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