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    = kzalloc(sizeof(add->grants[0])    * count, GFP_KERNEL);
 118         add->map_ops   = kzalloc(sizeof(add->map_ops[0])   * count, GFP_KERNEL);
 119         add->unmap_ops = kzalloc(sizeof(add->unmap_ops[0]) * count, GFP_KERNEL);
 120         add->kmap_ops  = kzalloc(sizeof(add->kmap_ops[0])  * count, GFP_KERNEL);
 121         add->pages     = kzalloc(sizeof(add->pages[0])     * count, 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
 200         if (map->pages) {
 201                 if (!use_ptemod)
 202                         unmap_grant_pages(map, 0, map->count);
 203
 204                 free_xenballooned_pages(map->count, map->pages);
 205         }
 206         kfree(map->pages);
 207         kfree(map->grants);
 208         kfree(map->map_ops);
 209         kfree(map->unmap_ops);
 210         kfree(map);
 211 }
 212
 213 /* ------------------------------------------------------------------ */
 214
 215 static int find_grant_ptes(pte_t *pte, pgtable_t token,
 216                 unsigned long addr, void *data)
 217 {
 218         struct grant_map *map = data;
 219         unsigned int pgnr = (addr - map->vma->vm_start) >> PAGE_SHIFT;
 220         int flags = map->flags | GNTMAP_application_map | GNTMAP_contains_pte;
 221         u64 pte_maddr;
 222
 223         BUG_ON(pgnr >= map->count);
 224         pte_maddr = arbitrary_virt_to_machine(pte).maddr;
 225
 226         gnttab_set_map_op(&map->map_ops[pgnr], pte_maddr, flags,
 227                           map->grants[pgnr].ref,
 228                           map->grants[pgnr].domid);
 229         gnttab_set_unmap_op(&map->unmap_ops[pgnr], pte_maddr, flags,
 230                             -1 /* handle */);
 231         return 0;
 232 }
 233
 234 static int map_grant_pages(struct grant_map *map)
 235 {
 236         int i, err = 0;
 237
 238         if (!use_ptemod) {
 239                 /* Note: it could already be mapped */
 240                 if (map->map_ops[0].handle != -1)
 241                         return 0;
 242                 for (i = 0; i < map->count; i++) {
 243                         unsigned long addr = (unsigned long)
 244                                 pfn_to_kaddr(page_to_pfn(map->pages[i]));
 245                         gnttab_set_map_op(&map->map_ops[i], addr, map->flags,
 246                                 map->grants[i].ref,
 247                                 map->grants[i].domid);
 248                         gnttab_set_unmap_op(&map->unmap_ops[i], addr,
 249                                 map->flags, -1 /* handle */);
 250                 }
 251         } else {
 252                 /*
 253                  * Setup the map_ops corresponding to the pte entries pointing
 254                  * to the kernel linear addresses of the struct pages.
 255                  * These ptes are completely different from the user ptes dealt
 256                  * with find_grant_ptes.
 257                  */
 258                 for (i = 0; i < map->count; i++) {
 259                         unsigned level;
 260                         unsigned long address = (unsigned long)
 261                                 pfn_to_kaddr(page_to_pfn(map->pages[i]));
 262                         pte_t *ptep;
 263                         u64 pte_maddr = 0;
 264                         BUG_ON(PageHighMem(map->pages[i]));
 265
 266                         ptep = lookup_address(address, &level);
 267                         pte_maddr = arbitrary_virt_to_machine(ptep).maddr;
 268                         gnttab_set_map_op(&map->kmap_ops[i], pte_maddr,
 269                                 map->flags |
 270                                 GNTMAP_host_map |
 271                                 GNTMAP_contains_pte,
 272                                 map->grants[i].ref,
 273                                 map->grants[i].domid);
 274                 }
 275         }
 276
 277         pr_debug("map %d+%d\n", map->index, map->count);
 278         err = gnttab_map_refs(map->map_ops, use_ptemod ? map->kmap_ops : NULL,
 279                         map->pages, map->count);
 280         if (err)
 281                 return err;
 282
 283         for (i = 0; i < map->count; i++) {
 284                 if (map->map_ops[i].status)
 285                         err = -EINVAL;
 286                 else {
 287                         BUG_ON(map->map_ops[i].handle == -1);
 288                         map->unmap_ops[i].handle = map->map_ops[i].handle;
 289                         pr_debug("map handle=%d\n", map->map_ops[i].handle);
 290                 }
 291         }
 292         return err;
 293 }
 294
 295 static int __unmap_grant_pages(struct grant_map *map, int offset, int pages)
 296 {
 297         int i, err = 0;
 298
 299         if (map->notify.flags & UNMAP_NOTIFY_CLEAR_BYTE) {
 300                 int pgno = (map->notify.addr >> PAGE_SHIFT);
 301                 if (pgno >= offset && pgno < offset + pages && use_ptemod) {
 302                         void __user *tmp = (void __user *)
 303                                 map->vma->vm_start + map->notify.addr;
 304                         err = copy_to_user(tmp, &err, 1);
 305                         if (err)
 306                                 return -EFAULT;
 307                         map->notify.flags &= ~UNMAP_NOTIFY_CLEAR_BYTE;
 308                 } else if (pgno >= offset && pgno < offset + pages) {
 309                         uint8_t *tmp = kmap(map->pages[pgno]);
 310                         tmp[map->notify.addr & (PAGE_SIZE-1)] = 0;
 311                         kunmap(map->pages[pgno]);
 312                         map->notify.flags &= ~UNMAP_NOTIFY_CLEAR_BYTE;
 313                 }
 314         }
 315
 316         err = gnttab_unmap_refs(map->unmap_ops + offset, map->pages + offset, pages);
 317         if (err)
 318                 return err;
 319
 320         for (i = 0; i < pages; i++) {
 321                 if (map->unmap_ops[offset+i].status)
 322                         err = -EINVAL;
 323                 pr_debug("unmap handle=%d st=%d\n",
 324                         map->unmap_ops[offset+i].handle,
 325                         map->unmap_ops[offset+i].status);
 326                 map->unmap_ops[offset+i].handle = -1;
 327         }
 328         return err;
 329 }
 330
 331 static int unmap_grant_pages(struct grant_map *map, int offset, int pages)
 332 {
 333         int range, err = 0;
 334
 335         pr_debug("unmap %d+%d [%d+%d]\n", map->index, map->count, offset, pages);
 336
 337         /* It is possible the requested range will have a "hole" where we
 338          * already unmapped some of the grants. Only unmap valid ranges.
 339          */
 340         while (pages && !err) {
 341                 while (pages && map->unmap_ops[offset].handle == -1) {
 342                         offset++;
 343                         pages--;
 344                 }
 345                 range = 0;
 346                 while (range < pages) {
 347                         if (map->unmap_ops[offset+range].handle == -1) {
 348                                 range--;
 349                                 break;
 350                         }
 351                         range++;
 352                 }
 353                 err = __unmap_grant_pages(map, offset, range);
 354                 offset += range;
 355                 pages -= range;
 356         }
 357
 358         return err;
 359 }
 360
 361 /* ------------------------------------------------------------------ */
 362
 363 static void gntdev_vma_open(struct vm_area_struct *vma)
 364 {
 365         struct grant_map *map = vma->vm_private_data;
 366
 367         pr_debug("gntdev_vma_open %p\n", vma);
 368         atomic_inc(&map->users);
 369 }
 370
 371 static void gntdev_vma_close(struct vm_area_struct *vma)
 372 {
 373         struct grant_map *map = vma->vm_private_data;
 374
 375         pr_debug("gntdev_vma_close %p\n", vma);
 376         map->vma = NULL;
 377         vma->vm_private_data = NULL;
 378         gntdev_put_map(map);
 379 }
 380
 381 static struct vm_operations_struct gntdev_vmops = {
 382         .open = gntdev_vma_open,
 383         .close = gntdev_vma_close,
 384 };
 385
 386 /* ------------------------------------------------------------------ */
 387
 388 static void mn_invl_range_start(struct mmu_notifier *mn,
 389                                 struct mm_struct *mm,
 390                                 unsigned long start, unsigned long end)
 391 {
 392         struct gntdev_priv *priv = container_of(mn, struct gntdev_priv, mn);
 393         struct grant_map *map;
 394         unsigned long mstart, mend;
 395         int err;
 396
 397         spin_lock(&priv->lock);
 398         list_for_each_entry(map, &priv->maps, next) {
 399                 if (!map->vma)
 400                         continue;
 401                 if (map->vma->vm_start >= end)
 402                         continue;
 403                 if (map->vma->vm_end <= start)
 404                         continue;
 405                 mstart = max(start, map->vma->vm_start);
 406                 mend   = min(end,   map->vma->vm_end);
 407                 pr_debug("map %d+%d (%lx %lx), range %lx %lx, mrange %lx %lx\n",
 408                                 map->index, map->count,
 409                                 map->vma->vm_start, map->vma->vm_end,
 410                                 start, end, mstart, mend);
 411                 err = unmap_grant_pages(map,
 412                                         (mstart - map->vma->vm_start) >> PAGE_SHIFT,
 413                                         (mend - mstart) >> PAGE_SHIFT);
 414                 WARN_ON(err);
 415         }
 416         spin_unlock(&priv->lock);
 417 }
 418
 419 static void mn_invl_page(struct mmu_notifier *mn,
 420                          struct mm_struct *mm,
 421                          unsigned long address)
 422 {
 423         mn_invl_range_start(mn, mm, address, address + PAGE_SIZE);
 424 }
 425
 426 static void mn_release(struct mmu_notifier *mn,
 427                        struct mm_struct *mm)
 428 {
 429         struct gntdev_priv *priv = container_of(mn, struct gntdev_priv, mn);
 430         struct grant_map *map;
 431         int err;
 432
 433         spin_lock(&priv->lock);
 434         list_for_each_entry(map, &priv->maps, next) {
 435                 if (!map->vma)
 436                         continue;
 437                 pr_debug("map %d+%d (%lx %lx)\n",
 438                                 map->index, map->count,
 439                                 map->vma->vm_start, map->vma->vm_end);
 440                 err = unmap_grant_pages(map, /* offset */ 0, map->count);
 441                 WARN_ON(err);
 442         }
 443         spin_unlock(&priv->lock);
 444 }
 445
 446 struct mmu_notifier_ops gntdev_mmu_ops = {
 447         .release                = mn_release,
 448         .invalidate_page        = mn_invl_page,
 449         .invalidate_range_start = mn_invl_range_start,
 450 };
 451
 452 /* ------------------------------------------------------------------ */
 453
 454 static int gntdev_open(struct inode *inode, struct file *flip)
 455 {
 456         struct gntdev_priv *priv;
 457         int ret = 0;
 458
 459         priv = kzalloc(sizeof(*priv), GFP_KERNEL);
 460         if (!priv)
 461                 return -ENOMEM;
 462
 463         INIT_LIST_HEAD(&priv->maps);
 464         spin_lock_init(&priv->lock);
 465
 466         if (use_ptemod) {
 467                 priv->mm = get_task_mm(current);
 468                 if (!priv->mm) {
 469                         kfree(priv);
 470                         return -ENOMEM;
 471                 }
 472                 priv->mn.ops = &gntdev_mmu_ops;
 473                 ret = mmu_notifier_register(&priv->mn, priv->mm);
 474                 mmput(priv->mm);
 475         }
 476
 477         if (ret) {
 478                 kfree(priv);
 479                 return ret;
 480         }
 481
 482         flip->private_data = priv;
 483         pr_debug("priv %p\n", priv);
 484
 485         return 0;
 486 }
 487
 488 static int gntdev_release(struct inode *inode, struct file *flip)
 489 {
 490         struct gntdev_priv *priv = flip->private_data;
 491         struct grant_map *map;
 492
 493         pr_debug("priv %p\n", priv);
 494
 495         while (!list_empty(&priv->maps)) {
 496                 map = list_entry(priv->maps.next, struct grant_map, next);
 497                 list_del(&map->next);
 498                 gntdev_put_map(map);
 499         }
 500
 501         if (use_ptemod)
 502                 mmu_notifier_unregister(&priv->mn, priv->mm);
 503         kfree(priv);
 504         return 0;
 505 }
 506
 507 static long gntdev_ioctl_map_grant_ref(struct gntdev_priv *priv,
 508                                        struct ioctl_gntdev_map_grant_ref __user *u)
 509 {
 510         struct ioctl_gntdev_map_grant_ref op;
 511         struct grant_map *map;
 512         int err;
 513
 514         if (copy_from_user(&op, u, sizeof(op)) != 0)
 515                 return -EFAULT;
 516         pr_debug("priv %p, add %d\n", priv, op.count);
 517         if (unlikely(op.count <= 0))
 518                 return -EINVAL;
 519
 520         err = -ENOMEM;
 521         map = gntdev_alloc_map(priv, op.count);
 522         if (!map)
 523                 return err;
 524
 525         if (unlikely(atomic_add_return(op.count, &pages_mapped) > limit)) {
 526                 pr_debug("can't map: over limit\n");
 527                 gntdev_put_map(map);
 528                 return err;
 529         }
 530
 531         if (copy_from_user(map->grants, &u->refs,
 532                            sizeof(map->grants[0]) * op.count) != 0) {
 533                 gntdev_put_map(map);
 534                 return err;
 535         }
 536
 537         spin_lock(&priv->lock);
 538         gntdev_add_map(priv, map);
 539         op.index = map->index << PAGE_SHIFT;
 540         spin_unlock(&priv->lock);
 541
 542         if (copy_to_user(u, &op, sizeof(op)) != 0)
 543                 return -EFAULT;
 544
 545         return 0;
 546 }
 547
 548 static long gntdev_ioctl_unmap_grant_ref(struct gntdev_priv *priv,
 549                                          struct ioctl_gntdev_unmap_grant_ref __user *u)
 550 {
 551         struct ioctl_gntdev_unmap_grant_ref op;
 552         struct grant_map *map;
 553         int err = -ENOENT;
 554
 555         if (copy_from_user(&op, u, sizeof(op)) != 0)
 556                 return -EFAULT;
 557         pr_debug("priv %p, del %d+%d\n", priv, (int)op.index, (int)op.count);
 558
 559         spin_lock(&priv->lock);
 560         map = gntdev_find_map_index(priv, op.index >> PAGE_SHIFT, op.count);
 561         if (map) {
 562                 list_del(&map->next);
 563                 err = 0;
 564         }
 565         spin_unlock(&priv->lock);
 566         if (map)
 567                 gntdev_put_map(map);
 568         return err;
 569 }
 570
 571 static long gntdev_ioctl_get_offset_for_vaddr(struct gntdev_priv *priv,
 572                                               struct ioctl_gntdev_get_offset_for_vaddr __user *u)
 573 {
 574         struct ioctl_gntdev_get_offset_for_vaddr op;
 575         struct vm_area_struct *vma;
 576         struct grant_map *map;
 577
 578         if (copy_from_user(&op, u, sizeof(op)) != 0)
 579                 return -EFAULT;
 580         pr_debug("priv %p, offset for vaddr %lx\n", priv, (unsigned long)op.vaddr);
 581
 582         vma = find_vma(current->mm, op.vaddr);
 583         if (!vma || vma->vm_ops != &gntdev_vmops)
 584                 return -EINVAL;
 585
 586         map = vma->vm_private_data;
 587         if (!map)
 588                 return -EINVAL;
 589
 590         op.offset = map->index << PAGE_SHIFT;
 591         op.count = map->count;
 592
 593         if (copy_to_user(u, &op, sizeof(op)) != 0)
 594                 return -EFAULT;
 595         return 0;
 596 }
 597
 598 static long gntdev_ioctl_notify(struct gntdev_priv *priv, void __user *u)
 599 {
 600         struct ioctl_gntdev_unmap_notify op;
 601         struct grant_map *map;
 602         int rc;
 603
 604         if (copy_from_user(&op, u, sizeof(op)))
 605                 return -EFAULT;
 606
 607         if (op.action & ~(UNMAP_NOTIFY_CLEAR_BYTE|UNMAP_NOTIFY_SEND_EVENT))
 608                 return -EINVAL;
 609
 610         spin_lock(&priv->lock);
 611
 612         list_for_each_entry(map, &priv->maps, next) {
 613                 uint64_t begin = map->index << PAGE_SHIFT;
 614                 uint64_t end = (map->index + map->count) << PAGE_SHIFT;
 615                 if (op.index >= begin && op.index < end)
 616                         goto found;
 617         }
 618         rc = -ENOENT;
 619         goto unlock_out;
 620
 621  found:
 622         if ((op.action & UNMAP_NOTIFY_CLEAR_BYTE) &&
 623                         (map->flags & GNTMAP_readonly)) {
 624                 rc = -EINVAL;
 625                 goto unlock_out;
 626         }
 627
 628         map->notify.flags = op.action;
 629         map->notify.addr = op.index - (map->index << PAGE_SHIFT);
 630         map->notify.event = op.event_channel_port;
 631         rc = 0;
 632  unlock_out:
 633         spin_unlock(&priv->lock);
 634         return rc;
 635 }
 636
 637 static long gntdev_ioctl(struct file *flip,
 638                          unsigned int cmd, unsigned long arg)
 639 {
 640         struct gntdev_priv *priv = flip->private_data;
 641         void __user *ptr = (void __user *)arg;
 642
 643         switch (cmd) {
 644         case IOCTL_GNTDEV_MAP_GRANT_REF:
 645                 return gntdev_ioctl_map_grant_ref(priv, ptr);
 646
 647         case IOCTL_GNTDEV_UNMAP_GRANT_REF:
 648                 return gntdev_ioctl_unmap_grant_ref(priv, ptr);
 649
 650         case IOCTL_GNTDEV_GET_OFFSET_FOR_VADDR:
 651                 return gntdev_ioctl_get_offset_for_vaddr(priv, ptr);
 652
 653         case IOCTL_GNTDEV_SET_UNMAP_NOTIFY:
 654                 return gntdev_ioctl_notify(priv, ptr);
 655
 656         default:
 657                 pr_debug("priv %p, unknown cmd %x\n", priv, cmd);
 658                 return -ENOIOCTLCMD;
 659         }
 660
 661         return 0;
 662 }
 663
 664 static int gntdev_mmap(struct file *flip, struct vm_area_struct *vma)
 665 {
 666         struct gntdev_priv *priv = flip->private_data;
 667         int index = vma->vm_pgoff;
 668         int count = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
 669         struct grant_map *map;
 670         int i, err = -EINVAL;
 671
 672         if ((vma->vm_flags & VM_WRITE) && !(vma->vm_flags & VM_SHARED))
 673                 return -EINVAL;
 674
 675         pr_debug("map %d+%d at %lx (pgoff %lx)\n",
 676                         index, count, vma->vm_start, vma->vm_pgoff);
 677
 678         spin_lock(&priv->lock);
 679         map = gntdev_find_map_index(priv, index, count);
 680         if (!map)
 681                 goto unlock_out;
 682         if (use_ptemod && map->vma)
 683                 goto unlock_out;
 684         if (use_ptemod && priv->mm != vma->vm_mm) {
 685                 printk(KERN_WARNING "Huh? Other mm?\n");
 686                 goto unlock_out;
 687         }
 688
 689         atomic_inc(&map->users);
 690
 691         vma->vm_ops = &gntdev_vmops;
 692
 693         vma->vm_flags |= VM_RESERVED|VM_DONTEXPAND;
 694
 695         if (use_ptemod)
 696                 vma->vm_flags |= VM_DONTCOPY|VM_PFNMAP;
 697
 698         vma->vm_private_data = map;
 699
 700         if (use_ptemod)
 701                 map->vma = vma;
 702
 703         if (map->flags) {
 704                 if ((vma->vm_flags & VM_WRITE) &&
 705                                 (map->flags & GNTMAP_readonly))
 706                         goto out_unlock_put;
 707         } else {
 708                 map->flags = GNTMAP_host_map;
 709                 if (!(vma->vm_flags & VM_WRITE))
 710                         map->flags |= GNTMAP_readonly;
 711         }
 712
 713         spin_unlock(&priv->lock);
 714
 715         if (use_ptemod) {
 716                 err = apply_to_page_range(vma->vm_mm, vma->vm_start,
 717                                           vma->vm_end - vma->vm_start,
 718                                           find_grant_ptes, map);
 719                 if (err) {
 720                         printk(KERN_WARNING "find_grant_ptes() failure.\n");
 721                         goto out_put_map;
 722                 }
 723         }
 724
 725         err = map_grant_pages(map);
 726         if (err)
 727                 goto out_put_map;
 728
 729         if (!use_ptemod) {
 730                 for (i = 0; i < count; i++) {
 731                         err = vm_insert_page(vma, vma->vm_start + i*PAGE_SIZE,
 732                                 map->pages[i]);
 733                         if (err)
 734                                 goto out_put_map;
 735                 }
 736         }
 737
 738         return 0;
 739
 740 unlock_out:
 741         spin_unlock(&priv->lock);
 742         return err;
 743
 744 out_unlock_put:
 745         spin_unlock(&priv->lock);
 746 out_put_map:
 747         if (use_ptemod)
 748                 map->vma = NULL;
 749         gntdev_put_map(map);
 750         return err;
 751 }
 752
 753 static const struct file_operations gntdev_fops = {
 754         .owner = THIS_MODULE,
 755         .open = gntdev_open,
 756         .release = gntdev_release,
 757         .mmap = gntdev_mmap,
 758         .unlocked_ioctl = gntdev_ioctl
 759 };
 760
 761 static struct miscdevice gntdev_miscdev = {
 762         .minor        = MISC_DYNAMIC_MINOR,
 763         .name         = "xen/gntdev",
 764         .fops         = &gntdev_fops,
 765 };
 766
 767 /* ------------------------------------------------------------------ */
 768
 769 static int __init gntdev_init(void)
 770 {
 771         int err;
 772
 773         if (!xen_domain())
 774                 return -ENODEV;
 775
 776         use_ptemod = xen_pv_domain();
 777
 778         err = misc_register(&gntdev_miscdev);
 779         if (err != 0) {
 780                 printk(KERN_ERR "Could not register gntdev device\n");
 781                 return err;
 782         }
 783         return 0;
 784 }
 785
 786 static void __exit gntdev_exit(void)
 787 {
 788         misc_deregister(&gntdev_miscdev);
 789 }
 790
 791 module_init(gntdev_init);
 792 module_exit(gntdev_exit);
 793
 794 /* ------------------------------------------------------------------ */