drivers/xen/grant-table.c

   1 /******************************************************************************
   2  * grant_table.c
   3  *
   4  * Granting foreign access to our memory reservation.
   5  *
   6  * Copyright (c) 2005-2006, Christopher Clark
   7  * Copyright (c) 2004-2005, K A Fraser
   8  *
   9  * This program is free software; you can redistribute it and/or
  10  * modify it under the terms of the GNU General Public License version 2
  11  * as published by the Free Software Foundation; or, when distributed
  12  * separately from the Linux kernel or incorporated into other
  13  * software packages, subject to the following license:
  14  *
  15  * Permission is hereby granted, free of charge, to any person obtaining a copy
  16  * of this source file (the "Software"), to deal in the Software without
  17  * restriction, including without limitation the rights to use, copy, modify,
  18  * merge, publish, distribute, sublicense, and/or sell copies of the Software,
  19  * and to permit persons to whom the Software is furnished to do so, subject to
  20  * the following conditions:
  21  *
  22  * The above copyright notice and this permission notice shall be included in
  23  * all copies or substantial portions of the Software.
  24  *
  25  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  26  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  27  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  28  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  29  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  30  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
  31  * IN THE SOFTWARE.
  32  */
  33
  34 #define pr_fmt(fmt) "xen:" KBUILD_MODNAME ": " fmt
  35
  36 #include <linux/module.h>
  37 #include <linux/sched.h>
  38 #include <linux/mm.h>
  39 #include <linux/slab.h>
  40 #include <linux/vmalloc.h>
  41 #include <linux/uaccess.h>
  42 #include <linux/io.h>
  43 #include <linux/delay.h>
  44 #include <linux/hardirq.h>
  45
  46 #include <xen/xen.h>
  47 #include <xen/interface/xen.h>
  48 #include <xen/page.h>
  49 #include <xen/grant_table.h>
  50 #include <xen/interface/memory.h>
  51 #include <xen/hvc-console.h>
  52 #include <xen/swiotlb-xen.h>
  53 #include <xen/balloon.h>
  54 #include <asm/xen/hypercall.h>
  55 #include <asm/xen/interface.h>
  56
  57 #include <asm/pgtable.h>
  58 #include <asm/sync_bitops.h>
  59
  60 /* External tools reserve first few grant table entries. */
  61 #define NR_RESERVED_ENTRIES 8
  62 #define GNTTAB_LIST_END 0xffffffff
  63
  64 static grant_ref_t **gnttab_list;
  65 static unsigned int nr_grant_frames;
  66 static int gnttab_free_count;
  67 static grant_ref_t gnttab_free_head;
  68 static DEFINE_SPINLOCK(gnttab_list_lock);
  69 struct grant_frames xen_auto_xlat_grant_frames;
  70
  71 static union {
  72         struct grant_entry_v1 *v1;
  73         void *addr;
  74 } gnttab_shared;
  75
  76 /*This is a structure of function pointers for grant table*/
  77 struct gnttab_ops {
  78         /*
  79          * Mapping a list of frames for storing grant entries. Frames parameter
  80          * is used to store grant table address when grant table being setup,
  81          * nr_gframes is the number of frames to map grant table. Returning
  82          * GNTST_okay means success and negative value means failure.
  83          */
  84         int (*map_frames)(xen_pfn_t *frames, unsigned int nr_gframes);
  85         /*
  86          * Release a list of frames which are mapped in map_frames for grant
  87          * entry status.
  88          */
  89         void (*unmap_frames)(void);
  90         /*
  91          * Introducing a valid entry into the grant table, granting the frame of
  92          * this grant entry to domain for accessing or transfering. Ref
  93          * parameter is reference of this introduced grant entry, domid is id of
  94          * granted domain, frame is the page frame to be granted, and flags is
  95          * status of the grant entry to be updated.
  96          */
  97         void (*update_entry)(grant_ref_t ref, domid_t domid,
  98                              unsigned long frame, unsigned flags);
  99         /*
 100          * Stop granting a grant entry to domain for accessing. Ref parameter is
 101          * reference of a grant entry whose grant access will be stopped,
 102          * readonly is not in use in this function. If the grant entry is
 103          * currently mapped for reading or writing, just return failure(==0)
 104          * directly and don't tear down the grant access. Otherwise, stop grant
 105          * access for this entry and return success(==1).
 106          */
 107         int (*end_foreign_access_ref)(grant_ref_t ref, int readonly);
 108         /*
 109          * Stop granting a grant entry to domain for transfer. Ref parameter is
 110          * reference of a grant entry whose grant transfer will be stopped. If
 111          * tranfer has not started, just reclaim the grant entry and return
 112          * failure(==0). Otherwise, wait for the transfer to complete and then
 113          * return the frame.
 114          */
 115         unsigned long (*end_foreign_transfer_ref)(grant_ref_t ref);
 116         /*
 117          * Query the status of a grant entry. Ref parameter is reference of
 118          * queried grant entry, return value is the status of queried entry.
 119          * Detailed status(writing/reading) can be gotten from the return value
 120          * by bit operations.
 121          */
 122         int (*query_foreign_access)(grant_ref_t ref);
 123 };
 124
 125 static struct gnttab_ops *gnttab_interface;
 126
 127 static int grant_table_version;
 128 static int grefs_per_grant_frame;
 129
 130 static struct gnttab_free_callback *gnttab_free_callback_list;
 131
 132 static int gnttab_expand(unsigned int req_entries);
 133
 134 #define RPP (PAGE_SIZE / sizeof(grant_ref_t))
 135 #define SPP (PAGE_SIZE / sizeof(grant_status_t))
 136
 137 static inline grant_ref_t *__gnttab_entry(grant_ref_t entry)
 138 {
 139         return &gnttab_list[(entry) / RPP][(entry) % RPP];
 140 }
 141 /* This can be used as an l-value */
 142 #define gnttab_entry(entry) (*__gnttab_entry(entry))
 143
 144 static int get_free_entries(unsigned count)
 145 {
 146         unsigned long flags;
 147         int ref, rc = 0;
 148         grant_ref_t head;
 149
 150         spin_lock_irqsave(&gnttab_list_lock, flags);
 151
 152         if ((gnttab_free_count < count) &&
 153             ((rc = gnttab_expand(count - gnttab_free_count)) < 0)) {
 154                 spin_unlock_irqrestore(&gnttab_list_lock, flags);
 155                 return rc;
 156         }
 157
 158         ref = head = gnttab_free_head;
 159         gnttab_free_count -= count;
 160         while (count-- > 1)
 161                 head = gnttab_entry(head);
 162         gnttab_free_head = gnttab_entry(head);
 163         gnttab_entry(head) = GNTTAB_LIST_END;
 164
 165         spin_unlock_irqrestore(&gnttab_list_lock, flags);
 166
 167         return ref;
 168 }
 169
 170 static void do_free_callbacks(void)
 171 {
 172         struct gnttab_free_callback *callback, *next;
 173
 174         callback = gnttab_free_callback_list;
 175         gnttab_free_callback_list = NULL;
 176
 177         while (callback != NULL) {
 178                 next = callback->next;
 179                 if (gnttab_free_count >= callback->count) {
 180                         callback->next = NULL;
 181                         callback->fn(callback->arg);
 182                 } else {
 183                         callback->next = gnttab_free_callback_list;
 184                         gnttab_free_callback_list = callback;
 185                 }
 186                 callback = next;
 187         }
 188 }
 189
 190 static inline void check_free_callbacks(void)
 191 {
 192         if (unlikely(gnttab_free_callback_list))
 193                 do_free_callbacks();
 194 }
 195
 196 static void put_free_entry(grant_ref_t ref)
 197 {
 198         unsigned long flags;
 199         spin_lock_irqsave(&gnttab_list_lock, flags);
 200         gnttab_entry(ref) = gnttab_free_head;
 201         gnttab_free_head = ref;
 202         gnttab_free_count++;
 203         check_free_callbacks();
 204         spin_unlock_irqrestore(&gnttab_list_lock, flags);
 205 }
 206
 207 /*
 208  * Following applies to gnttab_update_entry_v1.
 209  * Introducing a valid entry into the grant table:
 210  *  1. Write ent->domid.
 211  *  2. Write ent->frame:
 212  *      GTF_permit_access:   Frame to which access is permitted.
 213  *      GTF_accept_transfer: Pseudo-phys frame slot being filled by new
 214  *                           frame, or zero if none.
 215  *  3. Write memory barrier (WMB).
 216  *  4. Write ent->flags, inc. valid type.
 217  */
 218 static void gnttab_update_entry_v1(grant_ref_t ref, domid_t domid,
 219                                    unsigned long frame, unsigned flags)
 220 {
 221         gnttab_shared.v1[ref].domid = domid;
 222         gnttab_shared.v1[ref].frame = frame;
 223         wmb();
 224         gnttab_shared.v1[ref].flags = flags;
 225 }
 226
 227 /*
 228  * Public grant-issuing interface functions
 229  */
 230 void gnttab_grant_foreign_access_ref(grant_ref_t ref, domid_t domid,
 231                                      unsigned long frame, int readonly)
 232 {
 233         gnttab_interface->update_entry(ref, domid, frame,
 234                            GTF_permit_access | (readonly ? GTF_readonly : 0));
 235 }
 236 EXPORT_SYMBOL_GPL(gnttab_grant_foreign_access_ref);
 237
 238 int gnttab_grant_foreign_access(domid_t domid, unsigned long frame,
 239                                 int readonly)
 240 {
 241         int ref;
 242
 243         ref = get_free_entries(1);
 244         if (unlikely(ref < 0))
 245                 return -ENOSPC;
 246
 247         gnttab_grant_foreign_access_ref(ref, domid, frame, readonly);
 248
 249         return ref;
 250 }
 251 EXPORT_SYMBOL_GPL(gnttab_grant_foreign_access);
 252
 253 static int gnttab_query_foreign_access_v1(grant_ref_t ref)
 254 {
 255         return gnttab_shared.v1[ref].flags & (GTF_reading|GTF_writing);
 256 }
 257
 258 int gnttab_query_foreign_access(grant_ref_t ref)
 259 {
 260         return gnttab_interface->query_foreign_access(ref);
 261 }
 262 EXPORT_SYMBOL_GPL(gnttab_query_foreign_access);
 263
 264 static int gnttab_end_foreign_access_ref_v1(grant_ref_t ref, int readonly)
 265 {
 266         u16 flags, nflags;
 267         u16 *pflags;
 268
 269         pflags = &gnttab_shared.v1[ref].flags;
 270         nflags = *pflags;
 271         do {
 272                 flags = nflags;
 273                 if (flags & (GTF_reading|GTF_writing))
 274                         return 0;
 275         } while ((nflags = sync_cmpxchg(pflags, flags, 0)) != flags);
 276
 277         return 1;
 278 }
 279
 280 static inline int _gnttab_end_foreign_access_ref(grant_ref_t ref, int readonly)
 281 {
 282         return gnttab_interface->end_foreign_access_ref(ref, readonly);
 283 }
 284
 285 int gnttab_end_foreign_access_ref(grant_ref_t ref, int readonly)
 286 {
 287         if (_gnttab_end_foreign_access_ref(ref, readonly))
 288                 return 1;
 289         pr_warn("WARNING: g.e. %#x still in use!\n", ref);
 290         return 0;
 291 }
 292 EXPORT_SYMBOL_GPL(gnttab_end_foreign_access_ref);
 293
 294 struct deferred_entry {
 295         struct list_head list;
 296         grant_ref_t ref;
 297         bool ro;
 298         uint16_t warn_delay;
 299         struct page *page;
 300 };
 301 static LIST_HEAD(deferred_list);
 302 static void gnttab_handle_deferred(unsigned long);
 303 static DEFINE_TIMER(deferred_timer, gnttab_handle_deferred, 0, 0);
 304
 305 static void gnttab_handle_deferred(unsigned long unused)
 306 {
 307         unsigned int nr = 10;
 308         struct deferred_entry *first = NULL;
 309         unsigned long flags;
 310
 311         spin_lock_irqsave(&gnttab_list_lock, flags);
 312         while (nr--) {
 313                 struct deferred_entry *entry
 314                         = list_first_entry(&deferred_list,
 315                                            struct deferred_entry, list);
 316
 317                 if (entry == first)
 318                         break;
 319                 list_del(&entry->list);
 320                 spin_unlock_irqrestore(&gnttab_list_lock, flags);
 321                 if (_gnttab_end_foreign_access_ref(entry->ref, entry->ro)) {
 322                         put_free_entry(entry->ref);
 323                         if (entry->page) {
 324                                 pr_debug("freeing g.e. %#x (pfn %#lx)\n",
 325                                          entry->ref, page_to_pfn(entry->page));
 326                                 __free_page(entry->page);
 327                         } else
 328                                 pr_info("freeing g.e. %#x\n", entry->ref);
 329                         kfree(entry);
 330                         entry = NULL;
 331                 } else {
 332                         if (!--entry->warn_delay)
 333                                 pr_info("g.e. %#x still pending\n", entry->ref);
 334                         if (!first)
 335                                 first = entry;
 336                 }
 337                 spin_lock_irqsave(&gnttab_list_lock, flags);
 338                 if (entry)
 339                         list_add_tail(&entry->list, &deferred_list);
 340                 else if (list_empty(&deferred_list))
 341                         break;
 342         }
 343         if (!list_empty(&deferred_list) && !timer_pending(&deferred_timer)) {
 344                 deferred_timer.expires = jiffies + HZ;
 345                 add_timer(&deferred_timer);
 346         }
 347         spin_unlock_irqrestore(&gnttab_list_lock, flags);
 348 }
 349
 350 static void gnttab_add_deferred(grant_ref_t ref, bool readonly,
 351                                 struct page *page)
 352 {
 353         struct deferred_entry *entry = kmalloc(sizeof(*entry), GFP_ATOMIC);
 354         const char *what = KERN_WARNING "leaking";
 355
 356         if (entry) {
 357                 unsigned long flags;
 358
 359                 entry->ref = ref;
 360                 entry->ro = readonly;
 361                 entry->page = page;
 362                 entry->warn_delay = 60;
 363                 spin_lock_irqsave(&gnttab_list_lock, flags);
 364                 list_add_tail(&entry->list, &deferred_list);
 365                 if (!timer_pending(&deferred_timer)) {
 366                         deferred_timer.expires = jiffies + HZ;
 367                         add_timer(&deferred_timer);
 368                 }
 369                 spin_unlock_irqrestore(&gnttab_list_lock, flags);
 370                 what = KERN_DEBUG "deferring";
 371         }
 372         printk("%s g.e. %#x (pfn %#lx)\n",
 373                what, ref, page ? page_to_pfn(page) : -1);
 374 }
 375
 376 void gnttab_end_foreign_access(grant_ref_t ref, int readonly,
 377                                unsigned long page)
 378 {
 379         if (gnttab_end_foreign_access_ref(ref, readonly)) {
 380                 put_free_entry(ref);
 381                 if (page != 0)
 382                         free_page(page);
 383         } else
 384                 gnttab_add_deferred(ref, readonly,
 385                                     page ? virt_to_page(page) : NULL);
 386 }
 387 EXPORT_SYMBOL_GPL(gnttab_end_foreign_access);
 388
 389 int gnttab_grant_foreign_transfer(domid_t domid, unsigned long pfn)
 390 {
 391         int ref;
 392
 393         ref = get_free_entries(1);
 394         if (unlikely(ref < 0))
 395                 return -ENOSPC;
 396         gnttab_grant_foreign_transfer_ref(ref, domid, pfn);
 397
 398         return ref;
 399 }
 400 EXPORT_SYMBOL_GPL(gnttab_grant_foreign_transfer);
 401
 402 void gnttab_grant_foreign_transfer_ref(grant_ref_t ref, domid_t domid,
 403                                        unsigned long pfn)
 404 {
 405         gnttab_interface->update_entry(ref, domid, pfn, GTF_accept_transfer);
 406 }
 407 EXPORT_SYMBOL_GPL(gnttab_grant_foreign_transfer_ref);
 408
 409 static unsigned long gnttab_end_foreign_transfer_ref_v1(grant_ref_t ref)
 410 {
 411         unsigned long frame;
 412         u16           flags;
 413         u16          *pflags;
 414
 415         pflags = &gnttab_shared.v1[ref].flags;
 416
 417         /*
 418          * If a transfer is not even yet started, try to reclaim the grant
 419          * reference and return failure (== 0).
 420          */
 421         while (!((flags = *pflags) & GTF_transfer_committed)) {
 422                 if (sync_cmpxchg(pflags, flags, 0) == flags)
 423                         return 0;
 424                 cpu_relax();
 425         }
 426
 427         /* If a transfer is in progress then wait until it is completed. */
 428         while (!(flags & GTF_transfer_completed)) {
 429                 flags = *pflags;
 430                 cpu_relax();
 431         }
 432
 433         rmb();  /* Read the frame number /after/ reading completion status. */
 434         frame = gnttab_shared.v1[ref].frame;
 435         BUG_ON(frame == 0);
 436
 437         return frame;
 438 }
 439
 440 unsigned long gnttab_end_foreign_transfer_ref(grant_ref_t ref)
 441 {
 442         return gnttab_interface->end_foreign_transfer_ref(ref);
 443 }
 444 EXPORT_SYMBOL_GPL(gnttab_end_foreign_transfer_ref);
 445
 446 unsigned long gnttab_end_foreign_transfer(grant_ref_t ref)
 447 {
 448         unsigned long frame = gnttab_end_foreign_transfer_ref(ref);
 449         put_free_entry(ref);
 450         return frame;
 451 }
 452 EXPORT_SYMBOL_GPL(gnttab_end_foreign_transfer);
 453
 454 void gnttab_free_grant_reference(grant_ref_t ref)
 455 {
 456         put_free_entry(ref);
 457 }
 458 EXPORT_SYMBOL_GPL(gnttab_free_grant_reference);
 459
 460 void gnttab_free_grant_references(grant_ref_t head)
 461 {
 462         grant_ref_t ref;
 463         unsigned long flags;
 464         int count = 1;
 465         if (head == GNTTAB_LIST_END)
 466                 return;
 467         spin_lock_irqsave(&gnttab_list_lock, flags);
 468         ref = head;
 469         while (gnttab_entry(ref) != GNTTAB_LIST_END) {
 470                 ref = gnttab_entry(ref);
 471                 count++;
 472         }
 473         gnttab_entry(ref) = gnttab_free_head;
 474         gnttab_free_head = head;
 475         gnttab_free_count += count;
 476         check_free_callbacks();
 477         spin_unlock_irqrestore(&gnttab_list_lock, flags);
 478 }
 479 EXPORT_SYMBOL_GPL(gnttab_free_grant_references);
 480
 481 int gnttab_alloc_grant_references(u16 count, grant_ref_t *head)
 482 {
 483         int h = get_free_entries(count);
 484
 485         if (h < 0)
 486                 return -ENOSPC;
 487
 488         *head = h;
 489
 490         return 0;
 491 }
 492 EXPORT_SYMBOL_GPL(gnttab_alloc_grant_references);
 493
 494 int gnttab_empty_grant_references(const grant_ref_t *private_head)
 495 {
 496         return (*private_head == GNTTAB_LIST_END);
 497 }
 498 EXPORT_SYMBOL_GPL(gnttab_empty_grant_references);
 499
 500 int gnttab_claim_grant_reference(grant_ref_t *private_head)
 501 {
 502         grant_ref_t g = *private_head;
 503         if (unlikely(g == GNTTAB_LIST_END))
 504                 return -ENOSPC;
 505         *private_head = gnttab_entry(g);
 506         return g;
 507 }
 508 EXPORT_SYMBOL_GPL(gnttab_claim_grant_reference);
 509
 510 void gnttab_release_grant_reference(grant_ref_t *private_head,
 511                                     grant_ref_t release)
 512 {
 513         gnttab_entry(release) = *private_head;
 514         *private_head = release;
 515 }
 516 EXPORT_SYMBOL_GPL(gnttab_release_grant_reference);
 517
 518 void gnttab_request_free_callback(struct gnttab_free_callback *callback,
 519                                   void (*fn)(void *), void *arg, u16 count)
 520 {
 521         unsigned long flags;
 522         struct gnttab_free_callback *cb;
 523
 524         spin_lock_irqsave(&gnttab_list_lock, flags);
 525
 526         /* Check if the callback is already on the list */
 527         cb = gnttab_free_callback_list;
 528         while (cb) {
 529                 if (cb == callback)
 530                         goto out;
 531                 cb = cb->next;
 532         }
 533
 534         callback->fn = fn;
 535         callback->arg = arg;
 536         callback->count = count;
 537         callback->next = gnttab_free_callback_list;
 538         gnttab_free_callback_list = callback;
 539         check_free_callbacks();
 540 out:
 541         spin_unlock_irqrestore(&gnttab_list_lock, flags);
 542 }
 543 EXPORT_SYMBOL_GPL(gnttab_request_free_callback);
 544
 545 void gnttab_cancel_free_callback(struct gnttab_free_callback *callback)
 546 {
 547         struct gnttab_free_callback **pcb;
 548         unsigned long flags;
 549
 550         spin_lock_irqsave(&gnttab_list_lock, flags);
 551         for (pcb = &gnttab_free_callback_list; *pcb; pcb = &(*pcb)->next) {
 552                 if (*pcb == callback) {
 553                         *pcb = callback->next;
 554                         break;
 555                 }
 556         }
 557         spin_unlock_irqrestore(&gnttab_list_lock, flags);
 558 }
 559 EXPORT_SYMBOL_GPL(gnttab_cancel_free_callback);
 560
 561 static int grow_gnttab_list(unsigned int more_frames)
 562 {
 563         unsigned int new_nr_grant_frames, extra_entries, i;
 564         unsigned int nr_glist_frames, new_nr_glist_frames;
 565
 566         BUG_ON(grefs_per_grant_frame == 0);
 567
 568         new_nr_grant_frames = nr_grant_frames + more_frames;
 569         extra_entries       = more_frames * grefs_per_grant_frame;
 570
 571         nr_glist_frames = (nr_grant_frames * grefs_per_grant_frame + RPP - 1) / RPP;
 572         new_nr_glist_frames =
 573                 (new_nr_grant_frames * grefs_per_grant_frame + RPP - 1) / RPP;
 574         for (i = nr_glist_frames; i < new_nr_glist_frames; i++) {
 575                 gnttab_list[i] = (grant_ref_t *)__get_free_page(GFP_ATOMIC);
 576                 if (!gnttab_list[i])
 577                         goto grow_nomem;
 578         }
 579
 580
 581         for (i = grefs_per_grant_frame * nr_grant_frames;
 582              i < grefs_per_grant_frame * new_nr_grant_frames - 1; i++)
 583                 gnttab_entry(i) = i + 1;
 584
 585         gnttab_entry(i) = gnttab_free_head;
 586         gnttab_free_head = grefs_per_grant_frame * nr_grant_frames;
 587         gnttab_free_count += extra_entries;
 588
 589         nr_grant_frames = new_nr_grant_frames;
 590
 591         check_free_callbacks();
 592
 593         return 0;
 594
 595 grow_nomem:
 596         while (i-- > nr_glist_frames)
 597                 free_page((unsigned long) gnttab_list[i]);
 598         return -ENOMEM;
 599 }
 600
 601 static unsigned int __max_nr_grant_frames(void)
 602 {
 603         struct gnttab_query_size query;
 604         int rc;
 605
 606         query.dom = DOMID_SELF;
 607
 608         rc = HYPERVISOR_grant_table_op(GNTTABOP_query_size, &query, 1);
 609         if ((rc < 0) || (query.status != GNTST_okay))
 610                 return 4; /* Legacy max supported number of frames */
 611
 612         return query.max_nr_frames;
 613 }
 614
 615 unsigned int gnttab_max_grant_frames(void)
 616 {
 617         unsigned int xen_max = __max_nr_grant_frames();
 618         static unsigned int boot_max_nr_grant_frames;
 619
 620         /* First time, initialize it properly. */
 621         if (!boot_max_nr_grant_frames)
 622                 boot_max_nr_grant_frames = __max_nr_grant_frames();
 623
 624         if (xen_max > boot_max_nr_grant_frames)
 625                 return boot_max_nr_grant_frames;
 626         return xen_max;
 627 }
 628 EXPORT_SYMBOL_GPL(gnttab_max_grant_frames);
 629
 630 int gnttab_setup_auto_xlat_frames(phys_addr_t addr)
 631 {
 632         xen_pfn_t *pfn;
 633         unsigned int max_nr_gframes = __max_nr_grant_frames();
 634         unsigned int i;
 635         void *vaddr;
 636
 637         if (xen_auto_xlat_grant_frames.count)
 638                 return -EINVAL;
 639
 640         vaddr = xen_remap(addr, PAGE_SIZE * max_nr_gframes);
 641         if (vaddr == NULL) {
 642                 pr_warn("Failed to ioremap gnttab share frames (addr=%pa)!\n",
 643                         &addr);
 644                 return -ENOMEM;
 645         }
 646         pfn = kcalloc(max_nr_gframes, sizeof(pfn[0]), GFP_KERNEL);
 647         if (!pfn) {
 648                 xen_unmap(vaddr);
 649                 return -ENOMEM;
 650         }
 651         for (i = 0; i < max_nr_gframes; i++)
 652                 pfn[i] = PFN_DOWN(addr) + i;
 653
 654         xen_auto_xlat_grant_frames.vaddr = vaddr;
 655         xen_auto_xlat_grant_frames.pfn = pfn;
 656         xen_auto_xlat_grant_frames.count = max_nr_gframes;
 657
 658         return 0;
 659 }
 660 EXPORT_SYMBOL_GPL(gnttab_setup_auto_xlat_frames);
 661
 662 void gnttab_free_auto_xlat_frames(void)
 663 {
 664         if (!xen_auto_xlat_grant_frames.count)
 665                 return;
 666         kfree(xen_auto_xlat_grant_frames.pfn);
 667         xen_unmap(xen_auto_xlat_grant_frames.vaddr);
 668
 669         xen_auto_xlat_grant_frames.pfn = NULL;
 670         xen_auto_xlat_grant_frames.count = 0;
 671         xen_auto_xlat_grant_frames.vaddr = NULL;
 672 }
 673 EXPORT_SYMBOL_GPL(gnttab_free_auto_xlat_frames);
 674
 675 /**
 676  * gnttab_alloc_pages - alloc pages suitable for grant mapping into
 677  * @nr_pages: number of pages to alloc
 678  * @pages: returns the pages
 679  */
 680 int gnttab_alloc_pages(int nr_pages, struct page **pages)
 681 {
 682         int ret;
 683
 684         ret = alloc_xenballooned_pages(nr_pages, pages, false);
 685         if (ret < 0)
 686                 return ret;
 687
 688         return 0;
 689 }
 690 EXPORT_SYMBOL(gnttab_alloc_pages);
 691
 692 /**
 693  * gnttab_free_pages - free pages allocated by gnttab_alloc_pages()
 694  * @nr_pages; number of pages to free
 695  * @pages: the pages
 696  */
 697 void gnttab_free_pages(int nr_pages, struct page **pages)
 698 {
 699         free_xenballooned_pages(nr_pages, pages);
 700 }
 701 EXPORT_SYMBOL(gnttab_free_pages);
 702
 703 /* Handling of paged out grant targets (GNTST_eagain) */
 704 #define MAX_DELAY 256
 705 static inline void
 706 gnttab_retry_eagain_gop(unsigned int cmd, void *gop, int16_t *status,
 707                                                 const char *func)
 708 {
 709         unsigned delay = 1;
 710
 711         do {
 712                 BUG_ON(HYPERVISOR_grant_table_op(cmd, gop, 1));
 713                 if (*status == GNTST_eagain)
 714                         msleep(delay++);
 715         } while ((*status == GNTST_eagain) && (delay < MAX_DELAY));
 716
 717         if (delay >= MAX_DELAY) {
 718                 pr_err("%s: %s eagain grant\n", func, current->comm);
 719                 *status = GNTST_bad_page;
 720         }
 721 }
 722
 723 void gnttab_batch_map(struct gnttab_map_grant_ref *batch, unsigned count)
 724 {
 725         struct gnttab_map_grant_ref *op;
 726
 727         if (HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref, batch, count))
 728                 BUG();
 729         for (op = batch; op < batch + count; op++)
 730                 if (op->status == GNTST_eagain)
 731                         gnttab_retry_eagain_gop(GNTTABOP_map_grant_ref, op,
 732                                                 &op->status, __func__);
 733 }
 734 EXPORT_SYMBOL_GPL(gnttab_batch_map);
 735
 736 void gnttab_batch_copy(struct gnttab_copy *batch, unsigned count)
 737 {
 738         struct gnttab_copy *op;
 739
 740         if (HYPERVISOR_grant_table_op(GNTTABOP_copy, batch, count))
 741                 BUG();
 742         for (op = batch; op < batch + count; op++)
 743                 if (op->status == GNTST_eagain)
 744                         gnttab_retry_eagain_gop(GNTTABOP_copy, op,
 745                                                 &op->status, __func__);
 746 }
 747 EXPORT_SYMBOL_GPL(gnttab_batch_copy);
 748
 749 int gnttab_map_refs(struct gnttab_map_grant_ref *map_ops,
 750                     struct gnttab_map_grant_ref *kmap_ops,
 751                     struct page **pages, unsigned int count)
 752 {
 753         int i, ret;
 754
 755         ret = HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref, map_ops, count);
 756         if (ret)
 757                 return ret;
 758
 759         /* Retry eagain maps */
 760         for (i = 0; i < count; i++)
 761                 if (map_ops[i].status == GNTST_eagain)
 762                         gnttab_retry_eagain_gop(GNTTABOP_map_grant_ref, map_ops + i,
 763                                                 &map_ops[i].status, __func__);
 764
 765         return set_foreign_p2m_mapping(map_ops, kmap_ops, pages, count);
 766 }
 767 EXPORT_SYMBOL_GPL(gnttab_map_refs);
 768
 769 int gnttab_unmap_refs(struct gnttab_unmap_grant_ref *unmap_ops,
 770                       struct gnttab_unmap_grant_ref *kunmap_ops,
 771                       struct page **pages, unsigned int count)
 772 {
 773         int ret;
 774
 775         ret = HYPERVISOR_grant_table_op(GNTTABOP_unmap_grant_ref, unmap_ops, count);
 776         if (ret)
 777                 return ret;
 778
 779         return clear_foreign_p2m_mapping(unmap_ops, kunmap_ops, pages, count);
 780 }
 781 EXPORT_SYMBOL_GPL(gnttab_unmap_refs);
 782
 783 static int gnttab_map_frames_v1(xen_pfn_t *frames, unsigned int nr_gframes)
 784 {
 785         int rc;
 786
 787         rc = arch_gnttab_map_shared(frames, nr_gframes,
 788                                     gnttab_max_grant_frames(),
 789                                     &gnttab_shared.addr);
 790         BUG_ON(rc);
 791
 792         return 0;
 793 }
 794
 795 static void gnttab_unmap_frames_v1(void)
 796 {
 797         arch_gnttab_unmap(gnttab_shared.addr, nr_grant_frames);
 798 }
 799
 800 static int gnttab_map(unsigned int start_idx, unsigned int end_idx)
 801 {
 802         struct gnttab_setup_table setup;
 803         xen_pfn_t *frames;
 804         unsigned int nr_gframes = end_idx + 1;
 805         int rc;
 806
 807         if (xen_feature(XENFEAT_auto_translated_physmap)) {
 808                 struct xen_add_to_physmap xatp;
 809                 unsigned int i = end_idx;
 810                 rc = 0;
 811                 BUG_ON(xen_auto_xlat_grant_frames.count < nr_gframes);
 812                 /*
 813                  * Loop backwards, so that the first hypercall has the largest
 814                  * index, ensuring that the table will grow only once.
 815                  */
 816                 do {
 817                         xatp.domid = DOMID_SELF;
 818                         xatp.idx = i;
 819                         xatp.space = XENMAPSPACE_grant_table;
 820                         xatp.gpfn = xen_auto_xlat_grant_frames.pfn[i];
 821                         rc = HYPERVISOR_memory_op(XENMEM_add_to_physmap, &xatp);
 822                         if (rc != 0) {
 823                                 pr_warn("grant table add_to_physmap failed, err=%d\n",
 824                                         rc);
 825                                 break;
 826                         }
 827                 } while (i-- > start_idx);
 828
 829                 return rc;
 830         }
 831
 832         /* No need for kzalloc as it is initialized in following hypercall
 833          * GNTTABOP_setup_table.
 834          */
 835         frames = kmalloc(nr_gframes * sizeof(unsigned long), GFP_ATOMIC);
 836         if (!frames)
 837                 return -ENOMEM;
 838
 839         setup.dom        = DOMID_SELF;
 840         setup.nr_frames  = nr_gframes;
 841         set_xen_guest_handle(setup.frame_list, frames);
 842
 843         rc = HYPERVISOR_grant_table_op(GNTTABOP_setup_table, &setup, 1);
 844         if (rc == -ENOSYS) {
 845                 kfree(frames);
 846                 return -ENOSYS;
 847         }
 848
 849         BUG_ON(rc || setup.status);
 850
 851         rc = gnttab_interface->map_frames(frames, nr_gframes);
 852
 853         kfree(frames);
 854
 855         return rc;
 856 }
 857
 858 static struct gnttab_ops gnttab_v1_ops = {
 859         .map_frames                     = gnttab_map_frames_v1,
 860         .unmap_frames                   = gnttab_unmap_frames_v1,
 861         .update_entry                   = gnttab_update_entry_v1,
 862         .end_foreign_access_ref         = gnttab_end_foreign_access_ref_v1,
 863         .end_foreign_transfer_ref       = gnttab_end_foreign_transfer_ref_v1,
 864         .query_foreign_access           = gnttab_query_foreign_access_v1,
 865 };
 866
 867 static void gnttab_request_version(void)
 868 {
 869         /* Only version 1 is used, which will always be available. */
 870         grant_table_version = 1;
 871         grefs_per_grant_frame = PAGE_SIZE / sizeof(struct grant_entry_v1);
 872         gnttab_interface = &gnttab_v1_ops;
 873
 874         pr_info("Grant tables using version %d layout\n", grant_table_version);
 875 }
 876
 877 static int gnttab_setup(void)
 878 {
 879         unsigned int max_nr_gframes;
 880
 881         max_nr_gframes = gnttab_max_grant_frames();
 882         if (max_nr_gframes < nr_grant_frames)
 883                 return -ENOSYS;
 884
 885         if (xen_feature(XENFEAT_auto_translated_physmap) && gnttab_shared.addr == NULL) {
 886                 gnttab_shared.addr = xen_auto_xlat_grant_frames.vaddr;
 887                 if (gnttab_shared.addr == NULL) {
 888                         pr_warn("gnttab share frames (addr=0x%08lx) is not mapped!\n",
 889                                 (unsigned long)xen_auto_xlat_grant_frames.vaddr);
 890                         return -ENOMEM;
 891                 }
 892         }
 893         return gnttab_map(0, nr_grant_frames - 1);
 894 }
 895
 896 int gnttab_resume(void)
 897 {
 898         gnttab_request_version();
 899         return gnttab_setup();
 900 }
 901
 902 int gnttab_suspend(void)
 903 {
 904         if (!xen_feature(XENFEAT_auto_translated_physmap))
 905                 gnttab_interface->unmap_frames();
 906         return 0;
 907 }
 908
 909 static int gnttab_expand(unsigned int req_entries)
 910 {
 911         int rc;
 912         unsigned int cur, extra;
 913
 914         BUG_ON(grefs_per_grant_frame == 0);
 915         cur = nr_grant_frames;
 916         extra = ((req_entries + (grefs_per_grant_frame-1)) /
 917                  grefs_per_grant_frame);
 918         if (cur + extra > gnttab_max_grant_frames())
 919                 return -ENOSPC;
 920
 921         rc = gnttab_map(cur, cur + extra - 1);
 922         if (rc == 0)
 923                 rc = grow_gnttab_list(extra);
 924
 925         return rc;
 926 }
 927
 928 int gnttab_init(void)
 929 {
 930         int i;
 931         unsigned long max_nr_grant_frames;
 932         unsigned int max_nr_glist_frames, nr_glist_frames;
 933         unsigned int nr_init_grefs;
 934         int ret;
 935
 936         gnttab_request_version();
 937         max_nr_grant_frames = gnttab_max_grant_frames();
 938         nr_grant_frames = 1;
 939
 940         /* Determine the maximum number of frames required for the
 941          * grant reference free list on the current hypervisor.
 942          */
 943         BUG_ON(grefs_per_grant_frame == 0);
 944         max_nr_glist_frames = (max_nr_grant_frames *
 945                                grefs_per_grant_frame / RPP);
 946
 947         gnttab_list = kmalloc(max_nr_glist_frames * sizeof(grant_ref_t *),
 948                               GFP_KERNEL);
 949         if (gnttab_list == NULL)
 950                 return -ENOMEM;
 951
 952         nr_glist_frames = (nr_grant_frames * grefs_per_grant_frame + RPP - 1) / RPP;
 953         for (i = 0; i < nr_glist_frames; i++) {
 954                 gnttab_list[i] = (grant_ref_t *)__get_free_page(GFP_KERNEL);
 955                 if (gnttab_list[i] == NULL) {
 956                         ret = -ENOMEM;
 957                         goto ini_nomem;
 958                 }
 959         }
 960
 961         ret = arch_gnttab_init(max_nr_grant_frames);
 962         if (ret < 0)
 963                 goto ini_nomem;
 964
 965         if (gnttab_setup() < 0) {
 966                 ret = -ENODEV;
 967                 goto ini_nomem;
 968         }
 969
 970         nr_init_grefs = nr_grant_frames * grefs_per_grant_frame;
 971
 972         for (i = NR_RESERVED_ENTRIES; i < nr_init_grefs - 1; i++)
 973                 gnttab_entry(i) = i + 1;
 974
 975         gnttab_entry(nr_init_grefs - 1) = GNTTAB_LIST_END;
 976         gnttab_free_count = nr_init_grefs - NR_RESERVED_ENTRIES;
 977         gnttab_free_head  = NR_RESERVED_ENTRIES;
 978
 979         printk("Grant table initialized\n");
 980         return 0;
 981
 982  ini_nomem:
 983         for (i--; i >= 0; i--)
 984                 free_page((unsigned long)gnttab_list[i]);
 985         kfree(gnttab_list);
 986         return ret;
 987 }
 988 EXPORT_SYMBOL_GPL(gnttab_init);
 989
 990 static int __gnttab_init(void)
 991 {
 992         /* Delay grant-table initialization in the PV on HVM case */
 993         if (xen_hvm_domain())
 994                 return 0;
 995
 996         if (!xen_pv_domain())
 997                 return -ENODEV;
 998
 999         return gnttab_init();
1000 }
1001 /* Starts after core_initcall so that xen_pvh_gnttab_setup can be called
1002  * beforehand to initialize xen_auto_xlat_grant_frames. */
1003 core_initcall_sync(__gnttab_init);