drivers/xen/gntdev.c

   1 /******************************************************************************
   2  * gntdev.c
   3  *
   4  * Device for accessing (in user-space) pages that have been granted by other
   5  * domains.
   6  *
   7  * Copyright (c) 2006-2007, D G Murray.
   8  *           (c) 2009 Gerd Hoffmann <kraxel@redhat.com>
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  * GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License
  16  * along with this program; if not, write to the Free Software
  17  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  18  */
  19
  20 #undef DEBUG
  21
  22 #include <linux/module.h>
  23 #include <linux/kernel.h>
  24 #include <linux/init.h>
  25 #include <linux/miscdevice.h>
  26 #include <linux/fs.h>
  27 #include <linux/mm.h>
  28 #include <linux/mman.h>
  29 #include <linux/mmu_notifier.h>
  30 #include <linux/types.h>
  31 #include <linux/uaccess.h>
  32 #include <linux/sched.h>
  33 #include <linux/spinlock.h>
  34 #include <linux/slab.h>
  35 #include <linux/highmem.h>
  36
  37 #include <xen/xen.h>
  38 #include <xen/grant_table.h>
  39 #include <xen/gntdev.h>
  40 #include <xen/events.h>
  41 #include <asm/xen/hypervisor.h>
  42 #include <asm/xen/hypercall.h>
  43 #include <asm/xen/page.h>
  44
  45 MODULE_LICENSE("GPL");
  46 MODULE_AUTHOR("Derek G. Murray <Derek.Murray@cl.cam.ac.uk>, "
  47               "Gerd Hoffmann <kraxel@redhat.com>");
  48 MODULE_DESCRIPTION("User-space granted page access driver");
  49
  50 static int limit = 1024*1024;
  51 module_param(limit, int, 0644);
  52 MODULE_PARM_DESC(limit, "Maximum number of grants that may be mapped by "
  53                 "the gntdev device");
  54
  55 static atomic_t pages_mapped = ATOMIC_INIT(0);
  56
  57 static int use_ptemod;
  58
  59 struct gntdev_priv {
  60         struct list_head maps;
  61         /* lock protects maps from concurrent changes */
  62         spinlock_t lock;
  63         struct mm_struct *mm;
  64         struct mmu_notifier mn;
  65 };
  66
  67 struct unmap_notify {
  68         int flags;
  69         /* Address relative to the start of the grant_map */
  70         int addr;
  71         int event;
  72 };
  73
  74 struct grant_map {
  75         struct list_head next;
  76         struct vm_area_struct *vma;
  77         int index;
  78         int count;
  79         int flags;
  80         atomic_t users;
  81         struct unmap_notify notify;
  82         struct ioctl_gntdev_grant_ref *grants;
  83         struct gnttab_map_grant_ref   *map_ops;
  84         struct gnttab_unmap_grant_ref *unmap_ops;
  85         struct page **pages;
  86 };
  87
  88 static int unmap_grant_pages(struct grant_map *map, int offset, int pages);
  89
  90 /* ------------------------------------------------------------------ */
  91
  92 static void gntdev_print_maps(struct gntdev_priv *priv,
  93                               char *text, int text_index)
  94 {
  95 #ifdef DEBUG
  96         struct grant_map *map;
  97
  98         pr_debug("%s: maps list (priv %p)\n", __func__, priv);
  99         list_for_each_entry(map, &priv->maps, next)
 100                 pr_debug("  index %2d, count %2d %s\n",
 101                        map->index, map->count,
 102                        map->index == text_index && text ? text : "");
 103 #endif
 104 }
 105
 106 static struct grant_map *gntdev_alloc_map(struct gntdev_priv *priv, int count)
 107 {
 108         struct grant_map *add;
 109         int i;
 110
 111         add = kzalloc(sizeof(struct grant_map), GFP_KERNEL);
 112         if (NULL == add)
 113                 return NULL;
 114
 115         add->grants    = kzalloc(sizeof(add->grants[0])    * count, GFP_KERNEL);
 116         add->map_ops   = kzalloc(sizeof(add->map_ops[0])   * count, GFP_KERNEL);
 117         add->unmap_ops = kzalloc(sizeof(add->unmap_ops[0]) * count, GFP_KERNEL);
 118         add->pages     = kzalloc(sizeof(add->pages[0])     * count, GFP_KERNEL);
 119         if (NULL == add->grants    ||
 120             NULL == add->map_ops   ||
 121             NULL == add->unmap_ops ||
 122             NULL == add->pages)
 123                 goto err;
 124
 125         for (i = 0; i < count; i++) {
 126                 add->pages[i] = alloc_page(GFP_KERNEL | __GFP_HIGHMEM);
 127                 if (add->pages[i] == NULL)
 128                         goto err;
 129                 add->map_ops[i].handle = -1;
 130                 add->unmap_ops[i].handle = -1;
 131         }
 132
 133         add->index = 0;
 134         add->count = count;
 135         atomic_set(&add->users, 1);
 136
 137         return add;
 138
 139 err:
 140         if (add->pages)
 141                 for (i = 0; i < count; i++) {
 142                         if (add->pages[i])
 143                                 __free_page(add->pages[i]);
 144                 }
 145         kfree(add->pages);
 146         kfree(add->grants);
 147         kfree(add->map_ops);
 148         kfree(add->unmap_ops);
 149         kfree(add);
 150         return NULL;
 151 }
 152
 153 static void gntdev_add_map(struct gntdev_priv *priv, struct grant_map *add)
 154 {
 155         struct grant_map *map;
 156
 157         list_for_each_entry(map, &priv->maps, next) {
 158                 if (add->index + add->count < map->index) {
 159                         list_add_tail(&add->next, &map->next);
 160                         goto done;
 161                 }
 162                 add->index = map->index + map->count;
 163         }
 164         list_add_tail(&add->next, &priv->maps);
 165
 166 done:
 167         gntdev_print_maps(priv, "[new]", add->index);
 168 }
 169
 170 static struct grant_map *gntdev_find_map_index(struct gntdev_priv *priv,
 171                 int index, int count)
 172 {
 173         struct grant_map *map;
 174
 175         list_for_each_entry(map, &priv->maps, next) {
 176                 if (map->index != index)
 177                         continue;
 178                 if (count && map->count != count)
 179                         continue;
 180                 return map;
 181         }
 182         return NULL;
 183 }
 184
 185 static void gntdev_put_map(struct grant_map *map)
 186 {
 187         int i;
 188
 189         if (!map)
 190                 return;
 191
 192         if (!atomic_dec_and_test(&map->users))
 193                 return;
 194
 195         atomic_sub(map->count, &pages_mapped);
 196
 197         if (map->notify.flags & UNMAP_NOTIFY_SEND_EVENT) {
 198                 notify_remote_via_evtchn(map->notify.event);
 199         }
 200
 201         if (map->pages) {
 202                 if (!use_ptemod)
 203                         unmap_grant_pages(map, 0, map->count);
 204
 205                 for (i = 0; i < map->count; i++) {
 206                         uint32_t check, *tmp;
 207                         if (!map->pages[i])
 208                                 continue;
 209                         /* XXX When unmapping in an HVM domain, Xen will
 210                          * sometimes end up mapping the GFN to an invalid MFN.
 211                          * In this case, writes will be discarded and reads will
 212                          * return all 0xFF bytes.  Leak these unusable GFNs
 213                          * until Xen supports fixing their p2m mapping.
 214                          *
 215                          * Confirmed present in Xen 4.1-RC3 with HVM source
 216                          */
 217                         tmp = kmap(map->pages[i]);
 218                         *tmp = 0xdeaddead;
 219                         mb();
 220                         check = *tmp;
 221                         kunmap(map->pages[i]);
 222                         if (check == 0xdeaddead)
 223                                 __free_page(map->pages[i]);
 224                         else
 225                                 pr_debug("Discard page %d=%ld\n", i,
 226                                         page_to_pfn(map->pages[i]));
 227                 }
 228         }
 229         kfree(map->pages);
 230         kfree(map->grants);
 231         kfree(map->map_ops);
 232         kfree(map->unmap_ops);
 233         kfree(map);
 234 }
 235
 236 /* ------------------------------------------------------------------ */
 237
 238 static int find_grant_ptes(pte_t *pte, pgtable_t token,
 239                 unsigned long addr, void *data)
 240 {
 241         struct grant_map *map = data;
 242         unsigned int pgnr = (addr - map->vma->vm_start) >> PAGE_SHIFT;
 243         int flags = map->flags | GNTMAP_application_map | GNTMAP_contains_pte;
 244         u64 pte_maddr;
 245
 246         BUG_ON(pgnr >= map->count);
 247         pte_maddr = arbitrary_virt_to_machine(pte).maddr;
 248
 249         gnttab_set_map_op(&map->map_ops[pgnr], pte_maddr, flags,
 250                           map->grants[pgnr].ref,
 251                           map->grants[pgnr].domid);
 252         gnttab_set_unmap_op(&map->unmap_ops[pgnr], pte_maddr, flags,
 253                             -1 /* handle */);
 254         return 0;
 255 }
 256
 257 static int map_grant_pages(struct grant_map *map)
 258 {
 259         int i, err = 0;
 260         phys_addr_t addr;
 261
 262         if (!use_ptemod) {
 263                 /* Note: it could already be mapped */
 264                 if (map->map_ops[0].handle != -1)
 265                         return 0;
 266                 for (i = 0; i < map->count; i++) {
 267                         addr = (phys_addr_t)
 268                                 pfn_to_kaddr(page_to_pfn(map->pages[i]));
 269                         gnttab_set_map_op(&map->map_ops[i], addr, map->flags,
 270                                 map->grants[i].ref,
 271                                 map->grants[i].domid);
 272                         gnttab_set_unmap_op(&map->unmap_ops[i], addr,
 273                                 map->flags, -1 /* handle */);
 274                 }
 275         }
 276
 277         pr_debug("map %d+%d\n", map->index, map->count);
 278         err = gnttab_map_refs(map->map_ops, map->pages, map->count);
 279         if (err)
 280                 return err;
 281
 282         for (i = 0; i < map->count; i++) {
 283                 if (map->map_ops[i].status)
 284                         err = -EINVAL;
 285                 else {
 286                         BUG_ON(map->map_ops[i].handle == -1);
 287                         map->unmap_ops[i].handle = map->map_ops[i].handle;
 288                         pr_debug("map handle=%d\n", map->map_ops[i].handle);
 289                 }
 290         }
 291         return err;
 292 }
 293
 294 static int __unmap_grant_pages(struct grant_map *map, int offset, int pages)
 295 {
 296         int i, err = 0;
 297
 298         if (map->notify.flags & UNMAP_NOTIFY_CLEAR_BYTE) {
 299                 int pgno = (map->notify.addr >> PAGE_SHIFT);
 300                 if (pgno >= offset && pgno < offset + pages && use_ptemod) {
 301                         void __user *tmp;
 302                         tmp = map->vma->vm_start + map->notify.addr;
 303                         err = copy_to_user(tmp, &err, 1);
 304                         if (err)
 305                                 return err;
 306                         map->notify.flags &= ~UNMAP_NOTIFY_CLEAR_BYTE;
 307                 } else if (pgno >= offset && pgno < offset + pages) {
 308                         uint8_t *tmp = kmap(map->pages[pgno]);
 309                         tmp[map->notify.addr & (PAGE_SIZE-1)] = 0;
 310                         kunmap(map->pages[pgno]);
 311                         map->notify.flags &= ~UNMAP_NOTIFY_CLEAR_BYTE;
 312                 }
 313         }
 314
 315         err = gnttab_unmap_refs(map->unmap_ops + offset, map->pages + offset, pages);
 316         if (err)
 317                 return err;
 318
 319         for (i = 0; i < pages; i++) {
 320                 if (map->unmap_ops[offset+i].status)
 321                         err = -EINVAL;
 322                 pr_debug("unmap handle=%d st=%d\n",
 323                         map->unmap_ops[offset+i].handle,
 324                         map->unmap_ops[offset+i].status);
 325                 map->unmap_ops[offset+i].handle = -1;
 326         }
 327         return err;
 328 }
 329
 330 static int unmap_grant_pages(struct grant_map *map, int offset, int pages)
 331 {
 332         int range, err = 0;
 333
 334         pr_debug("unmap %d+%d [%d+%d]\n", map->index, map->count, offset, pages);
 335
 336         /* It is possible the requested range will have a "hole" where we
 337          * already unmapped some of the grants. Only unmap valid ranges.
 338          */
 339         while (pages && !err) {
 340                 while (pages && map->unmap_ops[offset].handle == -1) {
 341                         offset++;
 342                         pages--;
 343                 }
 344                 range = 0;
 345                 while (range < pages) {
 346                         if (map->unmap_ops[offset+range].handle == -1) {
 347                                 range--;
 348                                 break;
 349                         }
 350                         range++;
 351                 }
 352                 err = __unmap_grant_pages(map, offset, range);
 353                 offset += range;
 354                 pages -= range;
 355         }
 356
 357         return err;
 358 }
 359
 360 /* ------------------------------------------------------------------ */
 361
 362 static void gntdev_vma_close(struct vm_area_struct *vma)
 363 {
 364         struct grant_map *map = vma->vm_private_data;
 365
 366         pr_debug("close %p\n", vma);
 367         map->vma = NULL;
 368         vma->vm_private_data = NULL;
 369         gntdev_put_map(map);
 370 }
 371
 372 static struct vm_operations_struct gntdev_vmops = {
 373         .close = gntdev_vma_close,
 374 };
 375
 376 /* ------------------------------------------------------------------ */
 377
 378 static void mn_invl_range_start(struct mmu_notifier *mn,
 379                                 struct mm_struct *mm,
 380                                 unsigned long start, unsigned long end)
 381 {
 382         struct gntdev_priv *priv = container_of(mn, struct gntdev_priv, mn);
 383         struct grant_map *map;
 384         unsigned long mstart, mend;
 385         int err;
 386
 387         spin_lock(&priv->lock);
 388         list_for_each_entry(map, &priv->maps, next) {
 389                 if (!map->vma)
 390                         continue;
 391                 if (map->vma->vm_start >= end)
 392                         continue;
 393                 if (map->vma->vm_end <= start)
 394                         continue;
 395                 mstart = max(start, map->vma->vm_start);
 396                 mend   = min(end,   map->vma->vm_end);
 397                 pr_debug("map %d+%d (%lx %lx), range %lx %lx, mrange %lx %lx\n",
 398                                 map->index, map->count,
 399                                 map->vma->vm_start, map->vma->vm_end,
 400                                 start, end, mstart, mend);
 401                 err = unmap_grant_pages(map,
 402                                         (mstart - map->vma->vm_start) >> PAGE_SHIFT,
 403                                         (mend - mstart) >> PAGE_SHIFT);
 404                 WARN_ON(err);
 405         }
 406         spin_unlock(&priv->lock);
 407 }
 408
 409 static void mn_invl_page(struct mmu_notifier *mn,
 410                          struct mm_struct *mm,
 411                          unsigned long address)
 412 {
 413         mn_invl_range_start(mn, mm, address, address + PAGE_SIZE);
 414 }
 415
 416 static void mn_release(struct mmu_notifier *mn,
 417                        struct mm_struct *mm)
 418 {
 419         struct gntdev_priv *priv = container_of(mn, struct gntdev_priv, mn);
 420         struct grant_map *map;
 421         int err;
 422
 423         spin_lock(&priv->lock);
 424         list_for_each_entry(map, &priv->maps, next) {
 425                 if (!map->vma)
 426                         continue;
 427                 pr_debug("map %d+%d (%lx %lx)\n",
 428                                 map->index, map->count,
 429                                 map->vma->vm_start, map->vma->vm_end);
 430                 err = unmap_grant_pages(map, /* offset */ 0, map->count);
 431                 WARN_ON(err);
 432         }
 433         spin_unlock(&priv->lock);
 434 }
 435
 436 struct mmu_notifier_ops gntdev_mmu_ops = {
 437         .release                = mn_release,
 438         .invalidate_page        = mn_invl_page,
 439         .invalidate_range_start = mn_invl_range_start,
 440 };
 441
 442 /* ------------------------------------------------------------------ */
 443
 444 static int gntdev_open(struct inode *inode, struct file *flip)
 445 {
 446         struct gntdev_priv *priv;
 447         int ret = 0;
 448
 449         priv = kzalloc(sizeof(*priv), GFP_KERNEL);
 450         if (!priv)
 451                 return -ENOMEM;
 452
 453         INIT_LIST_HEAD(&priv->maps);
 454         spin_lock_init(&priv->lock);
 455
 456         if (use_ptemod) {
 457                 priv->mm = get_task_mm(current);
 458                 if (!priv->mm) {
 459                         kfree(priv);
 460                         return -ENOMEM;
 461                 }
 462                 priv->mn.ops = &gntdev_mmu_ops;
 463                 ret = mmu_notifier_register(&priv->mn, priv->mm);
 464                 mmput(priv->mm);
 465         }
 466
 467         if (ret) {
 468                 kfree(priv);
 469                 return ret;
 470         }
 471
 472         flip->private_data = priv;
 473         pr_debug("priv %p\n", priv);
 474
 475         return 0;
 476 }
 477
 478 static int gntdev_release(struct inode *inode, struct file *flip)
 479 {
 480         struct gntdev_priv *priv = flip->private_data;
 481         struct grant_map *map;
 482
 483         pr_debug("priv %p\n", priv);
 484
 485         spin_lock(&priv->lock);
 486         while (!list_empty(&priv->maps)) {
 487                 map = list_entry(priv->maps.next, struct grant_map, next);
 488                 list_del(&map->next);
 489                 gntdev_put_map(map);
 490         }
 491         spin_unlock(&priv->lock);
 492
 493         if (use_ptemod)
 494                 mmu_notifier_unregister(&priv->mn, priv->mm);
 495         kfree(priv);
 496         return 0;
 497 }
 498
 499 static long gntdev_ioctl_map_grant_ref(struct gntdev_priv *priv,
 500                                        struct ioctl_gntdev_map_grant_ref __user *u)
 501 {
 502         struct ioctl_gntdev_map_grant_ref op;
 503         struct grant_map *map;
 504         int err;
 505
 506         if (copy_from_user(&op, u, sizeof(op)) != 0)
 507                 return -EFAULT;
 508         pr_debug("priv %p, add %d\n", priv, op.count);
 509         if (unlikely(op.count <= 0))
 510                 return -EINVAL;
 511
 512         err = -ENOMEM;
 513         map = gntdev_alloc_map(priv, op.count);
 514         if (!map)
 515                 return err;
 516
 517         if (unlikely(atomic_add_return(op.count, &pages_mapped) > limit)) {
 518                 pr_debug("can't map: over limit\n");
 519                 gntdev_put_map(map);
 520                 return err;
 521         }
 522
 523         if (copy_from_user(map->grants, &u->refs,
 524                            sizeof(map->grants[0]) * op.count) != 0) {
 525                 gntdev_put_map(map);
 526                 return err;
 527         }
 528
 529         spin_lock(&priv->lock);
 530         gntdev_add_map(priv, map);
 531         op.index = map->index << PAGE_SHIFT;
 532         spin_unlock(&priv->lock);
 533
 534         if (copy_to_user(u, &op, sizeof(op)) != 0)
 535                 return -EFAULT;
 536
 537         return 0;
 538 }
 539
 540 static long gntdev_ioctl_unmap_grant_ref(struct gntdev_priv *priv,
 541                                          struct ioctl_gntdev_unmap_grant_ref __user *u)
 542 {
 543         struct ioctl_gntdev_unmap_grant_ref op;
 544         struct grant_map *map;
 545         int err = -ENOENT;
 546
 547         if (copy_from_user(&op, u, sizeof(op)) != 0)
 548                 return -EFAULT;
 549         pr_debug("priv %p, del %d+%d\n", priv, (int)op.index, (int)op.count);
 550
 551         spin_lock(&priv->lock);
 552         map = gntdev_find_map_index(priv, op.index >> PAGE_SHIFT, op.count);
 553         if (map) {
 554                 list_del(&map->next);
 555                 gntdev_put_map(map);
 556                 err = 0;
 557         }
 558         spin_unlock(&priv->lock);
 559         return err;
 560 }
 561
 562 static long gntdev_ioctl_get_offset_for_vaddr(struct gntdev_priv *priv,
 563                                               struct ioctl_gntdev_get_offset_for_vaddr __user *u)
 564 {
 565         struct ioctl_gntdev_get_offset_for_vaddr op;
 566         struct vm_area_struct *vma;
 567         struct grant_map *map;
 568
 569         if (copy_from_user(&op, u, sizeof(op)) != 0)
 570                 return -EFAULT;
 571         pr_debug("priv %p, offset for vaddr %lx\n", priv, (unsigned long)op.vaddr);
 572
 573         vma = find_vma(current->mm, op.vaddr);
 574         if (!vma || vma->vm_ops != &gntdev_vmops)
 575                 return -EINVAL;
 576
 577         map = vma->vm_private_data;
 578         if (!map)
 579                 return -EINVAL;
 580
 581         op.offset = map->index << PAGE_SHIFT;
 582         op.count = map->count;
 583
 584         if (copy_to_user(u, &op, sizeof(op)) != 0)
 585                 return -EFAULT;
 586         return 0;
 587 }
 588
 589 static long gntdev_ioctl_notify(struct gntdev_priv *priv, void __user *u)
 590 {
 591         struct ioctl_gntdev_unmap_notify op;
 592         struct grant_map *map;
 593         int rc;
 594
 595         if (copy_from_user(&op, u, sizeof(op)))
 596                 return -EFAULT;
 597
 598         if (op.action & ~(UNMAP_NOTIFY_CLEAR_BYTE|UNMAP_NOTIFY_SEND_EVENT))
 599                 return -EINVAL;
 600
 601         spin_lock(&priv->lock);
 602
 603         list_for_each_entry(map, &priv->maps, next) {
 604                 uint64_t begin = map->index << PAGE_SHIFT;
 605                 uint64_t end = (map->index + map->count) << PAGE_SHIFT;
 606                 if (op.index >= begin && op.index < end)
 607                         goto found;
 608         }
 609         rc = -ENOENT;
 610         goto unlock_out;
 611
 612  found:
 613         if ((op.action & UNMAP_NOTIFY_CLEAR_BYTE) &&
 614                         (map->flags & GNTMAP_readonly)) {
 615                 rc = -EINVAL;
 616                 goto unlock_out;
 617         }
 618
 619         map->notify.flags = op.action;
 620         map->notify.addr = op.index - (map->index << PAGE_SHIFT);
 621         map->notify.event = op.event_channel_port;
 622         rc = 0;
 623  unlock_out:
 624         spin_unlock(&priv->lock);
 625         return rc;
 626 }
 627
 628 static long gntdev_ioctl(struct file *flip,
 629                          unsigned int cmd, unsigned long arg)
 630 {
 631         struct gntdev_priv *priv = flip->private_data;
 632         void __user *ptr = (void __user *)arg;
 633
 634         switch (cmd) {
 635         case IOCTL_GNTDEV_MAP_GRANT_REF:
 636                 return gntdev_ioctl_map_grant_ref(priv, ptr);
 637
 638         case IOCTL_GNTDEV_UNMAP_GRANT_REF:
 639                 return gntdev_ioctl_unmap_grant_ref(priv, ptr);
 640
 641         case IOCTL_GNTDEV_GET_OFFSET_FOR_VADDR:
 642                 return gntdev_ioctl_get_offset_for_vaddr(priv, ptr);
 643
 644         case IOCTL_GNTDEV_SET_UNMAP_NOTIFY:
 645                 return gntdev_ioctl_notify(priv, ptr);
 646
 647         default:
 648                 pr_debug("priv %p, unknown cmd %x\n", priv, cmd);
 649                 return -ENOIOCTLCMD;
 650         }
 651
 652         return 0;
 653 }
 654
 655 static int gntdev_mmap(struct file *flip, struct vm_area_struct *vma)
 656 {
 657         struct gntdev_priv *priv = flip->private_data;
 658         int index = vma->vm_pgoff;
 659         int count = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
 660         struct grant_map *map;
 661         int i, err = -EINVAL;
 662
 663         if ((vma->vm_flags & VM_WRITE) && !(vma->vm_flags & VM_SHARED))
 664                 return -EINVAL;
 665
 666         pr_debug("map %d+%d at %lx (pgoff %lx)\n",
 667                         index, count, vma->vm_start, vma->vm_pgoff);
 668
 669         spin_lock(&priv->lock);
 670         map = gntdev_find_map_index(priv, index, count);
 671         if (!map)
 672                 goto unlock_out;
 673         if (use_ptemod && map->vma)
 674                 goto unlock_out;
 675         if (use_ptemod && priv->mm != vma->vm_mm) {
 676                 printk(KERN_WARNING "Huh? Other mm?\n");
 677                 goto unlock_out;
 678         }
 679
 680         atomic_inc(&map->users);
 681
 682         vma->vm_ops = &gntdev_vmops;
 683
 684         vma->vm_flags |= VM_RESERVED|VM_DONTCOPY|VM_DONTEXPAND|VM_PFNMAP;
 685
 686         vma->vm_private_data = map;
 687
 688         if (use_ptemod)
 689                 map->vma = vma;
 690
 691         if (map->flags) {
 692                 if ((vma->vm_flags & VM_WRITE) &&
 693                                 (map->flags & GNTMAP_readonly))
 694                         return -EINVAL;
 695         } else {
 696                 map->flags = GNTMAP_host_map;
 697                 if (!(vma->vm_flags & VM_WRITE))
 698                         map->flags |= GNTMAP_readonly;
 699         }
 700
 701         spin_unlock(&priv->lock);
 702
 703         if (use_ptemod) {
 704                 err = apply_to_page_range(vma->vm_mm, vma->vm_start,
 705                                           vma->vm_end - vma->vm_start,
 706                                           find_grant_ptes, map);
 707                 if (err) {
 708                         printk(KERN_WARNING "find_grant_ptes() failure.\n");
 709                         goto out_put_map;
 710                 }
 711         }
 712
 713         err = map_grant_pages(map);
 714         if (err)
 715                 goto out_put_map;
 716
 717         if (!use_ptemod) {
 718                 for (i = 0; i < count; i++) {
 719                         err = vm_insert_page(vma, vma->vm_start + i*PAGE_SIZE,
 720                                 map->pages[i]);
 721                         if (err)
 722                                 goto out_put_map;
 723                 }
 724         }
 725
 726         return 0;
 727
 728 unlock_out:
 729         spin_unlock(&priv->lock);
 730         return err;
 731
 732 out_put_map:
 733         if (use_ptemod)
 734                 map->vma = NULL;
 735         gntdev_put_map(map);
 736         return err;
 737 }
 738
 739 static const struct file_operations gntdev_fops = {
 740         .owner = THIS_MODULE,
 741         .open = gntdev_open,
 742         .release = gntdev_release,
 743         .mmap = gntdev_mmap,
 744         .unlocked_ioctl = gntdev_ioctl
 745 };
 746
 747 static struct miscdevice gntdev_miscdev = {
 748         .minor        = MISC_DYNAMIC_MINOR,
 749         .name         = "xen/gntdev",
 750         .fops         = &gntdev_fops,
 751 };
 752
 753 /* ------------------------------------------------------------------ */
 754
 755 static int __init gntdev_init(void)
 756 {
 757         int err;
 758
 759         if (!xen_domain())
 760                 return -ENODEV;
 761
 762         use_ptemod = xen_pv_domain();
 763
 764         err = misc_register(&gntdev_miscdev);
 765         if (err != 0) {
 766                 printk(KERN_ERR "Could not register gntdev device\n");
 767                 return err;
 768         }
 769         return 0;
 770 }
 771
 772 static void __exit gntdev_exit(void)
 773 {
 774         misc_deregister(&gntdev_miscdev);
 775 }
 776
 777 module_init(gntdev_init);
 778 module_exit(gntdev_exit);
 779
 780 /* ------------------------------------------------------------------ */