (obj->madv == I915_MADV_WILLNEED)
                        i915_gem_object_unpin_pages(obj);
                if (args->madv == I915_MADV_WILLNEED)
                        i915_gem_object_pin_pages(obj);
        }

        if (obj->madv != __I915_MADV_PURGED)
                obj->madv = args->madv;

        /* if the object is no longer attached, discard its backing storage */
        if (obj->madv == I915_MADV_DONTNEED && obj->pages == NULL)
                i915_gem_object_truncate(obj);

        args->retained = obj->madv != __I915_MADV_PURGED;

        i915_gem_object_put(obj);
unlock:
        mutex_unlock(&dev->struct_mutex);
        return ret;
}

void i915_gem_object_init(struct drm_i915_gem_object *obj,
                          const struct drm_i915_gem_object_ops *ops)
{
        int i;

        INIT_LIST_HEAD(&obj->global_list);
        for (i = 0; i < I915_NUM_ENGINES; i++)
                init_request_active(&obj->last_read[i],
                                    i915_gem_object_retire__read);
        init_request_active(&obj->last_write,
                            i915_gem_object_retire__write);
        INIT_LIST_HEAD(&obj->obj_exec_link);
        INIT_LIST_HEAD(&obj->vma_list);
        INIT_LIST_HEAD(&obj->batch_pool_link);

        obj->ops = ops;

        obj->frontbuffer_ggtt_origin = ORIGIN_GTT;
        obj->madv = I915_MADV_WILLNEED;

        i915_gem_info_add_obj(to_i915(obj->base.dev), obj->base.size);
}

static const struct drm_i915_gem_object_ops i915_gem_object_ops = {
        .flags = I915_GEM_OBJECT_HAS_STRUCT_PAGE,
        .get_pages = i915_gem_object_get_pages_gtt,
        .put_pages = i915_gem_object_put_pages_gtt,
};

struct drm_i915_gem_object *i915_gem_object_create(struct drm_device *dev,
                                                  size_t size)
{
        struct drm_i915_gem_object *obj;
        struct address_space *mapping;
        gfp_t mask;
        int ret;

        obj = i915_gem_object_alloc(dev);
        if (obj == NULL)
                return ERR_PTR(-ENOMEM);

        ret = drm_gem_object_init(dev, &obj->base, size);
        if (ret)
                goto fail;

        mask = GFP_HIGHUSER | __GFP_RECLAIMABLE;
        if (IS_CRESTLINE(dev) || IS_BROADWATER(dev)) {
                /* 965gm cannot relocate objects above 4GiB. */
                mask &= ~__GFP_HIGHMEM;
                mask |= __GFP_DMA32;
        }

        mapping = obj->base.filp->f_mapping;
        mapping_set_gfp_mask(mapping, mask);

        i915_gem_object_init(obj, &i915_gem_object_ops);

        obj->base.write_domain = I915_GEM_DOMAIN_CPU;
        obj->base.read_domains = I915_GEM_DOMAIN_CPU;

        if (HAS_LLC(dev)) {
                /* On some devices, we can have the GPU use the LLC (the CPU
                 * cache) for about a 10% performance improvement
                 * compared to uncached.  Graphics requests other than
                 * display scanout are coherent with the CPU in
                 * accessing this cache.  This means in this mode we
                 * don't need to clflush on the CPU side, and on the
                 * GPU side we only need to flush internal caches to
                 * get data visible to the CPU.
                 *
                 * However, we maintain the display planes as UC, and so
                 * need to rebind when first used as such.
                 */
                obj->cache_level = I915_CACHE_LLC;
        } else
                obj->cache_level = I915_CACHE_NONE;

        trace_i915_gem_object_create(obj);

        return obj;

fail:
        i915_gem_object_free(obj);

        return ERR_PTR(ret);
}

static bool discard_backing_storage(struct drm_i915_gem_object *obj)
{
        /* If we are the last user of the backing storage (be it shmemfs
         * pages or stolen etc), we know that the pages are going to be
         * immediately released. In this case, we can then skip copying
         * back the contents from the GPU.
         */

        if (obj->madv != I915_MADV_WILLNEED)
                return false;

        if (obj->base.filp == NULL)
                return true;

        /* At first glance, this looks racy, but then again so would be
         * userspace racing mmap against close. However, the first external
         * reference to the filp can only be obtained through the
         * i915_gem_mmap_ioctl() which safeguards us against the user
         * acquiring such a reference whilst we are in the middle of
         * freeing the object.
         */
        return atomic_long_read(&obj->base.filp->f_count) == 1;
}

void i915_gem_free_object(struct drm_gem_object *gem_obj)
{
        struct drm_i915_gem_object *obj = to_intel_bo(gem_obj);
        struct drm_device *dev = obj->base.dev;
        struct drm_i915_private *dev_priv = to_i915(dev);
        struct i915_vma *vma, *next;

        intel_runtime_pm_get(dev_priv);

        trace_i915_gem_object_destroy(obj);

        /* All file-owned VMA should have been released by this point through
         * i915_gem_close_object(), or earlier by i915_gem_context_close().
         * However, the object may also be bound into the global GTT (e.g.
         * older GPUs without per-process support, or for direct access through
         * the GTT either for the user or for scanout). Those VMA still need to
         * unbound now.
         */
        list_for_each_entry_safe(vma, next, &obj->vma_list, obj_link) {
                GEM_BUG_ON(!i915_vma_is_ggtt(vma));
                GEM_BUG_ON(i915_vma_is_active(vma));
                vma->flags &= ~I915_VMA_PIN_MASK;
                i915_vma_close(vma);
        }
        GEM_BUG_ON(obj->bind_count);

        /* Stolen objects don't hold a ref, but do hold pin count. Fix that up
         * before progressing. */
        if (obj->stolen)
                i915_gem_object_unpin_pages(obj);

        WARN_ON(atomic_read(&obj->frontbuffer_bits));

        if (obj->pages && obj->madv == I915_MADV_WILLNEED &&
            dev_priv->quirks & QUIRK_PIN_SWIZZLED_PAGES &&
            i915_gem_object_is_tiled(obj))
                i915_gem_object_unpin_pages(obj);

        if (WARN_ON(obj->pages_pin_count))
                obj->pages_pin_count = 0;
        if (discard_backing_storage(obj))
                obj->madv = I915_MADV_DONTNEED;
        i915_gem_object_put_pages(obj);

        BUG_ON(obj->pages);

        if (obj->base.import_attach)
                drm_prime_gem_destroy(&obj->base, NULL);

        if (obj->ops->release)
                obj->ops->release(obj);

        drm_gem_object_release(&obj->base);
        i915_gem_info_remove_obj(dev_priv, obj->base.size);

        kfree(obj->bit_17);
        i915_gem_object_free(obj);

        intel_runtime_pm_put(dev_priv);
}

int i915_gem_suspend(struct drm_device *dev)
{
        struct drm_i915_private *dev_priv = to_i915(dev);
        int ret;

        intel_suspend_gt_powersave(dev_priv);

        mutex_lock(&dev->struct_mutex);

        /* We have to flush all the executing contexts to main memory so
         * that they can saved in the hibernation image. To ensure the last
         * context image is coherent, we have to switch away from it. That
         * leaves the dev_priv->kernel_context still active when
         * we actually suspend, and its image in memory may not match the GPU
         * state. Fortunately, the kernel_context is disposable and we do
         * not rely on its state.
         */
        ret = i915_gem_switch_to_kernel_context(dev_priv);
        if (ret)
                goto err;

        ret = i915_gem_wait_for_idle(dev_priv,
                                     I915_WAIT_INTERRUPTIBLE |
                                     I915_WAIT_LOCKED);
        if (ret)
                goto err;

        i915_gem_retire_requests(dev_priv);

        i915_gem_context_lost(dev_priv);
        mutex_unlock(&dev->struct_mutex);

        cancel_delayed_work_sync(&dev_priv->gpu_error.hangcheck_work);
        cancel_delayed_work_sync(&dev_priv->gt.retire_work);
        flush_delayed_work(&dev_priv->gt.idle_work);

        /* Assert that we sucessfully flushed all the work and
         * reset the GPU back to its idle, low power state.
         */
        WARN_ON(dev_priv->gt.awake);

        return 0;

err:
        mutex_unlock(&dev->struct_mutex);
        return ret;
}

void i915_gem_resume(struct drm_device *dev)
{
        struct drm_i915_private *dev_priv = to_i915(dev);

        mutex_lock(&dev->struct_mutex);
        i915_gem_restore_gtt_mappings(dev);

        /* As we didn't flush the kernel context before suspend, we cannot
         * guarantee that the context image is complete. So let's just reset
         * it and start again.
         */
        dev_priv->gt.resume(dev_priv);

        mutex_unlock(&dev->struct_mutex);
}

void i915_gem_init_swizzling(struct drm_device *dev)
{
        struct drm_i915_private *dev_priv = to_i915(dev);

        if (INTEL_INFO(dev)->gen < 5 ||
            dev_priv->mm.bit_6_swizzle_x == I915_BIT_6_SWIZZLE_NONE)
                return;

        I915_WRITE(DISP_ARB_CTL, I915_READ(DISP_ARB_CTL) |
                                 DISP_TILE_SURFACE_SWIZZLING);

        if (IS_GEN5(dev))
                return;

        I915_WRITE(TILECTL, I915_READ(TILECTL) | TILECTL_SWZCTL);
        if (IS_GEN6(dev))
                I915_WRITE(ARB_MODE, _MASKED_BIT_ENABLE(ARB_MODE_SWIZZLE_SNB));
        else if (IS_GEN7(dev))
                I915_WRITE(ARB_MODE, _MASKED_BIT_ENABLE(ARB_MODE_SWIZZLE_IVB));
        else if (IS_GEN8(dev))
                I915_WRITE(GAMTARBMODE, _MASKED_BIT_ENABLE(ARB_MODE_SWIZZLE_BDW));
        else
                BUG();
}

static void init_unused_ring(struct drm_device *dev, u32 base)
{
        struct drm_i915_private *dev_priv = to_i915(dev);

        I915_WRITE(RING_CTL(base), 0);
        I915_WRITE(RING_HEAD(base), 0);
        I915_WRITE(RING_TAIL(base), 0);
        I915_WRITE(RING_START(base), 0);
}

static void init_unused_rings(struct drm_device *dev)
{
        if (IS_I830(dev)) {
                init_unused_ring(dev, PRB1_BASE);
                init_unused_ring(dev, SRB0_BASE);
                init_unused_ring(dev, SRB1_BASE);
                init_unused_ring(dev, SRB2_BASE);
                init_unused_ring(dev, SRB3_BASE);
        } else if (IS_GEN2(dev)) {
                init_unused_ring(dev, SRB0_BASE);
                init_unused_ring(dev, SRB1_BASE);
        } else if (IS_GEN3(dev)) {
                init_unused_ring(dev, PRB1_BASE);
                init_unused_ring(dev, PRB2_BASE);
        }
}

int
i915_gem_init_hw(struct drm_device *dev)
{
        struct drm_i915_private *dev_priv = to_i915(dev);
        struct intel_engine_cs *engine;
        int ret;

        /* Double layer security blanket, see i915_gem_init() */
        intel_uncore_forcewake_get(dev_priv, FORCEWAKE_ALL);

        if (HAS_EDRAM(dev) && INTEL_GEN(dev_priv) < 9)
                I915_WRITE(HSW_IDICR, I915_READ(HSW_IDICR) | IDIHASHMSK(0xf));

        if (IS_HASWELL(dev))
                I915_WRITE(MI_PREDICATE_RESULT_2, IS_HSW_GT3(dev) ?
                           LOWER_SLICE_ENABLED : LOWER_SLICE_DISABLED);

        if (HAS_PCH_NOP(dev)) {
                if (IS_IVYBRIDGE(dev)) {
                        u32 temp = I915_READ(GEN7_MSG_CTL);
                        temp &= ~(WAIT_FOR_PCH_FLR_ACK | WAIT_FOR_PCH_RESET_ACK);
                        I915_WRITE(GEN7_MSG_CTL, temp);
                } else if (INTEL_INFO(dev)->gen >= 7) {
                        u32 temp = I915_READ(HSW_NDE_RSTWRN_OPT);
                        temp &= ~RESET_PCH_HANDSHAKE_ENABLE;
                        I915_WRITE(HSW_NDE_RSTWRN_OPT, temp);
                }
        }

        i915_gem_init_swizzling(dev);

        /*
         * At least 830 can leave some of the unused rings
         * "active" (ie. head != tail) after resume which
         * will prevent c3 entry. Makes sure all unused rings
         * are totally idle.
         */
        init_unused_rings(dev);

        BUG_ON(!dev_priv->kernel_context);

        ret = i915_ppgtt_init_hw(dev);
        if (ret) {
                DRM_ERROR("PPGTT enable HW failed %d\n", ret);
                goto out;
        }

        /* Need to do basic initialisation of all rings first: */
        for_each_engine(engine, dev_priv) {
                ret = engine->init_hw(engine);
                if (ret)
                        goto out;
        }

        intel_mocs_init_l3cc_table(dev);

        /* We can't enable contexts until all firmware is loaded */
        ret = intel_guc_setup(dev);
        if (ret)
                goto out;

out:
        intel_uncore_forcewake_put(dev_priv, FORCEWAKE_ALL);
        return ret;
}

bool intel_sanitize_semaphores(struct drm_i915_private *dev_priv, int value)
{
        if (INTEL_INFO(dev_priv)->gen < 6)
                return false;

        /* TODO: make semaphores and Execlists play nicely together */
        if (i915.enable_execlists)
                return false;

        if (value >= 0)
                return value;

#ifdef CONFIG_INTEL_IOMMU
        /* Enable semaphores on SNB when IO remapping is off */
        if (INTEL_INFO(dev_priv)->gen == 6 && intel_iommu_gfx_mapped)
                return false;
#endif

        return true;
}

int i915_gem_init(struct drm_device *dev)
{
        struct drm_i915_private *dev_priv = to_i915(dev);
        int ret;

        mutex_lock(&dev->struct_mutex);

        if (!i915.enable_execlists) {
                dev_priv->gt.resume = intel_legacy_submission_resume;
                dev_priv->gt.cleanup_engine = intel_engine_cleanup;
        } else {
                dev_priv->gt.resume = intel_lr_context_resume;
                dev_priv->gt.cleanup_engine = intel_logical_ring_cleanup;
        }

        /* This is just a security blanket to placate dragons.
         * On some systems, we very sporadically observe that the first TLBs
         * used by the CS may be stale, despite us poking the TLB reset. If
         * we hold the forcewake during initialisation these problems
         * just magically go away.
         */
        intel_uncore_forcewake_get(dev_priv, FORCEWAKE_ALL);

        i915_gem_init_userptr(dev_priv);

        ret = i915_gem_init_ggtt(dev_priv);
        if (ret)
                goto out_unlock;

        ret = i915_gem_context_init(dev);
        if (ret)
                goto out_unlock;

        ret = intel_engines_init(dev);
        if (ret)
                goto out_unlock;

        ret = i915_gem_init_hw(dev);
        if (ret == -EIO) {
                /* Allow engine initialisation to fail by marking the GPU as
                 * wedged. But we only want to do this where the GPU is angry,
                 * for all other failure, such as an allocation failure, bail.
                 */
                DRM_ERROR("Failed to initialize GPU, declaring it wedged\n");
                i915_gem_set_wedged(dev_priv);
                ret = 0;
        }

out_unlock:
        intel_uncore_forcewake_put(dev_priv, FORCEWAKE_ALL);
        mutex_unlock(&dev->struct_mutex);

        return ret;
}

void
i915_gem_cleanup_engines(struct drm_device *dev)
{
        struct drm_i915_private *dev_priv = to_i915(dev);
        struct intel_engine_cs *engine;

        for_each_engine(engine, dev_priv)
                dev_priv->gt.cleanup_engine(engine);
}

static void
init_engine_lists(struct intel_engine_cs *engine)
{
        INIT_LIST_HEAD(&engine->request_list);
}

void
i915_gem_load_init_fences(struct drm_i915_private *dev_priv)
{
        struct drm_device *dev = &dev_priv->drm;
        int i;

        if (INTEL_INFO(dev_priv)->gen >= 7 && !IS_VALLEYVIEW(dev_priv) &&
            !IS_CHERRYVIEW(dev_priv))
                dev_priv->num_fence_regs = 32;
        else if (INTEL_INFO(dev_priv)->gen >= 4 || IS_I945G(dev_priv) ||
                 IS_I945GM(dev_priv) || IS_G33(dev_priv))
                dev_priv->num_fence_regs = 16;
        else
                dev_priv->num_fence_regs = 8;

        if (intel_vgpu_active(dev_priv))
                dev_priv->num_fence_regs =
                                I915_READ(vgtif_reg(avail_rs.fence_num));

        /* Initialize fence registers to zero */
        for (i = 0; i < dev_priv->num_fence_regs; i++) {
                struct drm_i915_fence_reg *fence = &dev_priv->fence_regs[i];

                fence->i915 = dev_priv;
                fence->id = i;
                list_add_tail(&fence->link, &dev_priv->mm.fence_list);
        }
        i915_gem_restore_fences(dev);

        i915_gem_detect_bit_6_swizzle(dev);
}

void
i915_gem_load_init(struct drm_device *dev)
{
        struct drm_i915_private *dev_priv = to_i915(dev);
        int i;

        dev_priv->objects =
                kmem_cache_create("i915_gem_object",
                                  sizeof(struct drm_i915_gem_object), 0,
                                  SLAB_HWCACHE_ALIGN,
                                  NULL);
        dev_priv->vmas =
                kmem_cache_create("i915_gem_vma",
                                  sizeof(struct i915_vma), 0,
                                  SLAB_HWCACHE_ALIGN,
                                  NULL);
        dev_priv->requests =
                kmem_cache_create("i915_gem_request",
                                  sizeof(struct drm_i915_gem_request), 0,
                                  SLAB_HWCACHE_ALIGN |
                                  SLAB_RECLAIM_ACCOUNT |
                                  SLAB_DESTROY_BY_RCU,
                                  NULL);

        INIT_LIST_HEAD(&dev_priv->context_list);
        INIT_LIST_HEAD(&dev_priv->mm.unbound_list);
        INIT_LIST_HEAD(&dev_priv->mm.bound_list);
        INIT_LIST_HEAD(&dev_priv->mm.fence_list);
        for (i = 0; i < I915_NUM_ENGINES; i++)
                init_engine_lists(&dev_priv->engine[i]);
        INIT_DELAYED_WORK(&dev_priv->gt.retire_work,
                          i915_gem_retire_work_handler);
        INIT_DELAYED_WORK(&dev_priv->gt.idle_work,
                          i915_gem_idle_work_handler);
        init_waitqueue_head(&dev_priv->gpu_error.wait_queue);
        init_waitqueue_head(&dev_priv->gpu_error.reset_queue);

        dev_priv->relative_constants_mode = I915_EXEC_CONSTANTS_REL_GENERAL;

        init_waitqueue_head(&dev_priv->pending_flip_queue);

        dev_priv->mm.interruptible = true;

        atomic_set(&dev_priv->mm.bsd_engine_dispatch_index, 0);

        spin_lock_init(&dev_priv->fb_tracking.lock);
}

void i915_gem_load_cleanup(struct drm_device *dev)
{
        struct drm_i915_private *dev_priv = to_i915(dev);

        kmem_cache_destroy(dev_priv->requests);
        kmem_cache_destroy(dev_priv->vmas);
        kmem_cache_destroy(dev_priv->objects);

        /* And ensure that our DESTROY_BY_RCU slabs are truly destroyed */
        rcu_barrier();
}

int i915_gem_freeze_late(struct drm_i915_private *dev_priv)
{
        struct drm_i915_gem_object *obj;
        struct list_head *phases[] = {
                &dev_priv->mm.unbound_list,
                &dev_priv->mm.bound_list,
                NULL
        }, **p;

        /* Called just before we write the hibernation image.
         *
         * We need to update the domain tracking to reflect that the CPU
         * will be accessing all the pages to create and restore from the
         * hibernation, and so upon restoration those pages will be in the
         * CPU domain.
         *
         * To make sure the hibernation image contains the latest state,
         * we update that state just before writing out the image.
         *
         * To try and reduce the hibernation image, we manually shrink
         * the objects as well.
         */

        i915_gem_shrink_all(dev_priv);

        for (p = phases; *p; p++) {
                list_for_each_entry(obj, *p, global_list) {
                        obj->base.read_domains = I915_GEM_DOMAIN_CPU;
                        obj->base.write_domain = I915_GEM_DOMAIN_CPU;
                }
        }

        return 0;
}

void i915_gem_release(struct drm_device *dev, struct drm_file *file)
{
        struct drm_i915_file_private *file_priv = file->driver_priv;
        struct drm_i915_gem_request *request;

        /* Clean up our request list when the client is going away, so that
         * later retire_requests won't dereference our soon-to-be-gone
         * file_priv.
         */
        spin_lock(&file_priv->mm.lock);
        list_for_each_entry(request, &file_priv->mm.request_list, client_list)
                request->file_priv = NULL;
        spin_unlock(&file_priv->mm.lock);

        if (!list_empty(&file_priv->rps.link)) {
                spin_lock(&to_i915(dev)->rps.client_lock);
                list_del(&file_priv->rps.link);
                spin_unlock(&to_i915(dev)->rps.client_lock);
        }
}

int i915_gem_open(struct drm_device *dev, struct drm_file *file)
{
        struct drm_i915_file_private *file_priv;
        int ret;

        DRM_DEBUG_DRIVER("\n");

        file_priv = kzalloc(sizeof(*file_priv), GFP_KERNEL);
        if (!file_priv)
                return -ENOMEM;

        file->driver_priv = file_priv;
        file_priv->dev_priv = to_i915(dev);
        file_priv->file = file;
        INIT_LIST_HEAD(&file_priv->rps.link);

        spin_lock_init(&file_priv->mm.lock);
        INIT_LIST_HEAD(&file_priv->mm.request_list);

        file_priv->bsd_engine = -1;

        ret = i915_gem_context_open(dev, file);
        if (ret)
                kfree(file_priv);

        return ret;
}

/**
 * i915_gem_track_fb - update frontbuffer tracking
 * @old: current GEM buffer for the frontbuffer slots
 * @new: new GEM buffer for the frontbuffer slots
 * @frontbuffer_bits: bitmask of frontbuffer slots
 *
 * This updates the frontbuffer tracking bits @frontbuffer_bits by clearing them
 * from @old and setting them in @new. Both @old and @new can be NULL.
 */
void i915_gem_track_fb(struct drm_i915_gem_object *old,
                       struct drm_i915_gem_object *new,
                       unsigned frontbuffer_bits)
{
        /* Control of individual bits within the mask are guarded by
         * the owning plane->mutex, i.e. we can never see concurrent
         * manipulation of individual bits. But since the bitfield as a whole
         * is updated using RMW, we need to use atomics in order to update
         * the bits.
         */
        BUILD_BUG_ON(INTEL_FRONTBUFFER_BITS_PER_PIPE * I915_MAX_PIPES >
                     sizeof(atomic_t) * BITS_PER_BYTE);

        if (old) {
                WARN_ON(!(atomic_read(&old->frontbuffer_bits) & frontbuffer_bits));
                atomic_andnot(frontbuffer_bits, &old->frontbuffer_bits);
        }

        if (new) {
                WARN_ON(atomic_read(&new->frontbuffer_bits) & frontbuffer_bits);
                atomic_or(frontbuffer_bits, &new->frontbuffer_bits);
        }
}

/* Like i915_gem_object_get_page(), but mark the returned page dirty */
struct page *
i915_gem_object_get_dirty_page(struct drm_i915_gem_object *obj, int n)
{
        struct page *page;

        /* Only default objects have per-page dirty tracking */
        if (WARN_ON(!i915_gem_object_has_struct_page(obj)))
                return NULL;

        page = i915_gem_object_get_page(obj, n);
        set_page_dirty(page);
        return page;
}

/* Allocate a new GEM object and fill it with the supplied data */
struct drm_i915_gem_object *
i915_gem_object_create_from_data(struct drm_device *dev,
                                 const void *data, size_t size)
{
        struct drm_i915_gem_object *obj;
        struct sg_table *sg;
        size_t bytes;
        int ret;

        obj = i915_gem_object_create(dev, round_up(size, PAGE_SIZE));
        if (IS_ERR(obj))
                return obj;

        ret = i915_gem_object_set_to_cpu_domain(obj, true);
        if (ret)
                goto fail;

        ret = i915_gem_object_get_pages(obj);
        if (ret)
                goto fail;

        i915_gem_object_pin_pages(obj);
        sg = obj->pages;
        bytes = sg_copy_from_buffer(sg->sgl, sg->nents, (void *)data, size);
        obj->dirty = 1;         /* Backing store is now out of date */
        i915_gem_object_unpin_pages(obj);

        if (WARN_ON(bytes != size)) {
                DRM_ERROR("Incomplete copy, wrote %zu of %zu", bytes, size);
                ret = -EFAULT;
                goto fail;
        }

        return obj;

fail:
        i915_gem_object_put(obj);
        return ERR_PTR(ret);
}