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