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 gnttab_map_grant_ref   *kmap_ops;
  87         struct page **pages;
  88 };
  89
  90 static int unmap_grant_pages(struct grant_map *map, int offset, int pages);
  91
  92 /* ------------------------------------------------------------------ */
  93
  94 static void gntdev_print_maps(struct gntdev_priv *priv,
  95                               char *text, int text_index)
  96 {
  97 #ifdef DEBUG
  98         struct grant_map *map;
  99
 100         pr_debug("%s: maps list (priv %p)\n", __func__, priv);
 101         list_for_each_entry(map, &priv->maps, next)
 102                 pr_debug("  index %2d, count %2d %s\n",
 103                        map->index, map->count,
 104                        map->index == text_index && text ? text : "");
 105 #endif
 106 }
 107
 108 static struct grant_map *gntdev_alloc_map(struct gntdev_priv *priv, int count)
 109 {
 110         struct grant_map *add;
 111         int i;
 112
 113         add = kzalloc(sizeof(struct grant_map), GFP_KERNEL);
 114         if (NULL == add)
 115                 return NULL;
 116
 117         add->grants    = kcalloc(count, sizeof(add->grants[0]), GFP_KERNEL);
 118         add->map_ops   = kcalloc(count, sizeof(add->map_ops[0]), GFP_KERNEL);
 119         add->unmap_ops = kcalloc(count, sizeof(add->unmap_ops[0]), GFP_KERNEL);
 120         add->kmap_ops  = kcalloc(count, sizeof(add->kmap_ops[0]), GFP_KERNEL);
 121         add->pages     = kcalloc(count, sizeof(add->pages[0]), GFP_KERNEL);
 122         if (NULL == add->grants    ||
 123             NULL == add->map_ops   ||
 124             NULL == add->unmap_ops ||
 125             NULL == add->kmap_ops  ||
 126             NULL == add->pages)
 127                 goto err;
 128
 129         if (alloc_xenballooned_pages(count, add->pages, false /* lowmem */))
 130                 goto err;
 131
 132         for (i = 0; i < count; i++) {
 133                 add->map_ops[i].handle = -1;
 134                 add->unmap_ops[i].handle = -1;
 135                 add->kmap_ops[i].handle = -1;
 136         }
 137
 138         add->index = 0;
 139         add->count = count;
 140         atomic_set(&add->users, 1);
 141
 142         return add;
 143
 144 err:
 145         kfree(add->pages);
 146         kfree(add->grants);
 147         kfree(add->map_ops);
 148         kfree(add->unmap_ops);
 149         kfree(add->kmap_ops);
 150         kfree(add);
 151         return NULL;
 152 }
 153
 154 static void gntdev_add_map(struct gntdev_priv *priv, struct grant_map *add)
 155 {
 156         struct grant_map *map;
 157
 158         list_for_each_entry(map, &priv->maps, next) {
 159                 if (add->index + add->count < map->index) {
 160                         list_add_tail(&add->next, &map->next);
 161                         goto done;
 162                 }
 163                 add->index = map->index + map->count;
 164         }
 165         list_add_tail(&add->next, &priv->maps);
 166
 167 done:
 168         gntdev_print_maps(priv, "[new]", add->index);
 169 }
 170
 171 static struct grant_map *gntdev_find_map_index(struct gntdev_priv *priv,
 172                 int index, int count)
 173 {
 174         struct grant_map *map;
 175
 176         list_for_each_entry(map, &priv->maps, next) {
 177                 if (map->index != index)
 178                         continue;
 179                 if (count && map->count != count)
 180                         continue;
 181                 return map;
 182         }
 183         return NULL;
 184 }
 185
 186 static void gntdev_put_map(struct grant_map *map)
 187 {
 188         if (!map)
 189                 return;
 190
 191         if (!atomic_dec_and_test(&map->users))
 192                 return;
 193
 194         atomic_sub(map->count, &pages_mapped);
 195
 196         if (map->notify.flags & UNMAP_NOTIFY_SEND_EVENT)
 197                 notify_remote_via_evtchn(map->notify.event);
 198
 199         if (map->pages) {
 200                 if (!use_ptemod)
 201                         unmap_grant_pages(map, 0, map->count);
 202
 203                 free_xenballooned_pages(map->count, map->pages);
 204         }
 205         kfree(map->pages);
 206         kfree(map->grants);
 207         kfree(map->map_ops);
 208         kfree(map->unmap_ops);
 209         kfree(map);
 210 }
 211
 212 /* ------------------------------------------------------------------ */
 213
 214 static int find_grant_ptes(pte_t *pte, pgtable_t token,
 215                 unsigned long addr, void *data)
 216 {
 217         struct grant_map *map = data;
 218         unsigned int pgnr = (addr - map->vma->vm_start) >> PAGE_SHIFT;
 219         int flags = map->flags | GNTMAP_application_map | GNTMAP_contains_pte;
 220         u64 pte_maddr;
 221
 222         BUG_ON(pgnr >= map->count);
 223         pte_maddr = arbitrary_virt_to_machine(pte).maddr;
 224
 225         gnttab_set_map_op(&map->map_ops[pgnr], pte_maddr, flags,
 226                           map->grants[pgnr].ref,
 227                           map->grants[pgnr].domid);
 228         gnttab_set_unmap_op(&map->unmap_ops[pgnr], pte_maddr, flags,
 229                             -1 /* handle */);
 230         return 0;
 231 }
 232
 233 static int map_grant_pages(struct grant_map *map)
 234 {
 235         int i, err = 0;
 236
 237         if (!use_ptemod) {
 238                 /* Note: it could already be mapped */
 239                 if (map->map_ops[0].handle != -1)
 240                         return 0;
 241                 for (i = 0; i < map->count; i++) {
 242                         unsigned long addr = (unsigned long)
 243                                 pfn_to_kaddr(page_to_pfn(map->pages[i]));
 244                         gnttab_set_map_op(&map->map_ops[i], addr, map->flags,
 245                                 map->grants[i].ref,
 246                                 map->grants[i].domid);
 247                         gnttab_set_unmap_op(&map->unmap_ops[i], addr,
 248                                 map->flags, -1 /* handle */);
 249                 }
 250         } else {
 251                 /*
 252                  * Setup the map_ops corresponding to the pte entries pointing
 253                  * to the kernel linear addresses of the struct pages.
 254                  * These ptes are completely different from the user ptes dealt
 255                  * with find_grant_ptes.
 256                  */
 257                 for (i = 0; i < map->count; i++) {
 258                         unsigned level;
 259                         unsigned long address = (unsigned long)
 260                                 pfn_to_kaddr(page_to_pfn(map->pages[i]));
 261                         pte_t *ptep;
 262                         u64 pte_maddr = 0;
 263                         BUG_ON(PageHighMem(map->pages[i]));
 264
 265                         ptep = lookup_address(address, &level);
 266                         pte_maddr = arbitrary_virt_to_machine(ptep).maddr;
 267                         gnttab_set_map_op(&map->kmap_ops[i], pte_maddr,
 268                                 map->flags |
 269                                 GNTMAP_host_map |
 270                                 GNTMAP_contains_pte,
 271                                 map->grants[i].ref,
 272                                 map->grants[i].domid);
 273                 }
 274         }
 275
 276         pr_debug("map %d+%d\n", map->index, map->count);
 277         err = gnttab_map_refs(map->map_ops, use_ptemod ? map->kmap_ops : NULL,
 278                         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 = (void __user *)
 302                                 map->vma->vm_start + map->notify.addr;
 303                         err = copy_to_user(tmp, &err, 1);
 304                         if (err)
 305                                 return -EFAULT;
 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_open(struct vm_area_struct *vma)
 363 {
 364         struct grant_map *map = vma->vm_private_data;
 365
 366         pr_debug("gntdev_vma_open %p\n", vma);
 367         atomic_inc(&map->users);
 368 }
 369
 370 static void gntdev_vma_close(struct vm_area_struct *vma)
 371 {
 372         struct grant_map *map = vma->vm_private_data;
 373
 374         pr_debug("gntdev_vma_close %p\n", vma);
 375         map->vma = NULL;
 376         vma->vm_private_data = NULL;
 377         gntdev_put_map(map);
 378 }
 379
 380 static struct vm_operations_struct gntdev_vmops = {
 381         .open = gntdev_vma_open,
 382         .close = gntdev_vma_close,
 383 };
 384
 385 /* ------------------------------------------------------------------ */
 386
 387 static void mn_invl_range_start(struct mmu_notifier *mn,
 388                                 struct mm_struct *mm,
 389                                 unsigned long start, unsigned long end)
 390 {
 391         struct gntdev_priv *priv = container_of(mn, struct gntdev_priv, mn);
 392         struct grant_map *map;
 393         unsigned long mstart, mend;
 394         int err;
 395
 396         spin_lock(&priv->lock);
 397         list_for_each_entry(map, &priv->maps, next) {
 398                 if (!map->vma)
 399                         continue;
 400                 if (map->vma->vm_start >= end)
 401                         continue;
 402                 if (map->vma->vm_end <= start)
 403                         continue;
 404                 mstart = max(start, map->vma->vm_start);
 405                 mend   = min(end,   map->vma->vm_end);
 406                 pr_debug("map %d+%d (%lx %lx), range %lx %lx, mrange %lx %lx\n",
 407                                 map->index, map->count,
 408                                 map->vma->vm_start, map->vma->vm_end,
 409                                 start, end, mstart, mend);
 410                 err = unmap_grant_pages(map,
 411                                         (mstart - map->vma->vm_start) >> PAGE_SHIFT,
 412                                         (mend - mstart) >> PAGE_SHIFT);
 413                 WARN_ON(err);
 414         }
 415         spin_unlock(&priv->lock);
 416 }
 417
 418 static void mn_invl_page(struct mmu_notifier *mn,
 419                          struct mm_struct *mm,
 420                          unsigned long address)
 421 {
 422         mn_invl_range_start(mn, mm, address, address + PAGE_SIZE);
 423 }
 424
 425 static void mn_release(struct mmu_notifier *mn,
 426                        struct mm_struct *mm)
 427 {
 428         struct gntdev_priv *priv = container_of(mn, struct gntdev_priv, mn);
 429         struct grant_map *map;
 430         int err;
 431
 432         spin_lock(&priv->lock);
 433         list_for_each_entry(map, &priv->maps, next) {
 434                 if (!map->vma)
 435                         continue;
 436                 pr_debug("map %d+%d (%lx %lx)\n",
 437                                 map->index, map->count,
 438                                 map->vma->vm_start, map->vma->vm_end);
 439                 err = unmap_grant_pages(map, /* offset */ 0, map->count);
 440                 WARN_ON(err);
 441         }
 442         spin_unlock(&priv->lock);
 443 }
 444
 445 struct mmu_notifier_ops gntdev_mmu_ops = {
 446         .release                = mn_release,
 447         .invalidate_page        = mn_invl_page,
 448         .invalidate_range_start = mn_invl_range_start,
 449 };
 450
 451 /* ------------------------------------------------------------------ */
 452
 453 static int gntdev_open(struct inode *inode, struct file *flip)
 454 {
 455         struct gntdev_priv *priv;
 456         int ret = 0;
 457
 458         priv = kzalloc(sizeof(*priv), GFP_KERNEL);
 459         if (!priv)
 460                 return -ENOMEM;
 461
 462         INIT_LIST_HEAD(&priv->maps);
 463         spin_lock_init(&priv->lock);
 464
 465         if (use_ptemod) {
 466                 priv->mm = get_task_mm(current);
 467                 if (!priv->mm) {
 468                         kfree(priv);
 469                         return -ENOMEM;
 470                 }
 471                 priv->mn.ops = &gntdev_mmu_ops;
 472                 ret = mmu_notifier_register(&priv->mn, priv->mm);
 473                 mmput(priv->mm);
 474         }
 475
 476         if (ret) {
 477                 kfree(priv);
 478                 return ret;
 479         }
 480
 481         flip->private_data = priv;
 482         pr_debug("priv %p\n", priv);
 483
 484         return 0;
 485 }
 486
 487 static int gntdev_release(struct inode *inode, struct file *flip)
 488 {
 489         struct gntdev_priv *priv = flip->private_data;
 490         struct grant_map *map;
 491
 492         pr_debug("priv %p\n", priv);
 493
 494         while (!list_empty(&priv->maps)) {
 495                 map = list_entry(priv->maps.next, struct grant_map, next);
 496                 list_del(&map->next);
 497                 gntdev_put_map(map);
 498         }
 499
 500         if (use_ptemod)
 501                 mmu_notifier_unregister(&priv->mn, priv->mm);
 502         kfree(priv);
 503         return 0;
 504 }
 505
 506 static long gntdev_ioctl_map_grant_ref(struct gntdev_priv *priv,
 507                                        struct ioctl_gntdev_map_grant_ref __user *u)
 508 {
 509         struct ioctl_gntdev_map_grant_ref op;
 510         struct grant_map *map;
 511         int err;
 512
 513         if (copy_from_user(&op, u, sizeof(op)) != 0)
 514                 return -EFAULT;
 515         pr_debug("priv %p, add %d\n", priv, op.count);
 516         if (unlikely(op.count <= 0))
 517                 return -EINVAL;
 518
 519         err = -ENOMEM;
 520         map = gntdev_alloc_map(priv, op.count);
 521         if (!map)
 522                 return err;
 523
 524         if (unlikely(atomic_add_return(op.count, &pages_mapped) > limit)) {
 525                 pr_debug("can't map: over limit\n");
 526                 gntdev_put_map(map);
 527                 return err;
 528         }
 529
 530         if (copy_from_user(map->grants, &u->refs,
 531                            sizeof(map->grants[0]) * op.count) != 0) {
 532                 gntdev_put_map(map);
 533                 return err;
 534         }
 535
 536         spin_lock(&priv->lock);
 537         gntdev_add_map(priv, map);
 538         op.index = map->index << PAGE_SHIFT;
 539         spin_unlock(&priv->lock);
 540
 541         if (copy_to_user(u, &op, sizeof(op)) != 0)
 542                 return -EFAULT;
 543
 544         return 0;
 545 }
 546
 547 static long gntdev_ioctl_unmap_grant_ref(struct gntdev_priv *priv,
 548                                          struct ioctl_gntdev_unmap_grant_ref __user *u)
 549 {
 550         struct ioctl_gntdev_unmap_grant_ref op;
 551         struct grant_map *map;
 552         int err = -ENOENT;
 553
 554         if (copy_from_user(&op, u, sizeof(op)) != 0)
 555                 return -EFAULT;
 556         pr_debug("priv %p, del %d+%d\n", priv, (int)op.index, (int)op.count);
 557
 558         spin_lock(&priv->lock);
 559         map = gntdev_find_map_index(priv, op.index >> PAGE_SHIFT, op.count);
 560         if (map) {
 561                 list_del(&map->next);
 562                 err = 0;
 563         }
 564         spin_unlock(&priv->lock);
 565         if (map)
 566                 gntdev_put_map(map);
 567         return err;
 568 }
 569
 570 static long gntdev_ioctl_get_offset_for_vaddr(struct gntdev_priv *priv,
 571                                               struct ioctl_gntdev_get_offset_for_vaddr __user *u)
 572 {
 573         struct ioctl_gntdev_get_offset_for_vaddr op;
 574         struct vm_area_struct *vma;
 575         struct grant_map *map;
 576
 577         if (copy_from_user(&op, u, sizeof(op)) != 0)
 578                 return -EFAULT;
 579         pr_debug("priv %p, offset for vaddr %lx\n", priv, (unsigned long)op.vaddr);
 580
 581         vma = find_vma(current->mm, op.vaddr);
 582         if (!vma || vma->vm_ops != &gntdev_vmops)
 583                 return -EINVAL;
 584
 585         map = vma->vm_private_data;
 586         if (!map)
 587                 return -EINVAL;
 588
 589         op.offset = map->index << PAGE_SHIFT;
 590         op.count = map->count;
 591
 592         if (copy_to_user(u, &op, sizeof(op)) != 0)
 593                 return -EFAULT;
 594         return 0;
 595 }
 596
 597 static long gntdev_ioctl_notify(struct gntdev_priv *priv, void __user *u)
 598 {
 599         struct ioctl_gntdev_unmap_notify op;
 600         struct grant_map *map;
 601         int rc;
 602
 603         if (copy_from_user(&op, u, sizeof(op)))
 604                 return -EFAULT;
 605
 606         if (op.action & ~(UNMAP_NOTIFY_CLEAR_BYTE|UNMAP_NOTIFY_SEND_EVENT))
 607                 return -EINVAL;
 608
 609         spin_lock(&priv->lock);
 610
 611         list_for_each_entry(map, &priv->maps, next) {
 612                 uint64_t begin = map->index << PAGE_SHIFT;
 613                 uint64_t end = (map->index + map->count) << PAGE_SHIFT;
 614                 if (op.index >= begin && op.index < end)
 615                         goto found;
 616         }
 617         rc = -ENOENT;
 618         goto unlock_out;
 619
 620  found:
 621         if ((op.action & UNMAP_NOTIFY_CLEAR_BYTE) &&
 622                         (map->flags & GNTMAP_readonly)) {
 623                 rc = -EINVAL;
 624                 goto unlock_out;
 625         }
 626
 627         map->notify.flags = op.action;
 628         map->notify.addr = op.index - (map->index << PAGE_SHIFT);
 629         map->notify.event = op.event_channel_port;
 630         rc = 0;
 631  unlock_out:
 632         spin_unlock(&priv->lock);
 633         return rc;
 634 }
 635
 636 static long gntdev_ioctl(struct file *flip,
 637                          unsigned int cmd, unsigned long arg)
 638 {
 639         struct gntdev_priv *priv = flip->private_data;
 640         void __user *ptr = (void __user *)arg;
 641
 642         switch (cmd) {
 643         case IOCTL_GNTDEV_MAP_GRANT_REF:
 644                 return gntdev_ioctl_map_grant_ref(priv, ptr);
 645
 646         case IOCTL_GNTDEV_UNMAP_GRANT_REF:
 647                 return gntdev_ioctl_unmap_grant_ref(priv, ptr);
 648
 649         case IOCTL_GNTDEV_GET_OFFSET_FOR_VADDR:
 650                 return gntdev_ioctl_get_offset_for_vaddr(priv, ptr);
 651
 652         case IOCTL_GNTDEV_SET_UNMAP_NOTIFY:
 653                 return gntdev_ioctl_notify(priv, ptr);
 654
 655         default:
 656                 pr_debug("priv %p, unknown cmd %x\n", priv, cmd);
 657                 return -ENOIOCTLCMD;
 658         }
 659
 660         return 0;
 661 }
 662
 663 static int gntdev_mmap(struct file *flip, struct vm_area_struct *vma)
 664 {
 665         struct gntdev_priv *priv = flip->private_data;
 666         int index = vma->vm_pgoff;
 667         int count = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
 668         struct grant_map *map;
 669         int i, err = -EINVAL;
 670
 671         if ((vma->vm_flags & VM_WRITE) && !(vma->vm_flags & VM_SHARED))
 672                 return -EINVAL;
 673
 674         pr_debug("map %d+%d at %lx (pgoff %lx)\n",
 675                         index, count, vma->vm_start, vma->vm_pgoff);
 676
 677         spin_lock(&priv->lock);
 678         map = gntdev_find_map_index(priv, index, count);
 679         if (!map)
 680                 goto unlock_out;
 681         if (use_ptemod && map->vma)
 682                 goto unlock_out;
 683         if (use_ptemod && priv->mm != vma->vm_mm) {
 684                 printk(KERN_WARNING "Huh? Other mm?\n");
 685                 goto unlock_out;
 686         }
 687
 688         atomic_inc(&map->users);
 689
 690         vma->vm_ops = &gntdev_vmops;
 691
 692         vma->vm_flags |= VM_RESERVED|VM_DONTEXPAND;
 693
 694         if (use_ptemod)
 695                 vma->vm_flags |= VM_DONTCOPY|VM_PFNMAP;
 696
 697         vma->vm_private_data = map;
 698
 699         if (use_ptemod)
 700                 map->vma = vma;
 701
 702         if (map->flags) {
 703                 if ((vma->vm_flags & VM_WRITE) &&
 704                                 (map->flags & GNTMAP_readonly))
 705                         goto out_unlock_put;
 706         } else {
 707                 map->flags = GNTMAP_host_map;
 708                 if (!(vma->vm_flags & VM_WRITE))
 709                         map->flags |= GNTMAP_readonly;
 710         }
 711
 712         spin_unlock(&priv->lock);
 713
 714         if (use_ptemod) {
 715                 err = apply_to_page_range(vma->vm_mm, vma->vm_start,
 716                                           vma->vm_end - vma->vm_start,
 717                                           find_grant_ptes, map);
 718                 if (err) {
 719                         printk(KERN_WARNING "find_grant_ptes() failure.\n");
 720                         goto out_put_map;
 721                 }
 722         }
 723
 724         err = map_grant_pages(map);
 725         if (err)
 726                 goto out_put_map;
 727
 728         if (!use_ptemod) {
 729                 for (i = 0; i < count; i++) {
 730                         err = vm_insert_page(vma, vma->vm_start + i*PAGE_SIZE,
 731                                 map->pages[i]);
 732                         if (err)
 733                                 goto out_put_map;
 734                 }
 735         }
 736
 737         return 0;
 738
 739 unlock_out:
 740         spin_unlock(&priv->lock);
 741         return err;
 742
 743 out_unlock_put:
 744         spin_unlock(&priv->lock);
 745 out_put_map:
 746         if (use_ptemod)
 747                 map->vma = NULL;
 748         gntdev_put_map(map);
 749         return err;
 750 }
 751
 752 static const struct file_operations gntdev_fops = {
 753         .owner = THIS_MODULE,
 754         .open = gntdev_open,
 755         .release = gntdev_release,
 756         .mmap = gntdev_mmap,
 757         .unlocked_ioctl = gntdev_ioctl
 758 };
 759
 760 static struct miscdevice gntdev_miscdev = {
 761         .minor        = MISC_DYNAMIC_MINOR,
 762         .name         = "xen/gntdev",
 763         .fops         = &gntdev_fops,
 764 };
 765
 766 /* ------------------------------------------------------------------ */
 767
 768 static int __init gntdev_init(void)
 769 {
 770         int err;
 771
 772         if (!xen_domain())
 773                 return -ENODEV;
 774
 775         use_ptemod = xen_pv_domain();
 776
 777         err = misc_register(&gntdev_miscdev);
 778         if (err != 0) {
 779                 printk(KERN_ERR "Could not register gntdev device\n");
 780                 return err;
 781         }
 782         return 0;
 783 }
 784
 785 static void __exit gntdev_exit(void)
 786 {
 787         misc_deregister(&gntdev_miscdev);
 788 }
 789
 790 module_init(gntdev_init);
 791 module_exit(gntdev_exit);
 792
 793 /* ------------------------------------------------------------------ */