drivers/xen/grant-table.c

   1 /******************************************************************************
   2  * grant_table.c
   3  *
   4  * Granting foreign access to our memory reservation.
   5  *
   6  * Copyright (c) 2005-2006, Christopher Clark
   7  * Copyright (c) 2004-2005, K A Fraser
   8  *
   9  * This program is free software; you can redistribute it and/or
  10  * modify it under the terms of the GNU General Public License version 2
  11  * as published by the Free Software Foundation; or, when distributed
  12  * separately from the Linux kernel or incorporated into other
  13  * software packages, subject to the following license:
  14  *
  15  * Permission is hereby granted, free of charge, to any person obtaining a copy
  16  * of this source file (the "Software"), to deal in the Software without
  17  * restriction, including without limitation the rights to use, copy, modify,
  18  * merge, publish, distribute, sublicense, and/or sell copies of the Software,
  19  * and to permit persons to whom the Software is furnished to do so, subject to
  20  * the following conditions:
  21  *
  22  * The above copyright notice and this permission notice shall be included in
  23  * all copies or substantial portions of the Software.
  24  *
  25  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  26  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  27  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  28  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  29  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  30  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
  31  * IN THE SOFTWARE.
  32  */
  33
  34 #define pr_fmt(fmt) "xen:" KBUILD_MODNAME ": " fmt
  35
  36 #include <linux/module.h>
  37 #include <linux/sched.h>
  38 #include <linux/mm.h>
  39 #include <linux/slab.h>
  40 #include <linux/vmalloc.h>
  41 #include <linux/uaccess.h>
  42 #include <linux/io.h>
  43 #include <linux/delay.h>
  44 #include <linux/hardirq.h>
  45 #include <linux/workqueue.h>
  46
  47 #include <xen/xen.h>
  48 #include <xen/interface/xen.h>
  49 #include <xen/page.h>
  50 #include <xen/grant_table.h>
  51 #include <xen/interface/memory.h>
  52 #include <xen/hvc-console.h>
  53 #include <xen/swiotlb-xen.h>
  54 #include <xen/balloon.h>
  55 #include <asm/xen/hypercall.h>
  56 #include <asm/xen/interface.h>
  57
  58 #include <asm/pgtable.h>
  59 #include <asm/sync_bitops.h>
  60
  61 /* External tools reserve first few grant table entries. */
  62 #define NR_RESERVED_ENTRIES 8
  63 #define GNTTAB_LIST_END 0xffffffff
  64
  65 static grant_ref_t **gnttab_list;
  66 static unsigned int nr_grant_frames;
  67 static int gnttab_free_count;
  68 static grant_ref_t gnttab_free_head;
  69 static DEFINE_SPINLOCK(gnttab_list_lock);
  70 struct grant_frames xen_auto_xlat_grant_frames;
  71
  72 static union {
  73         struct grant_entry_v1 *v1;
  74         void *addr;
  75 } gnttab_shared;
  76
  77 /*This is a structure of function pointers for grant table*/
  78 struct gnttab_ops {
  79         /*
  80          * Mapping a list of frames for storing grant entries. Frames parameter
  81          * is used to store grant table address when grant table being setup,
  82          * nr_gframes is the number of frames to map grant table. Returning
  83          * GNTST_okay means success and negative value means failure.
  84          */
  85         int (*map_frames)(xen_pfn_t *frames, unsigned int nr_gframes);
  86         /*
  87          * Release a list of frames which are mapped in map_frames for grant
  88          * entry status.
  89          */
  90         void (*unmap_frames)(void);
  91         /*
  92          * Introducing a valid entry into the grant table, granting the frame of
  93          * this grant entry to domain for accessing or transfering. Ref
  94          * parameter is reference of this introduced grant entry, domid is id of
  95          * granted domain, frame is the page frame to be granted, and flags is
  96          * status of the grant entry to be updated.
  97          */
  98         void (*update_entry)(grant_ref_t ref, domid_t domid,
  99                              unsigned long frame, unsigned flags);
 100         /*
 101          * Stop granting a grant entry to domain for accessing. Ref parameter is
 102          * reference of a grant entry whose grant access will be stopped,
 103          * readonly is not in use in this function. If the grant entry is
 104          * currently mapped for reading or writing, just return failure(==0)
 105          * directly and don't tear down the grant access. Otherwise, stop grant
 106          * access for this entry and return success(==1).
 107          */
 108         int (*end_foreign_access_ref)(grant_ref_t ref, int readonly);
 109         /*
 110          * Stop granting a grant entry to domain for transfer. Ref parameter is
 111          * reference of a grant entry whose grant transfer will be stopped. If
 112          * tranfer has not started, just reclaim the grant entry and return
 113          * failure(==0). Otherwise, wait for the transfer to complete and then
 114          * return the frame.
 115          */
 116         unsigned long (*end_foreign_transfer_ref)(grant_ref_t ref);
 117         /*
 118          * Query the status of a grant entry. Ref parameter is reference of
 119          * queried grant entry, return value is the status of queried entry.
 120          * Detailed status(writing/reading) can be gotten from the return value
 121          * by bit operations.
 122          */
 123         int (*query_foreign_access)(grant_ref_t ref);
 124 };
 125
 126 static struct gnttab_ops *gnttab_interface;
 127
 128 static int grant_table_version;
 129 static int grefs_per_grant_frame;
 130
 131 static struct gnttab_free_callback *gnttab_free_callback_list;
 132
 133 static int gnttab_expand(unsigned int req_entries);
 134
 135 #define RPP (PAGE_SIZE / sizeof(grant_ref_t))
 136 #define SPP (PAGE_SIZE / sizeof(grant_status_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_query_foreign_access_v1(grant_ref_t ref)
 255 {
 256         return gnttab_shared.v1[ref].flags & (GTF_reading|GTF_writing);
 257 }
 258
 259 int gnttab_query_foreign_access(grant_ref_t ref)
 260 {
 261         return gnttab_interface->query_foreign_access(ref);
 262 }
 263 EXPORT_SYMBOL_GPL(gnttab_query_foreign_access);
 264
 265 static int gnttab_end_foreign_access_ref_v1(grant_ref_t ref, int readonly)
 266 {
 267         u16 flags, nflags;
 268         u16 *pflags;
 269
 270         pflags = &gnttab_shared.v1[ref].flags;
 271         nflags = *pflags;
 272         do {
 273                 flags = nflags;
 274                 if (flags & (GTF_reading|GTF_writing))
 275                         return 0;
 276         } while ((nflags = sync_cmpxchg(pflags, flags, 0)) != flags);
 277
 278         return 1;
 279 }
 280
 281 static inline int _gnttab_end_foreign_access_ref(grant_ref_t ref, int readonly)
 282 {
 283         return gnttab_interface->end_foreign_access_ref(ref, readonly);
 284 }
 285
 286 int gnttab_end_foreign_access_ref(grant_ref_t ref, int readonly)
 287 {
 288         if (_gnttab_end_foreign_access_ref(ref, readonly))
 289                 return 1;
 290         pr_warn("WARNING: g.e. %#x still in use!\n", ref);
 291         return 0;
 292 }
 293 EXPORT_SYMBOL_GPL(gnttab_end_foreign_access_ref);
 294
 295 struct deferred_entry {
 296         struct list_head list;
 297         grant_ref_t ref;
 298         bool ro;
 299         uint16_t warn_delay;
 300         struct page *page;
 301 };
 302 static LIST_HEAD(deferred_list);
 303 static void gnttab_handle_deferred(unsigned long);
 304 static DEFINE_TIMER(deferred_timer, gnttab_handle_deferred, 0, 0);
 305
 306 static void gnttab_handle_deferred(unsigned long unused)
 307 {
 308         unsigned int nr = 10;
 309         struct deferred_entry *first = NULL;
 310         unsigned long flags;
 311
 312         spin_lock_irqsave(&gnttab_list_lock, flags);
 313         while (nr--) {
 314                 struct deferred_entry *entry
 315                         = list_first_entry(&deferred_list,
 316                                            struct deferred_entry, list);
 317
 318                 if (entry == first)
 319                         break;
 320                 list_del(&entry->list);
 321                 spin_unlock_irqrestore(&gnttab_list_lock, flags);
 322                 if (_gnttab_end_foreign_access_ref(entry->ref, entry->ro)) {
 323                         put_free_entry(entry->ref);
 324                         if (entry->page) {
 325                                 pr_debug("freeing g.e. %#x (pfn %#lx)\n",
 326                                          entry->ref, page_to_pfn(entry->page));
 327                                 __free_page(entry->page);
 328                         } else
 329                                 pr_info("freeing g.e. %#x\n", entry->ref);
 330                         kfree(entry);
 331                         entry = NULL;
 332                 } else {
 333                         if (!--entry->warn_delay)
 334                                 pr_info("g.e. %#x still pending\n", entry->ref);
 335                         if (!first)
 336                                 first = entry;
 337                 }
 338                 spin_lock_irqsave(&gnttab_list_lock, flags);
 339                 if (entry)
 340                         list_add_tail(&entry->list, &deferred_list);
 341                 else if (list_empty(&deferred_list))
 342                         break;
 343         }
 344         if (!list_empty(&deferred_list) && !timer_pending(&deferred_timer)) {
 345                 deferred_timer.expires = jiffies + HZ;
 346                 add_timer(&deferred_timer);
 347         }
 348         spin_unlock_irqrestore(&gnttab_list_lock, flags);
 349 }
 350
 351 static void gnttab_add_deferred(grant_ref_t ref, bool readonly,
 352                                 struct page *page)
 353 {
 354         struct deferred_entry *entry = kmalloc(sizeof(*entry), GFP_ATOMIC);
 355         const char *what = KERN_WARNING "leaking";
 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 void gnttab_end_foreign_access(grant_ref_t ref, int readonly,
 378                                unsigned long page)
 379 {
 380         if (gnttab_end_foreign_access_ref(ref, readonly)) {
 381                 put_free_entry(ref);
 382                 if (page != 0)
 383                         free_page(page);
 384         } else
 385                 gnttab_add_deferred(ref, readonly,
 386                                     page ? virt_to_page(page) : NULL);
 387 }
 388 EXPORT_SYMBOL_GPL(gnttab_end_foreign_access);
 389
 390 int gnttab_grant_foreign_transfer(domid_t domid, unsigned long pfn)
 391 {
 392         int ref;
 393
 394         ref = get_free_entries(1);
 395         if (unlikely(ref < 0))
 396                 return -ENOSPC;
 397         gnttab_grant_foreign_transfer_ref(ref, domid, pfn);
 398
 399         return ref;
 400 }
 401 EXPORT_SYMBOL_GPL(gnttab_grant_foreign_transfer);
 402
 403 void gnttab_grant_foreign_transfer_ref(grant_ref_t ref, domid_t domid,
 404                                        unsigned long pfn)
 405 {
 406         gnttab_interface->update_entry(ref, domid, pfn, GTF_accept_transfer);
 407 }
 408 EXPORT_SYMBOL_GPL(gnttab_grant_foreign_transfer_ref);
 409
 410 static unsigned long gnttab_end_foreign_transfer_ref_v1(grant_ref_t ref)
 411 {
 412         unsigned long frame;
 413         u16           flags;
 414         u16          *pflags;
 415
 416         pflags = &gnttab_shared.v1[ref].flags;
 417
 418         /*
 419          * If a transfer is not even yet started, try to reclaim the grant
 420          * reference and return failure (== 0).
 421          */
 422         while (!((flags = *pflags) & GTF_transfer_committed)) {
 423                 if (sync_cmpxchg(pflags, flags, 0) == flags)
 424                         return 0;
 425                 cpu_relax();
 426         }
 427
 428         /* If a transfer is in progress then wait until it is completed. */
 429         while (!(flags & GTF_transfer_completed)) {
 430                 flags = *pflags;
 431                 cpu_relax();
 432         }
 433
 434         rmb();  /* Read the frame number /after/ reading completion status. */
 435         frame = gnttab_shared.v1[ref].frame;
 436         BUG_ON(frame == 0);
 437
 438         return frame;
 439 }
 440
 441 unsigned long gnttab_end_foreign_transfer_ref(grant_ref_t ref)
 442 {
 443         return gnttab_interface->end_foreign_transfer_ref(ref);
 444 }
 445 EXPORT_SYMBOL_GPL(gnttab_end_foreign_transfer_ref);
 446
 447 unsigned long gnttab_end_foreign_transfer(grant_ref_t ref)
 448 {
 449         unsigned long frame = gnttab_end_foreign_transfer_ref(ref);
 450         put_free_entry(ref);
 451         return frame;
 452 }
 453 EXPORT_SYMBOL_GPL(gnttab_end_foreign_transfer);
 454
 455 void gnttab_free_grant_reference(grant_ref_t ref)
 456 {
 457         put_free_entry(ref);
 458 }
 459 EXPORT_SYMBOL_GPL(gnttab_free_grant_reference);
 460
 461 void gnttab_free_grant_references(grant_ref_t head)
 462 {
 463         grant_ref_t ref;
 464         unsigned long flags;
 465         int count = 1;
 466         if (head == GNTTAB_LIST_END)
 467                 return;
 468         spin_lock_irqsave(&gnttab_list_lock, flags);
 469         ref = head;
 470         while (gnttab_entry(ref) != GNTTAB_LIST_END) {
 471                 ref = gnttab_entry(ref);
 472                 count++;
 473         }
 474         gnttab_entry(ref) = gnttab_free_head;
 475         gnttab_free_head = head;
 476         gnttab_free_count += count;
 477         check_free_callbacks();
 478         spin_unlock_irqrestore(&gnttab_list_lock, flags);
 479 }
 480 EXPORT_SYMBOL_GPL(gnttab_free_grant_references);
 481
 482 int gnttab_alloc_grant_references(u16 count, grant_ref_t *head)
 483 {
 484         int h = get_free_entries(count);
 485
 486         if (h < 0)
 487                 return -ENOSPC;
 488
 489         *head = h;
 490
 491         return 0;
 492 }
 493 EXPORT_SYMBOL_GPL(gnttab_alloc_grant_references);
 494
 495 int gnttab_empty_grant_references(const grant_ref_t *private_head)
 496 {
 497         return (*private_head == GNTTAB_LIST_END);
 498 }
 499 EXPORT_SYMBOL_GPL(gnttab_empty_grant_references);
 500
 501 int gnttab_claim_grant_reference(grant_ref_t *private_head)
 502 {
 503         grant_ref_t g = *private_head;
 504         if (unlikely(g == GNTTAB_LIST_END))
 505                 return -ENOSPC;
 506         *private_head = gnttab_entry(g);
 507         return g;
 508 }
 509 EXPORT_SYMBOL_GPL(gnttab_claim_grant_reference);
 510
 511 void gnttab_release_grant_reference(grant_ref_t *private_head,
 512                                     grant_ref_t release)
 513 {
 514         gnttab_entry(release) = *private_head;
 515         *private_head = release;
 516 }
 517 EXPORT_SYMBOL_GPL(gnttab_release_grant_reference);
 518
 519 void gnttab_request_free_callback(struct gnttab_free_callback *callback,
 520                                   void (*fn)(void *), void *arg, u16 count)
 521 {
 522         unsigned long flags;
 523         struct gnttab_free_callback *cb;
 524
 525         spin_lock_irqsave(&gnttab_list_lock, flags);
 526
 527         /* Check if the callback is already on the list */
 528         cb = gnttab_free_callback_list;
 529         while (cb) {
 530                 if (cb == callback)
 531                         goto out;
 532                 cb = cb->next;
 533         }
 534
 535         callback->fn = fn;
 536         callback->arg = arg;
 537         callback->count = count;
 538         callback->next = gnttab_free_callback_list;
 539         gnttab_free_callback_list = callback;
 540         check_free_callbacks();
 541 out:
 542         spin_unlock_irqrestore(&gnttab_list_lock, flags);
 543 }
 544 EXPORT_SYMBOL_GPL(gnttab_request_free_callback);
 545
 546 void gnttab_cancel_free_callback(struct gnttab_free_callback *callback)
 547 {
 548         struct gnttab_free_callback **pcb;
 549         unsigned long flags;
 550
 551         spin_lock_irqsave(&gnttab_list_lock, flags);
 552         for (pcb = &gnttab_free_callback_list; *pcb; pcb = &(*pcb)->next) {
 553                 if (*pcb == callback) {
 554                         *pcb = callback->next;
 555                         break;
 556                 }
 557         }
 558         spin_unlock_irqrestore(&gnttab_list_lock, flags);
 559 }
 560 EXPORT_SYMBOL_GPL(gnttab_cancel_free_callback);
 561
 562 static int grow_gnttab_list(unsigned int more_frames)
 563 {
 564         unsigned int new_nr_grant_frames, extra_entries, i;
 565         unsigned int nr_glist_frames, new_nr_glist_frames;
 566
 567         BUG_ON(grefs_per_grant_frame == 0);
 568
 569         new_nr_grant_frames = nr_grant_frames + more_frames;
 570         extra_entries       = more_frames * grefs_per_grant_frame;
 571
 572         nr_glist_frames = (nr_grant_frames * grefs_per_grant_frame + RPP - 1) / RPP;
 573         new_nr_glist_frames =
 574                 (new_nr_grant_frames * grefs_per_grant_frame + RPP - 1) / RPP;
 575         for (i = nr_glist_frames; i < new_nr_glist_frames; i++) {
 576                 gnttab_list[i] = (grant_ref_t *)__get_free_page(GFP_ATOMIC);
 577                 if (!gnttab_list[i])
 578                         goto grow_nomem;
 579         }
 580
 581
 582         for (i = grefs_per_grant_frame * nr_grant_frames;
 583              i < grefs_per_grant_frame * new_nr_grant_frames - 1; i++)
 584                 gnttab_entry(i) = i + 1;
 585
 586         gnttab_entry(i) = gnttab_free_head;
 587         gnttab_free_head = grefs_per_grant_frame * nr_grant_frames;
 588         gnttab_free_count += extra_entries;
 589
 590         nr_grant_frames = new_nr_grant_frames;
 591
 592         check_free_callbacks();
 593
 594         return 0;
 595
 596 grow_nomem:
 597         while (i-- > nr_glist_frames)
 598                 free_page((unsigned long) gnttab_list[i]);
 599         return -ENOMEM;
 600 }
 601
 602 static unsigned int __max_nr_grant_frames(void)
 603 {
 604         struct gnttab_query_size query;
 605         int rc;
 606
 607         query.dom = DOMID_SELF;
 608
 609         rc = HYPERVISOR_grant_table_op(GNTTABOP_query_size, &query, 1);
 610         if ((rc < 0) || (query.status != GNTST_okay))
 611                 return 4; /* Legacy max supported number of frames */
 612
 613         return query.max_nr_frames;
 614 }
 615
 616 unsigned int gnttab_max_grant_frames(void)
 617 {
 618         unsigned int xen_max = __max_nr_grant_frames();
 619         static unsigned int boot_max_nr_grant_frames;
 620
 621         /* First time, initialize it properly. */
 622         if (!boot_max_nr_grant_frames)
 623                 boot_max_nr_grant_frames = __max_nr_grant_frames();
 624
 625         if (xen_max > boot_max_nr_grant_frames)
 626                 return boot_max_nr_grant_frames;
 627         return xen_max;
 628 }
 629 EXPORT_SYMBOL_GPL(gnttab_max_grant_frames);
 630
 631 int gnttab_setup_auto_xlat_frames(phys_addr_t addr)
 632 {
 633         xen_pfn_t *pfn;
 634         unsigned int max_nr_gframes = __max_nr_grant_frames();
 635         unsigned int i;
 636         void *vaddr;
 637
 638         if (xen_auto_xlat_grant_frames.count)
 639                 return -EINVAL;
 640
 641         vaddr = xen_remap(addr, PAGE_SIZE * max_nr_gframes);
 642         if (vaddr == NULL) {
 643                 pr_warn("Failed to ioremap gnttab share frames (addr=%pa)!\n",
 644                         &addr);
 645                 return -ENOMEM;
 646         }
 647         pfn = kcalloc(max_nr_gframes, sizeof(pfn[0]), GFP_KERNEL);
 648         if (!pfn) {
 649                 xen_unmap(vaddr);
 650                 return -ENOMEM;
 651         }
 652         for (i = 0; i < max_nr_gframes; i++)
 653                 pfn[i] = PFN_DOWN(addr) + i;
 654
 655         xen_auto_xlat_grant_frames.vaddr = vaddr;
 656         xen_auto_xlat_grant_frames.pfn = pfn;
 657         xen_auto_xlat_grant_frames.count = max_nr_gframes;
 658
 659         return 0;
 660 }
 661 EXPORT_SYMBOL_GPL(gnttab_setup_auto_xlat_frames);
 662
 663 void gnttab_free_auto_xlat_frames(void)
 664 {
 665         if (!xen_auto_xlat_grant_frames.count)
 666                 return;
 667         kfree(xen_auto_xlat_grant_frames.pfn);
 668         xen_unmap(xen_auto_xlat_grant_frames.vaddr);
 669
 670         xen_auto_xlat_grant_frames.pfn = NULL;
 671         xen_auto_xlat_grant_frames.count = 0;
 672         xen_auto_xlat_grant_frames.vaddr = NULL;
 673 }
 674 EXPORT_SYMBOL_GPL(gnttab_free_auto_xlat_frames);
 675
 676 /**
 677  * gnttab_alloc_pages - alloc pages suitable for grant mapping into
 678  * @nr_pages: number of pages to alloc
 679  * @pages: returns the pages
 680  */
 681 int gnttab_alloc_pages(int nr_pages, struct page **pages)
 682 {
 683         int i;
 684         int ret;
 685
 686         ret = alloc_xenballooned_pages(nr_pages, pages, false);
 687         if (ret < 0)
 688                 return ret;
 689
 690         for (i = 0; i < nr_pages; i++) {
 691 #if BITS_PER_LONG < 64
 692                 struct xen_page_foreign *foreign;
 693
 694                 foreign = kzalloc(sizeof(*foreign), GFP_KERNEL);
 695                 if (!foreign) {
 696                         gnttab_free_pages(nr_pages, pages);
 697                         return -ENOMEM;
 698                 }
 699                 set_page_private(pages[i], (unsigned long)foreign);
 700 #endif
 701                 SetPagePrivate(pages[i]);
 702         }
 703
 704         return 0;
 705 }
 706 EXPORT_SYMBOL(gnttab_alloc_pages);
 707
 708 /**
 709  * gnttab_free_pages - free pages allocated by gnttab_alloc_pages()
 710  * @nr_pages; number of pages to free
 711  * @pages: the pages
 712  */
 713 void gnttab_free_pages(int nr_pages, struct page **pages)
 714 {
 715         int i;
 716
 717         for (i = 0; i < nr_pages; i++) {
 718                 if (PagePrivate(pages[i])) {
 719 #if BITS_PER_LONG < 64
 720                         kfree((void *)page_private(pages[i]));
 721 #endif
 722                         ClearPagePrivate(pages[i]);
 723                 }
 724         }
 725         free_xenballooned_pages(nr_pages, pages);
 726 }
 727 EXPORT_SYMBOL(gnttab_free_pages);
 728
 729 /* Handling of paged out grant targets (GNTST_eagain) */
 730 #define MAX_DELAY 256
 731 static inline void
 732 gnttab_retry_eagain_gop(unsigned int cmd, void *gop, int16_t *status,
 733                                                 const char *func)
 734 {
 735         unsigned delay = 1;
 736
 737         do {
 738                 BUG_ON(HYPERVISOR_grant_table_op(cmd, gop, 1));
 739                 if (*status == GNTST_eagain)
 740                         msleep(delay++);
 741         } while ((*status == GNTST_eagain) && (delay < MAX_DELAY));
 742
 743         if (delay >= MAX_DELAY) {
 744                 pr_err("%s: %s eagain grant\n", func, current->comm);
 745                 *status = GNTST_bad_page;
 746         }
 747 }
 748
 749 void gnttab_batch_map(struct gnttab_map_grant_ref *batch, unsigned count)
 750 {
 751         struct gnttab_map_grant_ref *op;
 752
 753         if (HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref, batch, count))
 754                 BUG();
 755         for (op = batch; op < batch + count; op++)
 756                 if (op->status == GNTST_eagain)
 757                         gnttab_retry_eagain_gop(GNTTABOP_map_grant_ref, op,
 758                                                 &op->status, __func__);
 759 }
 760 EXPORT_SYMBOL_GPL(gnttab_batch_map);
 761
 762 void gnttab_batch_copy(struct gnttab_copy *batch, unsigned count)
 763 {
 764         struct gnttab_copy *op;
 765
 766         if (HYPERVISOR_grant_table_op(GNTTABOP_copy, batch, count))
 767                 BUG();
 768         for (op = batch; op < batch + count; op++)
 769                 if (op->status == GNTST_eagain)
 770                         gnttab_retry_eagain_gop(GNTTABOP_copy, op,
 771                                                 &op->status, __func__);
 772 }
 773 EXPORT_SYMBOL_GPL(gnttab_batch_copy);
 774
 775 int gnttab_map_refs(struct gnttab_map_grant_ref *map_ops,
 776                     struct gnttab_map_grant_ref *kmap_ops,
 777                     struct page **pages, unsigned int count)
 778 {
 779         int i, ret;
 780
 781         ret = HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref, map_ops, count);
 782         if (ret)
 783                 return ret;
 784
 785         for (i = 0; i < count; i++) {
 786                 /* Retry eagain maps */
 787                 if (map_ops[i].status == GNTST_eagain)
 788                         gnttab_retry_eagain_gop(GNTTABOP_map_grant_ref, map_ops + i,
 789                                                 &map_ops[i].status, __func__);
 790
 791                 if (map_ops[i].status == GNTST_okay) {
 792                         struct xen_page_foreign *foreign;
 793
 794                         SetPageForeign(pages[i]);
 795                         foreign = xen_page_foreign(pages[i]);
 796                         foreign->domid = map_ops[i].dom;
 797                         foreign->gref = map_ops[i].ref;
 798                 }
 799         }
 800
 801         return set_foreign_p2m_mapping(map_ops, kmap_ops, pages, count);
 802 }
 803 EXPORT_SYMBOL_GPL(gnttab_map_refs);
 804
 805 int gnttab_unmap_refs(struct gnttab_unmap_grant_ref *unmap_ops,
 806                       struct gnttab_unmap_grant_ref *kunmap_ops,
 807                       struct page **pages, unsigned int count)
 808 {
 809         unsigned int i;
 810         int ret;
 811
 812         ret = HYPERVISOR_grant_table_op(GNTTABOP_unmap_grant_ref, unmap_ops, count);
 813         if (ret)
 814                 return ret;
 815
 816         for (i = 0; i < count; i++)
 817                 ClearPageForeign(pages[i]);
 818
 819         return clear_foreign_p2m_mapping(unmap_ops, kunmap_ops, pages, count);
 820 }
 821 EXPORT_SYMBOL_GPL(gnttab_unmap_refs);
 822
 823 #define GNTTAB_UNMAP_REFS_DELAY 5
 824
 825 static void __gnttab_unmap_refs_async(struct gntab_unmap_queue_data* item);
 826
 827 static void gnttab_unmap_work(struct work_struct *work)
 828 {
 829         struct gntab_unmap_queue_data
 830                 *unmap_data = container_of(work,
 831                                            struct gntab_unmap_queue_data,
 832                                            gnttab_work.work);
 833         if (unmap_data->age != UINT_MAX)
 834                 unmap_data->age++;
 835         __gnttab_unmap_refs_async(unmap_data);
 836 }
 837
 838 static void __gnttab_unmap_refs_async(struct gntab_unmap_queue_data* item)
 839 {
 840         int ret;
 841         int pc;
 842
 843         for (pc = 0; pc < item->count; pc++) {
 844                 if (page_count(item->pages[pc]) > 1) {
 845                         unsigned long delay = GNTTAB_UNMAP_REFS_DELAY * (item->age + 1);
 846                         schedule_delayed_work(&item->gnttab_work,
 847                                               msecs_to_jiffies(delay));
 848                         return;
 849                 }
 850         }
 851
 852         ret = gnttab_unmap_refs(item->unmap_ops, item->kunmap_ops,
 853                                 item->pages, item->count);
 854         item->done(ret, item);
 855 }
 856
 857 void gnttab_unmap_refs_async(struct gntab_unmap_queue_data* item)
 858 {
 859         INIT_DELAYED_WORK(&item->gnttab_work, gnttab_unmap_work);
 860         item->age = 0;
 861
 862         __gnttab_unmap_refs_async(item);
 863 }
 864 EXPORT_SYMBOL_GPL(gnttab_unmap_refs_async);
 865
 866 static int gnttab_map_frames_v1(xen_pfn_t *frames, unsigned int nr_gframes)
 867 {
 868         int rc;
 869
 870         rc = arch_gnttab_map_shared(frames, nr_gframes,
 871                                     gnttab_max_grant_frames(),
 872                                     &gnttab_shared.addr);
 873         BUG_ON(rc);
 874
 875         return 0;
 876 }
 877
 878 static void gnttab_unmap_frames_v1(void)
 879 {
 880         arch_gnttab_unmap(gnttab_shared.addr, nr_grant_frames);
 881 }
 882
 883 static int gnttab_map(unsigned int start_idx, unsigned int end_idx)
 884 {
 885         struct gnttab_setup_table setup;
 886         xen_pfn_t *frames;
 887         unsigned int nr_gframes = end_idx + 1;
 888         int rc;
 889
 890         if (xen_feature(XENFEAT_auto_translated_physmap)) {
 891                 struct xen_add_to_physmap xatp;
 892                 unsigned int i = end_idx;
 893                 rc = 0;
 894                 BUG_ON(xen_auto_xlat_grant_frames.count < nr_gframes);
 895                 /*
 896                  * Loop backwards, so that the first hypercall has the largest
 897                  * index, ensuring that the table will grow only once.
 898                  */
 899                 do {
 900                         xatp.domid = DOMID_SELF;
 901                         xatp.idx = i;
 902                         xatp.space = XENMAPSPACE_grant_table;
 903                         xatp.gpfn = xen_auto_xlat_grant_frames.pfn[i];
 904                         rc = HYPERVISOR_memory_op(XENMEM_add_to_physmap, &xatp);
 905                         if (rc != 0) {
 906                                 pr_warn("grant table add_to_physmap failed, err=%d\n",
 907                                         rc);
 908                                 break;
 909                         }
 910                 } while (i-- > start_idx);
 911
 912                 return rc;
 913         }
 914
 915         /* No need for kzalloc as it is initialized in following hypercall
 916          * GNTTABOP_setup_table.
 917          */
 918         frames = kmalloc(nr_gframes * sizeof(unsigned long), GFP_ATOMIC);
 919         if (!frames)
 920                 return -ENOMEM;
 921
 922         setup.dom        = DOMID_SELF;
 923         setup.nr_frames  = nr_gframes;
 924         set_xen_guest_handle(setup.frame_list, frames);
 925
 926         rc = HYPERVISOR_grant_table_op(GNTTABOP_setup_table, &setup, 1);
 927         if (rc == -ENOSYS) {
 928                 kfree(frames);
 929                 return -ENOSYS;
 930         }
 931
 932         BUG_ON(rc || setup.status);
 933
 934         rc = gnttab_interface->map_frames(frames, nr_gframes);
 935
 936         kfree(frames);
 937
 938         return rc;
 939 }
 940
 941 static struct gnttab_ops gnttab_v1_ops = {
 942         .map_frames                     = gnttab_map_frames_v1,
 943         .unmap_frames                   = gnttab_unmap_frames_v1,
 944         .update_entry                   = gnttab_update_entry_v1,
 945         .end_foreign_access_ref         = gnttab_end_foreign_access_ref_v1,
 946         .end_foreign_transfer_ref       = gnttab_end_foreign_transfer_ref_v1,
 947         .query_foreign_access           = gnttab_query_foreign_access_v1,
 948 };
 949
 950 static void gnttab_request_version(void)
 951 {
 952         /* Only version 1 is used, which will always be available. */
 953         grant_table_version = 1;
 954         grefs_per_grant_frame = PAGE_SIZE / sizeof(struct grant_entry_v1);
 955         gnttab_interface = &gnttab_v1_ops;
 956
 957         pr_info("Grant tables using version %d layout\n", grant_table_version);
 958 }
 959
 960 static int gnttab_setup(void)
 961 {
 962         unsigned int max_nr_gframes;
 963
 964         max_nr_gframes = gnttab_max_grant_frames();
 965         if (max_nr_gframes < nr_grant_frames)
 966                 return -ENOSYS;
 967
 968         if (xen_feature(XENFEAT_auto_translated_physmap) && gnttab_shared.addr == NULL) {
 969                 gnttab_shared.addr = xen_auto_xlat_grant_frames.vaddr;
 970                 if (gnttab_shared.addr == NULL) {
 971                         pr_warn("gnttab share frames (addr=0x%08lx) is not mapped!\n",
 972                                 (unsigned long)xen_auto_xlat_grant_frames.vaddr);
 973                         return -ENOMEM;
 974                 }
 975         }
 976         return gnttab_map(0, nr_grant_frames - 1);
 977 }
 978
 979 int gnttab_resume(void)
 980 {
 981         gnttab_request_version();
 982         return gnttab_setup();
 983 }
 984
 985 int gnttab_suspend(void)
 986 {
 987         if (!xen_feature(XENFEAT_auto_translated_physmap))
 988                 gnttab_interface->unmap_frames();
 989         return 0;
 990 }
 991
 992 static int gnttab_expand(unsigned int req_entries)
 993 {
 994         int rc;
 995         unsigned int cur, extra;
 996
 997         BUG_ON(grefs_per_grant_frame == 0);
 998         cur = nr_grant_frames;
 999         extra = ((req_entries + (grefs_per_grant_frame-1)) /
1000                  grefs_per_grant_frame);
1001         if (cur + extra > gnttab_max_grant_frames())
1002                 return -ENOSPC;
1003
1004         rc = gnttab_map(cur, cur + extra - 1);
1005         if (rc == 0)
1006                 rc = grow_gnttab_list(extra);
1007
1008         return rc;
1009 }
1010
1011 int gnttab_init(void)
1012 {
1013         int i;
1014         unsigned long max_nr_grant_frames;
1015         unsigned int max_nr_glist_frames, nr_glist_frames;
1016         unsigned int nr_init_grefs;
1017         int ret;
1018
1019         gnttab_request_version();
1020         max_nr_grant_frames = gnttab_max_grant_frames();
1021         nr_grant_frames = 1;
1022
1023         /* Determine the maximum number of frames required for the
1024          * grant reference free list on the current hypervisor.
1025          */
1026         BUG_ON(grefs_per_grant_frame == 0);
1027         max_nr_glist_frames = (max_nr_grant_frames *
1028                                grefs_per_grant_frame / RPP);
1029
1030         gnttab_list = kmalloc(max_nr_glist_frames * sizeof(grant_ref_t *),
1031                               GFP_KERNEL);
1032         if (gnttab_list == NULL)
1033                 return -ENOMEM;
1034
1035         nr_glist_frames = (nr_grant_frames * grefs_per_grant_frame + RPP - 1) / RPP;
1036         for (i = 0; i < nr_glist_frames; i++) {
1037                 gnttab_list[i] = (grant_ref_t *)__get_free_page(GFP_KERNEL);
1038                 if (gnttab_list[i] == NULL) {
1039                         ret = -ENOMEM;
1040                         goto ini_nomem;
1041                 }
1042         }
1043
1044         ret = arch_gnttab_init(max_nr_grant_frames);
1045         if (ret < 0)
1046                 goto ini_nomem;
1047
1048         if (gnttab_setup() < 0) {
1049                 ret = -ENODEV;
1050                 goto ini_nomem;
1051         }
1052
1053         nr_init_grefs = nr_grant_frames * grefs_per_grant_frame;
1054
1055         for (i = NR_RESERVED_ENTRIES; i < nr_init_grefs - 1; i++)
1056                 gnttab_entry(i) = i + 1;
1057
1058         gnttab_entry(nr_init_grefs - 1) = GNTTAB_LIST_END;
1059         gnttab_free_count = nr_init_grefs - NR_RESERVED_ENTRIES;
1060         gnttab_free_head  = NR_RESERVED_ENTRIES;
1061
1062         printk("Grant table initialized\n");
1063         return 0;
1064
1065  ini_nomem:
1066         for (i--; i >= 0; i--)
1067                 free_page((unsigned long)gnttab_list[i]);
1068         kfree(gnttab_list);
1069         return ret;
1070 }
1071 EXPORT_SYMBOL_GPL(gnttab_init);
1072
1073 static int __gnttab_init(void)
1074 {
1075         /* Delay grant-table initialization in the PV on HVM case */
1076         if (xen_hvm_domain())
1077                 return 0;
1078
1079         if (!xen_pv_domain())
1080                 return -ENODEV;
1081
1082         return gnttab_init();
1083 }
1084 /* Starts after core_initcall so that xen_pvh_gnttab_setup can be called
1085  * beforehand to initialize xen_auto_xlat_grant_frames. */
1086 core_initcall_sync(__gnttab_init);