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          * Query the status of a grant entry. Ref parameter is reference of
 119          * queried grant entry, return value is the status of queried entry.
 120          * Detailed status(writing/reading) can be gotten from the return value
 121          * by bit operations.
 122          */
 123         int (*query_foreign_access)(grant_ref_t ref);
 124 };
 125
 126 struct unmap_refs_callback_data {
 127         struct completion completion;
 128         int result;
 129 };
 130
 131 static const struct gnttab_ops *gnttab_interface;
 132
 133 static int grant_table_version;
 134 static int grefs_per_grant_frame;
 135
 136 static struct gnttab_free_callback *gnttab_free_callback_list;
 137
 138 static int gnttab_expand(unsigned int req_entries);
 139
 140 #define RPP (PAGE_SIZE / sizeof(grant_ref_t))
 141
 142 static inline grant_ref_t *__gnttab_entry(grant_ref_t entry)
 143 {
 144         return &gnttab_list[(entry) / RPP][(entry) % RPP];
 145 }
 146 /* This can be used as an l-value */
 147 #define gnttab_entry(entry) (*__gnttab_entry(entry))
 148
 149 static int get_free_entries(unsigned count)
 150 {
 151         unsigned long flags;
 152         int ref, rc = 0;
 153         grant_ref_t head;
 154
 155         spin_lock_irqsave(&gnttab_list_lock, flags);
 156
 157         if ((gnttab_free_count < count) &&
 158             ((rc = gnttab_expand(count - gnttab_free_count)) < 0)) {
 159                 spin_unlock_irqrestore(&gnttab_list_lock, flags);
 160                 return rc;
 161         }
 162
 163         ref = head = gnttab_free_head;
 164         gnttab_free_count -= count;
 165         while (count-- > 1)
 166                 head = gnttab_entry(head);
 167         gnttab_free_head = gnttab_entry(head);
 168         gnttab_entry(head) = GNTTAB_LIST_END;
 169
 170         spin_unlock_irqrestore(&gnttab_list_lock, flags);
 171
 172         return ref;
 173 }
 174
 175 static void do_free_callbacks(void)
 176 {
 177         struct gnttab_free_callback *callback, *next;
 178
 179         callback = gnttab_free_callback_list;
 180         gnttab_free_callback_list = NULL;
 181
 182         while (callback != NULL) {
 183                 next = callback->next;
 184                 if (gnttab_free_count >= callback->count) {
 185                         callback->next = NULL;
 186                         callback->fn(callback->arg);
 187                 } else {
 188                         callback->next = gnttab_free_callback_list;
 189                         gnttab_free_callback_list = callback;
 190                 }
 191                 callback = next;
 192         }
 193 }
 194
 195 static inline void check_free_callbacks(void)
 196 {
 197         if (unlikely(gnttab_free_callback_list))
 198                 do_free_callbacks();
 199 }
 200
 201 static void put_free_entry(grant_ref_t ref)
 202 {
 203         unsigned long flags;
 204         spin_lock_irqsave(&gnttab_list_lock, flags);
 205         gnttab_entry(ref) = gnttab_free_head;
 206         gnttab_free_head = ref;
 207         gnttab_free_count++;
 208         check_free_callbacks();
 209         spin_unlock_irqrestore(&gnttab_list_lock, flags);
 210 }
 211
 212 /*
 213  * Following applies to gnttab_update_entry_v1.
 214  * Introducing a valid entry into the grant table:
 215  *  1. Write ent->domid.
 216  *  2. Write ent->frame:
 217  *      GTF_permit_access:   Frame to which access is permitted.
 218  *      GTF_accept_transfer: Pseudo-phys frame slot being filled by new
 219  *                           frame, or zero if none.
 220  *  3. Write memory barrier (WMB).
 221  *  4. Write ent->flags, inc. valid type.
 222  */
 223 static void gnttab_update_entry_v1(grant_ref_t ref, domid_t domid,
 224                                    unsigned long frame, unsigned flags)
 225 {
 226         gnttab_shared.v1[ref].domid = domid;
 227         gnttab_shared.v1[ref].frame = frame;
 228         wmb();
 229         gnttab_shared.v1[ref].flags = flags;
 230 }
 231
 232 /*
 233  * Public grant-issuing interface functions
 234  */
 235 void gnttab_grant_foreign_access_ref(grant_ref_t ref, domid_t domid,
 236                                      unsigned long frame, int readonly)
 237 {
 238         gnttab_interface->update_entry(ref, domid, frame,
 239                            GTF_permit_access | (readonly ? GTF_readonly : 0));
 240 }
 241 EXPORT_SYMBOL_GPL(gnttab_grant_foreign_access_ref);
 242
 243 int gnttab_grant_foreign_access(domid_t domid, unsigned long frame,
 244                                 int readonly)
 245 {
 246         int ref;
 247
 248         ref = get_free_entries(1);
 249         if (unlikely(ref < 0))
 250                 return -ENOSPC;
 251
 252         gnttab_grant_foreign_access_ref(ref, domid, frame, readonly);
 253
 254         return ref;
 255 }
 256 EXPORT_SYMBOL_GPL(gnttab_grant_foreign_access);
 257
 258 static int gnttab_query_foreign_access_v1(grant_ref_t ref)
 259 {
 260         return gnttab_shared.v1[ref].flags & (GTF_reading|GTF_writing);
 261 }
 262
 263 int gnttab_query_foreign_access(grant_ref_t ref)
 264 {
 265         return gnttab_interface->query_foreign_access(ref);
 266 }
 267 EXPORT_SYMBOL_GPL(gnttab_query_foreign_access);
 268
 269 static int gnttab_end_foreign_access_ref_v1(grant_ref_t ref, int readonly)
 270 {
 271         u16 flags, nflags;
 272         u16 *pflags;
 273
 274         pflags = &gnttab_shared.v1[ref].flags;
 275         nflags = *pflags;
 276         do {
 277                 flags = nflags;
 278                 if (flags & (GTF_reading|GTF_writing))
 279                         return 0;
 280         } while ((nflags = sync_cmpxchg(pflags, flags, 0)) != flags);
 281
 282         return 1;
 283 }
 284
 285 static inline int _gnttab_end_foreign_access_ref(grant_ref_t ref, int readonly)
 286 {
 287         return gnttab_interface->end_foreign_access_ref(ref, readonly);
 288 }
 289
 290 int gnttab_end_foreign_access_ref(grant_ref_t ref, int readonly)
 291 {
 292         if (_gnttab_end_foreign_access_ref(ref, readonly))
 293                 return 1;
 294         pr_warn("WARNING: g.e. %#x still in use!\n", ref);
 295         return 0;
 296 }
 297 EXPORT_SYMBOL_GPL(gnttab_end_foreign_access_ref);
 298
 299 struct deferred_entry {
 300         struct list_head list;
 301         grant_ref_t ref;
 302         bool ro;
 303         uint16_t warn_delay;
 304         struct page *page;
 305 };
 306 static LIST_HEAD(deferred_list);
 307 static void gnttab_handle_deferred(unsigned long);
 308 static DEFINE_TIMER(deferred_timer, gnttab_handle_deferred, 0, 0);
 309
 310 static void gnttab_handle_deferred(unsigned long unused)
 311 {
 312         unsigned int nr = 10;
 313         struct deferred_entry *first = NULL;
 314         unsigned long flags;
 315
 316         spin_lock_irqsave(&gnttab_list_lock, flags);
 317         while (nr--) {
 318                 struct deferred_entry *entry
 319                         = list_first_entry(&deferred_list,
 320                                            struct deferred_entry, list);
 321
 322                 if (entry == first)
 323                         break;
 324                 list_del(&entry->list);
 325                 spin_unlock_irqrestore(&gnttab_list_lock, flags);
 326                 if (_gnttab_end_foreign_access_ref(entry->ref, entry->ro)) {
 327                         put_free_entry(entry->ref);
 328                         if (entry->page) {
 329                                 pr_debug("freeing g.e. %#x (pfn %#lx)\n",
 330                                          entry->ref, page_to_pfn(entry->page));
 331                                 __free_page(entry->page);
 332                         } else
 333                                 pr_info("freeing g.e. %#x\n", entry->ref);
 334                         kfree(entry);
 335                         entry = NULL;
 336                 } else {
 337                         if (!--entry->warn_delay)
 338                                 pr_info("g.e. %#x still pending\n", entry->ref);
 339                         if (!first)
 340                                 first = entry;
 341                 }
 342                 spin_lock_irqsave(&gnttab_list_lock, flags);
 343                 if (entry)
 344                         list_add_tail(&entry->list, &deferred_list);
 345                 else if (list_empty(&deferred_list))
 346                         break;
 347         }
 348         if (!list_empty(&deferred_list) && !timer_pending(&deferred_timer)) {
 349                 deferred_timer.expires = jiffies + HZ;
 350                 add_timer(&deferred_timer);
 351         }
 352         spin_unlock_irqrestore(&gnttab_list_lock, flags);
 353 }
 354
 355 static void gnttab_add_deferred(grant_ref_t ref, bool readonly,
 356                                 struct page *page)
 357 {
 358         struct deferred_entry *entry = kmalloc(sizeof(*entry), GFP_ATOMIC);
 359         const char *what = KERN_WARNING "leaking";
 360
 361         if (entry) {
 362                 unsigned long flags;
 363
 364                 entry->ref = ref;
 365                 entry->ro = readonly;
 366                 entry->page = page;
 367                 entry->warn_delay = 60;
 368                 spin_lock_irqsave(&gnttab_list_lock, flags);
 369                 list_add_tail(&entry->list, &deferred_list);
 370                 if (!timer_pending(&deferred_timer)) {
 371                         deferred_timer.expires = jiffies + HZ;
 372                         add_timer(&deferred_timer);
 373                 }
 374                 spin_unlock_irqrestore(&gnttab_list_lock, flags);
 375                 what = KERN_DEBUG "deferring";
 376         }
 377         printk("%s g.e. %#x (pfn %#lx)\n",
 378                what, ref, page ? page_to_pfn(page) : -1);
 379 }
 380
 381 void gnttab_end_foreign_access(grant_ref_t ref, int readonly,
 382                                unsigned long page)
 383 {
 384         if (gnttab_end_foreign_access_ref(ref, readonly)) {
 385                 put_free_entry(ref);
 386                 if (page != 0)
 387                         free_page(page);
 388         } else
 389                 gnttab_add_deferred(ref, readonly,
 390                                     page ? virt_to_page(page) : NULL);
 391 }
 392 EXPORT_SYMBOL_GPL(gnttab_end_foreign_access);
 393
 394 int gnttab_grant_foreign_transfer(domid_t domid, unsigned long pfn)
 395 {
 396         int ref;
 397
 398         ref = get_free_entries(1);
 399         if (unlikely(ref < 0))
 400                 return -ENOSPC;
 401         gnttab_grant_foreign_transfer_ref(ref, domid, pfn);
 402
 403         return ref;
 404 }
 405 EXPORT_SYMBOL_GPL(gnttab_grant_foreign_transfer);
 406
 407 void gnttab_grant_foreign_transfer_ref(grant_ref_t ref, domid_t domid,
 408                                        unsigned long pfn)
 409 {
 410         gnttab_interface->update_entry(ref, domid, pfn, GTF_accept_transfer);
 411 }
 412 EXPORT_SYMBOL_GPL(gnttab_grant_foreign_transfer_ref);
 413
 414 static unsigned long gnttab_end_foreign_transfer_ref_v1(grant_ref_t ref)
 415 {
 416         unsigned long frame;
 417         u16           flags;
 418         u16          *pflags;
 419
 420         pflags = &gnttab_shared.v1[ref].flags;
 421
 422         /*
 423          * If a transfer is not even yet started, try to reclaim the grant
 424          * reference and return failure (== 0).
 425          */
 426         while (!((flags = *pflags) & GTF_transfer_committed)) {
 427                 if (sync_cmpxchg(pflags, flags, 0) == flags)
 428                         return 0;
 429                 cpu_relax();
 430         }
 431
 432         /* If a transfer is in progress then wait until it is completed. */
 433         while (!(flags & GTF_transfer_completed)) {
 434                 flags = *pflags;
 435                 cpu_relax();
 436         }
 437
 438         rmb();  /* Read the frame number /after/ reading completion status. */
 439         frame = gnttab_shared.v1[ref].frame;
 440         BUG_ON(frame == 0);
 441
 442         return frame;
 443 }
 444
 445 unsigned long gnttab_end_foreign_transfer_ref(grant_ref_t ref)
 446 {
 447         return gnttab_interface->end_foreign_transfer_ref(ref);
 448 }
 449 EXPORT_SYMBOL_GPL(gnttab_end_foreign_transfer_ref);
 450
 451 unsigned long gnttab_end_foreign_transfer(grant_ref_t ref)
 452 {
 453         unsigned long frame = gnttab_end_foreign_transfer_ref(ref);
 454         put_free_entry(ref);
 455         return frame;
 456 }
 457 EXPORT_SYMBOL_GPL(gnttab_end_foreign_transfer);
 458
 459 void gnttab_free_grant_reference(grant_ref_t ref)
 460 {
 461         put_free_entry(ref);
 462 }
 463 EXPORT_SYMBOL_GPL(gnttab_free_grant_reference);
 464
 465 void gnttab_free_grant_references(grant_ref_t head)
 466 {
 467         grant_ref_t ref;
 468         unsigned long flags;
 469         int count = 1;
 470         if (head == GNTTAB_LIST_END)
 471                 return;
 472         spin_lock_irqsave(&gnttab_list_lock, flags);
 473         ref = head;
 474         while (gnttab_entry(ref) != GNTTAB_LIST_END) {
 475                 ref = gnttab_entry(ref);
 476                 count++;
 477         }
 478         gnttab_entry(ref) = gnttab_free_head;
 479         gnttab_free_head = head;
 480         gnttab_free_count += count;
 481         check_free_callbacks();
 482         spin_unlock_irqrestore(&gnttab_list_lock, flags);
 483 }
 484 EXPORT_SYMBOL_GPL(gnttab_free_grant_references);
 485
 486 int gnttab_alloc_grant_references(u16 count, grant_ref_t *head)
 487 {
 488         int h = get_free_entries(count);
 489
 490         if (h < 0)
 491                 return -ENOSPC;
 492
 493         *head = h;
 494
 495         return 0;
 496 }
 497 EXPORT_SYMBOL_GPL(gnttab_alloc_grant_references);
 498
 499 int gnttab_empty_grant_references(const grant_ref_t *private_head)
 500 {
 501         return (*private_head == GNTTAB_LIST_END);
 502 }
 503 EXPORT_SYMBOL_GPL(gnttab_empty_grant_references);
 504
 505 int gnttab_claim_grant_reference(grant_ref_t *private_head)
 506 {
 507         grant_ref_t g = *private_head;
 508         if (unlikely(g == GNTTAB_LIST_END))
 509                 return -ENOSPC;
 510         *private_head = gnttab_entry(g);
 511         return g;
 512 }
 513 EXPORT_SYMBOL_GPL(gnttab_claim_grant_reference);
 514
 515 void gnttab_release_grant_reference(grant_ref_t *private_head,
 516                                     grant_ref_t release)
 517 {
 518         gnttab_entry(release) = *private_head;
 519         *private_head = release;
 520 }
 521 EXPORT_SYMBOL_GPL(gnttab_release_grant_reference);
 522
 523 void gnttab_request_free_callback(struct gnttab_free_callback *callback,
 524                                   void (*fn)(void *), void *arg, u16 count)
 525 {
 526         unsigned long flags;
 527         struct gnttab_free_callback *cb;
 528
 529         spin_lock_irqsave(&gnttab_list_lock, flags);
 530
 531         /* Check if the callback is already on the list */
 532         cb = gnttab_free_callback_list;
 533         while (cb) {
 534                 if (cb == callback)
 535                         goto out;
 536                 cb = cb->next;
 537         }
 538
 539         callback->fn = fn;
 540         callback->arg = arg;
 541         callback->count = count;
 542         callback->next = gnttab_free_callback_list;
 543         gnttab_free_callback_list = callback;
 544         check_free_callbacks();
 545 out:
 546         spin_unlock_irqrestore(&gnttab_list_lock, flags);
 547 }
 548 EXPORT_SYMBOL_GPL(gnttab_request_free_callback);
 549
 550 void gnttab_cancel_free_callback(struct gnttab_free_callback *callback)
 551 {
 552         struct gnttab_free_callback **pcb;
 553         unsigned long flags;
 554
 555         spin_lock_irqsave(&gnttab_list_lock, flags);
 556         for (pcb = &gnttab_free_callback_list; *pcb; pcb = &(*pcb)->next) {
 557                 if (*pcb == callback) {
 558                         *pcb = callback->next;
 559                         break;
 560                 }
 561         }
 562         spin_unlock_irqrestore(&gnttab_list_lock, flags);
 563 }
 564 EXPORT_SYMBOL_GPL(gnttab_cancel_free_callback);
 565
 566 static int grow_gnttab_list(unsigned int more_frames)
 567 {
 568         unsigned int new_nr_grant_frames, extra_entries, i;
 569         unsigned int nr_glist_frames, new_nr_glist_frames;
 570
 571         BUG_ON(grefs_per_grant_frame == 0);
 572
 573         new_nr_grant_frames = nr_grant_frames + more_frames;
 574         extra_entries       = more_frames * grefs_per_grant_frame;
 575
 576         nr_glist_frames = (nr_grant_frames * grefs_per_grant_frame + RPP - 1) / RPP;
 577         new_nr_glist_frames =
 578                 (new_nr_grant_frames * grefs_per_grant_frame + RPP - 1) / RPP;
 579         for (i = nr_glist_frames; i < new_nr_glist_frames; i++) {
 580                 gnttab_list[i] = (grant_ref_t *)__get_free_page(GFP_ATOMIC);
 581                 if (!gnttab_list[i])
 582                         goto grow_nomem;
 583         }
 584
 585
 586         for (i = grefs_per_grant_frame * nr_grant_frames;
 587              i < grefs_per_grant_frame * new_nr_grant_frames - 1; i++)
 588                 gnttab_entry(i) = i + 1;
 589
 590         gnttab_entry(i) = gnttab_free_head;
 591         gnttab_free_head = grefs_per_grant_frame * nr_grant_frames;
 592         gnttab_free_count += extra_entries;
 593
 594         nr_grant_frames = new_nr_grant_frames;
 595
 596         check_free_callbacks();
 597
 598         return 0;
 599
 600 grow_nomem:
 601         while (i-- > nr_glist_frames)
 602                 free_page((unsigned long) gnttab_list[i]);
 603         return -ENOMEM;
 604 }
 605
 606 static unsigned int __max_nr_grant_frames(void)
 607 {
 608         struct gnttab_query_size query;
 609         int rc;
 610
 611         query.dom = DOMID_SELF;
 612
 613         rc = HYPERVISOR_grant_table_op(GNTTABOP_query_size, &query, 1);
 614         if ((rc < 0) || (query.status != GNTST_okay))
 615                 return 4; /* Legacy max supported number of frames */
 616
 617         return query.max_nr_frames;
 618 }
 619
 620 unsigned int gnttab_max_grant_frames(void)
 621 {
 622         unsigned int xen_max = __max_nr_grant_frames();
 623         static unsigned int boot_max_nr_grant_frames;
 624
 625         /* First time, initialize it properly. */
 626         if (!boot_max_nr_grant_frames)
 627                 boot_max_nr_grant_frames = __max_nr_grant_frames();
 628
 629         if (xen_max > boot_max_nr_grant_frames)
 630                 return boot_max_nr_grant_frames;
 631         return xen_max;
 632 }
 633 EXPORT_SYMBOL_GPL(gnttab_max_grant_frames);
 634
 635 int gnttab_setup_auto_xlat_frames(phys_addr_t addr)
 636 {
 637         xen_pfn_t *pfn;
 638         unsigned int max_nr_gframes = __max_nr_grant_frames();
 639         unsigned int i;
 640         void *vaddr;
 641
 642         if (xen_auto_xlat_grant_frames.count)
 643                 return -EINVAL;
 644
 645         vaddr = xen_remap(addr, XEN_PAGE_SIZE * max_nr_gframes);
 646         if (vaddr == NULL) {
 647                 pr_warn("Failed to ioremap gnttab share frames (addr=%pa)!\n",
 648                         &addr);
 649                 return -ENOMEM;
 650         }
 651         pfn = kcalloc(max_nr_gframes, sizeof(pfn[0]), GFP_KERNEL);
 652         if (!pfn) {
 653                 xen_unmap(vaddr);
 654                 return -ENOMEM;
 655         }
 656         for (i = 0; i < max_nr_gframes; i++)
 657                 pfn[i] = XEN_PFN_DOWN(addr) + i;
 658
 659         xen_auto_xlat_grant_frames.vaddr = vaddr;
 660         xen_auto_xlat_grant_frames.pfn = pfn;
 661         xen_auto_xlat_grant_frames.count = max_nr_gframes;
 662
 663         return 0;
 664 }
 665 EXPORT_SYMBOL_GPL(gnttab_setup_auto_xlat_frames);
 666
 667 void gnttab_free_auto_xlat_frames(void)
 668 {
 669         if (!xen_auto_xlat_grant_frames.count)
 670                 return;
 671         kfree(xen_auto_xlat_grant_frames.pfn);
 672         xen_unmap(xen_auto_xlat_grant_frames.vaddr);
 673
 674         xen_auto_xlat_grant_frames.pfn = NULL;
 675         xen_auto_xlat_grant_frames.count = 0;
 676         xen_auto_xlat_grant_frames.vaddr = NULL;
 677 }
 678 EXPORT_SYMBOL_GPL(gnttab_free_auto_xlat_frames);
 679
 680 /**
 681  * gnttab_alloc_pages - alloc pages suitable for grant mapping into
 682  * @nr_pages: number of pages to alloc
 683  * @pages: returns the pages
 684  */
 685 int gnttab_alloc_pages(int nr_pages, struct page **pages)
 686 {
 687         int i;
 688         int ret;
 689
 690         ret = alloc_xenballooned_pages(nr_pages, pages);
 691         if (ret < 0)
 692                 return ret;
 693
 694         for (i = 0; i < nr_pages; i++) {
 695 #if BITS_PER_LONG < 64
 696                 struct xen_page_foreign *foreign;
 697
 698                 foreign = kzalloc(sizeof(*foreign), GFP_KERNEL);
 699                 if (!foreign) {
 700                         gnttab_free_pages(nr_pages, pages);
 701                         return -ENOMEM;
 702                 }
 703                 set_page_private(pages[i], (unsigned long)foreign);
 704 #endif
 705                 SetPagePrivate(pages[i]);
 706         }
 707
 708         return 0;
 709 }
 710 EXPORT_SYMBOL(gnttab_alloc_pages);
 711
 712 /**
 713  * gnttab_free_pages - free pages allocated by gnttab_alloc_pages()
 714  * @nr_pages; number of pages to free
 715  * @pages: the pages
 716  */
 717 void gnttab_free_pages(int nr_pages, struct page **pages)
 718 {
 719         int i;
 720
 721         for (i = 0; i < nr_pages; i++) {
 722                 if (PagePrivate(pages[i])) {
 723 #if BITS_PER_LONG < 64
 724                         kfree((void *)page_private(pages[i]));
 725 #endif
 726                         ClearPagePrivate(pages[i]);
 727                 }
 728         }
 729         free_xenballooned_pages(nr_pages, pages);
 730 }
 731 EXPORT_SYMBOL(gnttab_free_pages);
 732
 733 /* Handling of paged out grant targets (GNTST_eagain) */
 734 #define MAX_DELAY 256
 735 static inline void
 736 gnttab_retry_eagain_gop(unsigned int cmd, void *gop, int16_t *status,
 737                                                 const char *func)
 738 {
 739         unsigned delay = 1;
 740
 741         do {
 742                 BUG_ON(HYPERVISOR_grant_table_op(cmd, gop, 1));
 743                 if (*status == GNTST_eagain)
 744                         msleep(delay++);
 745         } while ((*status == GNTST_eagain) && (delay < MAX_DELAY));
 746
 747         if (delay >= MAX_DELAY) {
 748                 pr_err("%s: %s eagain grant\n", func, current->comm);
 749                 *status = GNTST_bad_page;
 750         }
 751 }
 752
 753 void gnttab_batch_map(struct gnttab_map_grant_ref *batch, unsigned count)
 754 {
 755         struct gnttab_map_grant_ref *op;
 756
 757         if (HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref, batch, count))
 758                 BUG();
 759         for (op = batch; op < batch + count; op++)
 760                 if (op->status == GNTST_eagain)
 761                         gnttab_retry_eagain_gop(GNTTABOP_map_grant_ref, op,
 762                                                 &op->status, __func__);
 763 }
 764 EXPORT_SYMBOL_GPL(gnttab_batch_map);
 765
 766 void gnttab_batch_copy(struct gnttab_copy *batch, unsigned count)
 767 {
 768         struct gnttab_copy *op;
 769
 770         if (HYPERVISOR_grant_table_op(GNTTABOP_copy, batch, count))
 771                 BUG();
 772         for (op = batch; op < batch + count; op++)
 773                 if (op->status == GNTST_eagain)
 774                         gnttab_retry_eagain_gop(GNTTABOP_copy, op,
 775                                                 &op->status, __func__);
 776 }
 777 EXPORT_SYMBOL_GPL(gnttab_batch_copy);
 778
 779 void gnttab_foreach_grant_in_range(struct page *page,
 780                                    unsigned int offset,
 781                                    unsigned int len,
 782                                    xen_grant_fn_t fn,
 783                                    void *data)
 784 {
 785         unsigned int goffset;
 786         unsigned int glen;
 787         unsigned long xen_pfn;
 788
 789         len = min_t(unsigned int, PAGE_SIZE - offset, len);
 790         goffset = xen_offset_in_page(offset);
 791
 792         xen_pfn = page_to_xen_pfn(page) + XEN_PFN_DOWN(offset);
 793
 794         while (len) {
 795                 glen = min_t(unsigned int, XEN_PAGE_SIZE - goffset, len);
 796                 fn(pfn_to_gfn(xen_pfn), goffset, glen, data);
 797
 798                 goffset = 0;
 799                 xen_pfn++;
 800                 len -= glen;
 801         }
 802 }
 803 EXPORT_SYMBOL_GPL(gnttab_foreach_grant_in_range);
 804
 805 void gnttab_foreach_grant(struct page **pages,
 806                           unsigned int nr_grefs,
 807                           xen_grant_fn_t fn,
 808                           void *data)
 809 {
 810         unsigned int goffset = 0;
 811         unsigned long xen_pfn = 0;
 812         unsigned int i;
 813
 814         for (i = 0; i < nr_grefs; i++) {
 815                 if ((i % XEN_PFN_PER_PAGE) == 0) {
 816                         xen_pfn = page_to_xen_pfn(pages[i / XEN_PFN_PER_PAGE]);
 817                         goffset = 0;
 818                 }
 819
 820                 fn(pfn_to_gfn(xen_pfn), goffset, XEN_PAGE_SIZE, data);
 821
 822                 goffset += XEN_PAGE_SIZE;
 823                 xen_pfn++;
 824         }
 825 }
 826
 827 int gnttab_map_refs(struct gnttab_map_grant_ref *map_ops,
 828                     struct gnttab_map_grant_ref *kmap_ops,
 829                     struct page **pages, unsigned int count)
 830 {
 831         int i, ret;
 832
 833         ret = HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref, map_ops, count);
 834         if (ret)
 835                 return ret;
 836
 837         for (i = 0; i < count; i++) {
 838                 /* Retry eagain maps */
 839                 if (map_ops[i].status == GNTST_eagain)
 840                         gnttab_retry_eagain_gop(GNTTABOP_map_grant_ref, map_ops + i,
 841                                                 &map_ops[i].status, __func__);
 842
 843                 if (map_ops[i].status == GNTST_okay) {
 844                         struct xen_page_foreign *foreign;
 845
 846                         SetPageForeign(pages[i]);
 847                         foreign = xen_page_foreign(pages[i]);
 848                         foreign->domid = map_ops[i].dom;
 849                         foreign->gref = map_ops[i].ref;
 850                 }
 851         }
 852
 853         return set_foreign_p2m_mapping(map_ops, kmap_ops, pages, count);
 854 }
 855 EXPORT_SYMBOL_GPL(gnttab_map_refs);
 856
 857 int gnttab_unmap_refs(struct gnttab_unmap_grant_ref *unmap_ops,
 858                       struct gnttab_unmap_grant_ref *kunmap_ops,
 859                       struct page **pages, unsigned int count)
 860 {
 861         unsigned int i;
 862         int ret;
 863
 864         ret = HYPERVISOR_grant_table_op(GNTTABOP_unmap_grant_ref, unmap_ops, count);
 865         if (ret)
 866                 return ret;
 867
 868         for (i = 0; i < count; i++)
 869                 ClearPageForeign(pages[i]);
 870
 871         return clear_foreign_p2m_mapping(unmap_ops, kunmap_ops, pages, count);
 872 }
 873 EXPORT_SYMBOL_GPL(gnttab_unmap_refs);
 874
 875 #define GNTTAB_UNMAP_REFS_DELAY 5
 876
 877 static void __gnttab_unmap_refs_async(struct gntab_unmap_queue_data* item);
 878
 879 static void gnttab_unmap_work(struct work_struct *work)
 880 {
 881         struct gntab_unmap_queue_data
 882                 *unmap_data = container_of(work,
 883                                            struct gntab_unmap_queue_data,
 884                                            gnttab_work.work);
 885         if (unmap_data->age != UINT_MAX)
 886                 unmap_data->age++;
 887         __gnttab_unmap_refs_async(unmap_data);
 888 }
 889
 890 static void __gnttab_unmap_refs_async(struct gntab_unmap_queue_data* item)
 891 {
 892         int ret;
 893         int pc;
 894
 895         for (pc = 0; pc < item->count; pc++) {
 896                 if (page_count(item->pages[pc]) > 1) {
 897                         unsigned long delay = GNTTAB_UNMAP_REFS_DELAY * (item->age + 1);
 898                         schedule_delayed_work(&item->gnttab_work,
 899                                               msecs_to_jiffies(delay));
 900                         return;
 901                 }
 902         }
 903
 904         ret = gnttab_unmap_refs(item->unmap_ops, item->kunmap_ops,
 905                                 item->pages, item->count);
 906         item->done(ret, item);
 907 }
 908
 909 void gnttab_unmap_refs_async(struct gntab_unmap_queue_data* item)
 910 {
 911         INIT_DELAYED_WORK(&item->gnttab_work, gnttab_unmap_work);
 912         item->age = 0;
 913
 914         __gnttab_unmap_refs_async(item);
 915 }
 916 EXPORT_SYMBOL_GPL(gnttab_unmap_refs_async);
 917
 918 static void unmap_refs_callback(int result,
 919                 struct gntab_unmap_queue_data *data)
 920 {
 921         struct unmap_refs_callback_data *d = data->data;
 922
 923         d->result = result;
 924         complete(&d->completion);
 925 }
 926
 927 int gnttab_unmap_refs_sync(struct gntab_unmap_queue_data *item)
 928 {
 929         struct unmap_refs_callback_data data;
 930
 931         init_completion(&data.completion);
 932         item->data = &data;
 933         item->done = &unmap_refs_callback;
 934         gnttab_unmap_refs_async(item);
 935         wait_for_completion(&data.completion);
 936
 937         return data.result;
 938 }
 939 EXPORT_SYMBOL_GPL(gnttab_unmap_refs_sync);
 940
 941 static int gnttab_map_frames_v1(xen_pfn_t *frames, unsigned int nr_gframes)
 942 {
 943         int rc;
 944
 945         rc = arch_gnttab_map_shared(frames, nr_gframes,
 946                                     gnttab_max_grant_frames(),
 947                                     &gnttab_shared.addr);
 948         BUG_ON(rc);
 949
 950         return 0;
 951 }
 952
 953 static void gnttab_unmap_frames_v1(void)
 954 {
 955         arch_gnttab_unmap(gnttab_shared.addr, nr_grant_frames);
 956 }
 957
 958 static int gnttab_map(unsigned int start_idx, unsigned int end_idx)
 959 {
 960         struct gnttab_setup_table setup;
 961         xen_pfn_t *frames;
 962         unsigned int nr_gframes = end_idx + 1;
 963         int rc;
 964
 965         if (xen_feature(XENFEAT_auto_translated_physmap)) {
 966                 struct xen_add_to_physmap xatp;
 967                 unsigned int i = end_idx;
 968                 rc = 0;
 969                 BUG_ON(xen_auto_xlat_grant_frames.count < nr_gframes);
 970                 /*
 971                  * Loop backwards, so that the first hypercall has the largest
 972                  * index, ensuring that the table will grow only once.
 973                  */
 974                 do {
 975                         xatp.domid = DOMID_SELF;
 976                         xatp.idx = i;
 977                         xatp.space = XENMAPSPACE_grant_table;
 978                         xatp.gpfn = xen_auto_xlat_grant_frames.pfn[i];
 979                         rc = HYPERVISOR_memory_op(XENMEM_add_to_physmap, &xatp);
 980                         if (rc != 0) {
 981                                 pr_warn("grant table add_to_physmap failed, err=%d\n",
 982                                         rc);
 983                                 break;
 984                         }
 985                 } while (i-- > start_idx);
 986
 987                 return rc;
 988         }
 989
 990         /* No need for kzalloc as it is initialized in following hypercall
 991          * GNTTABOP_setup_table.
 992          */
 993         frames = kmalloc(nr_gframes * sizeof(unsigned long), GFP_ATOMIC);
 994         if (!frames)
 995                 return -ENOMEM;
 996
 997         setup.dom        = DOMID_SELF;
 998         setup.nr_frames  = nr_gframes;
 999         set_xen_guest_handle(setup.frame_list, frames);
1000
1001         rc = HYPERVISOR_grant_table_op(GNTTABOP_setup_table, &setup, 1);
1002         if (rc == -ENOSYS) {
1003                 kfree(frames);
1004                 return -ENOSYS;
1005         }
1006
1007         BUG_ON(rc || setup.status);
1008
1009         rc = gnttab_interface->map_frames(frames, nr_gframes);
1010
1011         kfree(frames);
1012
1013         return rc;
1014 }
1015
1016 static const struct gnttab_ops gnttab_v1_ops = {
1017         .map_frames                     = gnttab_map_frames_v1,
1018         .unmap_frames                   = gnttab_unmap_frames_v1,
1019         .update_entry                   = gnttab_update_entry_v1,
1020         .end_foreign_access_ref         = gnttab_end_foreign_access_ref_v1,
1021         .end_foreign_transfer_ref       = gnttab_end_foreign_transfer_ref_v1,
1022         .query_foreign_access           = gnttab_query_foreign_access_v1,
1023 };
1024
1025 static void gnttab_request_version(void)
1026 {
1027         /* Only version 1 is used, which will always be available. */
1028         grant_table_version = 1;
1029         grefs_per_grant_frame = XEN_PAGE_SIZE / sizeof(struct grant_entry_v1);
1030         gnttab_interface = &gnttab_v1_ops;
1031
1032         pr_info("Grant tables using version %d layout\n", grant_table_version);
1033 }
1034
1035 static int gnttab_setup(void)
1036 {
1037         unsigned int max_nr_gframes;
1038
1039         max_nr_gframes = gnttab_max_grant_frames();
1040         if (max_nr_gframes < nr_grant_frames)
1041                 return -ENOSYS;
1042
1043         if (xen_feature(XENFEAT_auto_translated_physmap) && gnttab_shared.addr == NULL) {
1044                 gnttab_shared.addr = xen_auto_xlat_grant_frames.vaddr;
1045                 if (gnttab_shared.addr == NULL) {
1046                         pr_warn("gnttab share frames (addr=0x%08lx) is not mapped!\n",
1047                                 (unsigned long)xen_auto_xlat_grant_frames.vaddr);
1048                         return -ENOMEM;
1049                 }
1050         }
1051         return gnttab_map(0, nr_grant_frames - 1);
1052 }
1053
1054 int gnttab_resume(void)
1055 {
1056         gnttab_request_version();
1057         return gnttab_setup();
1058 }
1059
1060 int gnttab_suspend(void)
1061 {
1062         if (!xen_feature(XENFEAT_auto_translated_physmap))
1063                 gnttab_interface->unmap_frames();
1064         return 0;
1065 }
1066
1067 static int gnttab_expand(unsigned int req_entries)
1068 {
1069         int rc;
1070         unsigned int cur, extra;
1071
1072         BUG_ON(grefs_per_grant_frame == 0);
1073         cur = nr_grant_frames;
1074         extra = ((req_entries + (grefs_per_grant_frame-1)) /
1075                  grefs_per_grant_frame);
1076         if (cur + extra > gnttab_max_grant_frames()) {
1077                 pr_warn_ratelimited("xen/grant-table: max_grant_frames reached"
1078                                     " cur=%u extra=%u limit=%u"
1079                                     " gnttab_free_count=%u req_entries=%u\n",
1080                                     cur, extra, gnttab_max_grant_frames(),
1081                                     gnttab_free_count, req_entries);
1082                 return -ENOSPC;
1083         }
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         if (!xen_domain())
1157                 return -ENODEV;
1158
1159         /* Delay grant-table initialization in the PV on HVM case */
1160         if (xen_hvm_domain() && !xen_pvh_domain())
1161                 return 0;
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);