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
 195         if (map->pages) {
 196                 if (!use_ptemod)
 197                         unmap_grant_pages(map, 0, map->count);
 198
 199                 free_xenballooned_pages(map->count, map->pages);
 200         }
 201         kfree(map->pages);
 202         kfree(map->grants);
 203         kfree(map->map_ops);
 204         kfree(map->unmap_ops);
 205         kfree(map);
 206 }
 207
 208 /* ------------------------------------------------------------------ */
 209
 210 static int find_grant_ptes(pte_t *pte, pgtable_t token,
 211                 unsigned long addr, void *data)
 212 {
 213         struct grant_map *map = data;
 214         unsigned int pgnr = (addr - map->vma->vm_start) >> PAGE_SHIFT;
 215         int flags = map->flags | GNTMAP_application_map | GNTMAP_contains_pte;
 216         u64 pte_maddr;
 217
 218         BUG_ON(pgnr >= map->count);
 219         pte_maddr = arbitrary_virt_to_machine(pte).maddr;
 220
 221         gnttab_set_map_op(&map->map_ops[pgnr], pte_maddr, flags,
 222                           map->grants[pgnr].ref,
 223                           map->grants[pgnr].domid);
 224         gnttab_set_unmap_op(&map->unmap_ops[pgnr], pte_maddr, flags,
 225                             -1 /* handle */);
 226         return 0;
 227 }
 228
 229 static int map_grant_pages(struct grant_map *map)
 230 {
 231         int i, err = 0;
 232
 233         if (!use_ptemod) {
 234                 /* Note: it could already be mapped */
 235                 if (map->map_ops[0].handle != -1)
 236                         return 0;
 237                 for (i = 0; i < map->count; i++) {
 238                         unsigned long addr = (unsigned long)
 239                                 pfn_to_kaddr(page_to_pfn(map->pages[i]));
 240                         gnttab_set_map_op(&map->map_ops[i], addr, map->flags,
 241                                 map->grants[i].ref,
 242                                 map->grants[i].domid);
 243                         gnttab_set_unmap_op(&map->unmap_ops[i], addr,
 244                                 map->flags, -1 /* handle */);
 245                 }
 246         }
 247
 248         pr_debug("map %d+%d\n", map->index, map->count);
 249         err = gnttab_map_refs(map->map_ops, map->pages, map->count);
 250         if (err)
 251                 return err;
 252
 253         for (i = 0; i < map->count; i++) {
 254                 if (map->map_ops[i].status)
 255                         err = -EINVAL;
 256                 else {
 257                         BUG_ON(map->map_ops[i].handle == -1);
 258                         map->unmap_ops[i].handle = map->map_ops[i].handle;
 259                         pr_debug("map handle=%d\n", map->map_ops[i].handle);
 260                 }
 261         }
 262         return err;
 263 }
 264
 265 static int __unmap_grant_pages(struct grant_map *map, int offset, int pages)
 266 {
 267         int i, err = 0;
 268
 269         if (map->notify.flags & UNMAP_NOTIFY_CLEAR_BYTE) {
 270                 int pgno = (map->notify.addr >> PAGE_SHIFT);
 271                 if (pgno >= offset && pgno < offset + pages && use_ptemod) {
 272                         void __user *tmp = (void __user *)
 273                                 map->vma->vm_start + map->notify.addr;
 274                         err = copy_to_user(tmp, &err, 1);
 275                         if (err)
 276                                 return -EFAULT;
 277                         map->notify.flags &= ~UNMAP_NOTIFY_CLEAR_BYTE;
 278                 } else if (pgno >= offset && pgno < offset + pages) {
 279                         uint8_t *tmp = kmap(map->pages[pgno]);
 280                         tmp[map->notify.addr & (PAGE_SIZE-1)] = 0;
 281                         kunmap(map->pages[pgno]);
 282                         map->notify.flags &= ~UNMAP_NOTIFY_CLEAR_BYTE;
 283                 }
 284         }
 285
 286         err = gnttab_unmap_refs(map->unmap_ops + offset, map->pages + offset, pages);
 287         if (err)
 288                 return err;
 289
 290         for (i = 0; i < pages; i++) {
 291                 if (map->unmap_ops[offset+i].status)
 292                         err = -EINVAL;
 293                 pr_debug("unmap handle=%d st=%d\n",
 294                         map->unmap_ops[offset+i].handle,
 295                         map->unmap_ops[offset+i].status);
 296                 map->unmap_ops[offset+i].handle = -1;
 297         }
 298         return err;
 299 }
 300
 301 static int unmap_grant_pages(struct grant_map *map, int offset, int pages)
 302 {
 303         int range, err = 0;
 304
 305         pr_debug("unmap %d+%d [%d+%d]\n", map->index, map->count, offset, pages);
 306
 307         /* It is possible the requested range will have a "hole" where we
 308          * already unmapped some of the grants. Only unmap valid ranges.
 309          */
 310         while (pages && !err) {
 311                 while (pages && map->unmap_ops[offset].handle == -1) {
 312                         offset++;
 313                         pages--;
 314                 }
 315                 range = 0;
 316                 while (range < pages) {
 317                         if (map->unmap_ops[offset+range].handle == -1) {
 318                                 range--;
 319                                 break;
 320                         }
 321                         range++;
 322                 }
 323                 err = __unmap_grant_pages(map, offset, range);
 324                 offset += range;
 325                 pages -= range;
 326         }
 327
 328         return err;
 329 }
 330
 331 /* ------------------------------------------------------------------ */
 332
 333 static void gntdev_vma_open(struct vm_area_struct *vma)
 334 {
 335         struct grant_map *map = vma->vm_private_data;
 336
 337         pr_debug("gntdev_vma_open %p\n", vma);
 338         atomic_inc(&map->users);
 339 }
 340
 341 static void gntdev_vma_close(struct vm_area_struct *vma)
 342 {
 343         struct grant_map *map = vma->vm_private_data;
 344
 345         pr_debug("gntdev_vma_close %p\n", vma);
 346         map->vma = NULL;
 347         vma->vm_private_data = NULL;
 348         gntdev_put_map(map);
 349 }
 350
 351 static struct vm_operations_struct gntdev_vmops = {
 352         .open = gntdev_vma_open,
 353         .close = gntdev_vma_close,
 354 };
 355
 356 /* ------------------------------------------------------------------ */
 357
 358 static void mn_invl_range_start(struct mmu_notifier *mn,
 359                                 struct mm_struct *mm,
 360                                 unsigned long start, unsigned long end)
 361 {
 362         struct gntdev_priv *priv = container_of(mn, struct gntdev_priv, mn);
 363         struct grant_map *map;
 364         unsigned long mstart, mend;
 365         int err;
 366
 367         spin_lock(&priv->lock);
 368         list_for_each_entry(map, &priv->maps, next) {
 369                 if (!map->vma)
 370                         continue;
 371                 if (map->vma->vm_start >= end)
 372                         continue;
 373                 if (map->vma->vm_end <= start)
 374                         continue;
 375                 mstart = max(start, map->vma->vm_start);
 376                 mend   = min(end,   map->vma->vm_end);
 377                 pr_debug("map %d+%d (%lx %lx), range %lx %lx, mrange %lx %lx\n",
 378                                 map->index, map->count,
 379                                 map->vma->vm_start, map->vma->vm_end,
 380                                 start, end, mstart, mend);
 381                 err = unmap_grant_pages(map,
 382                                         (mstart - map->vma->vm_start) >> PAGE_SHIFT,
 383                                         (mend - mstart) >> PAGE_SHIFT);
 384                 WARN_ON(err);
 385         }
 386         spin_unlock(&priv->lock);
 387 }
 388
 389 static void mn_invl_page(struct mmu_notifier *mn,
 390                          struct mm_struct *mm,
 391                          unsigned long address)
 392 {
 393         mn_invl_range_start(mn, mm, address, address + PAGE_SIZE);
 394 }
 395
 396 static void mn_release(struct mmu_notifier *mn,
 397                        struct mm_struct *mm)
 398 {
 399         struct gntdev_priv *priv = container_of(mn, struct gntdev_priv, mn);
 400         struct grant_map *map;
 401         int err;
 402
 403         spin_lock(&priv->lock);
 404         list_for_each_entry(map, &priv->maps, next) {
 405                 if (!map->vma)
 406                         continue;
 407                 pr_debug("map %d+%d (%lx %lx)\n",
 408                                 map->index, map->count,
 409                                 map->vma->vm_start, map->vma->vm_end);
 410                 err = unmap_grant_pages(map, /* offset */ 0, map->count);
 411                 WARN_ON(err);
 412         }
 413         spin_unlock(&priv->lock);
 414 }
 415
 416 struct mmu_notifier_ops gntdev_mmu_ops = {
 417         .release                = mn_release,
 418         .invalidate_page        = mn_invl_page,
 419         .invalidate_range_start = mn_invl_range_start,
 420 };
 421
 422 /* ------------------------------------------------------------------ */
 423
 424 static int gntdev_open(struct inode *inode, struct file *flip)
 425 {
 426         struct gntdev_priv *priv;
 427         int ret = 0;
 428
 429         priv = kzalloc(sizeof(*priv), GFP_KERNEL);
 430         if (!priv)
 431                 return -ENOMEM;
 432
 433         INIT_LIST_HEAD(&priv->maps);
 434         spin_lock_init(&priv->lock);
 435
 436         if (use_ptemod) {
 437                 priv->mm = get_task_mm(current);
 438                 if (!priv->mm) {
 439                         kfree(priv);
 440                         return -ENOMEM;
 441                 }
 442                 priv->mn.ops = &gntdev_mmu_ops;
 443                 ret = mmu_notifier_register(&priv->mn, priv->mm);
 444                 mmput(priv->mm);
 445         }
 446
 447         if (ret) {
 448                 kfree(priv);
 449                 return ret;
 450         }
 451
 452         flip->private_data = priv;
 453         pr_debug("priv %p\n", priv);
 454
 455         return 0;
 456 }
 457
 458 static int gntdev_release(struct inode *inode, struct file *flip)
 459 {
 460         struct gntdev_priv *priv = flip->private_data;
 461         struct grant_map *map;
 462
 463         pr_debug("priv %p\n", priv);
 464
 465         spin_lock(&priv->lock);
 466         while (!list_empty(&priv->maps)) {
 467                 map = list_entry(priv->maps.next, struct grant_map, next);
 468                 list_del(&map->next);
 469                 gntdev_put_map(map);
 470         }
 471         spin_unlock(&priv->lock);
 472
 473         if (use_ptemod)
 474                 mmu_notifier_unregister(&priv->mn, priv->mm);
 475         kfree(priv);
 476         return 0;
 477 }
 478
 479 static long gntdev_ioctl_map_grant_ref(struct gntdev_priv *priv,
 480                                        struct ioctl_gntdev_map_grant_ref __user *u)
 481 {
 482         struct ioctl_gntdev_map_grant_ref op;
 483         struct grant_map *map;
 484         int err;
 485
 486         if (copy_from_user(&op, u, sizeof(op)) != 0)
 487                 return -EFAULT;
 488         pr_debug("priv %p, add %d\n", priv, op.count);
 489         if (unlikely(op.count <= 0))
 490                 return -EINVAL;
 491
 492         err = -ENOMEM;
 493         map = gntdev_alloc_map(priv, op.count);
 494         if (!map)
 495                 return err;
 496
 497         if (unlikely(atomic_add_return(op.count, &pages_mapped) > limit)) {
 498                 pr_debug("can't map: over limit\n");
 499                 gntdev_put_map(map);
 500                 return err;
 501         }
 502
 503         if (copy_from_user(map->grants, &u->refs,
 504                            sizeof(map->grants[0]) * op.count) != 0) {
 505                 gntdev_put_map(map);
 506                 return err;
 507         }
 508
 509         spin_lock(&priv->lock);
 510         gntdev_add_map(priv, map);
 511         op.index = map->index << PAGE_SHIFT;
 512         spin_unlock(&priv->lock);
 513
 514         if (copy_to_user(u, &op, sizeof(op)) != 0)
 515                 return -EFAULT;
 516
 517         return 0;
 518 }
 519
 520 static long gntdev_ioctl_unmap_grant_ref(struct gntdev_priv *priv,
 521                                          struct ioctl_gntdev_unmap_grant_ref __user *u)
 522 {
 523         struct ioctl_gntdev_unmap_grant_ref op;
 524         struct grant_map *map;
 525         int err = -ENOENT;
 526
 527         if (copy_from_user(&op, u, sizeof(op)) != 0)
 528                 return -EFAULT;
 529         pr_debug("priv %p, del %d+%d\n", priv, (int)op.index, (int)op.count);
 530
 531         spin_lock(&priv->lock);
 532         map = gntdev_find_map_index(priv, op.index >> PAGE_SHIFT, op.count);
 533         if (map) {
 534                 list_del(&map->next);
 535                 gntdev_put_map(map);
 536                 err = 0;
 537         }
 538         spin_unlock(&priv->lock);
 539         return err;
 540 }
 541
 542 static long gntdev_ioctl_get_offset_for_vaddr(struct gntdev_priv *priv,
 543                                               struct ioctl_gntdev_get_offset_for_vaddr __user *u)
 544 {
 545         struct ioctl_gntdev_get_offset_for_vaddr op;
 546         struct vm_area_struct *vma;
 547         struct grant_map *map;
 548
 549         if (copy_from_user(&op, u, sizeof(op)) != 0)
 550                 return -EFAULT;
 551         pr_debug("priv %p, offset for vaddr %lx\n", priv, (unsigned long)op.vaddr);
 552
 553         vma = find_vma(current->mm, op.vaddr);
 554         if (!vma || vma->vm_ops != &gntdev_vmops)
 555                 return -EINVAL;
 556
 557         map = vma->vm_private_data;
 558         if (!map)
 559                 return -EINVAL;
 560
 561         op.offset = map->index << PAGE_SHIFT;
 562         op.count = map->count;
 563
 564         if (copy_to_user(u, &op, sizeof(op)) != 0)
 565                 return -EFAULT;
 566         return 0;
 567 }
 568
 569 static long gntdev_ioctl_notify(struct gntdev_priv *priv, void __user *u)
 570 {
 571         struct ioctl_gntdev_unmap_notify op;
 572         struct grant_map *map;
 573         int rc;
 574
 575         if (copy_from_user(&op, u, sizeof(op)))
 576                 return -EFAULT;
 577
 578         if (op.action & ~(UNMAP_NOTIFY_CLEAR_BYTE|UNMAP_NOTIFY_SEND_EVENT))
 579                 return -EINVAL;
 580
 581         spin_lock(&priv->lock);
 582
 583         list_for_each_entry(map, &priv->maps, next) {
 584                 uint64_t begin = map->index << PAGE_SHIFT;
 585                 uint64_t end = (map->index + map->count) << PAGE_SHIFT;
 586                 if (op.index >= begin && op.index < end)
 587                         goto found;
 588         }
 589         rc = -ENOENT;
 590         goto unlock_out;
 591
 592  found:
 593         if ((op.action & UNMAP_NOTIFY_CLEAR_BYTE) &&
 594                         (map->flags & GNTMAP_readonly)) {
 595                 rc = -EINVAL;
 596                 goto unlock_out;
 597         }
 598
 599         map->notify.flags = op.action;
 600         map->notify.addr = op.index - (map->index << PAGE_SHIFT);
 601         map->notify.event = op.event_channel_port;
 602         rc = 0;
 603  unlock_out:
 604         spin_unlock(&priv->lock);
 605         return rc;
 606 }
 607
 608 static long gntdev_ioctl(struct file *flip,
 609                          unsigned int cmd, unsigned long arg)
 610 {
 611         struct gntdev_priv *priv = flip->private_data;
 612         void __user *ptr = (void __user *)arg;
 613
 614         switch (cmd) {
 615         case IOCTL_GNTDEV_MAP_GRANT_REF:
 616                 return gntdev_ioctl_map_grant_ref(priv, ptr);
 617
 618         case IOCTL_GNTDEV_UNMAP_GRANT_REF:
 619                 return gntdev_ioctl_unmap_grant_ref(priv, ptr);
 620
 621         case IOCTL_GNTDEV_GET_OFFSET_FOR_VADDR:
 622                 return gntdev_ioctl_get_offset_for_vaddr(priv, ptr);
 623
 624         case IOCTL_GNTDEV_SET_UNMAP_NOTIFY:
 625                 return gntdev_ioctl_notify(priv, ptr);
 626
 627         default:
 628                 pr_debug("priv %p, unknown cmd %x\n", priv, cmd);
 629                 return -ENOIOCTLCMD;
 630         }
 631
 632         return 0;
 633 }
 634
 635 static int gntdev_mmap(struct file *flip, struct vm_area_struct *vma)
 636 {
 637         struct gntdev_priv *priv = flip->private_data;
 638         int index = vma->vm_pgoff;
 639         int count = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
 640         struct grant_map *map;
 641         int i, err = -EINVAL;
 642
 643         if ((vma->vm_flags & VM_WRITE) && !(vma->vm_flags & VM_SHARED))
 644                 return -EINVAL;
 645
 646         pr_debug("map %d+%d at %lx (pgoff %lx)\n",
 647                         index, count, vma->vm_start, vma->vm_pgoff);
 648
 649         spin_lock(&priv->lock);
 650         map = gntdev_find_map_index(priv, index, count);
 651         if (!map)
 652                 goto unlock_out;
 653         if (use_ptemod && map->vma)
 654                 goto unlock_out;
 655         if (use_ptemod && priv->mm != vma->vm_mm) {
 656                 printk(KERN_WARNING "Huh? Other mm?\n");
 657                 goto unlock_out;
 658         }
 659
 660         atomic_inc(&map->users);
 661
 662         vma->vm_ops = &gntdev_vmops;
 663
 664         vma->vm_flags |= VM_RESERVED|VM_DONTEXPAND;
 665
 666         if (use_ptemod)
 667                 vma->vm_flags |= VM_DONTCOPY|VM_PFNMAP;
 668
 669         vma->vm_private_data = map;
 670
 671         if (use_ptemod)
 672                 map->vma = vma;
 673
 674         if (map->flags) {
 675                 if ((vma->vm_flags & VM_WRITE) &&
 676                                 (map->flags & GNTMAP_readonly))
 677                         goto out_unlock_put;
 678         } else {
 679                 map->flags = GNTMAP_host_map;
 680                 if (!(vma->vm_flags & VM_WRITE))
 681                         map->flags |= GNTMAP_readonly;
 682         }
 683
 684         spin_unlock(&priv->lock);
 685
 686         if (use_ptemod) {
 687                 err = apply_to_page_range(vma->vm_mm, vma->vm_start,
 688                                           vma->vm_end - vma->vm_start,
 689                                           find_grant_ptes, map);
 690                 if (err) {
 691                         printk(KERN_WARNING "find_grant_ptes() failure.\n");
 692                         goto out_put_map;
 693                 }
 694         }
 695
 696         err = map_grant_pages(map);
 697         if (err)
 698                 goto out_put_map;
 699
 700         if (!use_ptemod) {
 701                 for (i = 0; i < count; i++) {
 702                         err = vm_insert_page(vma, vma->vm_start + i*PAGE_SIZE,
 703                                 map->pages[i]);
 704                         if (err)
 705                                 goto out_put_map;
 706                 }
 707         }
 708
 709         return 0;
 710
 711 unlock_out:
 712         spin_unlock(&priv->lock);
 713         return err;
 714
 715 out_unlock_put:
 716         spin_unlock(&priv->lock);
 717 out_put_map:
 718         if (use_ptemod)
 719                 map->vma = NULL;
 720         gntdev_put_map(map);
 721         return err;
 722 }
 723
 724 static const struct file_operations gntdev_fops = {
 725         .owner = THIS_MODULE,
 726         .open = gntdev_open,
 727         .release = gntdev_release,
 728         .mmap = gntdev_mmap,
 729         .unlocked_ioctl = gntdev_ioctl
 730 };
 731
 732 static struct miscdevice gntdev_miscdev = {
 733         .minor        = MISC_DYNAMIC_MINOR,
 734         .name         = "xen/gntdev",
 735         .fops         = &gntdev_fops,
 736 };
 737
 738 /* ------------------------------------------------------------------ */
 739
 740 static int __init gntdev_init(void)
 741 {
 742         int err;
 743
 744         if (!xen_domain())
 745                 return -ENODEV;
 746
 747         use_ptemod = xen_pv_domain();
 748
 749         err = misc_register(&gntdev_miscdev);
 750         if (err != 0) {
 751                 printk(KERN_ERR "Could not register gntdev device\n");
 752                 return err;
 753         }
 754         return 0;
 755 }
 756
 757 static void __exit gntdev_exit(void)
 758 {
 759         misc_deregister(&gntdev_miscdev);
 760 }
 761
 762 module_init(gntdev_init);
 763 module_exit(gntdev_exit);
 764
 765 /* ------------------------------------------------------------------ */