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 #include <linux/module.h>
  35 #include <linux/sched.h>
  36 #include <linux/mm.h>
  37 #include <linux/slab.h>
  38 #include <linux/vmalloc.h>
  39 #include <linux/uaccess.h>
  40 #include <linux/io.h>
  41 #include <linux/delay.h>
  42 #include <linux/hardirq.h>
  43
  44 #include <xen/xen.h>
  45 #include <xen/interface/xen.h>
  46 #include <xen/page.h>
  47 #include <xen/grant_table.h>
  48 #include <xen/interface/memory.h>
  49 #include <xen/hvc-console.h>
  50 #include <asm/xen/hypercall.h>
  51 #include <asm/xen/interface.h>
  52
  53 #include <asm/pgtable.h>
  54 #include <asm/sync_bitops.h>
  55
  56 /* External tools reserve first few grant table entries. */
  57 #define NR_RESERVED_ENTRIES 8
  58 #define GNTTAB_LIST_END 0xffffffff
  59 #define GREFS_PER_GRANT_FRAME \
  60 (grant_table_version == 1 ?                      \
  61 (PAGE_SIZE / sizeof(struct grant_entry_v1)) :   \
  62 (PAGE_SIZE / sizeof(union grant_entry_v2)))
  63
  64 static grant_ref_t **gnttab_list;
  65 static unsigned int nr_grant_frames;
  66 static unsigned int boot_max_nr_grant_frames;
  67 static int gnttab_free_count;
  68 static grant_ref_t gnttab_free_head;
  69 static DEFINE_SPINLOCK(gnttab_list_lock);
  70 unsigned long xen_hvm_resume_frames;
  71 EXPORT_SYMBOL_GPL(xen_hvm_resume_frames);
  72
  73 static union {
  74         struct grant_entry_v1 *v1;
  75         union grant_entry_v2 *v2;
  76         void *addr;
  77 } gnttab_shared;
  78
  79 /*This is a structure of function pointers for grant table*/
  80 struct gnttab_ops {
  81         /*
  82          * Mapping a list of frames for storing grant entries. Frames parameter
  83          * is used to store grant table address when grant table being setup,
  84          * nr_gframes is the number of frames to map grant table. Returning
  85          * GNTST_okay means success and negative value means failure.
  86          */
  87         int (*map_frames)(unsigned long *frames, unsigned int nr_gframes);
  88         /*
  89          * Release a list of frames which are mapped in map_frames for grant
  90          * entry status.
  91          */
  92         void (*unmap_frames)(void);
  93         /*
  94          * Introducing a valid entry into the grant table, granting the frame of
  95          * this grant entry to domain for accessing or transfering. Ref
  96          * parameter is reference of this introduced grant entry, domid is id of
  97          * granted domain, frame is the page frame to be granted, and flags is
  98          * status of the grant entry to be updated.
  99          */
 100         void (*update_entry)(grant_ref_t ref, domid_t domid,
 101                              unsigned long frame, unsigned flags);
 102         /*
 103          * Stop granting a grant entry to domain for accessing. Ref parameter is
 104          * reference of a grant entry whose grant access will be stopped,
 105          * readonly is not in use in this function. If the grant entry is
 106          * currently mapped for reading or writing, just return failure(==0)
 107          * directly and don't tear down the grant access. Otherwise, stop grant
 108          * access for this entry and return success(==1).
 109          */
 110         int (*end_foreign_access_ref)(grant_ref_t ref, int readonly);
 111         /*
 112          * Stop granting a grant entry to domain for transfer. Ref parameter is
 113          * reference of a grant entry whose grant transfer will be stopped. If
 114          * tranfer has not started, just reclaim the grant entry and return
 115          * failure(==0). Otherwise, wait for the transfer to complete and then
 116          * return the frame.
 117          */
 118         unsigned long (*end_foreign_transfer_ref)(grant_ref_t ref);
 119         /*
 120          * Query the status of a grant entry. Ref parameter is reference of
 121          * queried grant entry, return value is the status of queried entry.
 122          * Detailed status(writing/reading) can be gotten from the return value
 123          * by bit operations.
 124          */
 125         int (*query_foreign_access)(grant_ref_t ref);
 126         /*
 127          * Grant a domain to access a range of bytes within the page referred by
 128          * an available grant entry. Ref parameter is reference of a grant entry
 129          * which will be sub-page accessed, domid is id of grantee domain, frame
 130          * is frame address of subpage grant, flags is grant type and flag
 131          * information, page_off is offset of the range of bytes, and length is
 132          * length of bytes to be accessed.
 133          */
 134         void (*update_subpage_entry)(grant_ref_t ref, domid_t domid,
 135                                      unsigned long frame, int flags,
 136                                      unsigned page_off, unsigned length);
 137         /*
 138          * Redirect an available grant entry on domain A to another grant
 139          * reference of domain B, then allow domain C to use grant reference
 140          * of domain B transitively. Ref parameter is an available grant entry
 141          * reference on domain A, domid is id of domain C which accesses grant
 142          * entry transitively, flags is grant type and flag information,
 143          * trans_domid is id of domain B whose grant entry is finally accessed
 144          * transitively, trans_gref is grant entry transitive reference of
 145          * domain B.
 146          */
 147         void (*update_trans_entry)(grant_ref_t ref, domid_t domid, int flags,
 148                                    domid_t trans_domid, grant_ref_t trans_gref);
 149 };
 150
 151 static struct gnttab_ops *gnttab_interface;
 152
 153 /*This reflects status of grant entries, so act as a global value*/
 154 static grant_status_t *grstatus;
 155
 156 static int grant_table_version;
 157
 158 static struct gnttab_free_callback *gnttab_free_callback_list;
 159
 160 static int gnttab_expand(unsigned int req_entries);
 161
 162 #define RPP (PAGE_SIZE / sizeof(grant_ref_t))
 163 #define SPP (PAGE_SIZE / sizeof(grant_status_t))
 164
 165 static inline grant_ref_t *__gnttab_entry(grant_ref_t entry)
 166 {
 167         return &gnttab_list[(entry) / RPP][(entry) % RPP];
 168 }
 169 /* This can be used as an l-value */
 170 #define gnttab_entry(entry) (*__gnttab_entry(entry))
 171
 172 static int get_free_entries(unsigned count)
 173 {
 174         unsigned long flags;
 175         int ref, rc = 0;
 176         grant_ref_t head;
 177
 178         spin_lock_irqsave(&gnttab_list_lock, flags);
 179
 180         if ((gnttab_free_count < count) &&
 181             ((rc = gnttab_expand(count - gnttab_free_count)) < 0)) {
 182                 spin_unlock_irqrestore(&gnttab_list_lock, flags);
 183                 return rc;
 184         }
 185
 186         ref = head = gnttab_free_head;
 187         gnttab_free_count -= count;
 188         while (count-- > 1)
 189                 head = gnttab_entry(head);
 190         gnttab_free_head = gnttab_entry(head);
 191         gnttab_entry(head) = GNTTAB_LIST_END;
 192
 193         spin_unlock_irqrestore(&gnttab_list_lock, flags);
 194
 195         return ref;
 196 }
 197
 198 static void do_free_callbacks(void)
 199 {
 200         struct gnttab_free_callback *callback, *next;
 201
 202         callback = gnttab_free_callback_list;
 203         gnttab_free_callback_list = NULL;
 204
 205         while (callback != NULL) {
 206                 next = callback->next;
 207                 if (gnttab_free_count >= callback->count) {
 208                         callback->next = NULL;
 209                         callback->fn(callback->arg);
 210                 } else {
 211                         callback->next = gnttab_free_callback_list;
 212                         gnttab_free_callback_list = callback;
 213                 }
 214                 callback = next;
 215         }
 216 }
 217
 218 static inline void check_free_callbacks(void)
 219 {
 220         if (unlikely(gnttab_free_callback_list))
 221                 do_free_callbacks();
 222 }
 223
 224 static void put_free_entry(grant_ref_t ref)
 225 {
 226         unsigned long flags;
 227         spin_lock_irqsave(&gnttab_list_lock, flags);
 228         gnttab_entry(ref) = gnttab_free_head;
 229         gnttab_free_head = ref;
 230         gnttab_free_count++;
 231         check_free_callbacks();
 232         spin_unlock_irqrestore(&gnttab_list_lock, flags);
 233 }
 234
 235 /*
 236  * Following applies to gnttab_update_entry_v1 and gnttab_update_entry_v2.
 237  * Introducing a valid entry into the grant table:
 238  *  1. Write ent->domid.
 239  *  2. Write ent->frame:
 240  *      GTF_permit_access:   Frame to which access is permitted.
 241  *      GTF_accept_transfer: Pseudo-phys frame slot being filled by new
 242  *                           frame, or zero if none.
 243  *  3. Write memory barrier (WMB).
 244  *  4. Write ent->flags, inc. valid type.
 245  */
 246 static void gnttab_update_entry_v1(grant_ref_t ref, domid_t domid,
 247                                    unsigned long frame, unsigned flags)
 248 {
 249         gnttab_shared.v1[ref].domid = domid;
 250         gnttab_shared.v1[ref].frame = frame;
 251         wmb();
 252         gnttab_shared.v1[ref].flags = flags;
 253 }
 254
 255 static void gnttab_update_entry_v2(grant_ref_t ref, domid_t domid,
 256                                    unsigned long frame, unsigned flags)
 257 {
 258         gnttab_shared.v2[ref].hdr.domid = domid;
 259         gnttab_shared.v2[ref].full_page.frame = frame;
 260         wmb();
 261         gnttab_shared.v2[ref].hdr.flags = GTF_permit_access | flags;
 262 }
 263
 264 /*
 265  * Public grant-issuing interface functions
 266  */
 267 void gnttab_grant_foreign_access_ref(grant_ref_t ref, domid_t domid,
 268                                      unsigned long frame, int readonly)
 269 {
 270         gnttab_interface->update_entry(ref, domid, frame,
 271                            GTF_permit_access | (readonly ? GTF_readonly : 0));
 272 }
 273 EXPORT_SYMBOL_GPL(gnttab_grant_foreign_access_ref);
 274
 275 int gnttab_grant_foreign_access(domid_t domid, unsigned long frame,
 276                                 int readonly)
 277 {
 278         int ref;
 279
 280         ref = get_free_entries(1);
 281         if (unlikely(ref < 0))
 282                 return -ENOSPC;
 283
 284         gnttab_grant_foreign_access_ref(ref, domid, frame, readonly);
 285
 286         return ref;
 287 }
 288 EXPORT_SYMBOL_GPL(gnttab_grant_foreign_access);
 289
 290 static void gnttab_update_subpage_entry_v2(grant_ref_t ref, domid_t domid,
 291                                            unsigned long frame, int flags,
 292                                            unsigned page_off, unsigned length)
 293 {
 294         gnttab_shared.v2[ref].sub_page.frame = frame;
 295         gnttab_shared.v2[ref].sub_page.page_off = page_off;
 296         gnttab_shared.v2[ref].sub_page.length = length;
 297         gnttab_shared.v2[ref].hdr.domid = domid;
 298         wmb();
 299         gnttab_shared.v2[ref].hdr.flags =
 300                                 GTF_permit_access | GTF_sub_page | flags;
 301 }
 302
 303 int gnttab_grant_foreign_access_subpage_ref(grant_ref_t ref, domid_t domid,
 304                                             unsigned long frame, int flags,
 305                                             unsigned page_off,
 306                                             unsigned length)
 307 {
 308         if (flags & (GTF_accept_transfer | GTF_reading |
 309                      GTF_writing | GTF_transitive))
 310                 return -EPERM;
 311
 312         if (gnttab_interface->update_subpage_entry == NULL)
 313                 return -ENOSYS;
 314
 315         gnttab_interface->update_subpage_entry(ref, domid, frame, flags,
 316                                                page_off, length);
 317
 318         return 0;
 319 }
 320 EXPORT_SYMBOL_GPL(gnttab_grant_foreign_access_subpage_ref);
 321
 322 int gnttab_grant_foreign_access_subpage(domid_t domid, unsigned long frame,
 323                                         int flags, unsigned page_off,
 324                                         unsigned length)
 325 {
 326         int ref, rc;
 327
 328         ref = get_free_entries(1);
 329         if (unlikely(ref < 0))
 330                 return -ENOSPC;
 331
 332         rc = gnttab_grant_foreign_access_subpage_ref(ref, domid, frame, flags,
 333                                                      page_off, length);
 334         if (rc < 0) {
 335                 put_free_entry(ref);
 336                 return rc;
 337         }
 338
 339         return ref;
 340 }
 341 EXPORT_SYMBOL_GPL(gnttab_grant_foreign_access_subpage);
 342
 343 bool gnttab_subpage_grants_available(void)
 344 {
 345         return gnttab_interface->update_subpage_entry != NULL;
 346 }
 347 EXPORT_SYMBOL_GPL(gnttab_subpage_grants_available);
 348
 349 static void gnttab_update_trans_entry_v2(grant_ref_t ref, domid_t domid,
 350                                          int flags, domid_t trans_domid,
 351                                          grant_ref_t trans_gref)
 352 {
 353         gnttab_shared.v2[ref].transitive.trans_domid = trans_domid;
 354         gnttab_shared.v2[ref].transitive.gref = trans_gref;
 355         gnttab_shared.v2[ref].hdr.domid = domid;
 356         wmb();
 357         gnttab_shared.v2[ref].hdr.flags =
 358                                 GTF_permit_access | GTF_transitive | flags;
 359 }
 360
 361 int gnttab_grant_foreign_access_trans_ref(grant_ref_t ref, domid_t domid,
 362                                           int flags, domid_t trans_domid,
 363                                           grant_ref_t trans_gref)
 364 {
 365         if (flags & (GTF_accept_transfer | GTF_reading |
 366                      GTF_writing | GTF_sub_page))
 367                 return -EPERM;
 368
 369         if (gnttab_interface->update_trans_entry == NULL)
 370                 return -ENOSYS;
 371
 372         gnttab_interface->update_trans_entry(ref, domid, flags, trans_domid,
 373                                              trans_gref);
 374
 375         return 0;
 376 }
 377 EXPORT_SYMBOL_GPL(gnttab_grant_foreign_access_trans_ref);
 378
 379 int gnttab_grant_foreign_access_trans(domid_t domid, int flags,
 380                                       domid_t trans_domid,
 381                                       grant_ref_t trans_gref)
 382 {
 383         int ref, rc;
 384
 385         ref = get_free_entries(1);
 386         if (unlikely(ref < 0))
 387                 return -ENOSPC;
 388
 389         rc = gnttab_grant_foreign_access_trans_ref(ref, domid, flags,
 390                                                    trans_domid, trans_gref);
 391         if (rc < 0) {
 392                 put_free_entry(ref);
 393                 return rc;
 394         }
 395
 396         return ref;
 397 }
 398 EXPORT_SYMBOL_GPL(gnttab_grant_foreign_access_trans);
 399
 400 bool gnttab_trans_grants_available(void)
 401 {
 402         return gnttab_interface->update_trans_entry != NULL;
 403 }
 404 EXPORT_SYMBOL_GPL(gnttab_trans_grants_available);
 405
 406 static int gnttab_query_foreign_access_v1(grant_ref_t ref)
 407 {
 408         return gnttab_shared.v1[ref].flags & (GTF_reading|GTF_writing);
 409 }
 410
 411 static int gnttab_query_foreign_access_v2(grant_ref_t ref)
 412 {
 413         return grstatus[ref] & (GTF_reading|GTF_writing);
 414 }
 415
 416 int gnttab_query_foreign_access(grant_ref_t ref)
 417 {
 418         return gnttab_interface->query_foreign_access(ref);
 419 }
 420 EXPORT_SYMBOL_GPL(gnttab_query_foreign_access);
 421
 422 static int gnttab_end_foreign_access_ref_v1(grant_ref_t ref, int readonly)
 423 {
 424         u16 flags, nflags;
 425         u16 *pflags;
 426
 427         pflags = &gnttab_shared.v1[ref].flags;
 428         nflags = *pflags;
 429         do {
 430                 flags = nflags;
 431                 if (flags & (GTF_reading|GTF_writing))
 432                         return 0;
 433         } while ((nflags = sync_cmpxchg(pflags, flags, 0)) != flags);
 434
 435         return 1;
 436 }
 437
 438 static int gnttab_end_foreign_access_ref_v2(grant_ref_t ref, int readonly)
 439 {
 440         gnttab_shared.v2[ref].hdr.flags = 0;
 441         mb();
 442         if (grstatus[ref] & (GTF_reading|GTF_writing)) {
 443                 return 0;
 444         } else {
 445                 /* The read of grstatus needs to have acquire
 446                 semantics.  On x86, reads already have
 447                 that, and we just need to protect against
 448                 compiler reorderings.  On other
 449                 architectures we may need a full
 450                 barrier. */
 451 #ifdef CONFIG_X86
 452                 barrier();
 453 #else
 454                 mb();
 455 #endif
 456         }
 457
 458         return 1;
 459 }
 460
 461 static inline int _gnttab_end_foreign_access_ref(grant_ref_t ref, int readonly)
 462 {
 463         return gnttab_interface->end_foreign_access_ref(ref, readonly);
 464 }
 465
 466 int gnttab_end_foreign_access_ref(grant_ref_t ref, int readonly)
 467 {
 468         if (_gnttab_end_foreign_access_ref(ref, readonly))
 469                 return 1;
 470         pr_warn("WARNING: g.e. %#x still in use!\n", ref);
 471         return 0;
 472 }
 473 EXPORT_SYMBOL_GPL(gnttab_end_foreign_access_ref);
 474
 475 struct deferred_entry {
 476         struct list_head list;
 477         grant_ref_t ref;
 478         bool ro;
 479         uint16_t warn_delay;
 480         struct page *page;
 481 };
 482 static LIST_HEAD(deferred_list);
 483 static void gnttab_handle_deferred(unsigned long);
 484 static DEFINE_TIMER(deferred_timer, gnttab_handle_deferred, 0, 0);
 485
 486 static void gnttab_handle_deferred(unsigned long unused)
 487 {
 488         unsigned int nr = 10;
 489         struct deferred_entry *first = NULL;
 490         unsigned long flags;
 491
 492         spin_lock_irqsave(&gnttab_list_lock, flags);
 493         while (nr--) {
 494                 struct deferred_entry *entry
 495                         = list_first_entry(&deferred_list,
 496                                            struct deferred_entry, list);
 497
 498                 if (entry == first)
 499                         break;
 500                 list_del(&entry->list);
 501                 spin_unlock_irqrestore(&gnttab_list_lock, flags);
 502                 if (_gnttab_end_foreign_access_ref(entry->ref, entry->ro)) {
 503                         put_free_entry(entry->ref);
 504                         if (entry->page) {
 505                                 pr_debug("freeing g.e. %#x (pfn %#lx)\n",
 506                                          entry->ref, page_to_pfn(entry->page));
 507                                 __free_page(entry->page);
 508                         } else
 509                                 pr_info("freeing g.e. %#x\n", entry->ref);
 510                         kfree(entry);
 511                         entry = NULL;
 512                 } else {
 513                         if (!--entry->warn_delay)
 514                                 pr_info("g.e. %#x still pending\n",
 515                                         entry->ref);
 516                         if (!first)
 517                                 first = entry;
 518                 }
 519                 spin_lock_irqsave(&gnttab_list_lock, flags);
 520                 if (entry)
 521                         list_add_tail(&entry->list, &deferred_list);
 522                 else if (list_empty(&deferred_list))
 523                         break;
 524         }
 525         if (!list_empty(&deferred_list) && !timer_pending(&deferred_timer)) {
 526                 deferred_timer.expires = jiffies + HZ;
 527                 add_timer(&deferred_timer);
 528         }
 529         spin_unlock_irqrestore(&gnttab_list_lock, flags);
 530 }
 531
 532 static void gnttab_add_deferred(grant_ref_t ref, bool readonly,
 533                                 struct page *page)
 534 {
 535         struct deferred_entry *entry = kmalloc(sizeof(*entry), GFP_ATOMIC);
 536         const char *what = KERN_WARNING "leaking";
 537
 538         if (entry) {
 539                 unsigned long flags;
 540
 541                 entry->ref = ref;
 542                 entry->ro = readonly;
 543                 entry->page = page;
 544                 entry->warn_delay = 60;
 545                 spin_lock_irqsave(&gnttab_list_lock, flags);
 546                 list_add_tail(&entry->list, &deferred_list);
 547                 if (!timer_pending(&deferred_timer)) {
 548                         deferred_timer.expires = jiffies + HZ;
 549                         add_timer(&deferred_timer);
 550                 }
 551                 spin_unlock_irqrestore(&gnttab_list_lock, flags);
 552                 what = KERN_DEBUG "deferring";
 553         }
 554         printk("%s g.e. %#x (pfn %#lx)\n",
 555                what, ref, page ? page_to_pfn(page) : -1);
 556 }
 557
 558 void gnttab_end_foreign_access(grant_ref_t ref, int readonly,
 559                                unsigned long page)
 560 {
 561         if (gnttab_end_foreign_access_ref(ref, readonly)) {
 562                 put_free_entry(ref);
 563                 if (page != 0)
 564                         free_page(page);
 565         } else
 566                 gnttab_add_deferred(ref, readonly,
 567                                     page ? virt_to_page(page) : NULL);
 568 }
 569 EXPORT_SYMBOL_GPL(gnttab_end_foreign_access);
 570
 571 int gnttab_grant_foreign_transfer(domid_t domid, unsigned long pfn)
 572 {
 573         int ref;
 574
 575         ref = get_free_entries(1);
 576         if (unlikely(ref < 0))
 577                 return -ENOSPC;
 578         gnttab_grant_foreign_transfer_ref(ref, domid, pfn);
 579
 580         return ref;
 581 }
 582 EXPORT_SYMBOL_GPL(gnttab_grant_foreign_transfer);
 583
 584 void gnttab_grant_foreign_transfer_ref(grant_ref_t ref, domid_t domid,
 585                                        unsigned long pfn)
 586 {
 587         gnttab_interface->update_entry(ref, domid, pfn, GTF_accept_transfer);
 588 }
 589 EXPORT_SYMBOL_GPL(gnttab_grant_foreign_transfer_ref);
 590
 591 static unsigned long gnttab_end_foreign_transfer_ref_v1(grant_ref_t ref)
 592 {
 593         unsigned long frame;
 594         u16           flags;
 595         u16          *pflags;
 596
 597         pflags = &gnttab_shared.v1[ref].flags;
 598
 599         /*
 600          * If a transfer is not even yet started, try to reclaim the grant
 601          * reference and return failure (== 0).
 602          */
 603         while (!((flags = *pflags) & GTF_transfer_committed)) {
 604                 if (sync_cmpxchg(pflags, flags, 0) == flags)
 605                         return 0;
 606                 cpu_relax();
 607         }
 608
 609         /* If a transfer is in progress then wait until it is completed. */
 610         while (!(flags & GTF_transfer_completed)) {
 611                 flags = *pflags;
 612                 cpu_relax();
 613         }
 614
 615         rmb();  /* Read the frame number /after/ reading completion status. */
 616         frame = gnttab_shared.v1[ref].frame;
 617         BUG_ON(frame == 0);
 618
 619         return frame;
 620 }
 621
 622 static unsigned long gnttab_end_foreign_transfer_ref_v2(grant_ref_t ref)
 623 {
 624         unsigned long frame;
 625         u16           flags;
 626         u16          *pflags;
 627
 628         pflags = &gnttab_shared.v2[ref].hdr.flags;
 629
 630         /*
 631          * If a transfer is not even yet started, try to reclaim the grant
 632          * reference and return failure (== 0).
 633          */
 634         while (!((flags = *pflags) & GTF_transfer_committed)) {
 635                 if (sync_cmpxchg(pflags, flags, 0) == flags)
 636                         return 0;
 637                 cpu_relax();
 638         }
 639
 640         /* If a transfer is in progress then wait until it is completed. */
 641         while (!(flags & GTF_transfer_completed)) {
 642                 flags = *pflags;
 643                 cpu_relax();
 644         }
 645
 646         rmb();  /* Read the frame number /after/ reading completion status. */
 647         frame = gnttab_shared.v2[ref].full_page.frame;
 648         BUG_ON(frame == 0);
 649
 650         return frame;
 651 }
 652
 653 unsigned long gnttab_end_foreign_transfer_ref(grant_ref_t ref)
 654 {
 655         return gnttab_interface->end_foreign_transfer_ref(ref);
 656 }
 657 EXPORT_SYMBOL_GPL(gnttab_end_foreign_transfer_ref);
 658
 659 unsigned long gnttab_end_foreign_transfer(grant_ref_t ref)
 660 {
 661         unsigned long frame = gnttab_end_foreign_transfer_ref(ref);
 662         put_free_entry(ref);
 663         return frame;
 664 }
 665 EXPORT_SYMBOL_GPL(gnttab_end_foreign_transfer);
 666
 667 void gnttab_free_grant_reference(grant_ref_t ref)
 668 {
 669         put_free_entry(ref);
 670 }
 671 EXPORT_SYMBOL_GPL(gnttab_free_grant_reference);
 672
 673 void gnttab_free_grant_references(grant_ref_t head)
 674 {
 675         grant_ref_t ref;
 676         unsigned long flags;
 677         int count = 1;
 678         if (head == GNTTAB_LIST_END)
 679                 return;
 680         spin_lock_irqsave(&gnttab_list_lock, flags);
 681         ref = head;
 682         while (gnttab_entry(ref) != GNTTAB_LIST_END) {
 683                 ref = gnttab_entry(ref);
 684                 count++;
 685         }
 686         gnttab_entry(ref) = gnttab_free_head;
 687         gnttab_free_head = head;
 688         gnttab_free_count += count;
 689         check_free_callbacks();
 690         spin_unlock_irqrestore(&gnttab_list_lock, flags);
 691 }
 692 EXPORT_SYMBOL_GPL(gnttab_free_grant_references);
 693
 694 int gnttab_alloc_grant_references(u16 count, grant_ref_t *head)
 695 {
 696         int h = get_free_entries(count);
 697
 698         if (h < 0)
 699                 return -ENOSPC;
 700
 701         *head = h;
 702
 703         return 0;
 704 }
 705 EXPORT_SYMBOL_GPL(gnttab_alloc_grant_references);
 706
 707 int gnttab_empty_grant_references(const grant_ref_t *private_head)
 708 {
 709         return (*private_head == GNTTAB_LIST_END);
 710 }
 711 EXPORT_SYMBOL_GPL(gnttab_empty_grant_references);
 712
 713 int gnttab_claim_grant_reference(grant_ref_t *private_head)
 714 {
 715         grant_ref_t g = *private_head;
 716         if (unlikely(g == GNTTAB_LIST_END))
 717                 return -ENOSPC;
 718         *private_head = gnttab_entry(g);
 719         return g;
 720 }
 721 EXPORT_SYMBOL_GPL(gnttab_claim_grant_reference);
 722
 723 void gnttab_release_grant_reference(grant_ref_t *private_head,
 724                                     grant_ref_t release)
 725 {
 726         gnttab_entry(release) = *private_head;
 727         *private_head = release;
 728 }
 729 EXPORT_SYMBOL_GPL(gnttab_release_grant_reference);
 730
 731 void gnttab_request_free_callback(struct gnttab_free_callback *callback,
 732                                   void (*fn)(void *), void *arg, u16 count)
 733 {
 734         unsigned long flags;
 735         spin_lock_irqsave(&gnttab_list_lock, flags);
 736         if (callback->next)
 737                 goto out;
 738         callback->fn = fn;
 739         callback->arg = arg;
 740         callback->count = count;
 741         callback->next = gnttab_free_callback_list;
 742         gnttab_free_callback_list = callback;
 743         check_free_callbacks();
 744 out:
 745         spin_unlock_irqrestore(&gnttab_list_lock, flags);
 746 }
 747 EXPORT_SYMBOL_GPL(gnttab_request_free_callback);
 748
 749 void gnttab_cancel_free_callback(struct gnttab_free_callback *callback)
 750 {
 751         struct gnttab_free_callback **pcb;
 752         unsigned long flags;
 753
 754         spin_lock_irqsave(&gnttab_list_lock, flags);
 755         for (pcb = &gnttab_free_callback_list; *pcb; pcb = &(*pcb)->next) {
 756                 if (*pcb == callback) {
 757                         *pcb = callback->next;
 758                         break;
 759                 }
 760         }
 761         spin_unlock_irqrestore(&gnttab_list_lock, flags);
 762 }
 763 EXPORT_SYMBOL_GPL(gnttab_cancel_free_callback);
 764
 765 static int grow_gnttab_list(unsigned int more_frames)
 766 {
 767         unsigned int new_nr_grant_frames, extra_entries, i;
 768         unsigned int nr_glist_frames, new_nr_glist_frames;
 769
 770         new_nr_grant_frames = nr_grant_frames + more_frames;
 771         extra_entries       = more_frames * GREFS_PER_GRANT_FRAME;
 772
 773         nr_glist_frames = (nr_grant_frames * GREFS_PER_GRANT_FRAME + RPP - 1) / RPP;
 774         new_nr_glist_frames =
 775                 (new_nr_grant_frames * GREFS_PER_GRANT_FRAME + RPP - 1) / RPP;
 776         for (i = nr_glist_frames; i < new_nr_glist_frames; i++) {
 777                 gnttab_list[i] = (grant_ref_t *)__get_free_page(GFP_ATOMIC);
 778                 if (!gnttab_list[i])
 779                         goto grow_nomem;
 780         }
 781
 782
 783         for (i = GREFS_PER_GRANT_FRAME * nr_grant_frames;
 784              i < GREFS_PER_GRANT_FRAME * new_nr_grant_frames - 1; i++)
 785                 gnttab_entry(i) = i + 1;
 786
 787         gnttab_entry(i) = gnttab_free_head;
 788         gnttab_free_head = GREFS_PER_GRANT_FRAME * nr_grant_frames;
 789         gnttab_free_count += extra_entries;
 790
 791         nr_grant_frames = new_nr_grant_frames;
 792
 793         check_free_callbacks();
 794
 795         return 0;
 796
 797 grow_nomem:
 798         for ( ; i >= nr_glist_frames; i--)
 799                 free_page((unsigned long) gnttab_list[i]);
 800         return -ENOMEM;
 801 }
 802
 803 static unsigned int __max_nr_grant_frames(void)
 804 {
 805         struct gnttab_query_size query;
 806         int rc;
 807
 808         query.dom = DOMID_SELF;
 809
 810         rc = HYPERVISOR_grant_table_op(GNTTABOP_query_size, &query, 1);
 811         if ((rc < 0) || (query.status != GNTST_okay))
 812                 return 4; /* Legacy max supported number of frames */
 813
 814         return query.max_nr_frames;
 815 }
 816
 817 unsigned int gnttab_max_grant_frames(void)
 818 {
 819         unsigned int xen_max = __max_nr_grant_frames();
 820
 821         if (xen_max > boot_max_nr_grant_frames)
 822                 return boot_max_nr_grant_frames;
 823         return xen_max;
 824 }
 825 EXPORT_SYMBOL_GPL(gnttab_max_grant_frames);
 826
 827 /* Handling of paged out grant targets (GNTST_eagain) */
 828 #define MAX_DELAY 256
 829 static inline void
 830 gnttab_retry_eagain_gop(unsigned int cmd, void *gop, int16_t *status,
 831                                                 const char *func)
 832 {
 833         unsigned delay = 1;
 834
 835         do {
 836                 BUG_ON(HYPERVISOR_grant_table_op(cmd, gop, 1));
 837                 if (*status == GNTST_eagain)
 838                         msleep(delay++);
 839         } while ((*status == GNTST_eagain) && (delay < MAX_DELAY));
 840
 841         if (delay >= MAX_DELAY) {
 842                 printk(KERN_ERR "%s: %s eagain grant\n", func, current->comm);
 843                 *status = GNTST_bad_page;
 844         }
 845 }
 846
 847 void gnttab_batch_map(struct gnttab_map_grant_ref *batch, unsigned count)
 848 {
 849         struct gnttab_map_grant_ref *op;
 850
 851         if (HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref, batch, count))
 852                 BUG();
 853         for (op = batch; op < batch + count; op++)
 854                 if (op->status == GNTST_eagain)
 855                         gnttab_retry_eagain_gop(GNTTABOP_map_grant_ref, op,
 856                                                 &op->status, __func__);
 857 }
 858 EXPORT_SYMBOL_GPL(gnttab_batch_map);
 859
 860 void gnttab_batch_copy(struct gnttab_copy *batch, unsigned count)
 861 {
 862         struct gnttab_copy *op;
 863
 864         if (HYPERVISOR_grant_table_op(GNTTABOP_copy, batch, count))
 865                 BUG();
 866         for (op = batch; op < batch + count; op++)
 867                 if (op->status == GNTST_eagain)
 868                         gnttab_retry_eagain_gop(GNTTABOP_copy, op,
 869                                                 &op->status, __func__);
 870 }
 871 EXPORT_SYMBOL_GPL(gnttab_batch_copy);
 872
 873 int gnttab_map_refs(struct gnttab_map_grant_ref *map_ops,
 874                     struct gnttab_map_grant_ref *kmap_ops,
 875                     struct page **pages, unsigned int count)
 876 {
 877         int i, ret;
 878         bool lazy = false;
 879         pte_t *pte;
 880         unsigned long mfn;
 881
 882         ret = HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref, map_ops, count);
 883         if (ret)
 884                 return ret;
 885
 886         /* Retry eagain maps */
 887         for (i = 0; i < count; i++)
 888                 if (map_ops[i].status == GNTST_eagain)
 889                         gnttab_retry_eagain_gop(GNTTABOP_map_grant_ref, map_ops + i,
 890                                                 &map_ops[i].status, __func__);
 891
 892         if (xen_feature(XENFEAT_auto_translated_physmap))
 893                 return ret;
 894
 895         if (!in_interrupt() && paravirt_get_lazy_mode() == PARAVIRT_LAZY_NONE) {
 896                 arch_enter_lazy_mmu_mode();
 897                 lazy = true;
 898         }
 899
 900         for (i = 0; i < count; i++) {
 901                 /* Do not add to override if the map failed. */
 902                 if (map_ops[i].status)
 903                         continue;
 904
 905                 if (map_ops[i].flags & GNTMAP_contains_pte) {
 906                         pte = (pte_t *) (mfn_to_virt(PFN_DOWN(map_ops[i].host_addr)) +
 907                                 (map_ops[i].host_addr & ~PAGE_MASK));
 908                         mfn = pte_mfn(*pte);
 909                 } else {
 910                         mfn = PFN_DOWN(map_ops[i].dev_bus_addr);
 911                 }
 912                 ret = m2p_add_override(mfn, pages[i], kmap_ops ?
 913                                        &kmap_ops[i] : NULL);
 914                 if (ret)
 915                         return ret;
 916         }
 917
 918         if (lazy)
 919                 arch_leave_lazy_mmu_mode();
 920
 921         return ret;
 922 }
 923 EXPORT_SYMBOL_GPL(gnttab_map_refs);
 924
 925 int gnttab_unmap_refs(struct gnttab_unmap_grant_ref *unmap_ops,
 926                       struct gnttab_map_grant_ref *kmap_ops,
 927                       struct page **pages, unsigned int count)
 928 {
 929         int i, ret;
 930         bool lazy = false;
 931
 932         ret = HYPERVISOR_grant_table_op(GNTTABOP_unmap_grant_ref, unmap_ops, count);
 933         if (ret)
 934                 return ret;
 935
 936         if (xen_feature(XENFEAT_auto_translated_physmap))
 937                 return ret;
 938
 939         if (!in_interrupt() && paravirt_get_lazy_mode() == PARAVIRT_LAZY_NONE) {
 940                 arch_enter_lazy_mmu_mode();
 941                 lazy = true;
 942         }
 943
 944         for (i = 0; i < count; i++) {
 945                 ret = m2p_remove_override(pages[i], kmap_ops ?
 946                                        &kmap_ops[i] : NULL);
 947                 if (ret)
 948                         return ret;
 949         }
 950
 951         if (lazy)
 952                 arch_leave_lazy_mmu_mode();
 953
 954         return ret;
 955 }
 956 EXPORT_SYMBOL_GPL(gnttab_unmap_refs);
 957
 958 static unsigned nr_status_frames(unsigned nr_grant_frames)
 959 {
 960         return (nr_grant_frames * GREFS_PER_GRANT_FRAME + SPP - 1) / SPP;
 961 }
 962
 963 static int gnttab_map_frames_v1(unsigned long *frames, unsigned int nr_gframes)
 964 {
 965         int rc;
 966
 967         rc = arch_gnttab_map_shared(frames, nr_gframes,
 968                                     gnttab_max_grant_frames(),
 969                                     &gnttab_shared.addr);
 970         BUG_ON(rc);
 971
 972         return 0;
 973 }
 974
 975 static void gnttab_unmap_frames_v1(void)
 976 {
 977         arch_gnttab_unmap(gnttab_shared.addr, nr_grant_frames);
 978 }
 979
 980 static int gnttab_map_frames_v2(unsigned long *frames, unsigned int nr_gframes)
 981 {
 982         uint64_t *sframes;
 983         unsigned int nr_sframes;
 984         struct gnttab_get_status_frames getframes;
 985         int rc;
 986
 987         nr_sframes = nr_status_frames(nr_gframes);
 988
 989         /* No need for kzalloc as it is initialized in following hypercall
 990          * GNTTABOP_get_status_frames.
 991          */
 992         sframes = kmalloc(nr_sframes  * sizeof(uint64_t), GFP_ATOMIC);
 993         if (!sframes)
 994                 return -ENOMEM;
 995
 996         getframes.dom        = DOMID_SELF;
 997         getframes.nr_frames  = nr_sframes;
 998         set_xen_guest_handle(getframes.frame_list, sframes);
 999
1000         rc = HYPERVISOR_grant_table_op(GNTTABOP_get_status_frames,
1001                                        &getframes, 1);
1002         if (rc == -ENOSYS) {
1003                 kfree(sframes);
1004                 return -ENOSYS;
1005         }
1006
1007         BUG_ON(rc || getframes.status);
1008
1009         rc = arch_gnttab_map_status(sframes, nr_sframes,
1010                                     nr_status_frames(gnttab_max_grant_frames()),
1011                                     &grstatus);
1012         BUG_ON(rc);
1013         kfree(sframes);
1014
1015         rc = arch_gnttab_map_shared(frames, nr_gframes,
1016                                     gnttab_max_grant_frames(),
1017                                     &gnttab_shared.addr);
1018         BUG_ON(rc);
1019
1020         return 0;
1021 }
1022
1023 static void gnttab_unmap_frames_v2(void)
1024 {
1025         arch_gnttab_unmap(gnttab_shared.addr, nr_grant_frames);
1026         arch_gnttab_unmap(grstatus, nr_status_frames(nr_grant_frames));
1027 }
1028
1029 static int gnttab_map(unsigned int start_idx, unsigned int end_idx)
1030 {
1031         struct gnttab_setup_table setup;
1032         unsigned long *frames;
1033         unsigned int nr_gframes = end_idx + 1;
1034         int rc;
1035
1036         if (xen_hvm_domain()) {
1037                 struct xen_add_to_physmap xatp;
1038                 unsigned int i = end_idx;
1039                 rc = 0;
1040                 /*
1041                  * Loop backwards, so that the first hypercall has the largest
1042                  * index, ensuring that the table will grow only once.
1043                  */
1044                 do {
1045                         xatp.domid = DOMID_SELF;
1046                         xatp.idx = i;
1047                         xatp.space = XENMAPSPACE_grant_table;
1048                         xatp.gpfn = (xen_hvm_resume_frames >> PAGE_SHIFT) + i;
1049                         rc = HYPERVISOR_memory_op(XENMEM_add_to_physmap, &xatp);
1050                         if (rc != 0) {
1051                                 printk(KERN_WARNING
1052                                                 "grant table add_to_physmap failed, err=%d\n", rc);
1053                                 break;
1054                         }
1055                 } while (i-- > start_idx);
1056
1057                 return rc;
1058         }
1059
1060         /* No need for kzalloc as it is initialized in following hypercall
1061          * GNTTABOP_setup_table.
1062          */
1063         frames = kmalloc(nr_gframes * sizeof(unsigned long), GFP_ATOMIC);
1064         if (!frames)
1065                 return -ENOMEM;
1066
1067         setup.dom        = DOMID_SELF;
1068         setup.nr_frames  = nr_gframes;
1069         set_xen_guest_handle(setup.frame_list, frames);
1070
1071         rc = HYPERVISOR_grant_table_op(GNTTABOP_setup_table, &setup, 1);
1072         if (rc == -ENOSYS) {
1073                 kfree(frames);
1074                 return -ENOSYS;
1075         }
1076
1077         BUG_ON(rc || setup.status);
1078
1079         rc = gnttab_interface->map_frames(frames, nr_gframes);
1080
1081         kfree(frames);
1082
1083         return rc;
1084 }
1085
1086 static struct gnttab_ops gnttab_v1_ops = {
1087         .map_frames                     = gnttab_map_frames_v1,
1088         .unmap_frames                   = gnttab_unmap_frames_v1,
1089         .update_entry                   = gnttab_update_entry_v1,
1090         .end_foreign_access_ref         = gnttab_end_foreign_access_ref_v1,
1091         .end_foreign_transfer_ref       = gnttab_end_foreign_transfer_ref_v1,
1092         .query_foreign_access           = gnttab_query_foreign_access_v1,
1093 };
1094
1095 static struct gnttab_ops gnttab_v2_ops = {
1096         .map_frames                     = gnttab_map_frames_v2,
1097         .unmap_frames                   = gnttab_unmap_frames_v2,
1098         .update_entry                   = gnttab_update_entry_v2,
1099         .end_foreign_access_ref         = gnttab_end_foreign_access_ref_v2,
1100         .end_foreign_transfer_ref       = gnttab_end_foreign_transfer_ref_v2,
1101         .query_foreign_access           = gnttab_query_foreign_access_v2,
1102         .update_subpage_entry           = gnttab_update_subpage_entry_v2,
1103         .update_trans_entry             = gnttab_update_trans_entry_v2,
1104 };
1105
1106 static void gnttab_request_version(void)
1107 {
1108         int rc;
1109         struct gnttab_set_version gsv;
1110
1111         if (xen_hvm_domain())
1112                 gsv.version = 1;
1113         else
1114                 gsv.version = 2;
1115         rc = HYPERVISOR_grant_table_op(GNTTABOP_set_version, &gsv, 1);
1116         if (rc == 0 && gsv.version == 2) {
1117                 grant_table_version = 2;
1118                 gnttab_interface = &gnttab_v2_ops;
1119         } else if (grant_table_version == 2) {
1120                 /*
1121                  * If we've already used version 2 features,
1122                  * but then suddenly discover that they're not
1123                  * available (e.g. migrating to an older
1124                  * version of Xen), almost unbounded badness
1125                  * can happen.
1126                  */
1127                 panic("we need grant tables version 2, but only version 1 is available");
1128         } else {
1129                 grant_table_version = 1;
1130                 gnttab_interface = &gnttab_v1_ops;
1131         }
1132         printk(KERN_INFO "Grant tables using version %d layout.\n",
1133                 grant_table_version);
1134 }
1135
1136 int gnttab_resume(void)
1137 {
1138         unsigned int max_nr_gframes;
1139
1140         gnttab_request_version();
1141         max_nr_gframes = gnttab_max_grant_frames();
1142         if (max_nr_gframes < nr_grant_frames)
1143                 return -ENOSYS;
1144
1145         if (xen_pv_domain())
1146                 return gnttab_map(0, nr_grant_frames - 1);
1147
1148         if (gnttab_shared.addr == NULL) {
1149                 gnttab_shared.addr = ioremap(xen_hvm_resume_frames,
1150                                                 PAGE_SIZE * max_nr_gframes);
1151                 if (gnttab_shared.addr == NULL) {
1152                         printk(KERN_WARNING
1153                                         "Failed to ioremap gnttab share frames!");
1154                         return -ENOMEM;
1155                 }
1156         }
1157
1158         gnttab_map(0, nr_grant_frames - 1);
1159
1160         return 0;
1161 }
1162
1163 int gnttab_suspend(void)
1164 {
1165         gnttab_interface->unmap_frames();
1166         return 0;
1167 }
1168
1169 static int gnttab_expand(unsigned int req_entries)
1170 {
1171         int rc;
1172         unsigned int cur, extra;
1173
1174         cur = nr_grant_frames;
1175         extra = ((req_entries + (GREFS_PER_GRANT_FRAME-1)) /
1176                  GREFS_PER_GRANT_FRAME);
1177         if (cur + extra > gnttab_max_grant_frames())
1178                 return -ENOSPC;
1179
1180         rc = gnttab_map(cur, cur + extra - 1);
1181         if (rc == 0)
1182                 rc = grow_gnttab_list(extra);
1183
1184         return rc;
1185 }
1186
1187 int gnttab_init(void)
1188 {
1189         int i;
1190         unsigned int max_nr_glist_frames, nr_glist_frames;
1191         unsigned int nr_init_grefs;
1192         int ret;
1193
1194         nr_grant_frames = 1;
1195         boot_max_nr_grant_frames = __max_nr_grant_frames();
1196
1197         /* Determine the maximum number of frames required for the
1198          * grant reference free list on the current hypervisor.
1199          */
1200         max_nr_glist_frames = (boot_max_nr_grant_frames *
1201                                GREFS_PER_GRANT_FRAME / RPP);
1202
1203         gnttab_list = kmalloc(max_nr_glist_frames * sizeof(grant_ref_t *),
1204                               GFP_KERNEL);
1205         if (gnttab_list == NULL)
1206                 return -ENOMEM;
1207
1208         nr_glist_frames = (nr_grant_frames * GREFS_PER_GRANT_FRAME + RPP - 1) / RPP;
1209         for (i = 0; i < nr_glist_frames; i++) {
1210                 gnttab_list[i] = (grant_ref_t *)__get_free_page(GFP_KERNEL);
1211                 if (gnttab_list[i] == NULL) {
1212                         ret = -ENOMEM;
1213                         goto ini_nomem;
1214                 }
1215         }
1216
1217         if (gnttab_resume() < 0) {
1218                 ret = -ENODEV;
1219                 goto ini_nomem;
1220         }
1221
1222         nr_init_grefs = nr_grant_frames * GREFS_PER_GRANT_FRAME;
1223
1224         for (i = NR_RESERVED_ENTRIES; i < nr_init_grefs - 1; i++)
1225                 gnttab_entry(i) = i + 1;
1226
1227         gnttab_entry(nr_init_grefs - 1) = GNTTAB_LIST_END;
1228         gnttab_free_count = nr_init_grefs - NR_RESERVED_ENTRIES;
1229         gnttab_free_head  = NR_RESERVED_ENTRIES;
1230
1231         printk("Grant table initialized\n");
1232         return 0;
1233
1234  ini_nomem:
1235         for (i--; i >= 0; i--)
1236                 free_page((unsigned long)gnttab_list[i]);
1237         kfree(gnttab_list);
1238         return ret;
1239 }
1240 EXPORT_SYMBOL_GPL(gnttab_init);
1241
1242 static int __devinit __gnttab_init(void)
1243 {
1244         /* Delay grant-table initialization in the PV on HVM case */
1245         if (xen_hvm_domain())
1246                 return 0;
1247
1248         if (!xen_pv_domain())
1249                 return -ENODEV;
1250
1251         return gnttab_init();
1252 }
1253
1254 core_initcall(__gnttab_init);