drivers/xen/grant-table.c

   1 /******************************************************************************
   2  * grant_table.c
   3  *
   4  * Granting foreign access to our memory reservation.
   5  *
   6  * Copyright (c) 2005-2006, Christopher Clark
   7  * Copyright (c) 2004-2005, K A Fraser
   8  *
   9  * This program is free software; you can redistribute it and/or
  10  * modify it under the terms of the GNU General Public License version 2
  11  * as published by the Free Software Foundation; or, when distributed
  12  * separately from the Linux kernel or incorporated into other
  13  * software packages, subject to the following license:
  14  *
  15  * Permission is hereby granted, free of charge, to any person obtaining a copy
  16  * of this source file (the "Software"), to deal in the Software without
  17  * restriction, including without limitation the rights to use, copy, modify,
  18  * merge, publish, distribute, sublicense, and/or sell copies of the Software,
  19  * and to permit persons to whom the Software is furnished to do so, subject to
  20  * the following conditions:
  21  *
  22  * The above copyright notice and this permission notice shall be included in
  23  * all copies or substantial portions of the Software.
  24  *
  25  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  26  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  27  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  28  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  29  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  30  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
  31  * IN THE SOFTWARE.
  32  */
  33
  34 #define pr_fmt(fmt) "xen:" KBUILD_MODNAME ": " fmt
  35
  36 #include <linux/sched.h>
  37 #include <linux/mm.h>
  38 #include <linux/slab.h>
  39 #include <linux/vmalloc.h>
  40 #include <linux/uaccess.h>
  41 #include <linux/io.h>
  42 #include <linux/delay.h>
  43 #include <linux/hardirq.h>
  44 #include <linux/workqueue.h>
  45
  46 #include <xen/xen.h>
  47 #include <xen/interface/xen.h>
  48 #include <xen/page.h>
  49 #include <xen/grant_table.h>
  50 #include <xen/interface/memory.h>
  51 #include <xen/hvc-console.h>
  52 #include <xen/swiotlb-xen.h>
  53 #include <xen/balloon.h>
  54 #include <asm/xen/hypercall.h>
  55 #include <asm/xen/interface.h>
  56
  57 #include <asm/pgtable.h>
  58 #include <asm/sync_bitops.h>
  59
  60 /* External tools reserve first few grant table entries. */
  61 #define NR_RESERVED_ENTRIES 8
  62 #define GNTTAB_LIST_END 0xffffffff
  63
  64 static grant_ref_t **gnttab_list;
  65 static unsigned int nr_grant_frames;
  66 static int gnttab_free_count;
  67 static grant_ref_t gnttab_free_head;
  68 static DEFINE_SPINLOCK(gnttab_list_lock);
  69 struct grant_frames xen_auto_xlat_grant_frames;
  70
  71 static union {
  72         struct grant_entry_v1 *v1;
  73         void *addr;
  74 } gnttab_shared;
  75
  76 /*This is a structure of function pointers for grant table*/
  77 struct gnttab_ops {
  78         /*
  79          * Mapping a list of frames for storing grant entries. Frames parameter
  80          * is used to store grant table address when grant table being setup,
  81          * nr_gframes is the number of frames to map grant table. Returning
  82          * GNTST_okay means success and negative value means failure.
  83          */
  84         int (*map_frames)(xen_pfn_t *frames, unsigned int nr_gframes);
  85         /*
  86          * Release a list of frames which are mapped in map_frames for grant
  87          * entry status.
  88          */
  89         void (*unmap_frames)(void);
  90         /*
  91          * Introducing a valid entry into the grant table, granting the frame of
  92          * this grant entry to domain for accessing or transfering. Ref
  93          * parameter is reference of this introduced grant entry, domid is id of
  94          * granted domain, frame is the page frame to be granted, and flags is
  95          * status of the grant entry to be updated.
  96          */
  97         void (*update_entry)(grant_ref_t ref, domid_t domid,
  98                              unsigned long frame, unsigned flags);
  99         /*
 100          * Stop granting a grant entry to domain for accessing. Ref parameter is
 101          * reference of a grant entry whose grant access will be stopped,
 102          * readonly is not in use in this function. If the grant entry is
 103          * currently mapped for reading or writing, just return failure(==0)
 104          * directly and don't tear down the grant access. Otherwise, stop grant
 105          * access for this entry and return success(==1).
 106          */
 107         int (*end_foreign_access_ref)(grant_ref_t ref, int readonly);
 108         /*
 109          * Stop granting a grant entry to domain for transfer. Ref parameter is
 110          * reference of a grant entry whose grant transfer will be stopped. If
 111          * tranfer has not started, just reclaim the grant entry and return
 112          * failure(==0). Otherwise, wait for the transfer to complete and then
 113          * return the frame.
 114          */
 115         unsigned long (*end_foreign_transfer_ref)(grant_ref_t ref);
 116         /*
 117          * Query the status of a grant entry. Ref parameter is reference of
 118          * queried grant entry, return value is the status of queried entry.
 119          * Detailed status(writing/reading) can be gotten from the return value
 120          * by bit operations.
 121          */
 122         int (*query_foreign_access)(grant_ref_t ref);
 123 };
 124
 125 struct unmap_refs_callback_data {
 126         struct completion completion;
 127         int result;
 128 };
 129
 130 static const struct gnttab_ops *gnttab_interface;
 131
 132 static int grant_table_version;
 133 static int grefs_per_grant_frame;
 134
 135 static struct gnttab_free_callback *gnttab_free_callback_list;
 136
 137 static int gnttab_expand(unsigned int req_entries);
 138
 139 #define RPP (PAGE_SIZE / sizeof(grant_ref_t))
 140
 141 static inline grant_ref_t *__gnttab_entry(grant_ref_t entry)
 142 {
 143         return &gnttab_list[(entry) / RPP][(entry) % RPP];
 144 }
 145 /* This can be used as an l-value */
 146 #define gnttab_entry(entry) (*__gnttab_entry(entry))
 147
 148 static int get_free_entries(unsigned count)
 149 {
 150         unsigned long flags;
 151         int ref, rc = 0;
 152         grant_ref_t head;
 153
 154         spin_lock_irqsave(&gnttab_list_lock, flags);
 155
 156         if ((gnttab_free_count < count) &&
 157             ((rc = gnttab_expand(count - gnttab_free_count)) < 0)) {
 158                 spin_unlock_irqrestore(&gnttab_list_lock, flags);
 159                 return rc;
 160         }
 161
 162         ref = head = gnttab_free_head;
 163         gnttab_free_count -= count;
 164         while (count-- > 1)
 165                 head = gnttab_entry(head);
 166         gnttab_free_head = gnttab_entry(head);
 167         gnttab_entry(head) = GNTTAB_LIST_END;
 168
 169         spin_unlock_irqrestore(&gnttab_list_lock, flags);
 170
 171         return ref;
 172 }
 173
 174 static void do_free_callbacks(void)
 175 {
 176         struct gnttab_free_callback *callback, *next;
 177
 178         callback = gnttab_free_callback_list;
 179         gnttab_free_callback_list = NULL;
 180
 181         while (callback != NULL) {
 182                 next = callback->next;
 183                 if (gnttab_free_count >= callback->count) {
 184                         callback->next = NULL;
 185                         callback->fn(callback->arg);
 186                 } else {
 187                         callback->next = gnttab_free_callback_list;
 188                         gnttab_free_callback_list = callback;
 189                 }
 190                 callback = next;
 191         }
 192 }
 193
 194 static inline void check_free_callbacks(void)
 195 {
 196         if (unlikely(gnttab_free_callback_list))
 197                 do_free_callbacks();
 198 }
 199
 200 static void put_free_entry(grant_ref_t ref)
 201 {
 202         unsigned long flags;
 203         spin_lock_irqsave(&gnttab_list_lock, flags);
 204         gnttab_entry(ref) = gnttab_free_head;
 205         gnttab_free_head = ref;
 206         gnttab_free_count++;
 207         check_free_callbacks();
 208         spin_unlock_irqrestore(&gnttab_list_lock, flags);
 209 }
 210
 211 /*
 212  * Following applies to gnttab_update_entry_v1.
 213  * Introducing a valid entry into the grant table:
 214  *  1. Write ent->domid.
 215  *  2. Write ent->frame:
 216  *      GTF_permit_access:   Frame to which access is permitted.
 217  *      GTF_accept_transfer: Pseudo-phys frame slot being filled by new
 218  *                           frame, or zero if none.
 219  *  3. Write memory barrier (WMB).
 220  *  4. Write ent->flags, inc. valid type.
 221  */
 222 static void gnttab_update_entry_v1(grant_ref_t ref, domid_t domid,
 223                                    unsigned long frame, unsigned flags)
 224 {
 225         gnttab_shared.v1[ref].domid = domid;
 226         gnttab_shared.v1[ref].frame = frame;
 227         wmb();
 228         gnttab_shared.v1[ref].flags = flags;
 229 }
 230
 231 /*
 232  * Public grant-issuing interface functions
 233  */
 234 void gnttab_grant_foreign_access_ref(grant_ref_t ref, domid_t domid,
 235                                      unsigned long frame, int readonly)
 236 {
 237         gnttab_interface->update_entry(ref, domid, frame,
 238                            GTF_permit_access | (readonly ? GTF_readonly : 0));
 239 }
 240 EXPORT_SYMBOL_GPL(gnttab_grant_foreign_access_ref);
 241
 242 int gnttab_grant_foreign_access(domid_t domid, unsigned long frame,
 243                                 int readonly)
 244 {
 245         int ref;
 246
 247         ref = get_free_entries(1);
 248         if (unlikely(ref < 0))
 249                 return -ENOSPC;
 250
 251         gnttab_grant_foreign_access_ref(ref, domid, frame, readonly);
 252
 253         return ref;
 254 }
 255 EXPORT_SYMBOL_GPL(gnttab_grant_foreign_access);
 256
 257 static int gnttab_query_foreign_access_v1(grant_ref_t ref)
 258 {
 259         return gnttab_shared.v1[ref].flags & (GTF_reading|GTF_writing);
 260 }
 261
 262 int gnttab_query_foreign_access(grant_ref_t ref)
 263 {
 264         return gnttab_interface->query_foreign_access(ref);
 265 }
 266 EXPORT_SYMBOL_GPL(gnttab_query_foreign_access);
 267
 268 static int gnttab_end_foreign_access_ref_v1(grant_ref_t ref, int readonly)
 269 {
 270         u16 flags, nflags;
 271         u16 *pflags;
 272
 273         pflags = &gnttab_shared.v1[ref].flags;
 274         nflags = *pflags;
 275         do {
 276                 flags = nflags;
 277                 if (flags & (GTF_reading|GTF_writing))
 278                         return 0;
 279         } while ((nflags = sync_cmpxchg(pflags, flags, 0)) != flags);
 280
 281         return 1;
 282 }
 283
 284 static inline int _gnttab_end_foreign_access_ref(grant_ref_t ref, int readonly)
 285 {
 286         return gnttab_interface->end_foreign_access_ref(ref, readonly);
 287 }
 288
 289 int gnttab_end_foreign_access_ref(grant_ref_t ref, int readonly)
 290 {
 291         if (_gnttab_end_foreign_access_ref(ref, readonly))
 292                 return 1;
 293         pr_warn("WARNING: g.e. %#x still in use!\n", ref);
 294         return 0;
 295 }
 296 EXPORT_SYMBOL_GPL(gnttab_end_foreign_access_ref);
 297
 298 struct deferred_entry {
 299         struct list_head list;
 300         grant_ref_t ref;
 301         bool ro;
 302         uint16_t warn_delay;
 303         struct page *page;
 304 };
 305 static LIST_HEAD(deferred_list);
 306 static void gnttab_handle_deferred(unsigned long);
 307 static DEFINE_TIMER(deferred_timer, gnttab_handle_deferred, 0, 0);
 308
 309 static void gnttab_handle_deferred(unsigned long unused)
 310 {
 311         unsigned int nr = 10;
 312         struct deferred_entry *first = NULL;
 313         unsigned long flags;
 314
 315         spin_lock_irqsave(&gnttab_list_lock, flags);
 316         while (nr--) {
 317                 struct deferred_entry *entry
 318                         = list_first_entry(&deferred_list,
 319                                            struct deferred_entry, list);
 320
 321                 if (entry == first)
 322                         break;
 323                 list_del(&entry->list);
 324                 spin_unlock_irqrestore(&gnttab_list_lock, flags);
 325                 if (_gnttab_end_foreign_access_ref(entry->ref, entry->ro)) {
 326                         put_free_entry(entry->ref);
 327                         if (entry->page) {
 328                                 pr_debug("freeing g.e. %#x (pfn %#lx)\n",
 329                                          entry->ref, page_to_pfn(entry->page));
 330                                 __free_page(entry->page);
 331                         } else
 332                                 pr_info("freeing g.e. %#x\n", entry->ref);
 333                         kfree(entry);
 334                         entry = NULL;
 335                 } else {
 336                         if (!--entry->warn_delay)
 337                                 pr_info("g.e. %#x still pending\n", entry->ref);
 338                         if (!first)
 339                                 first = entry;
 340                 }
 341                 spin_lock_irqsave(&gnttab_list_lock, flags);
 342                 if (entry)
 343                         list_add_tail(&entry->list, &deferred_list);
 344                 else if (list_empty(&deferred_list))
 345                         break;
 346         }
 347         if (!list_empty(&deferred_list) && !timer_pending(&deferred_timer)) {
 348                 deferred_timer.expires = jiffies + HZ;
 349                 add_timer(&deferred_timer);
 350         }
 351         spin_unlock_irqrestore(&gnttab_list_lock, flags);
 352 }
 353
 354 static void gnttab_add_deferred(grant_ref_t ref, bool readonly,
 355                                 struct page *page)
 356 {
 357         struct deferred_entry *entry = kmalloc(sizeof(*entry), GFP_ATOMIC);
 358         const char *what = KERN_WARNING "leaking";
 359
 360         if (entry) {
 361                 unsigned long flags;
 362
 363                 entry->ref = ref;
 364                 entry->ro = readonly;
 365                 entry->page = page;
 366                 entry->warn_delay = 60;
 367                 spin_lock_irqsave(&gnttab_list_lock, flags);
 368                 list_add_tail(&entry->list, &deferred_list);
 369                 if (!timer_pending(&deferred_timer)) {
 370                         deferred_timer.expires = jiffies + HZ;
 371                         add_timer(&deferred_timer);
 372                 }
 373                 spin_unlock_irqrestore(&gnttab_list_lock, flags);
 374                 what = KERN_DEBUG "deferring";
 375         }
 376         printk("%s g.e. %#x (pfn %#lx)\n",
 377                what, ref, page ? page_to_pfn(page) : -1);
 378 }
 379
 380 void gnttab_end_foreign_access(grant_ref_t ref, int readonly,
 381                                unsigned long page)
 382 {
 383         if (gnttab_end_foreign_access_ref(ref, readonly)) {
 384                 put_free_entry(ref);
 385                 if (page != 0)
 386                         free_page(page);
 387         } else
 388                 gnttab_add_deferred(ref, readonly,
 389                                     page ? virt_to_page(page) : NULL);
 390 }
 391 EXPORT_SYMBOL_GPL(gnttab_end_foreign_access);
 392
 393 int gnttab_grant_foreign_transfer(domid_t domid, unsigned long pfn)
 394 {
 395         int ref;
 396
 397         ref = get_free_entries(1);
 398         if (unlikely(ref < 0))
 399                 return -ENOSPC;
 400         gnttab_grant_foreign_transfer_ref(ref, domid, pfn);
 401
 402         return ref;
 403 }
 404 EXPORT_SYMBOL_GPL(gnttab_grant_foreign_transfer);
 405
 406 void gnttab_grant_foreign_transfer_ref(grant_ref_t ref, domid_t domid,
 407                                        unsigned long pfn)
 408 {
 409         gnttab_interface->update_entry(ref, domid, pfn, GTF_accept_transfer);
 410 }
 411 EXPORT_SYMBOL_GPL(gnttab_grant_foreign_transfer_ref);
 412
 413 static unsigned long gnttab_end_foreign_transfer_ref_v1(grant_ref_t ref)
 414 {
 415         unsigned long frame;
 416         u16           flags;
 417         u16          *pflags;
 418
 419         pflags = &gnttab_shared.v1[ref].flags;
 420
 421         /*
 422          * If a transfer is not even yet started, try to reclaim the grant
 423          * reference and return failure (== 0).
 424          */
 425         while (!((flags = *pflags) & GTF_transfer_committed)) {
 426                 if (sync_cmpxchg(pflags, flags, 0) == flags)
 427                         return 0;
 428                 cpu_relax();
 429         }
 430
 431         /* If a transfer is in progress then wait until it is completed. */
 432         while (!(flags & GTF_transfer_completed)) {
 433                 flags = *pflags;
 434                 cpu_relax();
 435         }
 436
 437         rmb();  /* Read the frame number /after/ reading completion status. */
 438         frame = gnttab_shared.v1[ref].frame;
 439         BUG_ON(frame == 0);
 440
 441         return frame;
 442 }
 443
 444 unsigned long gnttab_end_foreign_transfer_ref(grant_ref_t ref)
 445 {
 446         return gnttab_interface->end_foreign_transfer_ref(ref);
 447 }
 448 EXPORT_SYMBOL_GPL(gnttab_end_foreign_transfer_ref);
 449
 450 unsigned long gnttab_end_foreign_transfer(grant_ref_t ref)
 451 {
 452         unsigned long frame = gnttab_end_foreign_transfer_ref(ref);
 453         put_free_entry(ref);
 454         return frame;
 455 }
 456 EXPORT_SYMBOL_GPL(gnttab_end_foreign_transfer);
 457
 458 void gnttab_free_grant_reference(grant_ref_t ref)
 459 {
 460         put_free_entry(ref);
 461 }
 462 EXPORT_SYMBOL_GPL(gnttab_free_grant_reference);
 463
 464 void gnttab_free_grant_references(grant_ref_t head)
 465 {
 466         grant_ref_t ref;
 467         unsigned long flags;
 468         int count = 1;
 469         if (head == GNTTAB_LIST_END)
 470                 return;
 471         spin_lock_irqsave(&gnttab_list_lock, flags);
 472         ref = head;
 473         while (gnttab_entry(ref) != GNTTAB_LIST_END) {
 474                 ref = gnttab_entry(ref);
 475                 count++;
 476         }
 477         gnttab_entry(ref) = gnttab_free_head;
 478         gnttab_free_head = head;
 479         gnttab_free_count += count;
 480         check_free_callbacks();
 481         spin_unlock_irqrestore(&gnttab_list_lock, flags);
 482 }
 483 EXPORT_SYMBOL_GPL(gnttab_free_grant_references);
 484
 485 int gnttab_alloc_grant_references(u16 count, grant_ref_t *head)
 486 {
 487         int h = get_free_entries(count);
 488
 489         if (h < 0)
 490                 return -ENOSPC;
 491
 492         *head = h;
 493
 494         return 0;
 495 }
 496 EXPORT_SYMBOL_GPL(gnttab_alloc_grant_references);
 497
 498 int gnttab_empty_grant_references(const grant_ref_t *private_head)
 499 {
 500         return (*private_head == GNTTAB_LIST_END);
 501 }
 502 EXPORT_SYMBOL_GPL(gnttab_empty_grant_references);
 503
 504 int gnttab_claim_grant_reference(grant_ref_t *private_head)
 505 {
 506         grant_ref_t g = *private_head;
 507         if (unlikely(g == GNTTAB_LIST_END))
 508                 return -ENOSPC;
 509         *private_head = gnttab_entry(g);
 510         return g;
 511 }
 512 EXPORT_SYMBOL_GPL(gnttab_claim_grant_reference);
 513
 514 void gnttab_release_grant_reference(grant_ref_t *private_head,
 515                                     grant_ref_t release)
 516 {
 517         gnttab_entry(release) = *private_head;
 518         *private_head = release;
 519 }
 520 EXPORT_SYMBOL_GPL(gnttab_release_grant_reference);
 521
 522 void gnttab_request_free_callback(struct gnttab_free_callback *callback,
 523                                   void (*fn)(void *), void *arg, u16 count)
 524 {
 525         unsigned long flags;
 526         struct gnttab_free_callback *cb;
 527
 528         spin_lock_irqsave(&gnttab_list_lock, flags);
 529
 530         /* Check if the callback is already on the list */
 531         cb = gnttab_free_callback_list;
 532         while (cb) {
 533                 if (cb == callback)
 534                         goto out;
 535                 cb = cb->next;
 536         }
 537
 538         callback->fn = fn;
 539         callback->arg = arg;
 540         callback->count = count;
 541         callback->next = gnttab_free_callback_list;
 542         gnttab_free_callback_list = callback;
 543         check_free_callbacks();
 544 out:
 545         spin_unlock_irqrestore(&gnttab_list_lock, flags);
 546 }
 547 EXPORT_SYMBOL_GPL(gnttab_request_free_callback);
 548
 549 void gnttab_cancel_free_callback(struct gnttab_free_callback *callback)
 550 {
 551         struct gnttab_free_callback **pcb;
 552         unsigned long flags;
 553
 554         spin_lock_irqsave(&gnttab_list_lock, flags);
 555         for (pcb = &gnttab_free_callback_list; *pcb; pcb = &(*pcb)->next) {
 556                 if (*pcb == callback) {
 557                         *pcb = callback->next;
 558                         break;
 559                 }
 560         }
 561         spin_unlock_irqrestore(&gnttab_list_lock, flags);
 562 }
 563 EXPORT_SYMBOL_GPL(gnttab_cancel_free_callback);
 564
 565 static int grow_gnttab_list(unsigned int more_frames)
 566 {
 567         unsigned int new_nr_grant_frames, extra_entries, i;
 568         unsigned int nr_glist_frames, new_nr_glist_frames;
 569
 570         BUG_ON(grefs_per_grant_frame == 0);
 571
 572         new_nr_grant_frames = nr_grant_frames + more_frames;
 573         extra_entries       = more_frames * grefs_per_grant_frame;
 574
 575         nr_glist_frames = (nr_grant_frames * grefs_per_grant_frame + RPP - 1) / RPP;
 576         new_nr_glist_frames =
 577                 (new_nr_grant_frames * grefs_per_grant_frame + RPP - 1) / RPP;
 578         for (i = nr_glist_frames; i < new_nr_glist_frames; i++) {
 579                 gnttab_list[i] = (grant_ref_t *)__get_free_page(GFP_ATOMIC);
 580                 if (!gnttab_list[i])
 581                         goto grow_nomem;
 582         }
 583
 584
 585         for (i = grefs_per_grant_frame * nr_grant_frames;
 586              i < grefs_per_grant_frame * new_nr_grant_frames - 1; i++)
 587                 gnttab_entry(i) = i + 1;
 588
 589         gnttab_entry(i) = gnttab_free_head;
 590         gnttab_free_head = grefs_per_grant_frame * nr_grant_frames;
 591         gnttab_free_count += extra_entries;
 592
 593         nr_grant_frames = new_nr_grant_frames;
 594
 595         check_free_callbacks();
 596
 597         return 0;
 598
 599 grow_nomem:
 600         while (i-- > nr_glist_frames)
 601                 free_page((unsigned long) gnttab_list[i]);
 602         return -ENOMEM;
 603 }
 604
 605 static unsigned int __max_nr_grant_frames(void)
 606 {
 607         struct gnttab_query_size query;
 608         int rc;
 609
 610         query.dom = DOMID_SELF;
 611
 612         rc = HYPERVISOR_grant_table_op(GNTTABOP_query_size, &query, 1);
 613         if ((rc < 0) || (query.status != GNTST_okay))
 614                 return 4; /* Legacy max supported number of frames */
 615
 616         return query.max_nr_frames;
 617 }
 618
 619 unsigned int gnttab_max_grant_frames(void)
 620 {
 621         unsigned int xen_max = __max_nr_grant_frames();
 622         static unsigned int boot_max_nr_grant_frames;
 623
 624         /* First time, initialize it properly. */
 625         if (!boot_max_nr_grant_frames)
 626                 boot_max_nr_grant_frames = __max_nr_grant_frames();
 627
 628         if (xen_max > boot_max_nr_grant_frames)
 629                 return boot_max_nr_grant_frames;
 630         return xen_max;
 631 }
 632 EXPORT_SYMBOL_GPL(gnttab_max_grant_frames);
 633
 634 int gnttab_setup_auto_xlat_frames(phys_addr_t addr)
 635 {
 636         xen_pfn_t *pfn;
 637         unsigned int max_nr_gframes = __max_nr_grant_frames();
 638         unsigned int i;
 639         void *vaddr;
 640
 641         if (xen_auto_xlat_grant_frames.count)
 642                 return -EINVAL;
 643
 644         vaddr = xen_remap(addr, XEN_PAGE_SIZE * max_nr_gframes);
 645         if (vaddr == NULL) {
 646                 pr_warn("Failed to ioremap gnttab share frames (addr=%pa)!\n",
 647                         &addr);
 648                 return -ENOMEM;
 649         }
 650         pfn = kcalloc(max_nr_gframes, sizeof(pfn[0]), GFP_KERNEL);
 651         if (!pfn) {
 652                 xen_unmap(vaddr);
 653                 return -ENOMEM;
 654         }
 655         for (i = 0; i < max_nr_gframes; i++)
 656                 pfn[i] = XEN_PFN_DOWN(addr) + i;
 657
 658         xen_auto_xlat_grant_frames.vaddr = vaddr;
 659         xen_auto_xlat_grant_frames.pfn = pfn;
 660         xen_auto_xlat_grant_frames.count = max_nr_gframes;
 661
 662         return 0;
 663 }
 664 EXPORT_SYMBOL_GPL(gnttab_setup_auto_xlat_frames);
 665
 666 void gnttab_free_auto_xlat_frames(void)
 667 {
 668         if (!xen_auto_xlat_grant_frames.count)
 669                 return;
 670         kfree(xen_auto_xlat_grant_frames.pfn);
 671         xen_unmap(xen_auto_xlat_grant_frames.vaddr);
 672
 673         xen_auto_xlat_grant_frames.pfn = NULL;
 674         xen_auto_xlat_grant_frames.count = 0;
 675         xen_auto_xlat_grant_frames.vaddr = NULL;
 676 }
 677 EXPORT_SYMBOL_GPL(gnttab_free_auto_xlat_frames);
 678
 679 /**
 680  * gnttab_alloc_pages - alloc pages suitable for grant mapping into
 681  * @nr_pages: number of pages to alloc
 682  * @pages: returns the pages
 683  */
 684 int gnttab_alloc_pages(int nr_pages, struct page **pages)
 685 {
 686         int i;
 687         int ret;
 688
 689         ret = alloc_xenballooned_pages(nr_pages, pages);
 690         if (ret < 0)
 691                 return ret;
 692
 693         for (i = 0; i < nr_pages; i++) {
 694 #if BITS_PER_LONG < 64
 695                 struct xen_page_foreign *foreign;
 696
 697                 foreign = kzalloc(sizeof(*foreign), GFP_KERNEL);
 698                 if (!foreign) {
 699                         gnttab_free_pages(nr_pages, pages);
 700                         return -ENOMEM;
 701                 }
 702                 set_page_private(pages[i], (unsigned long)foreign);
 703 #endif
 704                 SetPagePrivate(pages[i]);
 705         }
 706
 707         return 0;
 708 }
 709 EXPORT_SYMBOL(gnttab_alloc_pages);
 710
 711 /**
 712  * gnttab_free_pages - free pages allocated by gnttab_alloc_pages()
 713  * @nr_pages; number of pages to free
 714  * @pages: the pages
 715  */
 716 void gnttab_free_pages(int nr_pages, struct page **pages)
 717 {
 718         int i;
 719
 720         for (i = 0; i < nr_pages; i++) {
 721                 if (PagePrivate(pages[i])) {
 722 #if BITS_PER_LONG < 64
 723                         kfree((void *)page_private(pages[i]));
 724 #endif
 725                         ClearPagePrivate(pages[i]);
 726                 }
 727         }
 728         free_xenballooned_pages(nr_pages, pages);
 729 }
 730 EXPORT_SYMBOL(gnttab_free_pages);
 731
 732 /* Handling of paged out grant targets (GNTST_eagain) */
 733 #define MAX_DELAY 256
 734 static inline void
 735 gnttab_retry_eagain_gop(unsigned int cmd, void *gop, int16_t *status,
 736                                                 const char *func)
 737 {
 738         unsigned delay = 1;
 739
 740         do {
 741                 BUG_ON(HYPERVISOR_grant_table_op(cmd, gop, 1));
 742                 if (*status == GNTST_eagain)
 743                         msleep(delay++);
 744         } while ((*status == GNTST_eagain) && (delay < MAX_DELAY));
 745
 746         if (delay >= MAX_DELAY) {
 747                 pr_err("%s: %s eagain grant\n", func, current->comm);
 748                 *status = GNTST_bad_page;
 749         }
 750 }
 751
 752 void gnttab_batch_map(struct gnttab_map_grant_ref *batch, unsigned count)
 753 {
 754         struct gnttab_map_grant_ref *op;
 755
 756         if (HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref, batch, count))
 757                 BUG();
 758         for (op = batch; op < batch + count; op++)
 759                 if (op->status == GNTST_eagain)
 760                         gnttab_retry_eagain_gop(GNTTABOP_map_grant_ref, op,
 761                                                 &op->status, __func__);
 762 }
 763 EXPORT_SYMBOL_GPL(gnttab_batch_map);
 764
 765 void gnttab_batch_copy(struct gnttab_copy *batch, unsigned count)
 766 {
 767         struct gnttab_copy *op;
 768
 769         if (HYPERVISOR_grant_table_op(GNTTABOP_copy, batch, count))
 770                 BUG();
 771         for (op = batch; op < batch + count; op++)
 772                 if (op->status == GNTST_eagain)
 773                         gnttab_retry_eagain_gop(GNTTABOP_copy, op,
 774                                                 &op->status, __func__);
 775 }
 776 EXPORT_SYMBOL_GPL(gnttab_batch_copy);
 777
 778 void gnttab_foreach_grant_in_range(struct page *page,
 779                                    unsigned int offset,
 780                                    unsigned int len,
 781                                    xen_grant_fn_t fn,
 782                                    void *data)
 783 {
 784         unsigned int goffset;
 785         unsigned int glen;
 786         unsigned long xen_pfn;
 787
 788         len = min_t(unsigned int, PAGE_SIZE - offset, len);
 789         goffset = xen_offset_in_page(offset);
 790
 791         xen_pfn = page_to_xen_pfn(page) + XEN_PFN_DOWN(offset);
 792
 793         while (len) {
 794                 glen = min_t(unsigned int, XEN_PAGE_SIZE - goffset, len);
 795                 fn(pfn_to_gfn(xen_pfn), goffset, glen, data);
 796
 797                 goffset = 0;
 798                 xen_pfn++;
 799                 len -= glen;
 800         }
 801 }
 802 EXPORT_SYMBOL_GPL(gnttab_foreach_grant_in_range);
 803
 804 void gnttab_foreach_grant(struct page **pages,
 805                           unsigned int nr_grefs,
 806                           xen_grant_fn_t fn,
 807                           void *data)
 808 {
 809         unsigned int goffset = 0;
 810         unsigned long xen_pfn = 0;
 811         unsigned int i;
 812
 813         for (i = 0; i < nr_grefs; i++) {
 814                 if ((i % XEN_PFN_PER_PAGE) == 0) {
 815                         xen_pfn = page_to_xen_pfn(pages[i / XEN_PFN_PER_PAGE]);
 816                         goffset = 0;
 817                 }
 818
 819                 fn(pfn_to_gfn(xen_pfn), goffset, XEN_PAGE_SIZE, data);
 820
 821                 goffset += XEN_PAGE_SIZE;
 822                 xen_pfn++;
 823         }
 824 }
 825
 826 int gnttab_map_refs(struct gnttab_map_grant_ref *map_ops,
 827                     struct gnttab_map_grant_ref *kmap_ops,
 828                     struct page **pages, unsigned int count)
 829 {
 830         int i, ret;
 831
 832         ret = HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref, map_ops, count);
 833         if (ret)
 834                 return ret;
 835
 836         for (i = 0; i < count; i++) {
 837                 /* Retry eagain maps */
 838                 if (map_ops[i].status == GNTST_eagain)
 839                         gnttab_retry_eagain_gop(GNTTABOP_map_grant_ref, map_ops + i,
 840                                                 &map_ops[i].status, __func__);
 841
 842                 if (map_ops[i].status == GNTST_okay) {
 843                         struct xen_page_foreign *foreign;
 844
 845                         SetPageForeign(pages[i]);
 846                         foreign = xen_page_foreign(pages[i]);
 847                         foreign->domid = map_ops[i].dom;
 848                         foreign->gref = map_ops[i].ref;
 849                 }
 850         }
 851
 852         return set_foreign_p2m_mapping(map_ops, kmap_ops, pages, count);
 853 }
 854 EXPORT_SYMBOL_GPL(gnttab_map_refs);
 855
 856 int gnttab_unmap_refs(struct gnttab_unmap_grant_ref *unmap_ops,
 857                       struct gnttab_unmap_grant_ref *kunmap_ops,
 858                       struct page **pages, unsigned int count)
 859 {
 860         unsigned int i;
 861         int ret;
 862
 863         ret = HYPERVISOR_grant_table_op(GNTTABOP_unmap_grant_ref, unmap_ops, count);
 864         if (ret)
 865                 return ret;
 866
 867         for (i = 0; i < count; i++)
 868                 ClearPageForeign(pages[i]);
 869
 870         return clear_foreign_p2m_mapping(unmap_ops, kunmap_ops, pages, count);
 871 }
 872 EXPORT_SYMBOL_GPL(gnttab_unmap_refs);
 873
 874 #define GNTTAB_UNMAP_REFS_DELAY 5
 875
 876 static void __gnttab_unmap_refs_async(struct gntab_unmap_queue_data* item);
 877
 878 static void gnttab_unmap_work(struct work_struct *work)
 879 {
 880         struct gntab_unmap_queue_data
 881                 *unmap_data = container_of(work,
 882                                            struct gntab_unmap_queue_data,
 883                                            gnttab_work.work);
 884         if (unmap_data->age != UINT_MAX)
 885                 unmap_data->age++;
 886         __gnttab_unmap_refs_async(unmap_data);
 887 }
 888
 889 static void __gnttab_unmap_refs_async(struct gntab_unmap_queue_data* item)
 890 {
 891         int ret;
 892         int pc;
 893
 894         for (pc = 0; pc < item->count; pc++) {
 895                 if (page_count(item->pages[pc]) > 1) {
 896                         unsigned long delay = GNTTAB_UNMAP_REFS_DELAY * (item->age + 1);
 897                         schedule_delayed_work(&item->gnttab_work,
 898                                               msecs_to_jiffies(delay));
 899                         return;
 900                 }
 901         }
 902
 903         ret = gnttab_unmap_refs(item->unmap_ops, item->kunmap_ops,
 904                                 item->pages, item->count);
 905         item->done(ret, item);
 906 }
 907
 908 void gnttab_unmap_refs_async(struct gntab_unmap_queue_data* item)
 909 {
 910         INIT_DELAYED_WORK(&item->gnttab_work, gnttab_unmap_work);
 911         item->age = 0;
 912
 913         __gnttab_unmap_refs_async(item);
 914 }
 915 EXPORT_SYMBOL_GPL(gnttab_unmap_refs_async);
 916
 917 static void unmap_refs_callback(int result,
 918                 struct gntab_unmap_queue_data *data)
 919 {
 920         struct unmap_refs_callback_data *d = data->data;
 921
 922         d->result = result;
 923         complete(&d->completion);
 924 }
 925
 926 int gnttab_unmap_refs_sync(struct gntab_unmap_queue_data *item)
 927 {
 928         struct unmap_refs_callback_data data;
 929
 930         init_completion(&data.completion);
 931         item->data = &data;
 932         item->done = &unmap_refs_callback;
 933         gnttab_unmap_refs_async(item);
 934         wait_for_completion(&data.completion);
 935
 936         return data.result;
 937 }
 938 EXPORT_SYMBOL_GPL(gnttab_unmap_refs_sync);
 939
 940 static int gnttab_map_frames_v1(xen_pfn_t *frames, unsigned int nr_gframes)
 941 {
 942         int rc;
 943
 944         rc = arch_gnttab_map_shared(frames, nr_gframes,
 945                                     gnttab_max_grant_frames(),
 946                                     &gnttab_shared.addr);
 947         BUG_ON(rc);
 948
 949         return 0;
 950 }
 951
 952 static void gnttab_unmap_frames_v1(void)
 953 {
 954         arch_gnttab_unmap(gnttab_shared.addr, nr_grant_frames);
 955 }
 956
 957 static int gnttab_map(unsigned int start_idx, unsigned int end_idx)
 958 {
 959         struct gnttab_setup_table setup;
 960         xen_pfn_t *frames;
 961         unsigned int nr_gframes = end_idx + 1;
 962         int rc;
 963
 964         if (xen_feature(XENFEAT_auto_translated_physmap)) {
 965                 struct xen_add_to_physmap xatp;
 966                 unsigned int i = end_idx;
 967                 rc = 0;
 968                 BUG_ON(xen_auto_xlat_grant_frames.count < nr_gframes);
 969                 /*
 970                  * Loop backwards, so that the first hypercall has the largest
 971                  * index, ensuring that the table will grow only once.
 972                  */
 973                 do {
 974                         xatp.domid = DOMID_SELF;
 975                         xatp.idx = i;
 976                         xatp.space = XENMAPSPACE_grant_table;
 977                         xatp.gpfn = xen_auto_xlat_grant_frames.pfn[i];
 978                         rc = HYPERVISOR_memory_op(XENMEM_add_to_physmap, &xatp);
 979                         if (rc != 0) {
 980                                 pr_warn("grant table add_to_physmap failed, err=%d\n",
 981                                         rc);
 982                                 break;
 983                         }
 984                 } while (i-- > start_idx);
 985
 986                 return rc;
 987         }
 988
 989         /* No need for kzalloc as it is initialized in following hypercall
 990          * GNTTABOP_setup_table.
 991          */
 992         frames = kmalloc(nr_gframes * sizeof(unsigned long), GFP_ATOMIC);
 993         if (!frames)
 994                 return -ENOMEM;
 995
 996         setup.dom        = DOMID_SELF;
 997         setup.nr_frames  = nr_gframes;
 998         set_xen_guest_handle(setup.frame_list, frames);
 999
1000         rc = HYPERVISOR_grant_table_op(GNTTABOP_setup_table, &setup, 1);
1001         if (rc == -ENOSYS) {
1002                 kfree(frames);
1003                 return -ENOSYS;
1004         }
1005
1006         BUG_ON(rc || setup.status);
1007
1008         rc = gnttab_interface->map_frames(frames, nr_gframes);
1009
1010         kfree(frames);
1011
1012         return rc;
1013 }
1014
1015 static const struct gnttab_ops gnttab_v1_ops = {
1016         .map_frames                     = gnttab_map_frames_v1,
1017         .unmap_frames                   = gnttab_unmap_frames_v1,
1018         .update_entry                   = gnttab_update_entry_v1,
1019         .end_foreign_access_ref         = gnttab_end_foreign_access_ref_v1,
1020         .end_foreign_transfer_ref       = gnttab_end_foreign_transfer_ref_v1,
1021         .query_foreign_access           = gnttab_query_foreign_access_v1,
1022 };
1023
1024 static void gnttab_request_version(void)
1025 {
1026         /* Only version 1 is used, which will always be available. */
1027         grant_table_version = 1;
1028         grefs_per_grant_frame = XEN_PAGE_SIZE / sizeof(struct grant_entry_v1);
1029         gnttab_interface = &gnttab_v1_ops;
1030
1031         pr_info("Grant tables using version %d layout\n", grant_table_version);
1032 }
1033
1034 static int gnttab_setup(void)
1035 {
1036         unsigned int max_nr_gframes;
1037
1038         max_nr_gframes = gnttab_max_grant_frames();
1039         if (max_nr_gframes < nr_grant_frames)
1040                 return -ENOSYS;
1041
1042         if (xen_feature(XENFEAT_auto_translated_physmap) && gnttab_shared.addr == NULL) {
1043                 gnttab_shared.addr = xen_auto_xlat_grant_frames.vaddr;
1044                 if (gnttab_shared.addr == NULL) {
1045                         pr_warn("gnttab share frames (addr=0x%08lx) is not mapped!\n",
1046                                 (unsigned long)xen_auto_xlat_grant_frames.vaddr);
1047                         return -ENOMEM;
1048                 }
1049         }
1050         return gnttab_map(0, nr_grant_frames - 1);
1051 }
1052
1053 int gnttab_resume(void)
1054 {
1055         gnttab_request_version();
1056         return gnttab_setup();
1057 }
1058
1059 int gnttab_suspend(void)
1060 {
1061         if (!xen_feature(XENFEAT_auto_translated_physmap))
1062                 gnttab_interface->unmap_frames();
1063         return 0;
1064 }
1065
1066 static int gnttab_expand(unsigned int req_entries)
1067 {
1068         int rc;
1069         unsigned int cur, extra;
1070
1071         BUG_ON(grefs_per_grant_frame == 0);
1072         cur = nr_grant_frames;
1073         extra = ((req_entries + (grefs_per_grant_frame-1)) /
1074                  grefs_per_grant_frame);
1075         if (cur + extra > gnttab_max_grant_frames())
1076                 return -ENOSPC;
1077
1078         rc = gnttab_map(cur, cur + extra - 1);
1079         if (rc == 0)
1080                 rc = grow_gnttab_list(extra);
1081
1082         return rc;
1083 }
1084
1085 int gnttab_init(void)
1086 {
1087         int i;
1088         unsigned long max_nr_grant_frames;
1089         unsigned int max_nr_glist_frames, nr_glist_frames;
1090         unsigned int nr_init_grefs;
1091         int ret;
1092
1093         gnttab_request_version();
1094         max_nr_grant_frames = gnttab_max_grant_frames();
1095         nr_grant_frames = 1;
1096
1097         /* Determine the maximum number of frames required for the
1098          * grant reference free list on the current hypervisor.
1099          */
1100         BUG_ON(grefs_per_grant_frame == 0);
1101         max_nr_glist_frames = (max_nr_grant_frames *
1102                                grefs_per_grant_frame / RPP);
1103
1104         gnttab_list = kmalloc(max_nr_glist_frames * sizeof(grant_ref_t *),
1105                               GFP_KERNEL);
1106         if (gnttab_list == NULL)
1107                 return -ENOMEM;
1108
1109         nr_glist_frames = (nr_grant_frames * grefs_per_grant_frame + RPP - 1) / RPP;
1110         for (i = 0; i < nr_glist_frames; i++) {
1111                 gnttab_list[i] = (grant_ref_t *)__get_free_page(GFP_KERNEL);
1112                 if (gnttab_list[i] == NULL) {
1113                         ret = -ENOMEM;
1114                         goto ini_nomem;
1115                 }
1116         }
1117
1118         ret = arch_gnttab_init(max_nr_grant_frames);
1119         if (ret < 0)
1120                 goto ini_nomem;
1121
1122         if (gnttab_setup() < 0) {
1123                 ret = -ENODEV;
1124                 goto ini_nomem;
1125         }
1126
1127         nr_init_grefs = nr_grant_frames * grefs_per_grant_frame;
1128
1129         for (i = NR_RESERVED_ENTRIES; i < nr_init_grefs - 1; i++)
1130                 gnttab_entry(i) = i + 1;
1131
1132         gnttab_entry(nr_init_grefs - 1) = GNTTAB_LIST_END;
1133         gnttab_free_count = nr_init_grefs - NR_RESERVED_ENTRIES;
1134         gnttab_free_head  = NR_RESERVED_ENTRIES;
1135
1136         printk("Grant table initialized\n");
1137         return 0;
1138
1139  ini_nomem:
1140         for (i--; i >= 0; i--)
1141                 free_page((unsigned long)gnttab_list[i]);
1142         kfree(gnttab_list);
1143         return ret;
1144 }
1145 EXPORT_SYMBOL_GPL(gnttab_init);
1146
1147 static int __gnttab_init(void)
1148 {
1149         /* Delay grant-table initialization in the PV on HVM case */
1150         if (xen_hvm_domain())
1151                 return 0;
1152
1153         if (!xen_pv_domain())
1154                 return -ENODEV;
1155
1156         return gnttab_init();
1157 }
1158 /* Starts after core_initcall so that xen_pvh_gnttab_setup can be called
1159  * beforehand to initialize xen_auto_xlat_grant_frames. */
1160 core_initcall_sync(__gnttab_init);