drivers/xen/grant-table.c

   1 /******************************************************************************
   2  * grant_table.c
   3  *
   4  * Granting foreign access to our memory reservation.
   5  *
   6  * Copyright (c) 2005-2006, Christopher Clark
   7  * Copyright (c) 2004-2005, K A Fraser
   8  *
   9  * This program is free software; you can redistribute it and/or
  10  * modify it under the terms of the GNU General Public License version 2
  11  * as published by the Free Software Foundation; or, when distributed
  12  * separately from the Linux kernel or incorporated into other
  13  * software packages, subject to the following license:
  14  *
  15  * Permission is hereby granted, free of charge, to any person obtaining a copy
  16  * of this source file (the "Software"), to deal in the Software without
  17  * restriction, including without limitation the rights to use, copy, modify,
  18  * merge, publish, distribute, sublicense, and/or sell copies of the Software,
  19  * and to permit persons to whom the Software is furnished to do so, subject to
  20  * the following conditions:
  21  *
  22  * The above copyright notice and this permission notice shall be included in
  23  * all copies or substantial portions of the Software.
  24  *
  25  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  26  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  27  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  28  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  29  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  30  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
  31  * IN THE SOFTWARE.
  32  */
  33
  34 #define pr_fmt(fmt) "xen:" KBUILD_MODNAME ": " fmt
  35
  36 #include <linux/sched.h>
  37 #include <linux/mm.h>
  38 #include <linux/slab.h>
  39 #include <linux/vmalloc.h>
  40 #include <linux/uaccess.h>
  41 #include <linux/io.h>
  42 #include <linux/delay.h>
  43 #include <linux/hardirq.h>
  44 #include <linux/workqueue.h>
  45 #include <linux/ratelimit.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          * Read the frame number related to a given grant reference.
 119          */
 120         unsigned long (*read_frame)(grant_ref_t ref);
 121 };
 122
 123 struct unmap_refs_callback_data {
 124         struct completion completion;
 125         int result;
 126 };
 127
 128 static const struct gnttab_ops *gnttab_interface;
 129
 130 static int grant_table_version;
 131 static int grefs_per_grant_frame;
 132
 133 static struct gnttab_free_callback *gnttab_free_callback_list;
 134
 135 static int gnttab_expand(unsigned int req_entries);
 136
 137 #define RPP (PAGE_SIZE / sizeof(grant_ref_t))
 138
 139 static inline grant_ref_t *__gnttab_entry(grant_ref_t entry)
 140 {
 141         return &gnttab_list[(entry) / RPP][(entry) % RPP];
 142 }
 143 /* This can be used as an l-value */
 144 #define gnttab_entry(entry) (*__gnttab_entry(entry))
 145
 146 static int get_free_entries(unsigned count)
 147 {
 148         unsigned long flags;
 149         int ref, rc = 0;
 150         grant_ref_t head;
 151
 152         spin_lock_irqsave(&gnttab_list_lock, flags);
 153
 154         if ((gnttab_free_count < count) &&
 155             ((rc = gnttab_expand(count - gnttab_free_count)) < 0)) {
 156                 spin_unlock_irqrestore(&gnttab_list_lock, flags);
 157                 return rc;
 158         }
 159
 160         ref = head = gnttab_free_head;
 161         gnttab_free_count -= count;
 162         while (count-- > 1)
 163                 head = gnttab_entry(head);
 164         gnttab_free_head = gnttab_entry(head);
 165         gnttab_entry(head) = GNTTAB_LIST_END;
 166
 167         spin_unlock_irqrestore(&gnttab_list_lock, flags);
 168
 169         return ref;
 170 }
 171
 172 static void do_free_callbacks(void)
 173 {
 174         struct gnttab_free_callback *callback, *next;
 175
 176         callback = gnttab_free_callback_list;
 177         gnttab_free_callback_list = NULL;
 178
 179         while (callback != NULL) {
 180                 next = callback->next;
 181                 if (gnttab_free_count >= callback->count) {
 182                         callback->next = NULL;
 183                         callback->fn(callback->arg);
 184                 } else {
 185                         callback->next = gnttab_free_callback_list;
 186                         gnttab_free_callback_list = callback;
 187                 }
 188                 callback = next;
 189         }
 190 }
 191
 192 static inline void check_free_callbacks(void)
 193 {
 194         if (unlikely(gnttab_free_callback_list))
 195                 do_free_callbacks();
 196 }
 197
 198 static void put_free_entry(grant_ref_t ref)
 199 {
 200         unsigned long flags;
 201         spin_lock_irqsave(&gnttab_list_lock, flags);
 202         gnttab_entry(ref) = gnttab_free_head;
 203         gnttab_free_head = ref;
 204         gnttab_free_count++;
 205         check_free_callbacks();
 206         spin_unlock_irqrestore(&gnttab_list_lock, flags);
 207 }
 208
 209 /*
 210  * Following applies to gnttab_update_entry_v1.
 211  * Introducing a valid entry into the grant table:
 212  *  1. Write ent->domid.
 213  *  2. Write ent->frame:
 214  *      GTF_permit_access:   Frame to which access is permitted.
 215  *      GTF_accept_transfer: Pseudo-phys frame slot being filled by new
 216  *                           frame, or zero if none.
 217  *  3. Write memory barrier (WMB).
 218  *  4. Write ent->flags, inc. valid type.
 219  */
 220 static void gnttab_update_entry_v1(grant_ref_t ref, domid_t domid,
 221                                    unsigned long frame, unsigned flags)
 222 {
 223         gnttab_shared.v1[ref].domid = domid;
 224         gnttab_shared.v1[ref].frame = frame;
 225         wmb();
 226         gnttab_shared.v1[ref].flags = flags;
 227 }
 228
 229 /*
 230  * Public grant-issuing interface functions
 231  */
 232 void gnttab_grant_foreign_access_ref(grant_ref_t ref, domid_t domid,
 233                                      unsigned long frame, int readonly)
 234 {
 235         gnttab_interface->update_entry(ref, domid, frame,
 236                            GTF_permit_access | (readonly ? GTF_readonly : 0));
 237 }
 238 EXPORT_SYMBOL_GPL(gnttab_grant_foreign_access_ref);
 239
 240 int gnttab_grant_foreign_access(domid_t domid, unsigned long frame,
 241                                 int readonly)
 242 {
 243         int ref;
 244
 245         ref = get_free_entries(1);
 246         if (unlikely(ref < 0))
 247                 return -ENOSPC;
 248
 249         gnttab_grant_foreign_access_ref(ref, domid, frame, readonly);
 250
 251         return ref;
 252 }
 253 EXPORT_SYMBOL_GPL(gnttab_grant_foreign_access);
 254
 255 static int gnttab_end_foreign_access_ref_v1(grant_ref_t ref, int readonly)
 256 {
 257         u16 flags, nflags;
 258         u16 *pflags;
 259
 260         pflags = &gnttab_shared.v1[ref].flags;
 261         nflags = *pflags;
 262         do {
 263                 flags = nflags;
 264                 if (flags & (GTF_reading|GTF_writing))
 265                         return 0;
 266         } while ((nflags = sync_cmpxchg(pflags, flags, 0)) != flags);
 267
 268         return 1;
 269 }
 270
 271 static inline int _gnttab_end_foreign_access_ref(grant_ref_t ref, int readonly)
 272 {
 273         return gnttab_interface->end_foreign_access_ref(ref, readonly);
 274 }
 275
 276 int gnttab_end_foreign_access_ref(grant_ref_t ref, int readonly)
 277 {
 278         if (_gnttab_end_foreign_access_ref(ref, readonly))
 279                 return 1;
 280         pr_warn("WARNING: g.e. %#x still in use!\n", ref);
 281         return 0;
 282 }
 283 EXPORT_SYMBOL_GPL(gnttab_end_foreign_access_ref);
 284
 285 static unsigned long gnttab_read_frame_v1(grant_ref_t ref)
 286 {
 287         return gnttab_shared.v1[ref].frame;
 288 }
 289
 290 struct deferred_entry {
 291         struct list_head list;
 292         grant_ref_t ref;
 293         bool ro;
 294         uint16_t warn_delay;
 295         struct page *page;
 296 };
 297 static LIST_HEAD(deferred_list);
 298 static void gnttab_handle_deferred(unsigned long);
 299 static DEFINE_TIMER(deferred_timer, gnttab_handle_deferred, 0, 0);
 300
 301 static void gnttab_handle_deferred(unsigned long unused)
 302 {
 303         unsigned int nr = 10;
 304         struct deferred_entry *first = NULL;
 305         unsigned long flags;
 306
 307         spin_lock_irqsave(&gnttab_list_lock, flags);
 308         while (nr--) {
 309                 struct deferred_entry *entry
 310                         = list_first_entry(&deferred_list,
 311                                            struct deferred_entry, list);
 312
 313                 if (entry == first)
 314                         break;
 315                 list_del(&entry->list);
 316                 spin_unlock_irqrestore(&gnttab_list_lock, flags);
 317                 if (_gnttab_end_foreign_access_ref(entry->ref, entry->ro)) {
 318                         put_free_entry(entry->ref);
 319                         pr_debug("freeing g.e. %#x (pfn %#lx)\n",
 320                                  entry->ref, page_to_pfn(entry->page));
 321                         put_page(entry->page);
 322                         kfree(entry);
 323                         entry = NULL;
 324                 } else {
 325                         if (!--entry->warn_delay)
 326                                 pr_info("g.e. %#x still pending\n", entry->ref);
 327                         if (!first)
 328                                 first = entry;
 329                 }
 330                 spin_lock_irqsave(&gnttab_list_lock, flags);
 331                 if (entry)
 332                         list_add_tail(&entry->list, &deferred_list);
 333                 else if (list_empty(&deferred_list))
 334                         break;
 335         }
 336         if (!list_empty(&deferred_list) && !timer_pending(&deferred_timer)) {
 337                 deferred_timer.expires = jiffies + HZ;
 338                 add_timer(&deferred_timer);
 339         }
 340         spin_unlock_irqrestore(&gnttab_list_lock, flags);
 341 }
 342
 343 static void gnttab_add_deferred(grant_ref_t ref, bool readonly,
 344                                 struct page *page)
 345 {
 346         struct deferred_entry *entry;
 347         gfp_t gfp = (in_atomic() || irqs_disabled()) ? GFP_ATOMIC : GFP_KERNEL;
 348         const char *what = KERN_WARNING "leaking";
 349
 350         entry = kmalloc(sizeof(*entry), gfp);
 351         if (!page) {
 352                 unsigned long gfn = gnttab_interface->read_frame(ref);
 353
 354                 page = pfn_to_page(gfn_to_pfn(gfn));
 355                 get_page(page);
 356         }
 357
 358         if (entry) {
 359                 unsigned long flags;
 360
 361                 entry->ref = ref;
 362                 entry->ro = readonly;
 363                 entry->page = page;
 364                 entry->warn_delay = 60;
 365                 spin_lock_irqsave(&gnttab_list_lock, flags);
 366                 list_add_tail(&entry->list, &deferred_list);
 367                 if (!timer_pending(&deferred_timer)) {
 368                         deferred_timer.expires = jiffies + HZ;
 369                         add_timer(&deferred_timer);
 370                 }
 371                 spin_unlock_irqrestore(&gnttab_list_lock, flags);
 372                 what = KERN_DEBUG "deferring";
 373         }
 374         printk("%s g.e. %#x (pfn %#lx)\n",
 375                what, ref, page ? page_to_pfn(page) : -1);
 376 }
 377
 378 int gnttab_try_end_foreign_access(grant_ref_t ref)
 379 {
 380         int ret = _gnttab_end_foreign_access_ref(ref, 0);
 381
 382         if (ret)
 383                 put_free_entry(ref);
 384
 385         return ret;
 386 }
 387 EXPORT_SYMBOL_GPL(gnttab_try_end_foreign_access);
 388
 389 void gnttab_end_foreign_access(grant_ref_t ref, int readonly,
 390                                unsigned long page)
 391 {
 392         if (gnttab_try_end_foreign_access(ref)) {
 393                 if (page != 0)
 394                         put_page(virt_to_page(page));
 395         } else
 396                 gnttab_add_deferred(ref, readonly,
 397                                     page ? virt_to_page(page) : NULL);
 398 }
 399 EXPORT_SYMBOL_GPL(gnttab_end_foreign_access);
 400
 401 int gnttab_grant_foreign_transfer(domid_t domid, unsigned long pfn)
 402 {
 403         int ref;
 404
 405         ref = get_free_entries(1);
 406         if (unlikely(ref < 0))
 407                 return -ENOSPC;
 408         gnttab_grant_foreign_transfer_ref(ref, domid, pfn);
 409
 410         return ref;
 411 }
 412 EXPORT_SYMBOL_GPL(gnttab_grant_foreign_transfer);
 413
 414 void gnttab_grant_foreign_transfer_ref(grant_ref_t ref, domid_t domid,
 415                                        unsigned long pfn)
 416 {
 417         gnttab_interface->update_entry(ref, domid, pfn, GTF_accept_transfer);
 418 }
 419 EXPORT_SYMBOL_GPL(gnttab_grant_foreign_transfer_ref);
 420
 421 static unsigned long gnttab_end_foreign_transfer_ref_v1(grant_ref_t ref)
 422 {
 423         unsigned long frame;
 424         u16           flags;
 425         u16          *pflags;
 426
 427         pflags = &gnttab_shared.v1[ref].flags;
 428
 429         /*
 430          * If a transfer is not even yet started, try to reclaim the grant
 431          * reference and return failure (== 0).
 432          */
 433         while (!((flags = *pflags) & GTF_transfer_committed)) {
 434                 if (sync_cmpxchg(pflags, flags, 0) == flags)
 435                         return 0;
 436                 cpu_relax();
 437         }
 438
 439         /* If a transfer is in progress then wait until it is completed. */
 440         while (!(flags & GTF_transfer_completed)) {
 441                 flags = *pflags;
 442                 cpu_relax();
 443         }
 444
 445         rmb();  /* Read the frame number /after/ reading completion status. */
 446         frame = gnttab_shared.v1[ref].frame;
 447         BUG_ON(frame == 0);
 448
 449         return frame;
 450 }
 451
 452 unsigned long gnttab_end_foreign_transfer_ref(grant_ref_t ref)
 453 {
 454         return gnttab_interface->end_foreign_transfer_ref(ref);
 455 }
 456 EXPORT_SYMBOL_GPL(gnttab_end_foreign_transfer_ref);
 457
 458 unsigned long gnttab_end_foreign_transfer(grant_ref_t ref)
 459 {
 460         unsigned long frame = gnttab_end_foreign_transfer_ref(ref);
 461         put_free_entry(ref);
 462         return frame;
 463 }
 464 EXPORT_SYMBOL_GPL(gnttab_end_foreign_transfer);
 465
 466 void gnttab_free_grant_reference(grant_ref_t ref)
 467 {
 468         put_free_entry(ref);
 469 }
 470 EXPORT_SYMBOL_GPL(gnttab_free_grant_reference);
 471
 472 void gnttab_free_grant_references(grant_ref_t head)
 473 {
 474         grant_ref_t ref;
 475         unsigned long flags;
 476         int count = 1;
 477         if (head == GNTTAB_LIST_END)
 478                 return;
 479         spin_lock_irqsave(&gnttab_list_lock, flags);
 480         ref = head;
 481         while (gnttab_entry(ref) != GNTTAB_LIST_END) {
 482                 ref = gnttab_entry(ref);
 483                 count++;
 484         }
 485         gnttab_entry(ref) = gnttab_free_head;
 486         gnttab_free_head = head;
 487         gnttab_free_count += count;
 488         check_free_callbacks();
 489         spin_unlock_irqrestore(&gnttab_list_lock, flags);
 490 }
 491 EXPORT_SYMBOL_GPL(gnttab_free_grant_references);
 492
 493 int gnttab_alloc_grant_references(u16 count, grant_ref_t *head)
 494 {
 495         int h = get_free_entries(count);
 496
 497         if (h < 0)
 498                 return -ENOSPC;
 499
 500         *head = h;
 501
 502         return 0;
 503 }
 504 EXPORT_SYMBOL_GPL(gnttab_alloc_grant_references);
 505
 506 int gnttab_empty_grant_references(const grant_ref_t *private_head)
 507 {
 508         return (*private_head == GNTTAB_LIST_END);
 509 }
 510 EXPORT_SYMBOL_GPL(gnttab_empty_grant_references);
 511
 512 int gnttab_claim_grant_reference(grant_ref_t *private_head)
 513 {
 514         grant_ref_t g = *private_head;
 515         if (unlikely(g == GNTTAB_LIST_END))
 516                 return -ENOSPC;
 517         *private_head = gnttab_entry(g);
 518         return g;
 519 }
 520 EXPORT_SYMBOL_GPL(gnttab_claim_grant_reference);
 521
 522 void gnttab_release_grant_reference(grant_ref_t *private_head,
 523                                     grant_ref_t release)
 524 {
 525         gnttab_entry(release) = *private_head;
 526         *private_head = release;
 527 }
 528 EXPORT_SYMBOL_GPL(gnttab_release_grant_reference);
 529
 530 void gnttab_request_free_callback(struct gnttab_free_callback *callback,
 531                                   void (*fn)(void *), void *arg, u16 count)
 532 {
 533         unsigned long flags;
 534         struct gnttab_free_callback *cb;
 535
 536         spin_lock_irqsave(&gnttab_list_lock, flags);
 537
 538         /* Check if the callback is already on the list */
 539         cb = gnttab_free_callback_list;
 540         while (cb) {
 541                 if (cb == callback)
 542                         goto out;
 543                 cb = cb->next;
 544         }
 545
 546         callback->fn = fn;
 547         callback->arg = arg;
 548         callback->count = count;
 549         callback->next = gnttab_free_callback_list;
 550         gnttab_free_callback_list = callback;
 551         check_free_callbacks();
 552 out:
 553         spin_unlock_irqrestore(&gnttab_list_lock, flags);
 554 }
 555 EXPORT_SYMBOL_GPL(gnttab_request_free_callback);
 556
 557 void gnttab_cancel_free_callback(struct gnttab_free_callback *callback)
 558 {
 559         struct gnttab_free_callback **pcb;
 560         unsigned long flags;
 561
 562         spin_lock_irqsave(&gnttab_list_lock, flags);
 563         for (pcb = &gnttab_free_callback_list; *pcb; pcb = &(*pcb)->next) {
 564                 if (*pcb == callback) {
 565                         *pcb = callback->next;
 566                         break;
 567                 }
 568         }
 569         spin_unlock_irqrestore(&gnttab_list_lock, flags);
 570 }
 571 EXPORT_SYMBOL_GPL(gnttab_cancel_free_callback);
 572
 573 static int grow_gnttab_list(unsigned int more_frames)
 574 {
 575         unsigned int new_nr_grant_frames, extra_entries, i;
 576         unsigned int nr_glist_frames, new_nr_glist_frames;
 577
 578         BUG_ON(grefs_per_grant_frame == 0);
 579
 580         new_nr_grant_frames = nr_grant_frames + more_frames;
 581         extra_entries       = more_frames * grefs_per_grant_frame;
 582
 583         nr_glist_frames = (nr_grant_frames * grefs_per_grant_frame + RPP - 1) / RPP;
 584         new_nr_glist_frames =
 585                 (new_nr_grant_frames * grefs_per_grant_frame + RPP - 1) / RPP;
 586         for (i = nr_glist_frames; i < new_nr_glist_frames; i++) {
 587                 gnttab_list[i] = (grant_ref_t *)__get_free_page(GFP_ATOMIC);
 588                 if (!gnttab_list[i])
 589                         goto grow_nomem;
 590         }
 591
 592
 593         for (i = grefs_per_grant_frame * nr_grant_frames;
 594              i < grefs_per_grant_frame * new_nr_grant_frames - 1; i++)
 595                 gnttab_entry(i) = i + 1;
 596
 597         gnttab_entry(i) = gnttab_free_head;
 598         gnttab_free_head = grefs_per_grant_frame * nr_grant_frames;
 599         gnttab_free_count += extra_entries;
 600
 601         nr_grant_frames = new_nr_grant_frames;
 602
 603         check_free_callbacks();
 604
 605         return 0;
 606
 607 grow_nomem:
 608         while (i-- > nr_glist_frames)
 609                 free_page((unsigned long) gnttab_list[i]);
 610         return -ENOMEM;
 611 }
 612
 613 static unsigned int __max_nr_grant_frames(void)
 614 {
 615         struct gnttab_query_size query;
 616         int rc;
 617
 618         query.dom = DOMID_SELF;
 619
 620         rc = HYPERVISOR_grant_table_op(GNTTABOP_query_size, &query, 1);
 621         if ((rc < 0) || (query.status != GNTST_okay))
 622                 return 4; /* Legacy max supported number of frames */
 623
 624         return query.max_nr_frames;
 625 }
 626
 627 unsigned int gnttab_max_grant_frames(void)
 628 {
 629         unsigned int xen_max = __max_nr_grant_frames();
 630         static unsigned int boot_max_nr_grant_frames;
 631
 632         /* First time, initialize it properly. */
 633         if (!boot_max_nr_grant_frames)
 634                 boot_max_nr_grant_frames = __max_nr_grant_frames();
 635
 636         if (xen_max > boot_max_nr_grant_frames)
 637                 return boot_max_nr_grant_frames;
 638         return xen_max;
 639 }
 640 EXPORT_SYMBOL_GPL(gnttab_max_grant_frames);
 641
 642 int gnttab_setup_auto_xlat_frames(phys_addr_t addr)
 643 {
 644         xen_pfn_t *pfn;
 645         unsigned int max_nr_gframes = __max_nr_grant_frames();
 646         unsigned int i;
 647         void *vaddr;
 648
 649         if (xen_auto_xlat_grant_frames.count)
 650                 return -EINVAL;
 651
 652         vaddr = xen_remap(addr, XEN_PAGE_SIZE * max_nr_gframes);
 653         if (vaddr == NULL) {
 654                 pr_warn("Failed to ioremap gnttab share frames (addr=%pa)!\n",
 655                         &addr);
 656                 return -ENOMEM;
 657         }
 658         pfn = kcalloc(max_nr_gframes, sizeof(pfn[0]), GFP_KERNEL);
 659         if (!pfn) {
 660                 xen_unmap(vaddr);
 661                 return -ENOMEM;
 662         }
 663         for (i = 0; i < max_nr_gframes; i++)
 664                 pfn[i] = XEN_PFN_DOWN(addr) + i;
 665
 666         xen_auto_xlat_grant_frames.vaddr = vaddr;
 667         xen_auto_xlat_grant_frames.pfn = pfn;
 668         xen_auto_xlat_grant_frames.count = max_nr_gframes;
 669
 670         return 0;
 671 }
 672 EXPORT_SYMBOL_GPL(gnttab_setup_auto_xlat_frames);
 673
 674 void gnttab_free_auto_xlat_frames(void)
 675 {
 676         if (!xen_auto_xlat_grant_frames.count)
 677                 return;
 678         kfree(xen_auto_xlat_grant_frames.pfn);
 679         xen_unmap(xen_auto_xlat_grant_frames.vaddr);
 680
 681         xen_auto_xlat_grant_frames.pfn = NULL;
 682         xen_auto_xlat_grant_frames.count = 0;
 683         xen_auto_xlat_grant_frames.vaddr = NULL;
 684 }
 685 EXPORT_SYMBOL_GPL(gnttab_free_auto_xlat_frames);
 686
 687 /**
 688  * gnttab_alloc_pages - alloc pages suitable for grant mapping into
 689  * @nr_pages: number of pages to alloc
 690  * @pages: returns the pages
 691  */
 692 int gnttab_alloc_pages(int nr_pages, struct page **pages)
 693 {
 694         int i;
 695         int ret;
 696
 697         ret = alloc_xenballooned_pages(nr_pages, pages);
 698         if (ret < 0)
 699                 return ret;
 700
 701         for (i = 0; i < nr_pages; i++) {
 702 #if BITS_PER_LONG < 64
 703                 struct xen_page_foreign *foreign;
 704
 705                 foreign = kzalloc(sizeof(*foreign), GFP_KERNEL);
 706                 if (!foreign) {
 707                         gnttab_free_pages(nr_pages, pages);
 708                         return -ENOMEM;
 709                 }
 710                 set_page_private(pages[i], (unsigned long)foreign);
 711 #endif
 712                 SetPagePrivate(pages[i]);
 713         }
 714
 715         return 0;
 716 }
 717 EXPORT_SYMBOL(gnttab_alloc_pages);
 718
 719 /**
 720  * gnttab_free_pages - free pages allocated by gnttab_alloc_pages()
 721  * @nr_pages; number of pages to free
 722  * @pages: the pages
 723  */
 724 void gnttab_free_pages(int nr_pages, struct page **pages)
 725 {
 726         int i;
 727
 728         for (i = 0; i < nr_pages; i++) {
 729                 if (PagePrivate(pages[i])) {
 730 #if BITS_PER_LONG < 64
 731                         kfree((void *)page_private(pages[i]));
 732 #endif
 733                         ClearPagePrivate(pages[i]);
 734                 }
 735         }
 736         free_xenballooned_pages(nr_pages, pages);
 737 }
 738 EXPORT_SYMBOL(gnttab_free_pages);
 739
 740 /* Handling of paged out grant targets (GNTST_eagain) */
 741 #define MAX_DELAY 256
 742 static inline void
 743 gnttab_retry_eagain_gop(unsigned int cmd, void *gop, int16_t *status,
 744                                                 const char *func)
 745 {
 746         unsigned delay = 1;
 747
 748         do {
 749                 BUG_ON(HYPERVISOR_grant_table_op(cmd, gop, 1));
 750                 if (*status == GNTST_eagain)
 751                         msleep(delay++);
 752         } while ((*status == GNTST_eagain) && (delay < MAX_DELAY));
 753
 754         if (delay >= MAX_DELAY) {
 755                 pr_err("%s: %s eagain grant\n", func, current->comm);
 756                 *status = GNTST_bad_page;
 757         }
 758 }
 759
 760 void gnttab_batch_map(struct gnttab_map_grant_ref *batch, unsigned count)
 761 {
 762         struct gnttab_map_grant_ref *op;
 763
 764         if (HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref, batch, count))
 765                 BUG();
 766         for (op = batch; op < batch + count; op++)
 767                 if (op->status == GNTST_eagain)
 768                         gnttab_retry_eagain_gop(GNTTABOP_map_grant_ref, op,
 769                                                 &op->status, __func__);
 770 }
 771 EXPORT_SYMBOL_GPL(gnttab_batch_map);
 772
 773 void gnttab_batch_copy(struct gnttab_copy *batch, unsigned count)
 774 {
 775         struct gnttab_copy *op;
 776
 777         if (HYPERVISOR_grant_table_op(GNTTABOP_copy, batch, count))
 778                 BUG();
 779         for (op = batch; op < batch + count; op++)
 780                 if (op->status == GNTST_eagain)
 781                         gnttab_retry_eagain_gop(GNTTABOP_copy, op,
 782                                                 &op->status, __func__);
 783 }
 784 EXPORT_SYMBOL_GPL(gnttab_batch_copy);
 785
 786 void gnttab_foreach_grant_in_range(struct page *page,
 787                                    unsigned int offset,
 788                                    unsigned int len,
 789                                    xen_grant_fn_t fn,
 790                                    void *data)
 791 {
 792         unsigned int goffset;
 793         unsigned int glen;
 794         unsigned long xen_pfn;
 795
 796         len = min_t(unsigned int, PAGE_SIZE - offset, len);
 797         goffset = xen_offset_in_page(offset);
 798
 799         xen_pfn = page_to_xen_pfn(page) + XEN_PFN_DOWN(offset);
 800
 801         while (len) {
 802                 glen = min_t(unsigned int, XEN_PAGE_SIZE - goffset, len);
 803                 fn(pfn_to_gfn(xen_pfn), goffset, glen, data);
 804
 805                 goffset = 0;
 806                 xen_pfn++;
 807                 len -= glen;
 808         }
 809 }
 810 EXPORT_SYMBOL_GPL(gnttab_foreach_grant_in_range);
 811
 812 void gnttab_foreach_grant(struct page **pages,
 813                           unsigned int nr_grefs,
 814                           xen_grant_fn_t fn,
 815                           void *data)
 816 {
 817         unsigned int goffset = 0;
 818         unsigned long xen_pfn = 0;
 819         unsigned int i;
 820
 821         for (i = 0; i < nr_grefs; i++) {
 822                 if ((i % XEN_PFN_PER_PAGE) == 0) {
 823                         xen_pfn = page_to_xen_pfn(pages[i / XEN_PFN_PER_PAGE]);
 824                         goffset = 0;
 825                 }
 826
 827                 fn(pfn_to_gfn(xen_pfn), goffset, XEN_PAGE_SIZE, data);
 828
 829                 goffset += XEN_PAGE_SIZE;
 830                 xen_pfn++;
 831         }
 832 }
 833
 834 int gnttab_map_refs(struct gnttab_map_grant_ref *map_ops,
 835                     struct gnttab_map_grant_ref *kmap_ops,
 836                     struct page **pages, unsigned int count)
 837 {
 838         int i, ret;
 839
 840         ret = HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref, map_ops, count);
 841         if (ret)
 842                 return ret;
 843
 844         for (i = 0; i < count; i++) {
 845                 /* Retry eagain maps */
 846                 if (map_ops[i].status == GNTST_eagain)
 847                         gnttab_retry_eagain_gop(GNTTABOP_map_grant_ref, map_ops + i,
 848                                                 &map_ops[i].status, __func__);
 849
 850                 if (map_ops[i].status == GNTST_okay) {
 851                         struct xen_page_foreign *foreign;
 852
 853                         SetPageForeign(pages[i]);
 854                         foreign = xen_page_foreign(pages[i]);
 855                         foreign->domid = map_ops[i].dom;
 856                         foreign->gref = map_ops[i].ref;
 857                 }
 858         }
 859
 860         return set_foreign_p2m_mapping(map_ops, kmap_ops, pages, count);
 861 }
 862 EXPORT_SYMBOL_GPL(gnttab_map_refs);
 863
 864 int gnttab_unmap_refs(struct gnttab_unmap_grant_ref *unmap_ops,
 865                       struct gnttab_unmap_grant_ref *kunmap_ops,
 866                       struct page **pages, unsigned int count)
 867 {
 868         unsigned int i;
 869         int ret;
 870
 871         ret = HYPERVISOR_grant_table_op(GNTTABOP_unmap_grant_ref, unmap_ops, count);
 872         if (ret)
 873                 return ret;
 874
 875         for (i = 0; i < count; i++)
 876                 ClearPageForeign(pages[i]);
 877
 878         return clear_foreign_p2m_mapping(unmap_ops, kunmap_ops, pages, count);
 879 }
 880 EXPORT_SYMBOL_GPL(gnttab_unmap_refs);
 881
 882 #define GNTTAB_UNMAP_REFS_DELAY 5
 883
 884 static void __gnttab_unmap_refs_async(struct gntab_unmap_queue_data* item);
 885
 886 static void gnttab_unmap_work(struct work_struct *work)
 887 {
 888         struct gntab_unmap_queue_data
 889                 *unmap_data = container_of(work,
 890                                            struct gntab_unmap_queue_data,
 891                                            gnttab_work.work);
 892         if (unmap_data->age != UINT_MAX)
 893                 unmap_data->age++;
 894         __gnttab_unmap_refs_async(unmap_data);
 895 }
 896
 897 static void __gnttab_unmap_refs_async(struct gntab_unmap_queue_data* item)
 898 {
 899         int ret;
 900         int pc;
 901
 902         for (pc = 0; pc < item->count; pc++) {
 903                 if (page_count(item->pages[pc]) > 1) {
 904                         unsigned long delay = GNTTAB_UNMAP_REFS_DELAY * (item->age + 1);
 905                         schedule_delayed_work(&item->gnttab_work,
 906                                               msecs_to_jiffies(delay));
 907                         return;
 908                 }
 909         }
 910
 911         ret = gnttab_unmap_refs(item->unmap_ops, item->kunmap_ops,
 912                                 item->pages, item->count);
 913         item->done(ret, item);
 914 }
 915
 916 void gnttab_unmap_refs_async(struct gntab_unmap_queue_data* item)
 917 {
 918         INIT_DELAYED_WORK(&item->gnttab_work, gnttab_unmap_work);
 919         item->age = 0;
 920
 921         __gnttab_unmap_refs_async(item);
 922 }
 923 EXPORT_SYMBOL_GPL(gnttab_unmap_refs_async);
 924
 925 static void unmap_refs_callback(int result,
 926                 struct gntab_unmap_queue_data *data)
 927 {
 928         struct unmap_refs_callback_data *d = data->data;
 929
 930         d->result = result;
 931         complete(&d->completion);
 932 }
 933
 934 int gnttab_unmap_refs_sync(struct gntab_unmap_queue_data *item)
 935 {
 936         struct unmap_refs_callback_data data;
 937
 938         init_completion(&data.completion);
 939         item->data = &data;
 940         item->done = &unmap_refs_callback;
 941         gnttab_unmap_refs_async(item);
 942         wait_for_completion(&data.completion);
 943
 944         return data.result;
 945 }
 946 EXPORT_SYMBOL_GPL(gnttab_unmap_refs_sync);
 947
 948 static int gnttab_map_frames_v1(xen_pfn_t *frames, unsigned int nr_gframes)
 949 {
 950         int rc;
 951
 952         rc = arch_gnttab_map_shared(frames, nr_gframes,
 953                                     gnttab_max_grant_frames(),
 954                                     &gnttab_shared.addr);
 955         BUG_ON(rc);
 956
 957         return 0;
 958 }
 959
 960 static void gnttab_unmap_frames_v1(void)
 961 {
 962         arch_gnttab_unmap(gnttab_shared.addr, nr_grant_frames);
 963 }
 964
 965 static int gnttab_map(unsigned int start_idx, unsigned int end_idx)
 966 {
 967         struct gnttab_setup_table setup;
 968         xen_pfn_t *frames;
 969         unsigned int nr_gframes = end_idx + 1;
 970         int rc;
 971
 972         if (xen_feature(XENFEAT_auto_translated_physmap)) {
 973                 struct xen_add_to_physmap xatp;
 974                 unsigned int i = end_idx;
 975                 rc = 0;
 976                 BUG_ON(xen_auto_xlat_grant_frames.count < nr_gframes);
 977                 /*
 978                  * Loop backwards, so that the first hypercall has the largest
 979                  * index, ensuring that the table will grow only once.
 980                  */
 981                 do {
 982                         xatp.domid = DOMID_SELF;
 983                         xatp.idx = i;
 984                         xatp.space = XENMAPSPACE_grant_table;
 985                         xatp.gpfn = xen_auto_xlat_grant_frames.pfn[i];
 986                         rc = HYPERVISOR_memory_op(XENMEM_add_to_physmap, &xatp);
 987                         if (rc != 0) {
 988                                 pr_warn("grant table add_to_physmap failed, err=%d\n",
 989                                         rc);
 990                                 break;
 991                         }
 992                 } while (i-- > start_idx);
 993
 994                 return rc;
 995         }
 996
 997         /* No need for kzalloc as it is initialized in following hypercall
 998          * GNTTABOP_setup_table.
 999          */
1000         frames = kmalloc(nr_gframes * sizeof(unsigned long), GFP_ATOMIC);
1001         if (!frames)
1002                 return -ENOMEM;
1003
1004         setup.dom        = DOMID_SELF;
1005         setup.nr_frames  = nr_gframes;
1006         set_xen_guest_handle(setup.frame_list, frames);
1007
1008         rc = HYPERVISOR_grant_table_op(GNTTABOP_setup_table, &setup, 1);
1009         if (rc == -ENOSYS) {
1010                 kfree(frames);
1011                 return -ENOSYS;
1012         }
1013
1014         BUG_ON(rc || setup.status);
1015
1016         rc = gnttab_interface->map_frames(frames, nr_gframes);
1017
1018         kfree(frames);
1019
1020         return rc;
1021 }
1022
1023 static const struct gnttab_ops gnttab_v1_ops = {
1024         .map_frames                     = gnttab_map_frames_v1,
1025         .unmap_frames                   = gnttab_unmap_frames_v1,
1026         .update_entry                   = gnttab_update_entry_v1,
1027         .end_foreign_access_ref         = gnttab_end_foreign_access_ref_v1,
1028         .end_foreign_transfer_ref       = gnttab_end_foreign_transfer_ref_v1,
1029         .read_frame                     = gnttab_read_frame_v1,
1030 };
1031
1032 static void gnttab_request_version(void)
1033 {
1034         /* Only version 1 is used, which will always be available. */
1035         grant_table_version = 1;
1036         grefs_per_grant_frame = XEN_PAGE_SIZE / sizeof(struct grant_entry_v1);
1037         gnttab_interface = &gnttab_v1_ops;
1038
1039         pr_info("Grant tables using version %d layout\n", grant_table_version);
1040 }
1041
1042 static int gnttab_setup(void)
1043 {
1044         unsigned int max_nr_gframes;
1045
1046         max_nr_gframes = gnttab_max_grant_frames();
1047         if (max_nr_gframes < nr_grant_frames)
1048                 return -ENOSYS;
1049
1050         if (xen_feature(XENFEAT_auto_translated_physmap) && gnttab_shared.addr == NULL) {
1051                 gnttab_shared.addr = xen_auto_xlat_grant_frames.vaddr;
1052                 if (gnttab_shared.addr == NULL) {
1053                         pr_warn("gnttab share frames (addr=0x%08lx) is not mapped!\n",
1054                                 (unsigned long)xen_auto_xlat_grant_frames.vaddr);
1055                         return -ENOMEM;
1056                 }
1057         }
1058         return gnttab_map(0, nr_grant_frames - 1);
1059 }
1060
1061 int gnttab_resume(void)
1062 {
1063         gnttab_request_version();
1064         return gnttab_setup();
1065 }
1066
1067 int gnttab_suspend(void)
1068 {
1069         if (!xen_feature(XENFEAT_auto_translated_physmap))
1070                 gnttab_interface->unmap_frames();
1071         return 0;
1072 }
1073
1074 static int gnttab_expand(unsigned int req_entries)
1075 {
1076         int rc;
1077         unsigned int cur, extra;
1078
1079         BUG_ON(grefs_per_grant_frame == 0);
1080         cur = nr_grant_frames;
1081         extra = ((req_entries + (grefs_per_grant_frame-1)) /
1082                  grefs_per_grant_frame);
1083         if (cur + extra > gnttab_max_grant_frames()) {
1084                 pr_warn_ratelimited("xen/grant-table: max_grant_frames reached"
1085                                     " cur=%u extra=%u limit=%u"
1086                                     " gnttab_free_count=%u req_entries=%u\n",
1087                                     cur, extra, gnttab_max_grant_frames(),
1088                                     gnttab_free_count, req_entries);
1089                 return -ENOSPC;
1090         }
1091
1092         rc = gnttab_map(cur, cur + extra - 1);
1093         if (rc == 0)
1094                 rc = grow_gnttab_list(extra);
1095
1096         return rc;
1097 }
1098
1099 int gnttab_init(void)
1100 {
1101         int i;
1102         unsigned long max_nr_grant_frames;
1103         unsigned int max_nr_glist_frames, nr_glist_frames;
1104         unsigned int nr_init_grefs;
1105         int ret;
1106
1107         gnttab_request_version();
1108         max_nr_grant_frames = gnttab_max_grant_frames();
1109         nr_grant_frames = 1;
1110
1111         /* Determine the maximum number of frames required for the
1112          * grant reference free list on the current hypervisor.
1113          */
1114         BUG_ON(grefs_per_grant_frame == 0);
1115         max_nr_glist_frames = (max_nr_grant_frames *
1116                                grefs_per_grant_frame / RPP);
1117
1118         gnttab_list = kmalloc(max_nr_glist_frames * sizeof(grant_ref_t *),
1119                               GFP_KERNEL);
1120         if (gnttab_list == NULL)
1121                 return -ENOMEM;
1122
1123         nr_glist_frames = (nr_grant_frames * grefs_per_grant_frame + RPP - 1) / RPP;
1124         for (i = 0; i < nr_glist_frames; i++) {
1125                 gnttab_list[i] = (grant_ref_t *)__get_free_page(GFP_KERNEL);
1126                 if (gnttab_list[i] == NULL) {
1127                         ret = -ENOMEM;
1128                         goto ini_nomem;
1129                 }
1130         }
1131
1132         ret = arch_gnttab_init(max_nr_grant_frames);
1133         if (ret < 0)
1134                 goto ini_nomem;
1135
1136         if (gnttab_setup() < 0) {
1137                 ret = -ENODEV;
1138                 goto ini_nomem;
1139         }
1140
1141         nr_init_grefs = nr_grant_frames * grefs_per_grant_frame;
1142
1143         for (i = NR_RESERVED_ENTRIES; i < nr_init_grefs - 1; i++)
1144                 gnttab_entry(i) = i + 1;
1145
1146         gnttab_entry(nr_init_grefs - 1) = GNTTAB_LIST_END;
1147         gnttab_free_count = nr_init_grefs - NR_RESERVED_ENTRIES;
1148         gnttab_free_head  = NR_RESERVED_ENTRIES;
1149
1150         printk("Grant table initialized\n");
1151         return 0;
1152
1153  ini_nomem:
1154         for (i--; i >= 0; i--)
1155                 free_page((unsigned long)gnttab_list[i]);
1156         kfree(gnttab_list);
1157         return ret;
1158 }
1159 EXPORT_SYMBOL_GPL(gnttab_init);
1160
1161 static int __gnttab_init(void)
1162 {
1163         if (!xen_domain())
1164                 return -ENODEV;
1165
1166         /* Delay grant-table initialization in the PV on HVM case */
1167         if (xen_hvm_domain() && !xen_pvh_domain())
1168                 return 0;
1169
1170         return gnttab_init();
1171 }
1172 /* Starts after core_initcall so that xen_pvh_gnttab_setup can be called
1173  * beforehand to initialize xen_auto_xlat_grant_frames. */
1174 core_initcall_sync(__gnttab_init);