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
  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          * Read the frame number related to a given grant reference.
 118          */
 119         unsigned long (*read_frame)(grant_ref_t ref);
 120 };
 121
 122 struct unmap_refs_callback_data {
 123         struct completion completion;
 124         int result;
 125 };
 126
 127 static const struct gnttab_ops *gnttab_interface;
 128
 129 static int grant_table_version;
 130 static int grefs_per_grant_frame;
 131
 132 static struct gnttab_free_callback *gnttab_free_callback_list;
 133
 134 static int gnttab_expand(unsigned int req_entries);
 135
 136 #define RPP (PAGE_SIZE / sizeof(grant_ref_t))
 137
 138 static inline grant_ref_t *__gnttab_entry(grant_ref_t entry)
 139 {
 140         return &gnttab_list[(entry) / RPP][(entry) % RPP];
 141 }
 142 /* This can be used as an l-value */
 143 #define gnttab_entry(entry) (*__gnttab_entry(entry))
 144
 145 static int get_free_entries(unsigned count)
 146 {
 147         unsigned long flags;
 148         int ref, rc = 0;
 149         grant_ref_t head;
 150
 151         spin_lock_irqsave(&gnttab_list_lock, flags);
 152
 153         if ((gnttab_free_count < count) &&
 154             ((rc = gnttab_expand(count - gnttab_free_count)) < 0)) {
 155                 spin_unlock_irqrestore(&gnttab_list_lock, flags);
 156                 return rc;
 157         }
 158
 159         ref = head = gnttab_free_head;
 160         gnttab_free_count -= count;
 161         while (count-- > 1)
 162                 head = gnttab_entry(head);
 163         gnttab_free_head = gnttab_entry(head);
 164         gnttab_entry(head) = GNTTAB_LIST_END;
 165
 166         spin_unlock_irqrestore(&gnttab_list_lock, flags);
 167
 168         return ref;
 169 }
 170
 171 static void do_free_callbacks(void)
 172 {
 173         struct gnttab_free_callback *callback, *next;
 174
 175         callback = gnttab_free_callback_list;
 176         gnttab_free_callback_list = NULL;
 177
 178         while (callback != NULL) {
 179                 next = callback->next;
 180                 if (gnttab_free_count >= callback->count) {
 181                         callback->next = NULL;
 182                         callback->fn(callback->arg);
 183                 } else {
 184                         callback->next = gnttab_free_callback_list;
 185                         gnttab_free_callback_list = callback;
 186                 }
 187                 callback = next;
 188         }
 189 }
 190
 191 static inline void check_free_callbacks(void)
 192 {
 193         if (unlikely(gnttab_free_callback_list))
 194                 do_free_callbacks();
 195 }
 196
 197 static void put_free_entry(grant_ref_t ref)
 198 {
 199         unsigned long flags;
 200         spin_lock_irqsave(&gnttab_list_lock, flags);
 201         gnttab_entry(ref) = gnttab_free_head;
 202         gnttab_free_head = ref;
 203         gnttab_free_count++;
 204         check_free_callbacks();
 205         spin_unlock_irqrestore(&gnttab_list_lock, flags);
 206 }
 207
 208 /*
 209  * Following applies to gnttab_update_entry_v1.
 210  * Introducing a valid entry into the grant table:
 211  *  1. Write ent->domid.
 212  *  2. Write ent->frame:
 213  *      GTF_permit_access:   Frame to which access is permitted.
 214  *      GTF_accept_transfer: Pseudo-phys frame slot being filled by new
 215  *                           frame, or zero if none.
 216  *  3. Write memory barrier (WMB).
 217  *  4. Write ent->flags, inc. valid type.
 218  */
 219 static void gnttab_update_entry_v1(grant_ref_t ref, domid_t domid,
 220                                    unsigned long frame, unsigned flags)
 221 {
 222         gnttab_shared.v1[ref].domid = domid;
 223         gnttab_shared.v1[ref].frame = frame;
 224         wmb();
 225         gnttab_shared.v1[ref].flags = flags;
 226 }
 227
 228 /*
 229  * Public grant-issuing interface functions
 230  */
 231 void gnttab_grant_foreign_access_ref(grant_ref_t ref, domid_t domid,
 232                                      unsigned long frame, int readonly)
 233 {
 234         gnttab_interface->update_entry(ref, domid, frame,
 235                            GTF_permit_access | (readonly ? GTF_readonly : 0));
 236 }
 237 EXPORT_SYMBOL_GPL(gnttab_grant_foreign_access_ref);
 238
 239 int gnttab_grant_foreign_access(domid_t domid, unsigned long frame,
 240                                 int readonly)
 241 {
 242         int ref;
 243
 244         ref = get_free_entries(1);
 245         if (unlikely(ref < 0))
 246                 return -ENOSPC;
 247
 248         gnttab_grant_foreign_access_ref(ref, domid, frame, readonly);
 249
 250         return ref;
 251 }
 252 EXPORT_SYMBOL_GPL(gnttab_grant_foreign_access);
 253
 254 static int gnttab_end_foreign_access_ref_v1(grant_ref_t ref, int readonly)
 255 {
 256         u16 flags, nflags;
 257         u16 *pflags;
 258
 259         pflags = &gnttab_shared.v1[ref].flags;
 260         nflags = *pflags;
 261         do {
 262                 flags = nflags;
 263                 if (flags & (GTF_reading|GTF_writing))
 264                         return 0;
 265         } while ((nflags = sync_cmpxchg(pflags, flags, 0)) != flags);
 266
 267         return 1;
 268 }
 269
 270 static inline int _gnttab_end_foreign_access_ref(grant_ref_t ref, int readonly)
 271 {
 272         return gnttab_interface->end_foreign_access_ref(ref, readonly);
 273 }
 274
 275 int gnttab_end_foreign_access_ref(grant_ref_t ref, int readonly)
 276 {
 277         if (_gnttab_end_foreign_access_ref(ref, readonly))
 278                 return 1;
 279         pr_warn("WARNING: g.e. %#x still in use!\n", ref);
 280         return 0;
 281 }
 282 EXPORT_SYMBOL_GPL(gnttab_end_foreign_access_ref);
 283
 284 static unsigned long gnttab_read_frame_v1(grant_ref_t ref)
 285 {
 286         return gnttab_shared.v1[ref].frame;
 287 }
 288
 289 struct deferred_entry {
 290         struct list_head list;
 291         grant_ref_t ref;
 292         bool ro;
 293         uint16_t warn_delay;
 294         struct page *page;
 295 };
 296 static LIST_HEAD(deferred_list);
 297 static void gnttab_handle_deferred(unsigned long);
 298 static DEFINE_TIMER(deferred_timer, gnttab_handle_deferred, 0, 0);
 299
 300 static void gnttab_handle_deferred(unsigned long unused)
 301 {
 302         unsigned int nr = 10;
 303         struct deferred_entry *first = NULL;
 304         unsigned long flags;
 305
 306         spin_lock_irqsave(&gnttab_list_lock, flags);
 307         while (nr--) {
 308                 struct deferred_entry *entry
 309                         = list_first_entry(&deferred_list,
 310                                            struct deferred_entry, list);
 311
 312                 if (entry == first)
 313                         break;
 314                 list_del(&entry->list);
 315                 spin_unlock_irqrestore(&gnttab_list_lock, flags);
 316                 if (_gnttab_end_foreign_access_ref(entry->ref, entry->ro)) {
 317                         put_free_entry(entry->ref);
 318                         pr_debug("freeing g.e. %#x (pfn %#lx)\n",
 319                                  entry->ref, page_to_pfn(entry->page));
 320                         put_page(entry->page);
 321                         kfree(entry);
 322                         entry = NULL;
 323                 } else {
 324                         if (!--entry->warn_delay)
 325                                 pr_info("g.e. %#x still pending\n", entry->ref);
 326                         if (!first)
 327                                 first = entry;
 328                 }
 329                 spin_lock_irqsave(&gnttab_list_lock, flags);
 330                 if (entry)
 331                         list_add_tail(&entry->list, &deferred_list);
 332                 else if (list_empty(&deferred_list))
 333                         break;
 334         }
 335         if (!list_empty(&deferred_list) && !timer_pending(&deferred_timer)) {
 336                 deferred_timer.expires = jiffies + HZ;
 337                 add_timer(&deferred_timer);
 338         }
 339         spin_unlock_irqrestore(&gnttab_list_lock, flags);
 340 }
 341
 342 static void gnttab_add_deferred(grant_ref_t ref, bool readonly,
 343                                 struct page *page)
 344 {
 345         struct deferred_entry *entry;
 346         gfp_t gfp = (in_atomic() || irqs_disabled()) ? GFP_ATOMIC : GFP_KERNEL;
 347         const char *what = KERN_WARNING "leaking";
 348
 349         entry = kmalloc(sizeof(*entry), gfp);
 350         if (!page) {
 351                 unsigned long gfn = gnttab_interface->read_frame(ref);
 352
 353                 page = pfn_to_page(gfn_to_pfn(gfn));
 354                 get_page(page);
 355         }
 356
 357         if (entry) {
 358                 unsigned long flags;
 359
 360                 entry->ref = ref;
 361                 entry->ro = readonly;
 362                 entry->page = page;
 363                 entry->warn_delay = 60;
 364                 spin_lock_irqsave(&gnttab_list_lock, flags);
 365                 list_add_tail(&entry->list, &deferred_list);
 366                 if (!timer_pending(&deferred_timer)) {
 367                         deferred_timer.expires = jiffies + HZ;
 368                         add_timer(&deferred_timer);
 369                 }
 370                 spin_unlock_irqrestore(&gnttab_list_lock, flags);
 371                 what = KERN_DEBUG "deferring";
 372         }
 373         printk("%s g.e. %#x (pfn %#lx)\n",
 374                what, ref, page ? page_to_pfn(page) : -1);
 375 }
 376
 377 int gnttab_try_end_foreign_access(grant_ref_t ref)
 378 {
 379         int ret = _gnttab_end_foreign_access_ref(ref, 0);
 380
 381         if (ret)
 382                 put_free_entry(ref);
 383
 384         return ret;
 385 }
 386 EXPORT_SYMBOL_GPL(gnttab_try_end_foreign_access);
 387
 388 void gnttab_end_foreign_access(grant_ref_t ref, int readonly,
 389                                unsigned long page)
 390 {
 391         if (gnttab_try_end_foreign_access(ref)) {
 392                 if (page != 0)
 393                         put_page(virt_to_page(page));
 394         } else
 395                 gnttab_add_deferred(ref, readonly,
 396                                     page ? virt_to_page(page) : NULL);
 397 }
 398 EXPORT_SYMBOL_GPL(gnttab_end_foreign_access);
 399
 400 int gnttab_grant_foreign_transfer(domid_t domid, unsigned long pfn)
 401 {
 402         int ref;
 403
 404         ref = get_free_entries(1);
 405         if (unlikely(ref < 0))
 406                 return -ENOSPC;
 407         gnttab_grant_foreign_transfer_ref(ref, domid, pfn);
 408
 409         return ref;
 410 }
 411 EXPORT_SYMBOL_GPL(gnttab_grant_foreign_transfer);
 412
 413 void gnttab_grant_foreign_transfer_ref(grant_ref_t ref, domid_t domid,
 414                                        unsigned long pfn)
 415 {
 416         gnttab_interface->update_entry(ref, domid, pfn, GTF_accept_transfer);
 417 }
 418 EXPORT_SYMBOL_GPL(gnttab_grant_foreign_transfer_ref);
 419
 420 static unsigned long gnttab_end_foreign_transfer_ref_v1(grant_ref_t ref)
 421 {
 422         unsigned long frame;
 423         u16           flags;
 424         u16          *pflags;
 425
 426         pflags = &gnttab_shared.v1[ref].flags;
 427
 428         /*
 429          * If a transfer is not even yet started, try to reclaim the grant
 430          * reference and return failure (== 0).
 431          */
 432         while (!((flags = *pflags) & GTF_transfer_committed)) {
 433                 if (sync_cmpxchg(pflags, flags, 0) == flags)
 434                         return 0;
 435                 cpu_relax();
 436         }
 437
 438         /* If a transfer is in progress then wait until it is completed. */
 439         while (!(flags & GTF_transfer_completed)) {
 440                 flags = *pflags;
 441                 cpu_relax();
 442         }
 443
 444         rmb();  /* Read the frame number /after/ reading completion status. */
 445         frame = gnttab_shared.v1[ref].frame;
 446         BUG_ON(frame == 0);
 447
 448         return frame;
 449 }
 450
 451 unsigned long gnttab_end_foreign_transfer_ref(grant_ref_t ref)
 452 {
 453         return gnttab_interface->end_foreign_transfer_ref(ref);
 454 }
 455 EXPORT_SYMBOL_GPL(gnttab_end_foreign_transfer_ref);
 456
 457 unsigned long gnttab_end_foreign_transfer(grant_ref_t ref)
 458 {
 459         unsigned long frame = gnttab_end_foreign_transfer_ref(ref);
 460         put_free_entry(ref);
 461         return frame;
 462 }
 463 EXPORT_SYMBOL_GPL(gnttab_end_foreign_transfer);
 464
 465 void gnttab_free_grant_reference(grant_ref_t ref)
 466 {
 467         put_free_entry(ref);
 468 }
 469 EXPORT_SYMBOL_GPL(gnttab_free_grant_reference);
 470
 471 void gnttab_free_grant_references(grant_ref_t head)
 472 {
 473         grant_ref_t ref;
 474         unsigned long flags;
 475         int count = 1;
 476         if (head == GNTTAB_LIST_END)
 477                 return;
 478         spin_lock_irqsave(&gnttab_list_lock, flags);
 479         ref = head;
 480         while (gnttab_entry(ref) != GNTTAB_LIST_END) {
 481                 ref = gnttab_entry(ref);
 482                 count++;
 483         }
 484         gnttab_entry(ref) = gnttab_free_head;
 485         gnttab_free_head = head;
 486         gnttab_free_count += count;
 487         check_free_callbacks();
 488         spin_unlock_irqrestore(&gnttab_list_lock, flags);
 489 }
 490 EXPORT_SYMBOL_GPL(gnttab_free_grant_references);
 491
 492 int gnttab_alloc_grant_references(u16 count, grant_ref_t *head)
 493 {
 494         int h = get_free_entries(count);
 495
 496         if (h < 0)
 497                 return -ENOSPC;
 498
 499         *head = h;
 500
 501         return 0;
 502 }
 503 EXPORT_SYMBOL_GPL(gnttab_alloc_grant_references);
 504
 505 int gnttab_empty_grant_references(const grant_ref_t *private_head)
 506 {
 507         return (*private_head == GNTTAB_LIST_END);
 508 }
 509 EXPORT_SYMBOL_GPL(gnttab_empty_grant_references);
 510
 511 int gnttab_claim_grant_reference(grant_ref_t *private_head)
 512 {
 513         grant_ref_t g = *private_head;
 514         if (unlikely(g == GNTTAB_LIST_END))
 515                 return -ENOSPC;
 516         *private_head = gnttab_entry(g);
 517         return g;
 518 }
 519 EXPORT_SYMBOL_GPL(gnttab_claim_grant_reference);
 520
 521 void gnttab_release_grant_reference(grant_ref_t *private_head,
 522                                     grant_ref_t release)
 523 {
 524         gnttab_entry(release) = *private_head;
 525         *private_head = release;
 526 }
 527 EXPORT_SYMBOL_GPL(gnttab_release_grant_reference);
 528
 529 void gnttab_request_free_callback(struct gnttab_free_callback *callback,
 530                                   void (*fn)(void *), void *arg, u16 count)
 531 {
 532         unsigned long flags;
 533         struct gnttab_free_callback *cb;
 534
 535         spin_lock_irqsave(&gnttab_list_lock, flags);
 536
 537         /* Check if the callback is already on the list */
 538         cb = gnttab_free_callback_list;
 539         while (cb) {
 540                 if (cb == callback)
 541                         goto out;
 542                 cb = cb->next;
 543         }
 544
 545         callback->fn = fn;
 546         callback->arg = arg;
 547         callback->count = count;
 548         callback->next = gnttab_free_callback_list;
 549         gnttab_free_callback_list = callback;
 550         check_free_callbacks();
 551 out:
 552         spin_unlock_irqrestore(&gnttab_list_lock, flags);
 553 }
 554 EXPORT_SYMBOL_GPL(gnttab_request_free_callback);
 555
 556 void gnttab_cancel_free_callback(struct gnttab_free_callback *callback)
 557 {
 558         struct gnttab_free_callback **pcb;
 559         unsigned long flags;
 560
 561         spin_lock_irqsave(&gnttab_list_lock, flags);
 562         for (pcb = &gnttab_free_callback_list; *pcb; pcb = &(*pcb)->next) {
 563                 if (*pcb == callback) {
 564                         *pcb = callback->next;
 565                         break;
 566                 }
 567         }
 568         spin_unlock_irqrestore(&gnttab_list_lock, flags);
 569 }
 570 EXPORT_SYMBOL_GPL(gnttab_cancel_free_callback);
 571
 572 static int grow_gnttab_list(unsigned int more_frames)
 573 {
 574         unsigned int new_nr_grant_frames, extra_entries, i;
 575         unsigned int nr_glist_frames, new_nr_glist_frames;
 576
 577         BUG_ON(grefs_per_grant_frame == 0);
 578
 579         new_nr_grant_frames = nr_grant_frames + more_frames;
 580         extra_entries       = more_frames * grefs_per_grant_frame;
 581
 582         nr_glist_frames = (nr_grant_frames * grefs_per_grant_frame + RPP - 1) / RPP;
 583         new_nr_glist_frames =
 584                 (new_nr_grant_frames * grefs_per_grant_frame + RPP - 1) / RPP;
 585         for (i = nr_glist_frames; i < new_nr_glist_frames; i++) {
 586                 gnttab_list[i] = (grant_ref_t *)__get_free_page(GFP_ATOMIC);
 587                 if (!gnttab_list[i])
 588                         goto grow_nomem;
 589         }
 590
 591
 592         for (i = grefs_per_grant_frame * nr_grant_frames;
 593              i < grefs_per_grant_frame * new_nr_grant_frames - 1; i++)
 594                 gnttab_entry(i) = i + 1;
 595
 596         gnttab_entry(i) = gnttab_free_head;
 597         gnttab_free_head = grefs_per_grant_frame * nr_grant_frames;
 598         gnttab_free_count += extra_entries;
 599
 600         nr_grant_frames = new_nr_grant_frames;
 601
 602         check_free_callbacks();
 603
 604         return 0;
 605
 606 grow_nomem:
 607         while (i-- > nr_glist_frames)
 608                 free_page((unsigned long) gnttab_list[i]);
 609         return -ENOMEM;
 610 }
 611
 612 static unsigned int __max_nr_grant_frames(void)
 613 {
 614         struct gnttab_query_size query;
 615         int rc;
 616
 617         query.dom = DOMID_SELF;
 618
 619         rc = HYPERVISOR_grant_table_op(GNTTABOP_query_size, &query, 1);
 620         if ((rc < 0) || (query.status != GNTST_okay))
 621                 return 4; /* Legacy max supported number of frames */
 622
 623         return query.max_nr_frames;
 624 }
 625
 626 unsigned int gnttab_max_grant_frames(void)
 627 {
 628         unsigned int xen_max = __max_nr_grant_frames();
 629         static unsigned int boot_max_nr_grant_frames;
 630
 631         /* First time, initialize it properly. */
 632         if (!boot_max_nr_grant_frames)
 633                 boot_max_nr_grant_frames = __max_nr_grant_frames();
 634
 635         if (xen_max > boot_max_nr_grant_frames)
 636                 return boot_max_nr_grant_frames;
 637         return xen_max;
 638 }
 639 EXPORT_SYMBOL_GPL(gnttab_max_grant_frames);
 640
 641 int gnttab_setup_auto_xlat_frames(phys_addr_t addr)
 642 {
 643         xen_pfn_t *pfn;
 644         unsigned int max_nr_gframes = __max_nr_grant_frames();
 645         unsigned int i;
 646         void *vaddr;
 647
 648         if (xen_auto_xlat_grant_frames.count)
 649                 return -EINVAL;
 650
 651         vaddr = xen_remap(addr, XEN_PAGE_SIZE * max_nr_gframes);
 652         if (vaddr == NULL) {
 653                 pr_warn("Failed to ioremap gnttab share frames (addr=%pa)!\n",
 654                         &addr);
 655                 return -ENOMEM;
 656         }
 657         pfn = kcalloc(max_nr_gframes, sizeof(pfn[0]), GFP_KERNEL);
 658         if (!pfn) {
 659                 xen_unmap(vaddr);
 660                 return -ENOMEM;
 661         }
 662         for (i = 0; i < max_nr_gframes; i++)
 663                 pfn[i] = XEN_PFN_DOWN(addr) + i;
 664
 665         xen_auto_xlat_grant_frames.vaddr = vaddr;
 666         xen_auto_xlat_grant_frames.pfn = pfn;
 667         xen_auto_xlat_grant_frames.count = max_nr_gframes;
 668
 669         return 0;
 670 }
 671 EXPORT_SYMBOL_GPL(gnttab_setup_auto_xlat_frames);
 672
 673 void gnttab_free_auto_xlat_frames(void)
 674 {
 675         if (!xen_auto_xlat_grant_frames.count)
 676                 return;
 677         kfree(xen_auto_xlat_grant_frames.pfn);
 678         xen_unmap(xen_auto_xlat_grant_frames.vaddr);
 679
 680         xen_auto_xlat_grant_frames.pfn = NULL;
 681         xen_auto_xlat_grant_frames.count = 0;
 682         xen_auto_xlat_grant_frames.vaddr = NULL;
 683 }
 684 EXPORT_SYMBOL_GPL(gnttab_free_auto_xlat_frames);
 685
 686 /**
 687  * gnttab_alloc_pages - alloc pages suitable for grant mapping into
 688  * @nr_pages: number of pages to alloc
 689  * @pages: returns the pages
 690  */
 691 int gnttab_alloc_pages(int nr_pages, struct page **pages)
 692 {
 693         int i;
 694         int ret;
 695
 696         ret = alloc_xenballooned_pages(nr_pages, pages);
 697         if (ret < 0)
 698                 return ret;
 699
 700         for (i = 0; i < nr_pages; i++) {
 701 #if BITS_PER_LONG < 64
 702                 struct xen_page_foreign *foreign;
 703
 704                 foreign = kzalloc(sizeof(*foreign), GFP_KERNEL);
 705                 if (!foreign) {
 706                         gnttab_free_pages(nr_pages, pages);
 707                         return -ENOMEM;
 708                 }
 709                 set_page_private(pages[i], (unsigned long)foreign);
 710 #endif
 711                 SetPagePrivate(pages[i]);
 712         }
 713
 714         return 0;
 715 }
 716 EXPORT_SYMBOL(gnttab_alloc_pages);
 717
 718 /**
 719  * gnttab_free_pages - free pages allocated by gnttab_alloc_pages()
 720  * @nr_pages; number of pages to free
 721  * @pages: the pages
 722  */
 723 void gnttab_free_pages(int nr_pages, struct page **pages)
 724 {
 725         int i;
 726
 727         for (i = 0; i < nr_pages; i++) {
 728                 if (PagePrivate(pages[i])) {
 729 #if BITS_PER_LONG < 64
 730                         kfree((void *)page_private(pages[i]));
 731 #endif
 732                         ClearPagePrivate(pages[i]);
 733                 }
 734         }
 735         free_xenballooned_pages(nr_pages, pages);
 736 }
 737 EXPORT_SYMBOL(gnttab_free_pages);
 738
 739 /* Handling of paged out grant targets (GNTST_eagain) */
 740 #define MAX_DELAY 256
 741 static inline void
 742 gnttab_retry_eagain_gop(unsigned int cmd, void *gop, int16_t *status,
 743                                                 const char *func)
 744 {
 745         unsigned delay = 1;
 746
 747         do {
 748                 BUG_ON(HYPERVISOR_grant_table_op(cmd, gop, 1));
 749                 if (*status == GNTST_eagain)
 750                         msleep(delay++);
 751         } while ((*status == GNTST_eagain) && (delay < MAX_DELAY));
 752
 753         if (delay >= MAX_DELAY) {
 754                 pr_err("%s: %s eagain grant\n", func, current->comm);
 755                 *status = GNTST_bad_page;
 756         }
 757 }
 758
 759 void gnttab_batch_map(struct gnttab_map_grant_ref *batch, unsigned count)
 760 {
 761         struct gnttab_map_grant_ref *op;
 762
 763         if (HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref, batch, count))
 764                 BUG();
 765         for (op = batch; op < batch + count; op++)
 766                 if (op->status == GNTST_eagain)
 767                         gnttab_retry_eagain_gop(GNTTABOP_map_grant_ref, op,
 768                                                 &op->status, __func__);
 769 }
 770 EXPORT_SYMBOL_GPL(gnttab_batch_map);
 771
 772 void gnttab_batch_copy(struct gnttab_copy *batch, unsigned count)
 773 {
 774         struct gnttab_copy *op;
 775
 776         if (HYPERVISOR_grant_table_op(GNTTABOP_copy, batch, count))
 777                 BUG();
 778         for (op = batch; op < batch + count; op++)
 779                 if (op->status == GNTST_eagain)
 780                         gnttab_retry_eagain_gop(GNTTABOP_copy, op,
 781                                                 &op->status, __func__);
 782 }
 783 EXPORT_SYMBOL_GPL(gnttab_batch_copy);
 784
 785 void gnttab_foreach_grant_in_range(struct page *page,
 786                                    unsigned int offset,
 787                                    unsigned int len,
 788                                    xen_grant_fn_t fn,
 789                                    void *data)
 790 {
 791         unsigned int goffset;
 792         unsigned int glen;
 793         unsigned long xen_pfn;
 794
 795         len = min_t(unsigned int, PAGE_SIZE - offset, len);
 796         goffset = xen_offset_in_page(offset);
 797
 798         xen_pfn = page_to_xen_pfn(page) + XEN_PFN_DOWN(offset);
 799
 800         while (len) {
 801                 glen = min_t(unsigned int, XEN_PAGE_SIZE - goffset, len);
 802                 fn(pfn_to_gfn(xen_pfn), goffset, glen, data);
 803
 804                 goffset = 0;
 805                 xen_pfn++;
 806                 len -= glen;
 807         }
 808 }
 809 EXPORT_SYMBOL_GPL(gnttab_foreach_grant_in_range);
 810
 811 void gnttab_foreach_grant(struct page **pages,
 812                           unsigned int nr_grefs,
 813                           xen_grant_fn_t fn,
 814                           void *data)
 815 {
 816         unsigned int goffset = 0;
 817         unsigned long xen_pfn = 0;
 818         unsigned int i;
 819
 820         for (i = 0; i < nr_grefs; i++) {
 821                 if ((i % XEN_PFN_PER_PAGE) == 0) {
 822                         xen_pfn = page_to_xen_pfn(pages[i / XEN_PFN_PER_PAGE]);
 823                         goffset = 0;
 824                 }
 825
 826                 fn(pfn_to_gfn(xen_pfn), goffset, XEN_PAGE_SIZE, data);
 827
 828                 goffset += XEN_PAGE_SIZE;
 829                 xen_pfn++;
 830         }
 831 }
 832
 833 int gnttab_map_refs(struct gnttab_map_grant_ref *map_ops,
 834                     struct gnttab_map_grant_ref *kmap_ops,
 835                     struct page **pages, unsigned int count)
 836 {
 837         int i, ret;
 838
 839         ret = HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref, map_ops, count);
 840         if (ret)
 841                 return ret;
 842
 843         for (i = 0; i < count; i++) {
 844                 /* Retry eagain maps */
 845                 if (map_ops[i].status == GNTST_eagain)
 846                         gnttab_retry_eagain_gop(GNTTABOP_map_grant_ref, map_ops + i,
 847                                                 &map_ops[i].status, __func__);
 848
 849                 if (map_ops[i].status == GNTST_okay) {
 850                         struct xen_page_foreign *foreign;
 851
 852                         SetPageForeign(pages[i]);
 853                         foreign = xen_page_foreign(pages[i]);
 854                         foreign->domid = map_ops[i].dom;
 855                         foreign->gref = map_ops[i].ref;
 856                 }
 857         }
 858
 859         return set_foreign_p2m_mapping(map_ops, kmap_ops, pages, count);
 860 }
 861 EXPORT_SYMBOL_GPL(gnttab_map_refs);
 862
 863 int gnttab_unmap_refs(struct gnttab_unmap_grant_ref *unmap_ops,
 864                       struct gnttab_unmap_grant_ref *kunmap_ops,
 865                       struct page **pages, unsigned int count)
 866 {
 867         unsigned int i;
 868         int ret;
 869
 870         ret = HYPERVISOR_grant_table_op(GNTTABOP_unmap_grant_ref, unmap_ops, count);
 871         if (ret)
 872                 return ret;
 873
 874         for (i = 0; i < count; i++)
 875                 ClearPageForeign(pages[i]);
 876
 877         return clear_foreign_p2m_mapping(unmap_ops, kunmap_ops, pages, count);
 878 }
 879 EXPORT_SYMBOL_GPL(gnttab_unmap_refs);
 880
 881 #define GNTTAB_UNMAP_REFS_DELAY 5
 882
 883 static void __gnttab_unmap_refs_async(struct gntab_unmap_queue_data* item);
 884
 885 static void gnttab_unmap_work(struct work_struct *work)
 886 {
 887         struct gntab_unmap_queue_data
 888                 *unmap_data = container_of(work,
 889                                            struct gntab_unmap_queue_data,
 890                                            gnttab_work.work);
 891         if (unmap_data->age != UINT_MAX)
 892                 unmap_data->age++;
 893         __gnttab_unmap_refs_async(unmap_data);
 894 }
 895
 896 static void __gnttab_unmap_refs_async(struct gntab_unmap_queue_data* item)
 897 {
 898         int ret;
 899         int pc;
 900
 901         for (pc = 0; pc < item->count; pc++) {
 902                 if (page_count(item->pages[pc]) > 1) {
 903                         unsigned long delay = GNTTAB_UNMAP_REFS_DELAY * (item->age + 1);
 904                         schedule_delayed_work(&item->gnttab_work,
 905                                               msecs_to_jiffies(delay));
 906                         return;
 907                 }
 908         }
 909
 910         ret = gnttab_unmap_refs(item->unmap_ops, item->kunmap_ops,
 911                                 item->pages, item->count);
 912         item->done(ret, item);
 913 }
 914
 915 void gnttab_unmap_refs_async(struct gntab_unmap_queue_data* item)
 916 {
 917         INIT_DELAYED_WORK(&item->gnttab_work, gnttab_unmap_work);
 918         item->age = 0;
 919
 920         __gnttab_unmap_refs_async(item);
 921 }
 922 EXPORT_SYMBOL_GPL(gnttab_unmap_refs_async);
 923
 924 static void unmap_refs_callback(int result,
 925                 struct gntab_unmap_queue_data *data)
 926 {
 927         struct unmap_refs_callback_data *d = data->data;
 928
 929         d->result = result;
 930         complete(&d->completion);
 931 }
 932
 933 int gnttab_unmap_refs_sync(struct gntab_unmap_queue_data *item)
 934 {
 935         struct unmap_refs_callback_data data;
 936
 937         init_completion(&data.completion);
 938         item->data = &data;
 939         item->done = &unmap_refs_callback;
 940         gnttab_unmap_refs_async(item);
 941         wait_for_completion(&data.completion);
 942
 943         return data.result;
 944 }
 945 EXPORT_SYMBOL_GPL(gnttab_unmap_refs_sync);
 946
 947 static int gnttab_map_frames_v1(xen_pfn_t *frames, unsigned int nr_gframes)
 948 {
 949         int rc;
 950
 951         rc = arch_gnttab_map_shared(frames, nr_gframes,
 952                                     gnttab_max_grant_frames(),
 953                                     &gnttab_shared.addr);
 954         BUG_ON(rc);
 955
 956         return 0;
 957 }
 958
 959 static void gnttab_unmap_frames_v1(void)
 960 {
 961         arch_gnttab_unmap(gnttab_shared.addr, nr_grant_frames);
 962 }
 963
 964 static int gnttab_map(unsigned int start_idx, unsigned int end_idx)
 965 {
 966         struct gnttab_setup_table setup;
 967         xen_pfn_t *frames;
 968         unsigned int nr_gframes = end_idx + 1;
 969         int rc;
 970
 971         if (xen_feature(XENFEAT_auto_translated_physmap)) {
 972                 struct xen_add_to_physmap xatp;
 973                 unsigned int i = end_idx;
 974                 rc = 0;
 975                 BUG_ON(xen_auto_xlat_grant_frames.count < nr_gframes);
 976                 /*
 977                  * Loop backwards, so that the first hypercall has the largest
 978                  * index, ensuring that the table will grow only once.
 979                  */
 980                 do {
 981                         xatp.domid = DOMID_SELF;
 982                         xatp.idx = i;
 983                         xatp.space = XENMAPSPACE_grant_table;
 984                         xatp.gpfn = xen_auto_xlat_grant_frames.pfn[i];
 985                         rc = HYPERVISOR_memory_op(XENMEM_add_to_physmap, &xatp);
 986                         if (rc != 0) {
 987                                 pr_warn("grant table add_to_physmap failed, err=%d\n",
 988                                         rc);
 989                                 break;
 990                         }
 991                 } while (i-- > start_idx);
 992
 993                 return rc;
 994         }
 995
 996         /* No need for kzalloc as it is initialized in following hypercall
 997          * GNTTABOP_setup_table.
 998          */
 999         frames = kmalloc(nr_gframes * sizeof(unsigned long), GFP_ATOMIC);
1000         if (!frames)
1001                 return -ENOMEM;
1002
1003         setup.dom        = DOMID_SELF;
1004         setup.nr_frames  = nr_gframes;
1005         set_xen_guest_handle(setup.frame_list, frames);
1006
1007         rc = HYPERVISOR_grant_table_op(GNTTABOP_setup_table, &setup, 1);
1008         if (rc == -ENOSYS) {
1009                 kfree(frames);
1010                 return -ENOSYS;
1011         }
1012
1013         BUG_ON(rc || setup.status);
1014
1015         rc = gnttab_interface->map_frames(frames, nr_gframes);
1016
1017         kfree(frames);
1018
1019         return rc;
1020 }
1021
1022 static const struct gnttab_ops gnttab_v1_ops = {
1023         .map_frames                     = gnttab_map_frames_v1,
1024         .unmap_frames                   = gnttab_unmap_frames_v1,
1025         .update_entry                   = gnttab_update_entry_v1,
1026         .end_foreign_access_ref         = gnttab_end_foreign_access_ref_v1,
1027         .end_foreign_transfer_ref       = gnttab_end_foreign_transfer_ref_v1,
1028         .read_frame                     = gnttab_read_frame_v1,
1029 };
1030
1031 static void gnttab_request_version(void)
1032 {
1033         /* Only version 1 is used, which will always be available. */
1034         grant_table_version = 1;
1035         grefs_per_grant_frame = XEN_PAGE_SIZE / sizeof(struct grant_entry_v1);
1036         gnttab_interface = &gnttab_v1_ops;
1037
1038         pr_info("Grant tables using version %d layout\n", grant_table_version);
1039 }
1040
1041 static int gnttab_setup(void)
1042 {
1043         unsigned int max_nr_gframes;
1044
1045         max_nr_gframes = gnttab_max_grant_frames();
1046         if (max_nr_gframes < nr_grant_frames)
1047                 return -ENOSYS;
1048
1049         if (xen_feature(XENFEAT_auto_translated_physmap) && gnttab_shared.addr == NULL) {
1050                 gnttab_shared.addr = xen_auto_xlat_grant_frames.vaddr;
1051                 if (gnttab_shared.addr == NULL) {
1052                         pr_warn("gnttab share frames (addr=0x%08lx) is not mapped!\n",
1053                                 (unsigned long)xen_auto_xlat_grant_frames.vaddr);
1054                         return -ENOMEM;
1055                 }
1056         }
1057         return gnttab_map(0, nr_grant_frames - 1);
1058 }
1059
1060 int gnttab_resume(void)
1061 {
1062         gnttab_request_version();
1063         return gnttab_setup();
1064 }
1065
1066 int gnttab_suspend(void)
1067 {
1068         if (!xen_feature(XENFEAT_auto_translated_physmap))
1069                 gnttab_interface->unmap_frames();
1070         return 0;
1071 }
1072
1073 static int gnttab_expand(unsigned int req_entries)
1074 {
1075         int rc;
1076         unsigned int cur, extra;
1077
1078         BUG_ON(grefs_per_grant_frame == 0);
1079         cur = nr_grant_frames;
1080         extra = ((req_entries + (grefs_per_grant_frame-1)) /
1081                  grefs_per_grant_frame);
1082         if (cur + extra > gnttab_max_grant_frames())
1083                 return -ENOSPC;
1084
1085         rc = gnttab_map(cur, cur + extra - 1);
1086         if (rc == 0)
1087                 rc = grow_gnttab_list(extra);
1088
1089         return rc;
1090 }
1091
1092 int gnttab_init(void)
1093 {
1094         int i;
1095         unsigned long max_nr_grant_frames;
1096         unsigned int max_nr_glist_frames, nr_glist_frames;
1097         unsigned int nr_init_grefs;
1098         int ret;
1099
1100         gnttab_request_version();
1101         max_nr_grant_frames = gnttab_max_grant_frames();
1102         nr_grant_frames = 1;
1103
1104         /* Determine the maximum number of frames required for the
1105          * grant reference free list on the current hypervisor.
1106          */
1107         BUG_ON(grefs_per_grant_frame == 0);
1108         max_nr_glist_frames = (max_nr_grant_frames *
1109                                grefs_per_grant_frame / RPP);
1110
1111         gnttab_list = kmalloc(max_nr_glist_frames * sizeof(grant_ref_t *),
1112                               GFP_KERNEL);
1113         if (gnttab_list == NULL)
1114                 return -ENOMEM;
1115
1116         nr_glist_frames = (nr_grant_frames * grefs_per_grant_frame + RPP - 1) / RPP;
1117         for (i = 0; i < nr_glist_frames; i++) {
1118                 gnttab_list[i] = (grant_ref_t *)__get_free_page(GFP_KERNEL);
1119                 if (gnttab_list[i] == NULL) {
1120                         ret = -ENOMEM;
1121                         goto ini_nomem;
1122                 }
1123         }
1124
1125         ret = arch_gnttab_init(max_nr_grant_frames);
1126         if (ret < 0)
1127                 goto ini_nomem;
1128
1129         if (gnttab_setup() < 0) {
1130                 ret = -ENODEV;
1131                 goto ini_nomem;
1132         }
1133
1134         nr_init_grefs = nr_grant_frames * grefs_per_grant_frame;
1135
1136         for (i = NR_RESERVED_ENTRIES; i < nr_init_grefs - 1; i++)
1137                 gnttab_entry(i) = i + 1;
1138
1139         gnttab_entry(nr_init_grefs - 1) = GNTTAB_LIST_END;
1140         gnttab_free_count = nr_init_grefs - NR_RESERVED_ENTRIES;
1141         gnttab_free_head  = NR_RESERVED_ENTRIES;
1142
1143         printk("Grant table initialized\n");
1144         return 0;
1145
1146  ini_nomem:
1147         for (i--; i >= 0; i--)
1148                 free_page((unsigned long)gnttab_list[i]);
1149         kfree(gnttab_list);
1150         return ret;
1151 }
1152 EXPORT_SYMBOL_GPL(gnttab_init);
1153
1154 static int __gnttab_init(void)
1155 {
1156         /* Delay grant-table initialization in the PV on HVM case */
1157         if (xen_hvm_domain())
1158                 return 0;
1159
1160         if (!xen_pv_domain())
1161                 return -ENODEV;
1162
1163         return gnttab_init();
1164 }
1165 /* Starts after core_initcall so that xen_pvh_gnttab_setup can be called
1166  * beforehand to initialize xen_auto_xlat_grant_frames. */
1167 core_initcall_sync(__gnttab_init);