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/bootmem.h>
  37 #include <linux/sched.h>
  38 #include <linux/mm.h>
  39 #include <linux/slab.h>
  40 #include <linux/vmalloc.h>
  41 #include <linux/uaccess.h>
  42 #include <linux/io.h>
  43 #include <linux/delay.h>
  44 #include <linux/hardirq.h>
  45 #include <linux/workqueue.h>
  46 #include <linux/ratelimit.h>
  47 #include <linux/moduleparam.h>
  48
  49 #include <xen/xen.h>
  50 #include <xen/interface/xen.h>
  51 #include <xen/page.h>
  52 #include <xen/grant_table.h>
  53 #include <xen/interface/memory.h>
  54 #include <xen/hvc-console.h>
  55 #include <xen/swiotlb-xen.h>
  56 #include <xen/balloon.h>
  57 #ifdef CONFIG_X86
  58 #include <asm/xen/cpuid.h>
  59 #endif
  60 #include <asm/xen/hypercall.h>
  61 #include <asm/xen/interface.h>
  62
  63 #include <asm/pgtable.h>
  64 #include <asm/sync_bitops.h>
  65
  66 /* External tools reserve first few grant table entries. */
  67 #define NR_RESERVED_ENTRIES 8
  68 #define GNTTAB_LIST_END 0xffffffff
  69
  70 static grant_ref_t **gnttab_list;
  71 static unsigned int nr_grant_frames;
  72 static int gnttab_free_count;
  73 static grant_ref_t gnttab_free_head;
  74 static DEFINE_SPINLOCK(gnttab_list_lock);
  75 struct grant_frames xen_auto_xlat_grant_frames;
  76 static unsigned int xen_gnttab_version;
  77 module_param_named(version, xen_gnttab_version, uint, 0);
  78
  79 static union {
  80         struct grant_entry_v1 *v1;
  81         union grant_entry_v2 *v2;
  82         void *addr;
  83 } gnttab_shared;
  84
  85 /*This is a structure of function pointers for grant table*/
  86 struct gnttab_ops {
  87         /*
  88          * Version of the grant interface.
  89          */
  90         unsigned int version;
  91         /*
  92          * Grant refs per grant frame.
  93          */
  94         unsigned int grefs_per_grant_frame;
  95         /*
  96          * Mapping a list of frames for storing grant entries. Frames parameter
  97          * is used to store grant table address when grant table being setup,
  98          * nr_gframes is the number of frames to map grant table. Returning
  99          * GNTST_okay means success and negative value means failure.
 100          */
 101         int (*map_frames)(xen_pfn_t *frames, unsigned int nr_gframes);
 102         /*
 103          * Release a list of frames which are mapped in map_frames for grant
 104          * entry status.
 105          */
 106         void (*unmap_frames)(void);
 107         /*
 108          * Introducing a valid entry into the grant table, granting the frame of
 109          * this grant entry to domain for accessing or transfering. Ref
 110          * parameter is reference of this introduced grant entry, domid is id of
 111          * granted domain, frame is the page frame to be granted, and flags is
 112          * status of the grant entry to be updated.
 113          */
 114         void (*update_entry)(grant_ref_t ref, domid_t domid,
 115                              unsigned long frame, unsigned flags);
 116         /*
 117          * Stop granting a grant entry to domain for accessing. Ref parameter is
 118          * reference of a grant entry whose grant access will be stopped,
 119          * readonly is not in use in this function. If the grant entry is
 120          * currently mapped for reading or writing, just return failure(==0)
 121          * directly and don't tear down the grant access. Otherwise, stop grant
 122          * access for this entry and return success(==1).
 123          */
 124         int (*end_foreign_access_ref)(grant_ref_t ref, int readonly);
 125         /*
 126          * Stop granting a grant entry to domain for transfer. Ref parameter is
 127          * reference of a grant entry whose grant transfer will be stopped. If
 128          * tranfer has not started, just reclaim the grant entry and return
 129          * failure(==0). Otherwise, wait for the transfer to complete and then
 130          * return the frame.
 131          */
 132         unsigned long (*end_foreign_transfer_ref)(grant_ref_t ref);
 133         /*
 134          * Query the status of a grant entry. Ref parameter is reference of
 135          * queried grant entry, return value is the status of queried entry.
 136          * Detailed status(writing/reading) can be gotten from the return value
 137          * by bit operations.
 138          */
 139         int (*query_foreign_access)(grant_ref_t ref);
 140 };
 141
 142 struct unmap_refs_callback_data {
 143         struct completion completion;
 144         int result;
 145 };
 146
 147 static const struct gnttab_ops *gnttab_interface;
 148
 149 /* This reflects status of grant entries, so act as a global value. */
 150 static grant_status_t *grstatus;
 151
 152 static struct gnttab_free_callback *gnttab_free_callback_list;
 153
 154 static int gnttab_expand(unsigned int req_entries);
 155
 156 #define RPP (PAGE_SIZE / sizeof(grant_ref_t))
 157 #define SPP (PAGE_SIZE / sizeof(grant_status_t))
 158
 159 static inline grant_ref_t *__gnttab_entry(grant_ref_t entry)
 160 {
 161         return &gnttab_list[(entry) / RPP][(entry) % RPP];
 162 }
 163 /* This can be used as an l-value */
 164 #define gnttab_entry(entry) (*__gnttab_entry(entry))
 165
 166 static int get_free_entries(unsigned count)
 167 {
 168         unsigned long flags;
 169         int ref, rc = 0;
 170         grant_ref_t head;
 171
 172         spin_lock_irqsave(&gnttab_list_lock, flags);
 173
 174         if ((gnttab_free_count < count) &&
 175             ((rc = gnttab_expand(count - gnttab_free_count)) < 0)) {
 176                 spin_unlock_irqrestore(&gnttab_list_lock, flags);
 177                 return rc;
 178         }
 179
 180         ref = head = gnttab_free_head;
 181         gnttab_free_count -= count;
 182         while (count-- > 1)
 183                 head = gnttab_entry(head);
 184         gnttab_free_head = gnttab_entry(head);
 185         gnttab_entry(head) = GNTTAB_LIST_END;
 186
 187         spin_unlock_irqrestore(&gnttab_list_lock, flags);
 188
 189         return ref;
 190 }
 191
 192 static void do_free_callbacks(void)
 193 {
 194         struct gnttab_free_callback *callback, *next;
 195
 196         callback = gnttab_free_callback_list;
 197         gnttab_free_callback_list = NULL;
 198
 199         while (callback != NULL) {
 200                 next = callback->next;
 201                 if (gnttab_free_count >= callback->count) {
 202                         callback->next = NULL;
 203                         callback->fn(callback->arg);
 204                 } else {
 205                         callback->next = gnttab_free_callback_list;
 206                         gnttab_free_callback_list = callback;
 207                 }
 208                 callback = next;
 209         }
 210 }
 211
 212 static inline void check_free_callbacks(void)
 213 {
 214         if (unlikely(gnttab_free_callback_list))
 215                 do_free_callbacks();
 216 }
 217
 218 static void put_free_entry(grant_ref_t ref)
 219 {
 220         unsigned long flags;
 221         spin_lock_irqsave(&gnttab_list_lock, flags);
 222         gnttab_entry(ref) = gnttab_free_head;
 223         gnttab_free_head = ref;
 224         gnttab_free_count++;
 225         check_free_callbacks();
 226         spin_unlock_irqrestore(&gnttab_list_lock, flags);
 227 }
 228
 229 /*
 230  * Following applies to gnttab_update_entry_v1 and gnttab_update_entry_v2.
 231  * Introducing a valid entry into the grant table:
 232  *  1. Write ent->domid.
 233  *  2. Write ent->frame:
 234  *      GTF_permit_access:   Frame to which access is permitted.
 235  *      GTF_accept_transfer: Pseudo-phys frame slot being filled by new
 236  *                           frame, or zero if none.
 237  *  3. Write memory barrier (WMB).
 238  *  4. Write ent->flags, inc. valid type.
 239  */
 240 static void gnttab_update_entry_v1(grant_ref_t ref, domid_t domid,
 241                                    unsigned long frame, unsigned flags)
 242 {
 243         gnttab_shared.v1[ref].domid = domid;
 244         gnttab_shared.v1[ref].frame = frame;
 245         wmb();
 246         gnttab_shared.v1[ref].flags = flags;
 247 }
 248
 249 static void gnttab_update_entry_v2(grant_ref_t ref, domid_t domid,
 250                                    unsigned long frame, unsigned int flags)
 251 {
 252         gnttab_shared.v2[ref].hdr.domid = domid;
 253         gnttab_shared.v2[ref].full_page.frame = frame;
 254         wmb();  /* Hypervisor concurrent accesses. */
 255         gnttab_shared.v2[ref].hdr.flags = GTF_permit_access | flags;
 256 }
 257
 258 /*
 259  * Public grant-issuing interface functions
 260  */
 261 void gnttab_grant_foreign_access_ref(grant_ref_t ref, domid_t domid,
 262                                      unsigned long frame, int readonly)
 263 {
 264         gnttab_interface->update_entry(ref, domid, frame,
 265                            GTF_permit_access | (readonly ? GTF_readonly : 0));
 266 }
 267 EXPORT_SYMBOL_GPL(gnttab_grant_foreign_access_ref);
 268
 269 int gnttab_grant_foreign_access(domid_t domid, unsigned long frame,
 270                                 int readonly)
 271 {
 272         int ref;
 273
 274         ref = get_free_entries(1);
 275         if (unlikely(ref < 0))
 276                 return -ENOSPC;
 277
 278         gnttab_grant_foreign_access_ref(ref, domid, frame, readonly);
 279
 280         return ref;
 281 }
 282 EXPORT_SYMBOL_GPL(gnttab_grant_foreign_access);
 283
 284 static int gnttab_query_foreign_access_v1(grant_ref_t ref)
 285 {
 286         return gnttab_shared.v1[ref].flags & (GTF_reading|GTF_writing);
 287 }
 288
 289 static int gnttab_query_foreign_access_v2(grant_ref_t ref)
 290 {
 291         return grstatus[ref] & (GTF_reading|GTF_writing);
 292 }
 293
 294 int gnttab_query_foreign_access(grant_ref_t ref)
 295 {
 296         return gnttab_interface->query_foreign_access(ref);
 297 }
 298 EXPORT_SYMBOL_GPL(gnttab_query_foreign_access);
 299
 300 static int gnttab_end_foreign_access_ref_v1(grant_ref_t ref, int readonly)
 301 {
 302         u16 flags, nflags;
 303         u16 *pflags;
 304
 305         pflags = &gnttab_shared.v1[ref].flags;
 306         nflags = *pflags;
 307         do {
 308                 flags = nflags;
 309                 if (flags & (GTF_reading|GTF_writing))
 310                         return 0;
 311         } while ((nflags = sync_cmpxchg(pflags, flags, 0)) != flags);
 312
 313         return 1;
 314 }
 315
 316 static int gnttab_end_foreign_access_ref_v2(grant_ref_t ref, int readonly)
 317 {
 318         gnttab_shared.v2[ref].hdr.flags = 0;
 319         mb();   /* Concurrent access by hypervisor. */
 320         if (grstatus[ref] & (GTF_reading|GTF_writing)) {
 321                 return 0;
 322         } else {
 323                 /*
 324                  * The read of grstatus needs to have acquire semantics.
 325                  *  On x86, reads already have that, and we just need to
 326                  * protect against compiler reorderings.
 327                  * On other architectures we may need a full barrier.
 328                  */
 329 #ifdef CONFIG_X86
 330                 barrier();
 331 #else
 332                 mb();
 333 #endif
 334         }
 335
 336         return 1;
 337 }
 338
 339 static inline int _gnttab_end_foreign_access_ref(grant_ref_t ref, int readonly)
 340 {
 341         return gnttab_interface->end_foreign_access_ref(ref, readonly);
 342 }
 343
 344 int gnttab_end_foreign_access_ref(grant_ref_t ref, int readonly)
 345 {
 346         if (_gnttab_end_foreign_access_ref(ref, readonly))
 347                 return 1;
 348         pr_warn("WARNING: g.e. %#x still in use!\n", ref);
 349         return 0;
 350 }
 351 EXPORT_SYMBOL_GPL(gnttab_end_foreign_access_ref);
 352
 353 struct deferred_entry {
 354         struct list_head list;
 355         grant_ref_t ref;
 356         bool ro;
 357         uint16_t warn_delay;
 358         struct page *page;
 359 };
 360 static LIST_HEAD(deferred_list);
 361 static void gnttab_handle_deferred(struct timer_list *);
 362 static DEFINE_TIMER(deferred_timer, gnttab_handle_deferred);
 363
 364 static void gnttab_handle_deferred(struct timer_list *unused)
 365 {
 366         unsigned int nr = 10;
 367         struct deferred_entry *first = NULL;
 368         unsigned long flags;
 369
 370         spin_lock_irqsave(&gnttab_list_lock, flags);
 371         while (nr--) {
 372                 struct deferred_entry *entry
 373                         = list_first_entry(&deferred_list,
 374                                            struct deferred_entry, list);
 375
 376                 if (entry == first)
 377                         break;
 378                 list_del(&entry->list);
 379                 spin_unlock_irqrestore(&gnttab_list_lock, flags);
 380                 if (_gnttab_end_foreign_access_ref(entry->ref, entry->ro)) {
 381                         put_free_entry(entry->ref);
 382                         if (entry->page) {
 383                                 pr_debug("freeing g.e. %#x (pfn %#lx)\n",
 384                                          entry->ref, page_to_pfn(entry->page));
 385                                 put_page(entry->page);
 386                         } else
 387                                 pr_info("freeing g.e. %#x\n", entry->ref);
 388                         kfree(entry);
 389                         entry = NULL;
 390                 } else {
 391                         if (!--entry->warn_delay)
 392                                 pr_info("g.e. %#x still pending\n", entry->ref);
 393                         if (!first)
 394                                 first = entry;
 395                 }
 396                 spin_lock_irqsave(&gnttab_list_lock, flags);
 397                 if (entry)
 398                         list_add_tail(&entry->list, &deferred_list);
 399                 else if (list_empty(&deferred_list))
 400                         break;
 401         }
 402         if (!list_empty(&deferred_list) && !timer_pending(&deferred_timer)) {
 403                 deferred_timer.expires = jiffies + HZ;
 404                 add_timer(&deferred_timer);
 405         }
 406         spin_unlock_irqrestore(&gnttab_list_lock, flags);
 407 }
 408
 409 static void gnttab_add_deferred(grant_ref_t ref, bool readonly,
 410                                 struct page *page)
 411 {
 412         struct deferred_entry *entry = kmalloc(sizeof(*entry), GFP_ATOMIC);
 413         const char *what = KERN_WARNING "leaking";
 414
 415         if (entry) {
 416                 unsigned long flags;
 417
 418                 entry->ref = ref;
 419                 entry->ro = readonly;
 420                 entry->page = page;
 421                 entry->warn_delay = 60;
 422                 spin_lock_irqsave(&gnttab_list_lock, flags);
 423                 list_add_tail(&entry->list, &deferred_list);
 424                 if (!timer_pending(&deferred_timer)) {
 425                         deferred_timer.expires = jiffies + HZ;
 426                         add_timer(&deferred_timer);
 427                 }
 428                 spin_unlock_irqrestore(&gnttab_list_lock, flags);
 429                 what = KERN_DEBUG "deferring";
 430         }
 431         printk("%s g.e. %#x (pfn %#lx)\n",
 432                what, ref, page ? page_to_pfn(page) : -1);
 433 }
 434
 435 void gnttab_end_foreign_access(grant_ref_t ref, int readonly,
 436                                unsigned long page)
 437 {
 438         if (gnttab_end_foreign_access_ref(ref, readonly)) {
 439                 put_free_entry(ref);
 440                 if (page != 0)
 441                         put_page(virt_to_page(page));
 442         } else
 443                 gnttab_add_deferred(ref, readonly,
 444                                     page ? virt_to_page(page) : NULL);
 445 }
 446 EXPORT_SYMBOL_GPL(gnttab_end_foreign_access);
 447
 448 int gnttab_grant_foreign_transfer(domid_t domid, unsigned long pfn)
 449 {
 450         int ref;
 451
 452         ref = get_free_entries(1);
 453         if (unlikely(ref < 0))
 454                 return -ENOSPC;
 455         gnttab_grant_foreign_transfer_ref(ref, domid, pfn);
 456
 457         return ref;
 458 }
 459 EXPORT_SYMBOL_GPL(gnttab_grant_foreign_transfer);
 460
 461 void gnttab_grant_foreign_transfer_ref(grant_ref_t ref, domid_t domid,
 462                                        unsigned long pfn)
 463 {
 464         gnttab_interface->update_entry(ref, domid, pfn, GTF_accept_transfer);
 465 }
 466 EXPORT_SYMBOL_GPL(gnttab_grant_foreign_transfer_ref);
 467
 468 static unsigned long gnttab_end_foreign_transfer_ref_v1(grant_ref_t ref)
 469 {
 470         unsigned long frame;
 471         u16           flags;
 472         u16          *pflags;
 473
 474         pflags = &gnttab_shared.v1[ref].flags;
 475
 476         /*
 477          * If a transfer is not even yet started, try to reclaim the grant
 478          * reference and return failure (== 0).
 479          */
 480         while (!((flags = *pflags) & GTF_transfer_committed)) {
 481                 if (sync_cmpxchg(pflags, flags, 0) == flags)
 482                         return 0;
 483                 cpu_relax();
 484         }
 485
 486         /* If a transfer is in progress then wait until it is completed. */
 487         while (!(flags & GTF_transfer_completed)) {
 488                 flags = *pflags;
 489                 cpu_relax();
 490         }
 491
 492         rmb();  /* Read the frame number /after/ reading completion status. */
 493         frame = gnttab_shared.v1[ref].frame;
 494         BUG_ON(frame == 0);
 495
 496         return frame;
 497 }
 498
 499 static unsigned long gnttab_end_foreign_transfer_ref_v2(grant_ref_t ref)
 500 {
 501         unsigned long frame;
 502         u16           flags;
 503         u16          *pflags;
 504
 505         pflags = &gnttab_shared.v2[ref].hdr.flags;
 506
 507         /*
 508          * If a transfer is not even yet started, try to reclaim the grant
 509          * reference and return failure (== 0).
 510          */
 511         while (!((flags = *pflags) & GTF_transfer_committed)) {
 512                 if (sync_cmpxchg(pflags, flags, 0) == flags)
 513                         return 0;
 514                 cpu_relax();
 515         }
 516
 517         /* If a transfer is in progress then wait until it is completed. */
 518         while (!(flags & GTF_transfer_completed)) {
 519                 flags = *pflags;
 520                 cpu_relax();
 521         }
 522
 523         rmb();  /* Read the frame number /after/ reading completion status. */
 524         frame = gnttab_shared.v2[ref].full_page.frame;
 525         BUG_ON(frame == 0);
 526
 527         return frame;
 528 }
 529
 530 unsigned long gnttab_end_foreign_transfer_ref(grant_ref_t ref)
 531 {
 532         return gnttab_interface->end_foreign_transfer_ref(ref);
 533 }
 534 EXPORT_SYMBOL_GPL(gnttab_end_foreign_transfer_ref);
 535
 536 unsigned long gnttab_end_foreign_transfer(grant_ref_t ref)
 537 {
 538         unsigned long frame = gnttab_end_foreign_transfer_ref(ref);
 539         put_free_entry(ref);
 540         return frame;
 541 }
 542 EXPORT_SYMBOL_GPL(gnttab_end_foreign_transfer);
 543
 544 void gnttab_free_grant_reference(grant_ref_t ref)
 545 {
 546         put_free_entry(ref);
 547 }
 548 EXPORT_SYMBOL_GPL(gnttab_free_grant_reference);
 549
 550 void gnttab_free_grant_references(grant_ref_t head)
 551 {
 552         grant_ref_t ref;
 553         unsigned long flags;
 554         int count = 1;
 555         if (head == GNTTAB_LIST_END)
 556                 return;
 557         spin_lock_irqsave(&gnttab_list_lock, flags);
 558         ref = head;
 559         while (gnttab_entry(ref) != GNTTAB_LIST_END) {
 560                 ref = gnttab_entry(ref);
 561                 count++;
 562         }
 563         gnttab_entry(ref) = gnttab_free_head;
 564         gnttab_free_head = head;
 565         gnttab_free_count += count;
 566         check_free_callbacks();
 567         spin_unlock_irqrestore(&gnttab_list_lock, flags);
 568 }
 569 EXPORT_SYMBOL_GPL(gnttab_free_grant_references);
 570
 571 int gnttab_alloc_grant_references(u16 count, grant_ref_t *head)
 572 {
 573         int h = get_free_entries(count);
 574
 575         if (h < 0)
 576                 return -ENOSPC;
 577
 578         *head = h;
 579
 580         return 0;
 581 }
 582 EXPORT_SYMBOL_GPL(gnttab_alloc_grant_references);
 583
 584 int gnttab_empty_grant_references(const grant_ref_t *private_head)
 585 {
 586         return (*private_head == GNTTAB_LIST_END);
 587 }
 588 EXPORT_SYMBOL_GPL(gnttab_empty_grant_references);
 589
 590 int gnttab_claim_grant_reference(grant_ref_t *private_head)
 591 {
 592         grant_ref_t g = *private_head;
 593         if (unlikely(g == GNTTAB_LIST_END))
 594                 return -ENOSPC;
 595         *private_head = gnttab_entry(g);
 596         return g;
 597 }
 598 EXPORT_SYMBOL_GPL(gnttab_claim_grant_reference);
 599
 600 void gnttab_release_grant_reference(grant_ref_t *private_head,
 601                                     grant_ref_t release)
 602 {
 603         gnttab_entry(release) = *private_head;
 604         *private_head = release;
 605 }
 606 EXPORT_SYMBOL_GPL(gnttab_release_grant_reference);
 607
 608 void gnttab_request_free_callback(struct gnttab_free_callback *callback,
 609                                   void (*fn)(void *), void *arg, u16 count)
 610 {
 611         unsigned long flags;
 612         struct gnttab_free_callback *cb;
 613
 614         spin_lock_irqsave(&gnttab_list_lock, flags);
 615
 616         /* Check if the callback is already on the list */
 617         cb = gnttab_free_callback_list;
 618         while (cb) {
 619                 if (cb == callback)
 620                         goto out;
 621                 cb = cb->next;
 622         }
 623
 624         callback->fn = fn;
 625         callback->arg = arg;
 626         callback->count = count;
 627         callback->next = gnttab_free_callback_list;
 628         gnttab_free_callback_list = callback;
 629         check_free_callbacks();
 630 out:
 631         spin_unlock_irqrestore(&gnttab_list_lock, flags);
 632 }
 633 EXPORT_SYMBOL_GPL(gnttab_request_free_callback);
 634
 635 void gnttab_cancel_free_callback(struct gnttab_free_callback *callback)
 636 {
 637         struct gnttab_free_callback **pcb;
 638         unsigned long flags;
 639
 640         spin_lock_irqsave(&gnttab_list_lock, flags);
 641         for (pcb = &gnttab_free_callback_list; *pcb; pcb = &(*pcb)->next) {
 642                 if (*pcb == callback) {
 643                         *pcb = callback->next;
 644                         break;
 645                 }
 646         }
 647         spin_unlock_irqrestore(&gnttab_list_lock, flags);
 648 }
 649 EXPORT_SYMBOL_GPL(gnttab_cancel_free_callback);
 650
 651 static unsigned int gnttab_frames(unsigned int frames, unsigned int align)
 652 {
 653         return (frames * gnttab_interface->grefs_per_grant_frame + align - 1) /
 654                align;
 655 }
 656
 657 static int grow_gnttab_list(unsigned int more_frames)
 658 {
 659         unsigned int new_nr_grant_frames, extra_entries, i;
 660         unsigned int nr_glist_frames, new_nr_glist_frames;
 661         unsigned int grefs_per_frame;
 662
 663         BUG_ON(gnttab_interface == NULL);
 664         grefs_per_frame = gnttab_interface->grefs_per_grant_frame;
 665
 666         new_nr_grant_frames = nr_grant_frames + more_frames;
 667         extra_entries = more_frames * grefs_per_frame;
 668
 669         nr_glist_frames = gnttab_frames(nr_grant_frames, RPP);
 670         new_nr_glist_frames = gnttab_frames(new_nr_grant_frames, RPP);
 671         for (i = nr_glist_frames; i < new_nr_glist_frames; i++) {
 672                 gnttab_list[i] = (grant_ref_t *)__get_free_page(GFP_ATOMIC);
 673                 if (!gnttab_list[i])
 674                         goto grow_nomem;
 675         }
 676
 677
 678         for (i = grefs_per_frame * nr_grant_frames;
 679              i < grefs_per_frame * new_nr_grant_frames - 1; i++)
 680                 gnttab_entry(i) = i + 1;
 681
 682         gnttab_entry(i) = gnttab_free_head;
 683         gnttab_free_head = grefs_per_frame * nr_grant_frames;
 684         gnttab_free_count += extra_entries;
 685
 686         nr_grant_frames = new_nr_grant_frames;
 687
 688         check_free_callbacks();
 689
 690         return 0;
 691
 692 grow_nomem:
 693         while (i-- > nr_glist_frames)
 694                 free_page((unsigned long) gnttab_list[i]);
 695         return -ENOMEM;
 696 }
 697
 698 static unsigned int __max_nr_grant_frames(void)
 699 {
 700         struct gnttab_query_size query;
 701         int rc;
 702
 703         query.dom = DOMID_SELF;
 704
 705         rc = HYPERVISOR_grant_table_op(GNTTABOP_query_size, &query, 1);
 706         if ((rc < 0) || (query.status != GNTST_okay))
 707                 return 4; /* Legacy max supported number of frames */
 708
 709         return query.max_nr_frames;
 710 }
 711
 712 unsigned int gnttab_max_grant_frames(void)
 713 {
 714         unsigned int xen_max = __max_nr_grant_frames();
 715         static unsigned int boot_max_nr_grant_frames;
 716
 717         /* First time, initialize it properly. */
 718         if (!boot_max_nr_grant_frames)
 719                 boot_max_nr_grant_frames = __max_nr_grant_frames();
 720
 721         if (xen_max > boot_max_nr_grant_frames)
 722                 return boot_max_nr_grant_frames;
 723         return xen_max;
 724 }
 725 EXPORT_SYMBOL_GPL(gnttab_max_grant_frames);
 726
 727 int gnttab_setup_auto_xlat_frames(phys_addr_t addr)
 728 {
 729         xen_pfn_t *pfn;
 730         unsigned int max_nr_gframes = __max_nr_grant_frames();
 731         unsigned int i;
 732         void *vaddr;
 733
 734         if (xen_auto_xlat_grant_frames.count)
 735                 return -EINVAL;
 736
 737         vaddr = xen_remap(addr, XEN_PAGE_SIZE * max_nr_gframes);
 738         if (vaddr == NULL) {
 739                 pr_warn("Failed to ioremap gnttab share frames (addr=%pa)!\n",
 740                         &addr);
 741                 return -ENOMEM;
 742         }
 743         pfn = kcalloc(max_nr_gframes, sizeof(pfn[0]), GFP_KERNEL);
 744         if (!pfn) {
 745                 xen_unmap(vaddr);
 746                 return -ENOMEM;
 747         }
 748         for (i = 0; i < max_nr_gframes; i++)
 749                 pfn[i] = XEN_PFN_DOWN(addr) + i;
 750
 751         xen_auto_xlat_grant_frames.vaddr = vaddr;
 752         xen_auto_xlat_grant_frames.pfn = pfn;
 753         xen_auto_xlat_grant_frames.count = max_nr_gframes;
 754
 755         return 0;
 756 }
 757 EXPORT_SYMBOL_GPL(gnttab_setup_auto_xlat_frames);
 758
 759 void gnttab_free_auto_xlat_frames(void)
 760 {
 761         if (!xen_auto_xlat_grant_frames.count)
 762                 return;
 763         kfree(xen_auto_xlat_grant_frames.pfn);
 764         xen_unmap(xen_auto_xlat_grant_frames.vaddr);
 765
 766         xen_auto_xlat_grant_frames.pfn = NULL;
 767         xen_auto_xlat_grant_frames.count = 0;
 768         xen_auto_xlat_grant_frames.vaddr = NULL;
 769 }
 770 EXPORT_SYMBOL_GPL(gnttab_free_auto_xlat_frames);
 771
 772 /**
 773  * gnttab_alloc_pages - alloc pages suitable for grant mapping into
 774  * @nr_pages: number of pages to alloc
 775  * @pages: returns the pages
 776  */
 777 int gnttab_alloc_pages(int nr_pages, struct page **pages)
 778 {
 779         int i;
 780         int ret;
 781
 782         ret = alloc_xenballooned_pages(nr_pages, pages);
 783         if (ret < 0)
 784                 return ret;
 785
 786         for (i = 0; i < nr_pages; i++) {
 787 #if BITS_PER_LONG < 64
 788                 struct xen_page_foreign *foreign;
 789
 790                 foreign = kzalloc(sizeof(*foreign), GFP_KERNEL);
 791                 if (!foreign) {
 792                         gnttab_free_pages(nr_pages, pages);
 793                         return -ENOMEM;
 794                 }
 795                 set_page_private(pages[i], (unsigned long)foreign);
 796 #endif
 797                 SetPagePrivate(pages[i]);
 798         }
 799
 800         return 0;
 801 }
 802 EXPORT_SYMBOL(gnttab_alloc_pages);
 803
 804 /**
 805  * gnttab_free_pages - free pages allocated by gnttab_alloc_pages()
 806  * @nr_pages; number of pages to free
 807  * @pages: the pages
 808  */
 809 void gnttab_free_pages(int nr_pages, struct page **pages)
 810 {
 811         int i;
 812
 813         for (i = 0; i < nr_pages; i++) {
 814                 if (PagePrivate(pages[i])) {
 815 #if BITS_PER_LONG < 64
 816                         kfree((void *)page_private(pages[i]));
 817 #endif
 818                         ClearPagePrivate(pages[i]);
 819                 }
 820         }
 821         free_xenballooned_pages(nr_pages, pages);
 822 }
 823 EXPORT_SYMBOL(gnttab_free_pages);
 824
 825 /* Handling of paged out grant targets (GNTST_eagain) */
 826 #define MAX_DELAY 256
 827 static inline void
 828 gnttab_retry_eagain_gop(unsigned int cmd, void *gop, int16_t *status,
 829                                                 const char *func)
 830 {
 831         unsigned delay = 1;
 832
 833         do {
 834                 BUG_ON(HYPERVISOR_grant_table_op(cmd, gop, 1));
 835                 if (*status == GNTST_eagain)
 836                         msleep(delay++);
 837         } while ((*status == GNTST_eagain) && (delay < MAX_DELAY));
 838
 839         if (delay >= MAX_DELAY) {
 840                 pr_err("%s: %s eagain grant\n", func, current->comm);
 841                 *status = GNTST_bad_page;
 842         }
 843 }
 844
 845 void gnttab_batch_map(struct gnttab_map_grant_ref *batch, unsigned count)
 846 {
 847         struct gnttab_map_grant_ref *op;
 848
 849         if (HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref, batch, count))
 850                 BUG();
 851         for (op = batch; op < batch + count; op++)
 852                 if (op->status == GNTST_eagain)
 853                         gnttab_retry_eagain_gop(GNTTABOP_map_grant_ref, op,
 854                                                 &op->status, __func__);
 855 }
 856 EXPORT_SYMBOL_GPL(gnttab_batch_map);
 857
 858 void gnttab_batch_copy(struct gnttab_copy *batch, unsigned count)
 859 {
 860         struct gnttab_copy *op;
 861
 862         if (HYPERVISOR_grant_table_op(GNTTABOP_copy, batch, count))
 863                 BUG();
 864         for (op = batch; op < batch + count; op++)
 865                 if (op->status == GNTST_eagain)
 866                         gnttab_retry_eagain_gop(GNTTABOP_copy, op,
 867                                                 &op->status, __func__);
 868 }
 869 EXPORT_SYMBOL_GPL(gnttab_batch_copy);
 870
 871 void gnttab_foreach_grant_in_range(struct page *page,
 872                                    unsigned int offset,
 873                                    unsigned int len,
 874                                    xen_grant_fn_t fn,
 875                                    void *data)
 876 {
 877         unsigned int goffset;
 878         unsigned int glen;
 879         unsigned long xen_pfn;
 880
 881         len = min_t(unsigned int, PAGE_SIZE - offset, len);
 882         goffset = xen_offset_in_page(offset);
 883
 884         xen_pfn = page_to_xen_pfn(page) + XEN_PFN_DOWN(offset);
 885
 886         while (len) {
 887                 glen = min_t(unsigned int, XEN_PAGE_SIZE - goffset, len);
 888                 fn(pfn_to_gfn(xen_pfn), goffset, glen, data);
 889
 890                 goffset = 0;
 891                 xen_pfn++;
 892                 len -= glen;
 893         }
 894 }
 895 EXPORT_SYMBOL_GPL(gnttab_foreach_grant_in_range);
 896
 897 void gnttab_foreach_grant(struct page **pages,
 898                           unsigned int nr_grefs,
 899                           xen_grant_fn_t fn,
 900                           void *data)
 901 {
 902         unsigned int goffset = 0;
 903         unsigned long xen_pfn = 0;
 904         unsigned int i;
 905
 906         for (i = 0; i < nr_grefs; i++) {
 907                 if ((i % XEN_PFN_PER_PAGE) == 0) {
 908                         xen_pfn = page_to_xen_pfn(pages[i / XEN_PFN_PER_PAGE]);
 909                         goffset = 0;
 910                 }
 911
 912                 fn(pfn_to_gfn(xen_pfn), goffset, XEN_PAGE_SIZE, data);
 913
 914                 goffset += XEN_PAGE_SIZE;
 915                 xen_pfn++;
 916         }
 917 }
 918
 919 int gnttab_map_refs(struct gnttab_map_grant_ref *map_ops,
 920                     struct gnttab_map_grant_ref *kmap_ops,
 921                     struct page **pages, unsigned int count)
 922 {
 923         int i, ret;
 924
 925         ret = HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref, map_ops, count);
 926         if (ret)
 927                 return ret;
 928
 929         for (i = 0; i < count; i++) {
 930                 /* Retry eagain maps */
 931                 if (map_ops[i].status == GNTST_eagain)
 932                         gnttab_retry_eagain_gop(GNTTABOP_map_grant_ref, map_ops + i,
 933                                                 &map_ops[i].status, __func__);
 934
 935                 if (map_ops[i].status == GNTST_okay) {
 936                         struct xen_page_foreign *foreign;
 937
 938                         SetPageForeign(pages[i]);
 939                         foreign = xen_page_foreign(pages[i]);
 940                         foreign->domid = map_ops[i].dom;
 941                         foreign->gref = map_ops[i].ref;
 942                 }
 943         }
 944
 945         return set_foreign_p2m_mapping(map_ops, kmap_ops, pages, count);
 946 }
 947 EXPORT_SYMBOL_GPL(gnttab_map_refs);
 948
 949 int gnttab_unmap_refs(struct gnttab_unmap_grant_ref *unmap_ops,
 950                       struct gnttab_unmap_grant_ref *kunmap_ops,
 951                       struct page **pages, unsigned int count)
 952 {
 953         unsigned int i;
 954         int ret;
 955
 956         ret = HYPERVISOR_grant_table_op(GNTTABOP_unmap_grant_ref, unmap_ops, count);
 957         if (ret)
 958                 return ret;
 959
 960         for (i = 0; i < count; i++)
 961                 ClearPageForeign(pages[i]);
 962
 963         return clear_foreign_p2m_mapping(unmap_ops, kunmap_ops, pages, count);
 964 }
 965 EXPORT_SYMBOL_GPL(gnttab_unmap_refs);
 966
 967 #define GNTTAB_UNMAP_REFS_DELAY 5
 968
 969 static void __gnttab_unmap_refs_async(struct gntab_unmap_queue_data* item);
 970
 971 static void gnttab_unmap_work(struct work_struct *work)
 972 {
 973         struct gntab_unmap_queue_data
 974                 *unmap_data = container_of(work,
 975                                            struct gntab_unmap_queue_data,
 976                                            gnttab_work.work);
 977         if (unmap_data->age != UINT_MAX)
 978                 unmap_data->age++;
 979         __gnttab_unmap_refs_async(unmap_data);
 980 }
 981
 982 static void __gnttab_unmap_refs_async(struct gntab_unmap_queue_data* item)
 983 {
 984         int ret;
 985         int pc;
 986
 987         for (pc = 0; pc < item->count; pc++) {
 988                 if (page_count(item->pages[pc]) > 1) {
 989                         unsigned long delay = GNTTAB_UNMAP_REFS_DELAY * (item->age + 1);
 990                         schedule_delayed_work(&item->gnttab_work,
 991                                               msecs_to_jiffies(delay));
 992                         return;
 993                 }
 994         }
 995
 996         ret = gnttab_unmap_refs(item->unmap_ops, item->kunmap_ops,
 997                                 item->pages, item->count);
 998         item->done(ret, item);
 999 }
1000
1001 void gnttab_unmap_refs_async(struct gntab_unmap_queue_data* item)
1002 {
1003         INIT_DELAYED_WORK(&item->gnttab_work, gnttab_unmap_work);
1004         item->age = 0;
1005
1006         __gnttab_unmap_refs_async(item);
1007 }
1008 EXPORT_SYMBOL_GPL(gnttab_unmap_refs_async);
1009
1010 static void unmap_refs_callback(int result,
1011                 struct gntab_unmap_queue_data *data)
1012 {
1013         struct unmap_refs_callback_data *d = data->data;
1014
1015         d->result = result;
1016         complete(&d->completion);
1017 }
1018
1019 int gnttab_unmap_refs_sync(struct gntab_unmap_queue_data *item)
1020 {
1021         struct unmap_refs_callback_data data;
1022
1023         init_completion(&data.completion);
1024         item->data = &data;
1025         item->done = &unmap_refs_callback;
1026         gnttab_unmap_refs_async(item);
1027         wait_for_completion(&data.completion);
1028
1029         return data.result;
1030 }
1031 EXPORT_SYMBOL_GPL(gnttab_unmap_refs_sync);
1032
1033 static unsigned int nr_status_frames(unsigned int nr_grant_frames)
1034 {
1035         BUG_ON(gnttab_interface == NULL);
1036         return gnttab_frames(nr_grant_frames, SPP);
1037 }
1038
1039 static int gnttab_map_frames_v1(xen_pfn_t *frames, unsigned int nr_gframes)
1040 {
1041         int rc;
1042
1043         rc = arch_gnttab_map_shared(frames, nr_gframes,
1044                                     gnttab_max_grant_frames(),
1045                                     &gnttab_shared.addr);
1046         BUG_ON(rc);
1047
1048         return 0;
1049 }
1050
1051 static void gnttab_unmap_frames_v1(void)
1052 {
1053         arch_gnttab_unmap(gnttab_shared.addr, nr_grant_frames);
1054 }
1055
1056 static int gnttab_map_frames_v2(xen_pfn_t *frames, unsigned int nr_gframes)
1057 {
1058         uint64_t *sframes;
1059         unsigned int nr_sframes;
1060         struct gnttab_get_status_frames getframes;
1061         int rc;
1062
1063         nr_sframes = nr_status_frames(nr_gframes);
1064
1065         /* No need for kzalloc as it is initialized in following hypercall
1066          * GNTTABOP_get_status_frames.
1067          */
1068         sframes = kmalloc_array(nr_sframes, sizeof(uint64_t), GFP_ATOMIC);
1069         if (!sframes)
1070                 return -ENOMEM;
1071
1072         getframes.dom        = DOMID_SELF;
1073         getframes.nr_frames  = nr_sframes;
1074         set_xen_guest_handle(getframes.frame_list, sframes);
1075
1076         rc = HYPERVISOR_grant_table_op(GNTTABOP_get_status_frames,
1077                                        &getframes, 1);
1078         if (rc == -ENOSYS) {
1079                 kfree(sframes);
1080                 return -ENOSYS;
1081         }
1082
1083         BUG_ON(rc || getframes.status);
1084
1085         rc = arch_gnttab_map_status(sframes, nr_sframes,
1086                                     nr_status_frames(gnttab_max_grant_frames()),
1087                                     &grstatus);
1088         BUG_ON(rc);
1089         kfree(sframes);
1090
1091         rc = arch_gnttab_map_shared(frames, nr_gframes,
1092                                     gnttab_max_grant_frames(),
1093                                     &gnttab_shared.addr);
1094         BUG_ON(rc);
1095
1096         return 0;
1097 }
1098
1099 static void gnttab_unmap_frames_v2(void)
1100 {
1101         arch_gnttab_unmap(gnttab_shared.addr, nr_grant_frames);
1102         arch_gnttab_unmap(grstatus, nr_status_frames(nr_grant_frames));
1103 }
1104
1105 static int gnttab_map(unsigned int start_idx, unsigned int end_idx)
1106 {
1107         struct gnttab_setup_table setup;
1108         xen_pfn_t *frames;
1109         unsigned int nr_gframes = end_idx + 1;
1110         int rc;
1111
1112         if (xen_feature(XENFEAT_auto_translated_physmap)) {
1113                 struct xen_add_to_physmap xatp;
1114                 unsigned int i = end_idx;
1115                 rc = 0;
1116                 BUG_ON(xen_auto_xlat_grant_frames.count < nr_gframes);
1117                 /*
1118                  * Loop backwards, so that the first hypercall has the largest
1119                  * index, ensuring that the table will grow only once.
1120                  */
1121                 do {
1122                         xatp.domid = DOMID_SELF;
1123                         xatp.idx = i;
1124                         xatp.space = XENMAPSPACE_grant_table;
1125                         xatp.gpfn = xen_auto_xlat_grant_frames.pfn[i];
1126                         rc = HYPERVISOR_memory_op(XENMEM_add_to_physmap, &xatp);
1127                         if (rc != 0) {
1128                                 pr_warn("grant table add_to_physmap failed, err=%d\n",
1129                                         rc);
1130                                 break;
1131                         }
1132                 } while (i-- > start_idx);
1133
1134                 return rc;
1135         }
1136
1137         /* No need for kzalloc as it is initialized in following hypercall
1138          * GNTTABOP_setup_table.
1139          */
1140         frames = kmalloc_array(nr_gframes, sizeof(unsigned long), GFP_ATOMIC);
1141         if (!frames)
1142                 return -ENOMEM;
1143
1144         setup.dom        = DOMID_SELF;
1145         setup.nr_frames  = nr_gframes;
1146         set_xen_guest_handle(setup.frame_list, frames);
1147
1148         rc = HYPERVISOR_grant_table_op(GNTTABOP_setup_table, &setup, 1);
1149         if (rc == -ENOSYS) {
1150                 kfree(frames);
1151                 return -ENOSYS;
1152         }
1153
1154         BUG_ON(rc || setup.status);
1155
1156         rc = gnttab_interface->map_frames(frames, nr_gframes);
1157
1158         kfree(frames);
1159
1160         return rc;
1161 }
1162
1163 static const struct gnttab_ops gnttab_v1_ops = {
1164         .version                        = 1,
1165         .grefs_per_grant_frame          = XEN_PAGE_SIZE /
1166                                           sizeof(struct grant_entry_v1),
1167         .map_frames                     = gnttab_map_frames_v1,
1168         .unmap_frames                   = gnttab_unmap_frames_v1,
1169         .update_entry                   = gnttab_update_entry_v1,
1170         .end_foreign_access_ref         = gnttab_end_foreign_access_ref_v1,
1171         .end_foreign_transfer_ref       = gnttab_end_foreign_transfer_ref_v1,
1172         .query_foreign_access           = gnttab_query_foreign_access_v1,
1173 };
1174
1175 static const struct gnttab_ops gnttab_v2_ops = {
1176         .version                        = 2,
1177         .grefs_per_grant_frame          = XEN_PAGE_SIZE /
1178                                           sizeof(union grant_entry_v2),
1179         .map_frames                     = gnttab_map_frames_v2,
1180         .unmap_frames                   = gnttab_unmap_frames_v2,
1181         .update_entry                   = gnttab_update_entry_v2,
1182         .end_foreign_access_ref         = gnttab_end_foreign_access_ref_v2,
1183         .end_foreign_transfer_ref       = gnttab_end_foreign_transfer_ref_v2,
1184         .query_foreign_access           = gnttab_query_foreign_access_v2,
1185 };
1186
1187 static bool gnttab_need_v2(void)
1188 {
1189 #ifdef CONFIG_X86
1190         uint32_t base, width;
1191
1192         if (xen_pv_domain()) {
1193                 base = xen_cpuid_base();
1194                 if (cpuid_eax(base) < 5)
1195                         return false;   /* Information not available, use V1. */
1196                 width = cpuid_ebx(base + 5) &
1197                         XEN_CPUID_MACHINE_ADDRESS_WIDTH_MASK;
1198                 return width > 32 + PAGE_SHIFT;
1199         }
1200 #endif
1201         return !!(max_possible_pfn >> 32);
1202 }
1203
1204 static void gnttab_request_version(void)
1205 {
1206         long rc;
1207         struct gnttab_set_version gsv;
1208
1209         if (gnttab_need_v2())
1210                 gsv.version = 2;
1211         else
1212                 gsv.version = 1;
1213
1214         /* Boot parameter overrides automatic selection. */
1215         if (xen_gnttab_version >= 1 && xen_gnttab_version <= 2)
1216                 gsv.version = xen_gnttab_version;
1217
1218         rc = HYPERVISOR_grant_table_op(GNTTABOP_set_version, &gsv, 1);
1219         if (rc == 0 && gsv.version == 2)
1220                 gnttab_interface = &gnttab_v2_ops;
1221         else
1222                 gnttab_interface = &gnttab_v1_ops;
1223         pr_info("Grant tables using version %d layout\n",
1224                 gnttab_interface->version);
1225 }
1226
1227 static int gnttab_setup(void)
1228 {
1229         unsigned int max_nr_gframes;
1230
1231         max_nr_gframes = gnttab_max_grant_frames();
1232         if (max_nr_gframes < nr_grant_frames)
1233                 return -ENOSYS;
1234
1235         if (xen_feature(XENFEAT_auto_translated_physmap) && gnttab_shared.addr == NULL) {
1236                 gnttab_shared.addr = xen_auto_xlat_grant_frames.vaddr;
1237                 if (gnttab_shared.addr == NULL) {
1238                         pr_warn("gnttab share frames (addr=0x%08lx) is not mapped!\n",
1239                                 (unsigned long)xen_auto_xlat_grant_frames.vaddr);
1240                         return -ENOMEM;
1241                 }
1242         }
1243         return gnttab_map(0, nr_grant_frames - 1);
1244 }
1245
1246 int gnttab_resume(void)
1247 {
1248         gnttab_request_version();
1249         return gnttab_setup();
1250 }
1251
1252 int gnttab_suspend(void)
1253 {
1254         if (!xen_feature(XENFEAT_auto_translated_physmap))
1255                 gnttab_interface->unmap_frames();
1256         return 0;
1257 }
1258
1259 static int gnttab_expand(unsigned int req_entries)
1260 {
1261         int rc;
1262         unsigned int cur, extra;
1263
1264         BUG_ON(gnttab_interface == NULL);
1265         cur = nr_grant_frames;
1266         extra = ((req_entries + gnttab_interface->grefs_per_grant_frame - 1) /
1267                  gnttab_interface->grefs_per_grant_frame);
1268         if (cur + extra > gnttab_max_grant_frames()) {
1269                 pr_warn_ratelimited("xen/grant-table: max_grant_frames reached"
1270                                     " cur=%u extra=%u limit=%u"
1271                                     " gnttab_free_count=%u req_entries=%u\n",
1272                                     cur, extra, gnttab_max_grant_frames(),
1273                                     gnttab_free_count, req_entries);
1274                 return -ENOSPC;
1275         }
1276
1277         rc = gnttab_map(cur, cur + extra - 1);
1278         if (rc == 0)
1279                 rc = grow_gnttab_list(extra);
1280
1281         return rc;
1282 }
1283
1284 int gnttab_init(void)
1285 {
1286         int i;
1287         unsigned long max_nr_grant_frames;
1288         unsigned int max_nr_glist_frames, nr_glist_frames;
1289         unsigned int nr_init_grefs;
1290         int ret;
1291
1292         gnttab_request_version();
1293         max_nr_grant_frames = gnttab_max_grant_frames();
1294         nr_grant_frames = 1;
1295
1296         /* Determine the maximum number of frames required for the
1297          * grant reference free list on the current hypervisor.
1298          */
1299         BUG_ON(gnttab_interface == NULL);
1300         max_nr_glist_frames = (max_nr_grant_frames *
1301                                gnttab_interface->grefs_per_grant_frame / RPP);
1302
1303         gnttab_list = kmalloc_array(max_nr_glist_frames,
1304                                     sizeof(grant_ref_t *),
1305                                     GFP_KERNEL);
1306         if (gnttab_list == NULL)
1307                 return -ENOMEM;
1308
1309         nr_glist_frames = gnttab_frames(nr_grant_frames, RPP);
1310         for (i = 0; i < nr_glist_frames; i++) {
1311                 gnttab_list[i] = (grant_ref_t *)__get_free_page(GFP_KERNEL);
1312                 if (gnttab_list[i] == NULL) {
1313                         ret = -ENOMEM;
1314                         goto ini_nomem;
1315                 }
1316         }
1317
1318         ret = arch_gnttab_init(max_nr_grant_frames,
1319                                nr_status_frames(max_nr_grant_frames));
1320         if (ret < 0)
1321                 goto ini_nomem;
1322
1323         if (gnttab_setup() < 0) {
1324                 ret = -ENODEV;
1325                 goto ini_nomem;
1326         }
1327
1328         nr_init_grefs = nr_grant_frames *
1329                         gnttab_interface->grefs_per_grant_frame;
1330
1331         for (i = NR_RESERVED_ENTRIES; i < nr_init_grefs - 1; i++)
1332                 gnttab_entry(i) = i + 1;
1333
1334         gnttab_entry(nr_init_grefs - 1) = GNTTAB_LIST_END;
1335         gnttab_free_count = nr_init_grefs - NR_RESERVED_ENTRIES;
1336         gnttab_free_head  = NR_RESERVED_ENTRIES;
1337
1338         printk("Grant table initialized\n");
1339         return 0;
1340
1341  ini_nomem:
1342         for (i--; i >= 0; i--)
1343                 free_page((unsigned long)gnttab_list[i]);
1344         kfree(gnttab_list);
1345         return ret;
1346 }
1347 EXPORT_SYMBOL_GPL(gnttab_init);
1348
1349 static int __gnttab_init(void)
1350 {
1351         if (!xen_domain())
1352                 return -ENODEV;
1353
1354         /* Delay grant-table initialization in the PV on HVM case */
1355         if (xen_hvm_domain() && !xen_pvh_domain())
1356                 return 0;
1357
1358         return gnttab_init();
1359 }
1360 /* Starts after core_initcall so that xen_pvh_gnttab_setup can be called
1361  * beforehand to initialize xen_auto_xlat_grant_frames. */
1362 core_initcall_sync(__gnttab_init);