Merge tag 'xfs-rmap-for-linus-4.8-rc1' of git://git.kernel.org/pub/scm/linux/kernel...

[cascardo/linux.git] / drivers / vfio / pci / vfio_pci.c

diff --git a/drivers/vfio/pci/vfio_pci.c b/drivers/vfio/pci/vfio_pci.c
index 188b1ff..d624a52 100644 (file)
--- a/drivers/vfio/pci/vfio_pci.c
+++ b/drivers/vfio/pci/vfio_pci.c
@@ -110,6 +110,74 @@ static inline bool vfio_pci_is_vga(struct pci_dev *pdev)
        return (pdev->class >> 8) == PCI_CLASS_DISPLAY_VGA;
 }
 
+static void vfio_pci_probe_mmaps(struct vfio_pci_device *vdev)
+{
+       struct resource *res;
+       int bar;
+       struct vfio_pci_dummy_resource *dummy_res;
+
+       INIT_LIST_HEAD(&vdev->dummy_resources_list);
+
+       for (bar = PCI_STD_RESOURCES; bar <= PCI_STD_RESOURCE_END; bar++) {
+               res = vdev->pdev->resource + bar;
+
+               if (!IS_ENABLED(CONFIG_VFIO_PCI_MMAP))
+                       goto no_mmap;
+
+               if (!(res->flags & IORESOURCE_MEM))
+                       goto no_mmap;
+
+               /*
+                * The PCI core shouldn't set up a resource with a
+                * type but zero size. But there may be bugs that
+                * cause us to do that.
+                */
+               if (!resource_size(res))
+                       goto no_mmap;
+
+               if (resource_size(res) >= PAGE_SIZE) {
+                       vdev->bar_mmap_supported[bar] = true;
+                       continue;
+               }
+
+               if (!(res->start & ~PAGE_MASK)) {
+                       /*
+                        * Add a dummy resource to reserve the remainder
+                        * of the exclusive page in case that hot-add
+                        * device's bar is assigned into it.
+                        */
+                       dummy_res = kzalloc(sizeof(*dummy_res), GFP_KERNEL);
+                       if (dummy_res == NULL)
+                               goto no_mmap;
+
+                       dummy_res->resource.name = "vfio sub-page reserved";
+                       dummy_res->resource.start = res->end + 1;
+                       dummy_res->resource.end = res->start + PAGE_SIZE - 1;
+                       dummy_res->resource.flags = res->flags;
+                       if (request_resource(res->parent,
+                                               &dummy_res->resource)) {
+                               kfree(dummy_res);
+                               goto no_mmap;
+                       }
+                       dummy_res->index = bar;
+                       list_add(&dummy_res->res_next,
+                                       &vdev->dummy_resources_list);
+                       vdev->bar_mmap_supported[bar] = true;
+                       continue;
+               }
+               /*
+                * Here we don't handle the case when the BAR is not page
+                * aligned because we can't expect the BAR will be
+                * assigned into the same location in a page in guest
+                * when we passthrough the BAR. And it's hard to access
+                * this BAR in userspace because we have no way to get
+                * the BAR's location in a page.
+                */
+no_mmap:
+               vdev->bar_mmap_supported[bar] = false;
+       }
+}
+
 static void vfio_pci_try_bus_reset(struct vfio_pci_device *vdev);
 static void vfio_pci_disable(struct vfio_pci_device *vdev);
 
@@ -218,12 +286,15 @@ static int vfio_pci_enable(struct vfio_pci_device *vdev)
                }
        }
 
+       vfio_pci_probe_mmaps(vdev);
+
        return 0;
 }
 
 static void vfio_pci_disable(struct vfio_pci_device *vdev)
 {
        struct pci_dev *pdev = vdev->pdev;
+       struct vfio_pci_dummy_resource *dummy_res, *tmp;
        int i, bar;
 
        /* Stop the device from further DMA */
@@ -252,6 +323,13 @@ static void vfio_pci_disable(struct vfio_pci_device *vdev)
                vdev->barmap[bar] = NULL;
        }
 
+       list_for_each_entry_safe(dummy_res, tmp,
+                                &vdev->dummy_resources_list, res_next) {
+               list_del(&dummy_res->res_next);
+               release_resource(&dummy_res->resource);
+               kfree(dummy_res);
+       }
+
        vdev->needs_reset = true;
 
        /*
@@ -623,9 +701,7 @@ static long vfio_pci_ioctl(void *device_data,
 
                        info.flags = VFIO_REGION_INFO_FLAG_READ |
                                     VFIO_REGION_INFO_FLAG_WRITE;
-                       if (IS_ENABLED(CONFIG_VFIO_PCI_MMAP) &&
-                           pci_resource_flags(pdev, info.index) &
-                           IORESOURCE_MEM && info.size >= PAGE_SIZE) {
+                       if (vdev->bar_mmap_supported[info.index]) {
                                info.flags |= VFIO_REGION_INFO_FLAG_MMAP;
                                if (info.index == vdev->msix_bar) {
                                        ret = msix_sparse_mmap_cap(vdev, &caps);
@@ -1049,16 +1125,16 @@ static int vfio_pci_mmap(void *device_data, struct vm_area_struct *vma)
                return -EINVAL;
        if (index >= VFIO_PCI_ROM_REGION_INDEX)
                return -EINVAL;
-       if (!(pci_resource_flags(pdev, index) & IORESOURCE_MEM))
+       if (!vdev->bar_mmap_supported[index])
                return -EINVAL;
 
-       phys_len = pci_resource_len(pdev, index);
+       phys_len = PAGE_ALIGN(pci_resource_len(pdev, index));
        req_len = vma->vm_end - vma->vm_start;
        pgoff = vma->vm_pgoff &
                ((1U << (VFIO_PCI_OFFSET_SHIFT - PAGE_SHIFT)) - 1);
        req_start = pgoff << PAGE_SHIFT;
 
-       if (phys_len < PAGE_SIZE || req_start + req_len > phys_len)
+       if (req_start + req_len > phys_len)
                return -EINVAL;
 
        if (index == vdev->msix_bar) {