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/module.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
  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 <asm/xen/hypercall.h>
  54 #include <asm/xen/interface.h>
  55
  56 #include <asm/pgtable.h>
  57 #include <asm/sync_bitops.h>
  58
  59 /* External tools reserve first few grant table entries. */
  60 #define NR_RESERVED_ENTRIES 8
  61 #define GNTTAB_LIST_END 0xffffffff
  62
  63 static grant_ref_t **gnttab_list;
  64 static unsigned int nr_grant_frames;
  65 static int gnttab_free_count;
  66 static grant_ref_t gnttab_free_head;
  67 static DEFINE_SPINLOCK(gnttab_list_lock);
  68 struct grant_frames xen_auto_xlat_grant_frames;
  69
  70 static union {
  71         struct grant_entry_v1 *v1;
  72         union grant_entry_v2 *v2;
  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          * Grant a domain to access a range of bytes within the page referred by
 125          * an available grant entry. Ref parameter is reference of a grant entry
 126          * which will be sub-page accessed, domid is id of grantee domain, frame
 127          * is frame address of subpage grant, flags is grant type and flag
 128          * information, page_off is offset of the range of bytes, and length is
 129          * length of bytes to be accessed.
 130          */
 131         void (*update_subpage_entry)(grant_ref_t ref, domid_t domid,
 132                                      unsigned long frame, int flags,
 133                                      unsigned page_off, unsigned length);
 134         /*
 135          * Redirect an available grant entry on domain A to another grant
 136          * reference of domain B, then allow domain C to use grant reference
 137          * of domain B transitively. Ref parameter is an available grant entry
 138          * reference on domain A, domid is id of domain C which accesses grant
 139          * entry transitively, flags is grant type and flag information,
 140          * trans_domid is id of domain B whose grant entry is finally accessed
 141          * transitively, trans_gref is grant entry transitive reference of
 142          * domain B.
 143          */
 144         void (*update_trans_entry)(grant_ref_t ref, domid_t domid, int flags,
 145                                    domid_t trans_domid, grant_ref_t trans_gref);
 146 };
 147
 148 static struct gnttab_ops *gnttab_interface;
 149
 150 /*This reflects status of grant entries, so act as a global value*/
 151 static grant_status_t *grstatus;
 152
 153 static int grant_table_version;
 154 static int grefs_per_grant_frame;
 155
 156 static struct gnttab_free_callback *gnttab_free_callback_list;
 157
 158 static int gnttab_expand(unsigned int req_entries);
 159
 160 #define RPP (PAGE_SIZE / sizeof(grant_ref_t))
 161 #define SPP (PAGE_SIZE / sizeof(grant_status_t))
 162
 163 static inline grant_ref_t *__gnttab_entry(grant_ref_t entry)
 164 {
 165         return &gnttab_list[(entry) / RPP][(entry) % RPP];
 166 }
 167 /* This can be used as an l-value */
 168 #define gnttab_entry(entry) (*__gnttab_entry(entry))
 169
 170 static int get_free_entries(unsigned count)
 171 {
 172         unsigned long flags;
 173         int ref, rc = 0;
 174         grant_ref_t head;
 175
 176         spin_lock_irqsave(&gnttab_list_lock, flags);
 177
 178         if ((gnttab_free_count < count) &&
 179             ((rc = gnttab_expand(count - gnttab_free_count)) < 0)) {
 180                 spin_unlock_irqrestore(&gnttab_list_lock, flags);
 181                 return rc;
 182         }
 183
 184         ref = head = gnttab_free_head;
 185         gnttab_free_count -= count;
 186         while (count-- > 1)
 187                 head = gnttab_entry(head);
 188         gnttab_free_head = gnttab_entry(head);
 189         gnttab_entry(head) = GNTTAB_LIST_END;
 190
 191         spin_unlock_irqrestore(&gnttab_list_lock, flags);
 192
 193         return ref;
 194 }
 195
 196 static void do_free_callbacks(void)
 197 {
 198         struct gnttab_free_callback *callback, *next;
 199
 200         callback = gnttab_free_callback_list;
 201         gnttab_free_callback_list = NULL;
 202
 203         while (callback != NULL) {
 204                 next = callback->next;
 205                 if (gnttab_free_count >= callback->count) {
 206                         callback->next = NULL;
 207                         callback->fn(callback->arg);
 208                 } else {
 209                         callback->next = gnttab_free_callback_list;
 210                         gnttab_free_callback_list = callback;
 211                 }
 212                 callback = next;
 213         }
 214 }
 215
 216 static inline void check_free_callbacks(void)
 217 {
 218         if (unlikely(gnttab_free_callback_list))
 219                 do_free_callbacks();
 220 }
 221
 222 static void put_free_entry(grant_ref_t ref)
 223 {
 224         unsigned long flags;
 225         spin_lock_irqsave(&gnttab_list_lock, flags);
 226         gnttab_entry(ref) = gnttab_free_head;
 227         gnttab_free_head = ref;
 228         gnttab_free_count++;
 229         check_free_callbacks();
 230         spin_unlock_irqrestore(&gnttab_list_lock, flags);
 231 }
 232
 233 /*
 234  * Following applies to gnttab_update_entry_v1 and gnttab_update_entry_v2.
 235  * Introducing a valid entry into the grant table:
 236  *  1. Write ent->domid.
 237  *  2. Write ent->frame:
 238  *      GTF_permit_access:   Frame to which access is permitted.
 239  *      GTF_accept_transfer: Pseudo-phys frame slot being filled by new
 240  *                           frame, or zero if none.
 241  *  3. Write memory barrier (WMB).
 242  *  4. Write ent->flags, inc. valid type.
 243  */
 244 static void gnttab_update_entry_v1(grant_ref_t ref, domid_t domid,
 245                                    unsigned long frame, unsigned flags)
 246 {
 247         gnttab_shared.v1[ref].domid = domid;
 248         gnttab_shared.v1[ref].frame = frame;
 249         wmb();
 250         gnttab_shared.v1[ref].flags = flags;
 251 }
 252
 253 static void gnttab_update_entry_v2(grant_ref_t ref, domid_t domid,
 254                                    unsigned long frame, unsigned flags)
 255 {
 256         gnttab_shared.v2[ref].hdr.domid = domid;
 257         gnttab_shared.v2[ref].full_page.frame = frame;
 258         wmb();
 259         gnttab_shared.v2[ref].hdr.flags = GTF_permit_access | flags;
 260 }
 261
 262 /*
 263  * Public grant-issuing interface functions
 264  */
 265 void gnttab_grant_foreign_access_ref(grant_ref_t ref, domid_t domid,
 266                                      unsigned long frame, int readonly)
 267 {
 268         gnttab_interface->update_entry(ref, domid, frame,
 269                            GTF_permit_access | (readonly ? GTF_readonly : 0));
 270 }
 271 EXPORT_SYMBOL_GPL(gnttab_grant_foreign_access_ref);
 272
 273 int gnttab_grant_foreign_access(domid_t domid, unsigned long frame,
 274                                 int readonly)
 275 {
 276         int ref;
 277
 278         ref = get_free_entries(1);
 279         if (unlikely(ref < 0))
 280                 return -ENOSPC;
 281
 282         gnttab_grant_foreign_access_ref(ref, domid, frame, readonly);
 283
 284         return ref;
 285 }
 286 EXPORT_SYMBOL_GPL(gnttab_grant_foreign_access);
 287
 288 static void gnttab_update_subpage_entry_v2(grant_ref_t ref, domid_t domid,
 289                                            unsigned long frame, int flags,
 290                                            unsigned page_off, unsigned length)
 291 {
 292         gnttab_shared.v2[ref].sub_page.frame = frame;
 293         gnttab_shared.v2[ref].sub_page.page_off = page_off;
 294         gnttab_shared.v2[ref].sub_page.length = length;
 295         gnttab_shared.v2[ref].hdr.domid = domid;
 296         wmb();
 297         gnttab_shared.v2[ref].hdr.flags =
 298                                 GTF_permit_access | GTF_sub_page | flags;
 299 }
 300
 301 int gnttab_grant_foreign_access_subpage_ref(grant_ref_t ref, domid_t domid,
 302                                             unsigned long frame, int flags,
 303                                             unsigned page_off,
 304                                             unsigned length)
 305 {
 306         if (flags & (GTF_accept_transfer | GTF_reading |
 307                      GTF_writing | GTF_transitive))
 308                 return -EPERM;
 309
 310         if (gnttab_interface->update_subpage_entry == NULL)
 311                 return -ENOSYS;
 312
 313         gnttab_interface->update_subpage_entry(ref, domid, frame, flags,
 314                                                page_off, length);
 315
 316         return 0;
 317 }
 318 EXPORT_SYMBOL_GPL(gnttab_grant_foreign_access_subpage_ref);
 319
 320 int gnttab_grant_foreign_access_subpage(domid_t domid, unsigned long frame,
 321                                         int flags, unsigned page_off,
 322                                         unsigned length)
 323 {
 324         int ref, rc;
 325
 326         ref = get_free_entries(1);
 327         if (unlikely(ref < 0))
 328                 return -ENOSPC;
 329
 330         rc = gnttab_grant_foreign_access_subpage_ref(ref, domid, frame, flags,
 331                                                      page_off, length);
 332         if (rc < 0) {
 333                 put_free_entry(ref);
 334                 return rc;
 335         }
 336
 337         return ref;
 338 }
 339 EXPORT_SYMBOL_GPL(gnttab_grant_foreign_access_subpage);
 340
 341 bool gnttab_subpage_grants_available(void)
 342 {
 343         return gnttab_interface->update_subpage_entry != NULL;
 344 }
 345 EXPORT_SYMBOL_GPL(gnttab_subpage_grants_available);
 346
 347 static void gnttab_update_trans_entry_v2(grant_ref_t ref, domid_t domid,
 348                                          int flags, domid_t trans_domid,
 349                                          grant_ref_t trans_gref)
 350 {
 351         gnttab_shared.v2[ref].transitive.trans_domid = trans_domid;
 352         gnttab_shared.v2[ref].transitive.gref = trans_gref;
 353         gnttab_shared.v2[ref].hdr.domid = domid;
 354         wmb();
 355         gnttab_shared.v2[ref].hdr.flags =
 356                                 GTF_permit_access | GTF_transitive | flags;
 357 }
 358
 359 int gnttab_grant_foreign_access_trans_ref(grant_ref_t ref, domid_t domid,
 360                                           int flags, domid_t trans_domid,
 361                                           grant_ref_t trans_gref)
 362 {
 363         if (flags & (GTF_accept_transfer | GTF_reading |
 364                      GTF_writing | GTF_sub_page))
 365                 return -EPERM;
 366
 367         if (gnttab_interface->update_trans_entry == NULL)
 368                 return -ENOSYS;
 369
 370         gnttab_interface->update_trans_entry(ref, domid, flags, trans_domid,
 371                                              trans_gref);
 372
 373         return 0;
 374 }
 375 EXPORT_SYMBOL_GPL(gnttab_grant_foreign_access_trans_ref);
 376
 377 int gnttab_grant_foreign_access_trans(domid_t domid, int flags,
 378                                       domid_t trans_domid,
 379                                       grant_ref_t trans_gref)
 380 {
 381         int ref, rc;
 382
 383         ref = get_free_entries(1);
 384         if (unlikely(ref < 0))
 385                 return -ENOSPC;
 386
 387         rc = gnttab_grant_foreign_access_trans_ref(ref, domid, flags,
 388                                                    trans_domid, trans_gref);
 389         if (rc < 0) {
 390                 put_free_entry(ref);
 391                 return rc;
 392         }
 393
 394         return ref;
 395 }
 396 EXPORT_SYMBOL_GPL(gnttab_grant_foreign_access_trans);
 397
 398 bool gnttab_trans_grants_available(void)
 399 {
 400         return gnttab_interface->update_trans_entry != NULL;
 401 }
 402 EXPORT_SYMBOL_GPL(gnttab_trans_grants_available);
 403
 404 static int gnttab_query_foreign_access_v1(grant_ref_t ref)
 405 {
 406         return gnttab_shared.v1[ref].flags & (GTF_reading|GTF_writing);
 407 }
 408
 409 static int gnttab_query_foreign_access_v2(grant_ref_t ref)
 410 {
 411         return grstatus[ref] & (GTF_reading|GTF_writing);
 412 }
 413
 414 int gnttab_query_foreign_access(grant_ref_t ref)
 415 {
 416         return gnttab_interface->query_foreign_access(ref);
 417 }
 418 EXPORT_SYMBOL_GPL(gnttab_query_foreign_access);
 419
 420 static int gnttab_end_foreign_access_ref_v1(grant_ref_t ref, int readonly)
 421 {
 422         u16 flags, nflags;
 423         u16 *pflags;
 424
 425         pflags = &gnttab_shared.v1[ref].flags;
 426         nflags = *pflags;
 427         do {
 428                 flags = nflags;
 429                 if (flags & (GTF_reading|GTF_writing))
 430                         return 0;
 431         } while ((nflags = sync_cmpxchg(pflags, flags, 0)) != flags);
 432
 433         return 1;
 434 }
 435
 436 static int gnttab_end_foreign_access_ref_v2(grant_ref_t ref, int readonly)
 437 {
 438         gnttab_shared.v2[ref].hdr.flags = 0;
 439         mb();
 440         if (grstatus[ref] & (GTF_reading|GTF_writing)) {
 441                 return 0;
 442         } else {
 443                 /* The read of grstatus needs to have acquire
 444                 semantics.  On x86, reads already have
 445                 that, and we just need to protect against
 446                 compiler reorderings.  On other
 447                 architectures we may need a full
 448                 barrier. */
 449 #ifdef CONFIG_X86
 450                 barrier();
 451 #else
 452                 mb();
 453 #endif
 454         }
 455
 456         return 1;
 457 }
 458
 459 static inline int _gnttab_end_foreign_access_ref(grant_ref_t ref, int readonly)
 460 {
 461         return gnttab_interface->end_foreign_access_ref(ref, readonly);
 462 }
 463
 464 int gnttab_end_foreign_access_ref(grant_ref_t ref, int readonly)
 465 {
 466         if (_gnttab_end_foreign_access_ref(ref, readonly))
 467                 return 1;
 468         pr_warn("WARNING: g.e. %#x still in use!\n", ref);
 469         return 0;
 470 }
 471 EXPORT_SYMBOL_GPL(gnttab_end_foreign_access_ref);
 472
 473 struct deferred_entry {
 474         struct list_head list;
 475         grant_ref_t ref;
 476         bool ro;
 477         uint16_t warn_delay;
 478         struct page *page;
 479 };
 480 static LIST_HEAD(deferred_list);
 481 static void gnttab_handle_deferred(unsigned long);
 482 static DEFINE_TIMER(deferred_timer, gnttab_handle_deferred, 0, 0);
 483
 484 static void gnttab_handle_deferred(unsigned long unused)
 485 {
 486         unsigned int nr = 10;
 487         struct deferred_entry *first = NULL;
 488         unsigned long flags;
 489
 490         spin_lock_irqsave(&gnttab_list_lock, flags);
 491         while (nr--) {
 492                 struct deferred_entry *entry
 493                         = list_first_entry(&deferred_list,
 494                                            struct deferred_entry, list);
 495
 496                 if (entry == first)
 497                         break;
 498                 list_del(&entry->list);
 499                 spin_unlock_irqrestore(&gnttab_list_lock, flags);
 500                 if (_gnttab_end_foreign_access_ref(entry->ref, entry->ro)) {
 501                         put_free_entry(entry->ref);
 502                         if (entry->page) {
 503                                 pr_debug("freeing g.e. %#x (pfn %#lx)\n",
 504                                          entry->ref, page_to_pfn(entry->page));
 505                                 __free_page(entry->page);
 506                         } else
 507                                 pr_info("freeing g.e. %#x\n", entry->ref);
 508                         kfree(entry);
 509                         entry = NULL;
 510                 } else {
 511                         if (!--entry->warn_delay)
 512                                 pr_info("g.e. %#x still pending\n", entry->ref);
 513                         if (!first)
 514                                 first = entry;
 515                 }
 516                 spin_lock_irqsave(&gnttab_list_lock, flags);
 517                 if (entry)
 518                         list_add_tail(&entry->list, &deferred_list);
 519                 else if (list_empty(&deferred_list))
 520                         break;
 521         }
 522         if (!list_empty(&deferred_list) && !timer_pending(&deferred_timer)) {
 523                 deferred_timer.expires = jiffies + HZ;
 524                 add_timer(&deferred_timer);
 525         }
 526         spin_unlock_irqrestore(&gnttab_list_lock, flags);
 527 }
 528
 529 static void gnttab_add_deferred(grant_ref_t ref, bool readonly,
 530                                 struct page *page)
 531 {
 532         struct deferred_entry *entry = kmalloc(sizeof(*entry), GFP_ATOMIC);
 533         const char *what = KERN_WARNING "leaking";
 534
 535         if (entry) {
 536                 unsigned long flags;
 537
 538                 entry->ref = ref;
 539                 entry->ro = readonly;
 540                 entry->page = page;
 541                 entry->warn_delay = 60;
 542                 spin_lock_irqsave(&gnttab_list_lock, flags);
 543                 list_add_tail(&entry->list, &deferred_list);
 544                 if (!timer_pending(&deferred_timer)) {
 545                         deferred_timer.expires = jiffies + HZ;
 546                         add_timer(&deferred_timer);
 547                 }
 548                 spin_unlock_irqrestore(&gnttab_list_lock, flags);
 549                 what = KERN_DEBUG "deferring";
 550         }
 551         printk("%s g.e. %#x (pfn %#lx)\n",
 552                what, ref, page ? page_to_pfn(page) : -1);
 553 }
 554
 555 void gnttab_end_foreign_access(grant_ref_t ref, int readonly,
 556                                unsigned long page)
 557 {
 558         if (gnttab_end_foreign_access_ref(ref, readonly)) {
 559                 put_free_entry(ref);
 560                 if (page != 0)
 561                         free_page(page);
 562         } else
 563                 gnttab_add_deferred(ref, readonly,
 564                                     page ? virt_to_page(page) : NULL);
 565 }
 566 EXPORT_SYMBOL_GPL(gnttab_end_foreign_access);
 567
 568 int gnttab_grant_foreign_transfer(domid_t domid, unsigned long pfn)
 569 {
 570         int ref;
 571
 572         ref = get_free_entries(1);
 573         if (unlikely(ref < 0))
 574                 return -ENOSPC;
 575         gnttab_grant_foreign_transfer_ref(ref, domid, pfn);
 576
 577         return ref;
 578 }
 579 EXPORT_SYMBOL_GPL(gnttab_grant_foreign_transfer);
 580
 581 void gnttab_grant_foreign_transfer_ref(grant_ref_t ref, domid_t domid,
 582                                        unsigned long pfn)
 583 {
 584         gnttab_interface->update_entry(ref, domid, pfn, GTF_accept_transfer);
 585 }
 586 EXPORT_SYMBOL_GPL(gnttab_grant_foreign_transfer_ref);
 587
 588 static unsigned long gnttab_end_foreign_transfer_ref_v1(grant_ref_t ref)
 589 {
 590         unsigned long frame;
 591         u16           flags;
 592         u16          *pflags;
 593
 594         pflags = &gnttab_shared.v1[ref].flags;
 595
 596         /*
 597          * If a transfer is not even yet started, try to reclaim the grant
 598          * reference and return failure (== 0).
 599          */
 600         while (!((flags = *pflags) & GTF_transfer_committed)) {
 601                 if (sync_cmpxchg(pflags, flags, 0) == flags)
 602                         return 0;
 603                 cpu_relax();
 604         }
 605
 606         /* If a transfer is in progress then wait until it is completed. */
 607         while (!(flags & GTF_transfer_completed)) {
 608                 flags = *pflags;
 609                 cpu_relax();
 610         }
 611
 612         rmb();  /* Read the frame number /after/ reading completion status. */
 613         frame = gnttab_shared.v1[ref].frame;
 614         BUG_ON(frame == 0);
 615
 616         return frame;
 617 }
 618
 619 static unsigned long gnttab_end_foreign_transfer_ref_v2(grant_ref_t ref)
 620 {
 621         unsigned long frame;
 622         u16           flags;
 623         u16          *pflags;
 624
 625         pflags = &gnttab_shared.v2[ref].hdr.flags;
 626
 627         /*
 628          * If a transfer is not even yet started, try to reclaim the grant
 629          * reference and return failure (== 0).
 630          */
 631         while (!((flags = *pflags) & GTF_transfer_committed)) {
 632                 if (sync_cmpxchg(pflags, flags, 0) == flags)
 633                         return 0;
 634                 cpu_relax();
 635         }
 636
 637         /* If a transfer is in progress then wait until it is completed. */
 638         while (!(flags & GTF_transfer_completed)) {
 639                 flags = *pflags;
 640                 cpu_relax();
 641         }
 642
 643         rmb();  /* Read the frame number /after/ reading completion status. */
 644         frame = gnttab_shared.v2[ref].full_page.frame;
 645         BUG_ON(frame == 0);
 646
 647         return frame;
 648 }
 649
 650 unsigned long gnttab_end_foreign_transfer_ref(grant_ref_t ref)
 651 {
 652         return gnttab_interface->end_foreign_transfer_ref(ref);
 653 }
 654 EXPORT_SYMBOL_GPL(gnttab_end_foreign_transfer_ref);
 655
 656 unsigned long gnttab_end_foreign_transfer(grant_ref_t ref)
 657 {
 658         unsigned long frame = gnttab_end_foreign_transfer_ref(ref);
 659         put_free_entry(ref);
 660         return frame;
 661 }
 662 EXPORT_SYMBOL_GPL(gnttab_end_foreign_transfer);
 663
 664 void gnttab_free_grant_reference(grant_ref_t ref)
 665 {
 666         put_free_entry(ref);
 667 }
 668 EXPORT_SYMBOL_GPL(gnttab_free_grant_reference);
 669
 670 void gnttab_free_grant_references(grant_ref_t head)
 671 {
 672         grant_ref_t ref;
 673         unsigned long flags;
 674         int count = 1;
 675         if (head == GNTTAB_LIST_END)
 676                 return;
 677         spin_lock_irqsave(&gnttab_list_lock, flags);
 678         ref = head;
 679         while (gnttab_entry(ref) != GNTTAB_LIST_END) {
 680                 ref = gnttab_entry(ref);
 681                 count++;
 682         }
 683         gnttab_entry(ref) = gnttab_free_head;
 684         gnttab_free_head = head;
 685         gnttab_free_count += count;
 686         check_free_callbacks();
 687         spin_unlock_irqrestore(&gnttab_list_lock, flags);
 688 }
 689 EXPORT_SYMBOL_GPL(gnttab_free_grant_references);
 690
 691 int gnttab_alloc_grant_references(u16 count, grant_ref_t *head)
 692 {
 693         int h = get_free_entries(count);
 694
 695         if (h < 0)
 696                 return -ENOSPC;
 697
 698         *head = h;
 699
 700         return 0;
 701 }
 702 EXPORT_SYMBOL_GPL(gnttab_alloc_grant_references);
 703
 704 int gnttab_empty_grant_references(const grant_ref_t *private_head)
 705 {
 706         return (*private_head == GNTTAB_LIST_END);
 707 }
 708 EXPORT_SYMBOL_GPL(gnttab_empty_grant_references);
 709
 710 int gnttab_claim_grant_reference(grant_ref_t *private_head)
 711 {
 712         grant_ref_t g = *private_head;
 713         if (unlikely(g == GNTTAB_LIST_END))
 714                 return -ENOSPC;
 715         *private_head = gnttab_entry(g);
 716         return g;
 717 }
 718 EXPORT_SYMBOL_GPL(gnttab_claim_grant_reference);
 719
 720 void gnttab_release_grant_reference(grant_ref_t *private_head,
 721                                     grant_ref_t release)
 722 {
 723         gnttab_entry(release) = *private_head;
 724         *private_head = release;
 725 }
 726 EXPORT_SYMBOL_GPL(gnttab_release_grant_reference);
 727
 728 void gnttab_request_free_callback(struct gnttab_free_callback *callback,
 729                                   void (*fn)(void *), void *arg, u16 count)
 730 {
 731         unsigned long flags;
 732         struct gnttab_free_callback *cb;
 733
 734         spin_lock_irqsave(&gnttab_list_lock, flags);
 735
 736         /* Check if the callback is already on the list */
 737         cb = gnttab_free_callback_list;
 738         while (cb) {
 739                 if (cb == callback)
 740                         goto out;
 741                 cb = cb->next;
 742         }
 743
 744         callback->fn = fn;
 745         callback->arg = arg;
 746         callback->count = count;
 747         callback->next = gnttab_free_callback_list;
 748         gnttab_free_callback_list = callback;
 749         check_free_callbacks();
 750 out:
 751         spin_unlock_irqrestore(&gnttab_list_lock, flags);
 752 }
 753 EXPORT_SYMBOL_GPL(gnttab_request_free_callback);
 754
 755 void gnttab_cancel_free_callback(struct gnttab_free_callback *callback)
 756 {
 757         struct gnttab_free_callback **pcb;
 758         unsigned long flags;
 759
 760         spin_lock_irqsave(&gnttab_list_lock, flags);
 761         for (pcb = &gnttab_free_callback_list; *pcb; pcb = &(*pcb)->next) {
 762                 if (*pcb == callback) {
 763                         *pcb = callback->next;
 764                         break;
 765                 }
 766         }
 767         spin_unlock_irqrestore(&gnttab_list_lock, flags);
 768 }
 769 EXPORT_SYMBOL_GPL(gnttab_cancel_free_callback);
 770
 771 static int grow_gnttab_list(unsigned int more_frames)
 772 {
 773         unsigned int new_nr_grant_frames, extra_entries, i;
 774         unsigned int nr_glist_frames, new_nr_glist_frames;
 775
 776         BUG_ON(grefs_per_grant_frame == 0);
 777
 778         new_nr_grant_frames = nr_grant_frames + more_frames;
 779         extra_entries       = more_frames * grefs_per_grant_frame;
 780
 781         nr_glist_frames = (nr_grant_frames * grefs_per_grant_frame + RPP - 1) / RPP;
 782         new_nr_glist_frames =
 783                 (new_nr_grant_frames * grefs_per_grant_frame + RPP - 1) / RPP;
 784         for (i = nr_glist_frames; i < new_nr_glist_frames; i++) {
 785                 gnttab_list[i] = (grant_ref_t *)__get_free_page(GFP_ATOMIC);
 786                 if (!gnttab_list[i])
 787                         goto grow_nomem;
 788         }
 789
 790
 791         for (i = grefs_per_grant_frame * nr_grant_frames;
 792              i < grefs_per_grant_frame * new_nr_grant_frames - 1; i++)
 793                 gnttab_entry(i) = i + 1;
 794
 795         gnttab_entry(i) = gnttab_free_head;
 796         gnttab_free_head = grefs_per_grant_frame * nr_grant_frames;
 797         gnttab_free_count += extra_entries;
 798
 799         nr_grant_frames = new_nr_grant_frames;
 800
 801         check_free_callbacks();
 802
 803         return 0;
 804
 805 grow_nomem:
 806         for ( ; i >= nr_glist_frames; i--)
 807                 free_page((unsigned long) gnttab_list[i]);
 808         return -ENOMEM;
 809 }
 810
 811 static unsigned int __max_nr_grant_frames(void)
 812 {
 813         struct gnttab_query_size query;
 814         int rc;
 815
 816         query.dom = DOMID_SELF;
 817
 818         rc = HYPERVISOR_grant_table_op(GNTTABOP_query_size, &query, 1);
 819         if ((rc < 0) || (query.status != GNTST_okay))
 820                 return 4; /* Legacy max supported number of frames */
 821
 822         return query.max_nr_frames;
 823 }
 824
 825 unsigned int gnttab_max_grant_frames(void)
 826 {
 827         unsigned int xen_max = __max_nr_grant_frames();
 828         static unsigned int boot_max_nr_grant_frames;
 829
 830         /* First time, initialize it properly. */
 831         if (!boot_max_nr_grant_frames)
 832                 boot_max_nr_grant_frames = __max_nr_grant_frames();
 833
 834         if (xen_max > boot_max_nr_grant_frames)
 835                 return boot_max_nr_grant_frames;
 836         return xen_max;
 837 }
 838 EXPORT_SYMBOL_GPL(gnttab_max_grant_frames);
 839
 840 int gnttab_setup_auto_xlat_frames(unsigned long addr)
 841 {
 842         xen_pfn_t *pfn;
 843         unsigned int max_nr_gframes = __max_nr_grant_frames();
 844         unsigned int i;
 845         void *vaddr;
 846
 847         if (xen_auto_xlat_grant_frames.count)
 848                 return -EINVAL;
 849
 850         vaddr = xen_remap(addr, PAGE_SIZE * max_nr_gframes);
 851         if (vaddr == NULL) {
 852                 pr_warn("Failed to ioremap gnttab share frames (addr=0x%08lx)!\n",
 853                         addr);
 854                 return -ENOMEM;
 855         }
 856         pfn = kcalloc(max_nr_gframes, sizeof(pfn[0]), GFP_KERNEL);
 857         if (!pfn) {
 858                 xen_unmap(vaddr);
 859                 return -ENOMEM;
 860         }
 861         for (i = 0; i < max_nr_gframes; i++)
 862                 pfn[i] = PFN_DOWN(addr) + i;
 863
 864         xen_auto_xlat_grant_frames.vaddr = vaddr;
 865         xen_auto_xlat_grant_frames.pfn = pfn;
 866         xen_auto_xlat_grant_frames.count = max_nr_gframes;
 867
 868         return 0;
 869 }
 870 EXPORT_SYMBOL_GPL(gnttab_setup_auto_xlat_frames);
 871
 872 void gnttab_free_auto_xlat_frames(void)
 873 {
 874         if (!xen_auto_xlat_grant_frames.count)
 875                 return;
 876         kfree(xen_auto_xlat_grant_frames.pfn);
 877         xen_unmap(xen_auto_xlat_grant_frames.vaddr);
 878
 879         xen_auto_xlat_grant_frames.pfn = NULL;
 880         xen_auto_xlat_grant_frames.count = 0;
 881         xen_auto_xlat_grant_frames.vaddr = NULL;
 882 }
 883 EXPORT_SYMBOL_GPL(gnttab_free_auto_xlat_frames);
 884
 885 /* Handling of paged out grant targets (GNTST_eagain) */
 886 #define MAX_DELAY 256
 887 static inline void
 888 gnttab_retry_eagain_gop(unsigned int cmd, void *gop, int16_t *status,
 889                                                 const char *func)
 890 {
 891         unsigned delay = 1;
 892
 893         do {
 894                 BUG_ON(HYPERVISOR_grant_table_op(cmd, gop, 1));
 895                 if (*status == GNTST_eagain)
 896                         msleep(delay++);
 897         } while ((*status == GNTST_eagain) && (delay < MAX_DELAY));
 898
 899         if (delay >= MAX_DELAY) {
 900                 pr_err("%s: %s eagain grant\n", func, current->comm);
 901                 *status = GNTST_bad_page;
 902         }
 903 }
 904
 905 void gnttab_batch_map(struct gnttab_map_grant_ref *batch, unsigned count)
 906 {
 907         struct gnttab_map_grant_ref *op;
 908
 909         if (HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref, batch, count))
 910                 BUG();
 911         for (op = batch; op < batch + count; op++)
 912                 if (op->status == GNTST_eagain)
 913                         gnttab_retry_eagain_gop(GNTTABOP_map_grant_ref, op,
 914                                                 &op->status, __func__);
 915 }
 916 EXPORT_SYMBOL_GPL(gnttab_batch_map);
 917
 918 void gnttab_batch_copy(struct gnttab_copy *batch, unsigned count)
 919 {
 920         struct gnttab_copy *op;
 921
 922         if (HYPERVISOR_grant_table_op(GNTTABOP_copy, batch, count))
 923                 BUG();
 924         for (op = batch; op < batch + count; op++)
 925                 if (op->status == GNTST_eagain)
 926                         gnttab_retry_eagain_gop(GNTTABOP_copy, op,
 927                                                 &op->status, __func__);
 928 }
 929 EXPORT_SYMBOL_GPL(gnttab_batch_copy);
 930
 931 int gnttab_map_refs(struct gnttab_map_grant_ref *map_ops,
 932                     struct gnttab_map_grant_ref *kmap_ops,
 933                     struct page **pages, unsigned int count)
 934 {
 935         int i, ret;
 936         bool lazy = false;
 937         pte_t *pte;
 938         unsigned long mfn;
 939
 940         ret = HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref, map_ops, count);
 941         if (ret)
 942                 return ret;
 943
 944         /* Retry eagain maps */
 945         for (i = 0; i < count; i++)
 946                 if (map_ops[i].status == GNTST_eagain)
 947                         gnttab_retry_eagain_gop(GNTTABOP_map_grant_ref, map_ops + i,
 948                                                 &map_ops[i].status, __func__);
 949
 950         /* this is basically a nop on x86 */
 951         if (xen_feature(XENFEAT_auto_translated_physmap)) {
 952                 for (i = 0; i < count; i++) {
 953                         if (map_ops[i].status)
 954                                 continue;
 955                         set_phys_to_machine(map_ops[i].host_addr >> PAGE_SHIFT,
 956                                         map_ops[i].dev_bus_addr >> PAGE_SHIFT);
 957                 }
 958                 return ret;
 959         }
 960
 961         if (!in_interrupt() && paravirt_get_lazy_mode() == PARAVIRT_LAZY_NONE) {
 962                 arch_enter_lazy_mmu_mode();
 963                 lazy = true;
 964         }
 965
 966         for (i = 0; i < count; i++) {
 967                 /* Do not add to override if the map failed. */
 968                 if (map_ops[i].status)
 969                         continue;
 970
 971                 if (map_ops[i].flags & GNTMAP_contains_pte) {
 972                         pte = (pte_t *) (mfn_to_virt(PFN_DOWN(map_ops[i].host_addr)) +
 973                                 (map_ops[i].host_addr & ~PAGE_MASK));
 974                         mfn = pte_mfn(*pte);
 975                 } else {
 976                         mfn = PFN_DOWN(map_ops[i].dev_bus_addr);
 977                 }
 978                 ret = m2p_add_override(mfn, pages[i], kmap_ops ?
 979                                        &kmap_ops[i] : NULL);
 980                 if (ret)
 981                         goto out;
 982         }
 983
 984  out:
 985         if (lazy)
 986                 arch_leave_lazy_mmu_mode();
 987
 988         return ret;
 989 }
 990 EXPORT_SYMBOL_GPL(gnttab_map_refs);
 991
 992 int gnttab_unmap_refs(struct gnttab_unmap_grant_ref *unmap_ops,
 993                       struct gnttab_map_grant_ref *kmap_ops,
 994                       struct page **pages, unsigned int count)
 995 {
 996         int i, ret;
 997         bool lazy = false;
 998
 999         ret = HYPERVISOR_grant_table_op(GNTTABOP_unmap_grant_ref, unmap_ops, count);
1000         if (ret)
1001                 return ret;
1002
1003         /* this is basically a nop on x86 */
1004         if (xen_feature(XENFEAT_auto_translated_physmap)) {
1005                 for (i = 0; i < count; i++) {
1006                         set_phys_to_machine(unmap_ops[i].host_addr >> PAGE_SHIFT,
1007                                         INVALID_P2M_ENTRY);
1008                 }
1009                 return ret;
1010         }
1011
1012         if (!in_interrupt() && paravirt_get_lazy_mode() == PARAVIRT_LAZY_NONE) {
1013                 arch_enter_lazy_mmu_mode();
1014                 lazy = true;
1015         }
1016
1017         for (i = 0; i < count; i++) {
1018                 ret = m2p_remove_override(pages[i], kmap_ops ?
1019                                        &kmap_ops[i] : NULL);
1020                 if (ret)
1021                         goto out;
1022         }
1023
1024  out:
1025         if (lazy)
1026                 arch_leave_lazy_mmu_mode();
1027
1028         return ret;
1029 }
1030 EXPORT_SYMBOL_GPL(gnttab_unmap_refs);
1031
1032 static unsigned nr_status_frames(unsigned nr_grant_frames)
1033 {
1034         BUG_ON(grefs_per_grant_frame == 0);
1035         return (nr_grant_frames * grefs_per_grant_frame + SPP - 1) / SPP;
1036 }
1037
1038 static int gnttab_map_frames_v1(xen_pfn_t *frames, unsigned int nr_gframes)
1039 {
1040         int rc;
1041
1042         rc = arch_gnttab_map_shared(frames, nr_gframes,
1043                                     gnttab_max_grant_frames(),
1044                                     &gnttab_shared.addr);
1045         BUG_ON(rc);
1046
1047         return 0;
1048 }
1049
1050 static void gnttab_unmap_frames_v1(void)
1051 {
1052         arch_gnttab_unmap(gnttab_shared.addr, nr_grant_frames);
1053 }
1054
1055 static int gnttab_map_frames_v2(xen_pfn_t *frames, unsigned int nr_gframes)
1056 {
1057         uint64_t *sframes;
1058         unsigned int nr_sframes;
1059         struct gnttab_get_status_frames getframes;
1060         int rc;
1061
1062         nr_sframes = nr_status_frames(nr_gframes);
1063
1064         /* No need for kzalloc as it is initialized in following hypercall
1065          * GNTTABOP_get_status_frames.
1066          */
1067         sframes = kmalloc(nr_sframes  * sizeof(uint64_t), GFP_ATOMIC);
1068         if (!sframes)
1069                 return -ENOMEM;
1070
1071         getframes.dom        = DOMID_SELF;
1072         getframes.nr_frames  = nr_sframes;
1073         set_xen_guest_handle(getframes.frame_list, sframes);
1074
1075         rc = HYPERVISOR_grant_table_op(GNTTABOP_get_status_frames,
1076                                        &getframes, 1);
1077         if (rc == -ENOSYS) {
1078                 kfree(sframes);
1079                 return -ENOSYS;
1080         }
1081
1082         BUG_ON(rc || getframes.status);
1083
1084         rc = arch_gnttab_map_status(sframes, nr_sframes,
1085                                     nr_status_frames(gnttab_max_grant_frames()),
1086                                     &grstatus);
1087         BUG_ON(rc);
1088         kfree(sframes);
1089
1090         rc = arch_gnttab_map_shared(frames, nr_gframes,
1091                                     gnttab_max_grant_frames(),
1092                                     &gnttab_shared.addr);
1093         BUG_ON(rc);
1094
1095         return 0;
1096 }
1097
1098 static void gnttab_unmap_frames_v2(void)
1099 {
1100         arch_gnttab_unmap(gnttab_shared.addr, nr_grant_frames);
1101         arch_gnttab_unmap(grstatus, nr_status_frames(nr_grant_frames));
1102 }
1103
1104 static int gnttab_map(unsigned int start_idx, unsigned int end_idx)
1105 {
1106         struct gnttab_setup_table setup;
1107         xen_pfn_t *frames;
1108         unsigned int nr_gframes = end_idx + 1;
1109         int rc;
1110
1111         if (xen_feature(XENFEAT_auto_translated_physmap)) {
1112                 struct xen_add_to_physmap xatp;
1113                 unsigned int i = end_idx;
1114                 rc = 0;
1115                 BUG_ON(xen_auto_xlat_grant_frames.count < nr_gframes);
1116                 /*
1117                  * Loop backwards, so that the first hypercall has the largest
1118                  * index, ensuring that the table will grow only once.
1119                  */
1120                 do {
1121                         xatp.domid = DOMID_SELF;
1122                         xatp.idx = i;
1123                         xatp.space = XENMAPSPACE_grant_table;
1124                         xatp.gpfn = xen_auto_xlat_grant_frames.pfn[i];
1125                         rc = HYPERVISOR_memory_op(XENMEM_add_to_physmap, &xatp);
1126                         if (rc != 0) {
1127                                 pr_warn("grant table add_to_physmap failed, err=%d\n",
1128                                         rc);
1129                                 break;
1130                         }
1131                 } while (i-- > start_idx);
1132
1133                 return rc;
1134         }
1135
1136         /* No need for kzalloc as it is initialized in following hypercall
1137          * GNTTABOP_setup_table.
1138          */
1139         frames = kmalloc(nr_gframes * sizeof(unsigned long), GFP_ATOMIC);
1140         if (!frames)
1141                 return -ENOMEM;
1142
1143         setup.dom        = DOMID_SELF;
1144         setup.nr_frames  = nr_gframes;
1145         set_xen_guest_handle(setup.frame_list, frames);
1146
1147         rc = HYPERVISOR_grant_table_op(GNTTABOP_setup_table, &setup, 1);
1148         if (rc == -ENOSYS) {
1149                 kfree(frames);
1150                 return -ENOSYS;
1151         }
1152
1153         BUG_ON(rc || setup.status);
1154
1155         rc = gnttab_interface->map_frames(frames, nr_gframes);
1156
1157         kfree(frames);
1158
1159         return rc;
1160 }
1161
1162 static struct gnttab_ops gnttab_v1_ops = {
1163         .map_frames                     = gnttab_map_frames_v1,
1164         .unmap_frames                   = gnttab_unmap_frames_v1,
1165         .update_entry                   = gnttab_update_entry_v1,
1166         .end_foreign_access_ref         = gnttab_end_foreign_access_ref_v1,
1167         .end_foreign_transfer_ref       = gnttab_end_foreign_transfer_ref_v1,
1168         .query_foreign_access           = gnttab_query_foreign_access_v1,
1169 };
1170
1171 static struct gnttab_ops gnttab_v2_ops = {
1172         .map_frames                     = gnttab_map_frames_v2,
1173         .unmap_frames                   = gnttab_unmap_frames_v2,
1174         .update_entry                   = gnttab_update_entry_v2,
1175         .end_foreign_access_ref         = gnttab_end_foreign_access_ref_v2,
1176         .end_foreign_transfer_ref       = gnttab_end_foreign_transfer_ref_v2,
1177         .query_foreign_access           = gnttab_query_foreign_access_v2,
1178         .update_subpage_entry           = gnttab_update_subpage_entry_v2,
1179         .update_trans_entry             = gnttab_update_trans_entry_v2,
1180 };
1181
1182 static void gnttab_request_version(void)
1183 {
1184         int rc;
1185         struct gnttab_set_version gsv;
1186
1187         gsv.version = 1;
1188
1189         rc = HYPERVISOR_grant_table_op(GNTTABOP_set_version, &gsv, 1);
1190         if (rc == 0 && gsv.version == 2) {
1191                 grant_table_version = 2;
1192                 grefs_per_grant_frame = PAGE_SIZE / sizeof(union grant_entry_v2);
1193                 gnttab_interface = &gnttab_v2_ops;
1194         } else if (grant_table_version == 2) {
1195                 /*
1196                  * If we've already used version 2 features,
1197                  * but then suddenly discover that they're not
1198                  * available (e.g. migrating to an older
1199                  * version of Xen), almost unbounded badness
1200                  * can happen.
1201                  */
1202                 panic("we need grant tables version 2, but only version 1 is available");
1203         } else {
1204                 grant_table_version = 1;
1205                 grefs_per_grant_frame = PAGE_SIZE / sizeof(struct grant_entry_v1);
1206                 gnttab_interface = &gnttab_v1_ops;
1207         }
1208         pr_info("Grant tables using version %d layout\n", grant_table_version);
1209 }
1210
1211 static int gnttab_setup(void)
1212 {
1213         unsigned int max_nr_gframes;
1214
1215         max_nr_gframes = gnttab_max_grant_frames();
1216         if (max_nr_gframes < nr_grant_frames)
1217                 return -ENOSYS;
1218
1219         if (xen_feature(XENFEAT_auto_translated_physmap) && gnttab_shared.addr == NULL) {
1220                 gnttab_shared.addr = xen_auto_xlat_grant_frames.vaddr;
1221                 if (gnttab_shared.addr == NULL) {
1222                         pr_warn("gnttab share frames (addr=0x%08lx) is not mapped!\n",
1223                                 (unsigned long)xen_auto_xlat_grant_frames.vaddr);
1224                         return -ENOMEM;
1225                 }
1226         }
1227         return gnttab_map(0, nr_grant_frames - 1);
1228 }
1229
1230 int gnttab_resume(void)
1231 {
1232         gnttab_request_version();
1233         return gnttab_setup();
1234 }
1235
1236 int gnttab_suspend(void)
1237 {
1238         gnttab_interface->unmap_frames();
1239         return 0;
1240 }
1241
1242 static int gnttab_expand(unsigned int req_entries)
1243 {
1244         int rc;
1245         unsigned int cur, extra;
1246
1247         BUG_ON(grefs_per_grant_frame == 0);
1248         cur = nr_grant_frames;
1249         extra = ((req_entries + (grefs_per_grant_frame-1)) /
1250                  grefs_per_grant_frame);
1251         if (cur + extra > gnttab_max_grant_frames())
1252                 return -ENOSPC;
1253
1254         rc = gnttab_map(cur, cur + extra - 1);
1255         if (rc == 0)
1256                 rc = grow_gnttab_list(extra);
1257
1258         return rc;
1259 }
1260
1261 int gnttab_init(void)
1262 {
1263         int i;
1264         unsigned int max_nr_glist_frames, nr_glist_frames;
1265         unsigned int nr_init_grefs;
1266         int ret;
1267
1268         gnttab_request_version();
1269         nr_grant_frames = 1;
1270
1271         /* Determine the maximum number of frames required for the
1272          * grant reference free list on the current hypervisor.
1273          */
1274         BUG_ON(grefs_per_grant_frame == 0);
1275         max_nr_glist_frames = (gnttab_max_grant_frames() *
1276                                grefs_per_grant_frame / RPP);
1277
1278         gnttab_list = kmalloc(max_nr_glist_frames * sizeof(grant_ref_t *),
1279                               GFP_KERNEL);
1280         if (gnttab_list == NULL)
1281                 return -ENOMEM;
1282
1283         nr_glist_frames = (nr_grant_frames * grefs_per_grant_frame + RPP - 1) / RPP;
1284         for (i = 0; i < nr_glist_frames; i++) {
1285                 gnttab_list[i] = (grant_ref_t *)__get_free_page(GFP_KERNEL);
1286                 if (gnttab_list[i] == NULL) {
1287                         ret = -ENOMEM;
1288                         goto ini_nomem;
1289                 }
1290         }
1291
1292         if (gnttab_setup() < 0) {
1293                 ret = -ENODEV;
1294                 goto ini_nomem;
1295         }
1296
1297         nr_init_grefs = nr_grant_frames * grefs_per_grant_frame;
1298
1299         for (i = NR_RESERVED_ENTRIES; i < nr_init_grefs - 1; i++)
1300                 gnttab_entry(i) = i + 1;
1301
1302         gnttab_entry(nr_init_grefs - 1) = GNTTAB_LIST_END;
1303         gnttab_free_count = nr_init_grefs - NR_RESERVED_ENTRIES;
1304         gnttab_free_head  = NR_RESERVED_ENTRIES;
1305
1306         printk("Grant table initialized\n");
1307         return 0;
1308
1309  ini_nomem:
1310         for (i--; i >= 0; i--)
1311                 free_page((unsigned long)gnttab_list[i]);
1312         kfree(gnttab_list);
1313         return ret;
1314 }
1315 EXPORT_SYMBOL_GPL(gnttab_init);
1316
1317 static int __gnttab_init(void)
1318 {
1319         /* Delay grant-table initialization in the PV on HVM case */
1320         if (xen_hvm_domain())
1321                 return 0;
1322
1323         if (!xen_pv_domain())
1324                 return -ENODEV;
1325
1326         return gnttab_init();
1327 }
1328 /* Starts after core_initcall so that xen_pvh_gnttab_setup can be called
1329  * beforehand to initialize xen_auto_xlat_grant_frames. */
1330 core_initcall_sync(__gnttab_init);