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                 evtchn_put(map->notify.event);
 199         }
 200
 201         if (map->pages) {
 202                 if (!use_ptemod)
 203                         unmap_grant_pages(map, 0, map->count);
 204
 205                 free_xenballooned_pages(map->count, map->pages);
 206         }
 207         kfree(map->pages);
 208         kfree(map->grants);
 209         kfree(map->map_ops);
 210         kfree(map->unmap_ops);
 211         kfree(map);
 212 }
 213
 214 /* ------------------------------------------------------------------ */
 215
 216 static int find_grant_ptes(pte_t *pte, pgtable_t token,
 217                 unsigned long addr, void *data)
 218 {
 219         struct grant_map *map = data;
 220         unsigned int pgnr = (addr - map->vma->vm_start) >> PAGE_SHIFT;
 221         int flags = map->flags | GNTMAP_application_map | GNTMAP_contains_pte;
 222         u64 pte_maddr;
 223
 224         BUG_ON(pgnr >= map->count);
 225         pte_maddr = arbitrary_virt_to_machine(pte).maddr;
 226
 227         gnttab_set_map_op(&map->map_ops[pgnr], pte_maddr, flags,
 228                           map->grants[pgnr].ref,
 229                           map->grants[pgnr].domid);
 230         gnttab_set_unmap_op(&map->unmap_ops[pgnr], pte_maddr, flags,
 231                             -1 /* handle */);
 232         return 0;
 233 }
 234
 235 static int map_grant_pages(struct grant_map *map)
 236 {
 237         int i, err = 0;
 238
 239         if (!use_ptemod) {
 240                 /* Note: it could already be mapped */
 241                 if (map->map_ops[0].handle != -1)
 242                         return 0;
 243                 for (i = 0; i < map->count; i++) {
 244                         unsigned long addr = (unsigned long)
 245                                 pfn_to_kaddr(page_to_pfn(map->pages[i]));
 246                         gnttab_set_map_op(&map->map_ops[i], addr, map->flags,
 247                                 map->grants[i].ref,
 248                                 map->grants[i].domid);
 249                         gnttab_set_unmap_op(&map->unmap_ops[i], addr,
 250                                 map->flags, -1 /* handle */);
 251                 }
 252         } else {
 253                 /*
 254                  * Setup the map_ops corresponding to the pte entries pointing
 255                  * to the kernel linear addresses of the struct pages.
 256                  * These ptes are completely different from the user ptes dealt
 257                  * with find_grant_ptes.
 258                  */
 259                 for (i = 0; i < map->count; i++) {
 260                         unsigned level;
 261                         unsigned long address = (unsigned long)
 262                                 pfn_to_kaddr(page_to_pfn(map->pages[i]));
 263                         pte_t *ptep;
 264                         u64 pte_maddr = 0;
 265                         BUG_ON(PageHighMem(map->pages[i]));
 266
 267                         ptep = lookup_address(address, &level);
 268                         pte_maddr = arbitrary_virt_to_machine(ptep).maddr;
 269                         gnttab_set_map_op(&map->kmap_ops[i], pte_maddr,
 270                                 map->flags |
 271                                 GNTMAP_host_map |
 272                                 GNTMAP_contains_pte,
 273                                 map->grants[i].ref,
 274                                 map->grants[i].domid);
 275                 }
 276         }
 277
 278         pr_debug("map %d+%d\n", map->index, map->count);
 279         err = gnttab_map_refs(map->map_ops, use_ptemod ? map->kmap_ops : NULL,
 280                         map->pages, map->count);
 281         if (err)
 282                 return err;
 283
 284         for (i = 0; i < map->count; i++) {
 285                 if (map->map_ops[i].status)
 286                         err = -EINVAL;
 287                 else {
 288                         BUG_ON(map->map_ops[i].handle == -1);
 289                         map->unmap_ops[i].handle = map->map_ops[i].handle;
 290                         pr_debug("map handle=%d\n", map->map_ops[i].handle);
 291                 }
 292         }
 293         return err;
 294 }
 295
 296 static int __unmap_grant_pages(struct grant_map *map, int offset, int pages)
 297 {
 298         int i, err = 0;
 299
 300         if (map->notify.flags & UNMAP_NOTIFY_CLEAR_BYTE) {
 301                 int pgno = (map->notify.addr >> PAGE_SHIFT);
 302                 if (pgno >= offset && pgno < offset + pages && use_ptemod) {
 303                         void __user *tmp = (void __user *)
 304                                 map->vma->vm_start + map->notify.addr;
 305                         err = copy_to_user(tmp, &err, 1);
 306                         if (err)
 307                                 return -EFAULT;
 308                         map->notify.flags &= ~UNMAP_NOTIFY_CLEAR_BYTE;
 309                 } else if (pgno >= offset && pgno < offset + pages) {
 310                         uint8_t *tmp = kmap(map->pages[pgno]);
 311                         tmp[map->notify.addr & (PAGE_SIZE-1)] = 0;
 312                         kunmap(map->pages[pgno]);
 313                         map->notify.flags &= ~UNMAP_NOTIFY_CLEAR_BYTE;
 314                 }
 315         }
 316
 317         err = gnttab_unmap_refs(map->unmap_ops + offset, map->pages + offset,
 318                                 pages, true);
 319         if (err)
 320                 return err;
 321
 322         for (i = 0; i < pages; i++) {
 323                 if (map->unmap_ops[offset+i].status)
 324                         err = -EINVAL;
 325                 pr_debug("unmap handle=%d st=%d\n",
 326                         map->unmap_ops[offset+i].handle,
 327                         map->unmap_ops[offset+i].status);
 328                 map->unmap_ops[offset+i].handle = -1;
 329         }
 330         return err;
 331 }
 332
 333 static int unmap_grant_pages(struct grant_map *map, int offset, int pages)
 334 {
 335         int range, err = 0;
 336
 337         pr_debug("unmap %d+%d [%d+%d]\n", map->index, map->count, offset, pages);
 338
 339         /* It is possible the requested range will have a "hole" where we
 340          * already unmapped some of the grants. Only unmap valid ranges.
 341          */
 342         while (pages && !err) {
 343                 while (pages && map->unmap_ops[offset].handle == -1) {
 344                         offset++;
 345                         pages--;
 346                 }
 347                 range = 0;
 348                 while (range < pages) {
 349                         if (map->unmap_ops[offset+range].handle == -1) {
 350                                 range--;
 351                                 break;
 352                         }
 353                         range++;
 354                 }
 355                 err = __unmap_grant_pages(map, offset, range);
 356                 offset += range;
 357                 pages -= range;
 358         }
 359
 360         return err;
 361 }
 362
 363 /* ------------------------------------------------------------------ */
 364
 365 static void gntdev_vma_open(struct vm_area_struct *vma)
 366 {
 367         struct grant_map *map = vma->vm_private_data;
 368
 369         pr_debug("gntdev_vma_open %p\n", vma);
 370         atomic_inc(&map->users);
 371 }
 372
 373 static void gntdev_vma_close(struct vm_area_struct *vma)
 374 {
 375         struct grant_map *map = vma->vm_private_data;
 376
 377         pr_debug("gntdev_vma_close %p\n", vma);
 378         map->vma = NULL;
 379         vma->vm_private_data = NULL;
 380         gntdev_put_map(map);
 381 }
 382
 383 static struct vm_operations_struct gntdev_vmops = {
 384         .open = gntdev_vma_open,
 385         .close = gntdev_vma_close,
 386 };
 387
 388 /* ------------------------------------------------------------------ */
 389
 390 static void mn_invl_range_start(struct mmu_notifier *mn,
 391                                 struct mm_struct *mm,
 392                                 unsigned long start, unsigned long end)
 393 {
 394         struct gntdev_priv *priv = container_of(mn, struct gntdev_priv, mn);
 395         struct grant_map *map;
 396         unsigned long mstart, mend;
 397         int err;
 398
 399         spin_lock(&priv->lock);
 400         list_for_each_entry(map, &priv->maps, next) {
 401                 if (!map->vma)
 402                         continue;
 403                 if (map->vma->vm_start >= end)
 404                         continue;
 405                 if (map->vma->vm_end <= start)
 406                         continue;
 407                 mstart = max(start, map->vma->vm_start);
 408                 mend   = min(end,   map->vma->vm_end);
 409                 pr_debug("map %d+%d (%lx %lx), range %lx %lx, mrange %lx %lx\n",
 410                                 map->index, map->count,
 411                                 map->vma->vm_start, map->vma->vm_end,
 412                                 start, end, mstart, mend);
 413                 err = unmap_grant_pages(map,
 414                                         (mstart - map->vma->vm_start) >> PAGE_SHIFT,
 415                                         (mend - mstart) >> PAGE_SHIFT);
 416                 WARN_ON(err);
 417         }
 418         spin_unlock(&priv->lock);
 419 }
 420
 421 static void mn_invl_page(struct mmu_notifier *mn,
 422                          struct mm_struct *mm,
 423                          unsigned long address)
 424 {
 425         mn_invl_range_start(mn, mm, address, address + PAGE_SIZE);
 426 }
 427
 428 static void mn_release(struct mmu_notifier *mn,
 429                        struct mm_struct *mm)
 430 {
 431         struct gntdev_priv *priv = container_of(mn, struct gntdev_priv, mn);
 432         struct grant_map *map;
 433         int err;
 434
 435         spin_lock(&priv->lock);
 436         list_for_each_entry(map, &priv->maps, next) {
 437                 if (!map->vma)
 438                         continue;
 439                 pr_debug("map %d+%d (%lx %lx)\n",
 440                                 map->index, map->count,
 441                                 map->vma->vm_start, map->vma->vm_end);
 442                 err = unmap_grant_pages(map, /* offset */ 0, map->count);
 443                 WARN_ON(err);
 444         }
 445         spin_unlock(&priv->lock);
 446 }
 447
 448 struct mmu_notifier_ops gntdev_mmu_ops = {
 449         .release                = mn_release,
 450         .invalidate_page        = mn_invl_page,
 451         .invalidate_range_start = mn_invl_range_start,
 452 };
 453
 454 /* ------------------------------------------------------------------ */
 455
 456 static int gntdev_open(struct inode *inode, struct file *flip)
 457 {
 458         struct gntdev_priv *priv;
 459         int ret = 0;
 460
 461         priv = kzalloc(sizeof(*priv), GFP_KERNEL);
 462         if (!priv)
 463                 return -ENOMEM;
 464
 465         INIT_LIST_HEAD(&priv->maps);
 466         spin_lock_init(&priv->lock);
 467
 468         if (use_ptemod) {
 469                 priv->mm = get_task_mm(current);
 470                 if (!priv->mm) {
 471                         kfree(priv);
 472                         return -ENOMEM;
 473                 }
 474                 priv->mn.ops = &gntdev_mmu_ops;
 475                 ret = mmu_notifier_register(&priv->mn, priv->mm);
 476                 mmput(priv->mm);
 477         }
 478
 479         if (ret) {
 480                 kfree(priv);
 481                 return ret;
 482         }
 483
 484         flip->private_data = priv;
 485         pr_debug("priv %p\n", priv);
 486
 487         return 0;
 488 }
 489
 490 static int gntdev_release(struct inode *inode, struct file *flip)
 491 {
 492         struct gntdev_priv *priv = flip->private_data;
 493         struct grant_map *map;
 494
 495         pr_debug("priv %p\n", priv);
 496
 497         while (!list_empty(&priv->maps)) {
 498                 map = list_entry(priv->maps.next, struct grant_map, next);
 499                 list_del(&map->next);
 500                 gntdev_put_map(map);
 501         }
 502
 503         if (use_ptemod)
 504                 mmu_notifier_unregister(&priv->mn, priv->mm);
 505         kfree(priv);
 506         return 0;
 507 }
 508
 509 static long gntdev_ioctl_map_grant_ref(struct gntdev_priv *priv,
 510                                        struct ioctl_gntdev_map_grant_ref __user *u)
 511 {
 512         struct ioctl_gntdev_map_grant_ref op;
 513         struct grant_map *map;
 514         int err;
 515
 516         if (copy_from_user(&op, u, sizeof(op)) != 0)
 517                 return -EFAULT;
 518         pr_debug("priv %p, add %d\n", priv, op.count);
 519         if (unlikely(op.count <= 0))
 520                 return -EINVAL;
 521
 522         err = -ENOMEM;
 523         map = gntdev_alloc_map(priv, op.count);
 524         if (!map)
 525                 return err;
 526
 527         if (unlikely(atomic_add_return(op.count, &pages_mapped) > limit)) {
 528                 pr_debug("can't map: over limit\n");
 529                 gntdev_put_map(map);
 530                 return err;
 531         }
 532
 533         if (copy_from_user(map->grants, &u->refs,
 534                            sizeof(map->grants[0]) * op.count) != 0) {
 535                 gntdev_put_map(map);
 536                 return err;
 537         }
 538
 539         spin_lock(&priv->lock);
 540         gntdev_add_map(priv, map);
 541         op.index = map->index << PAGE_SHIFT;
 542         spin_unlock(&priv->lock);
 543
 544         if (copy_to_user(u, &op, sizeof(op)) != 0)
 545                 return -EFAULT;
 546
 547         return 0;
 548 }
 549
 550 static long gntdev_ioctl_unmap_grant_ref(struct gntdev_priv *priv,
 551                                          struct ioctl_gntdev_unmap_grant_ref __user *u)
 552 {
 553         struct ioctl_gntdev_unmap_grant_ref op;
 554         struct grant_map *map;
 555         int err = -ENOENT;
 556
 557         if (copy_from_user(&op, u, sizeof(op)) != 0)
 558                 return -EFAULT;
 559         pr_debug("priv %p, del %d+%d\n", priv, (int)op.index, (int)op.count);
 560
 561         spin_lock(&priv->lock);
 562         map = gntdev_find_map_index(priv, op.index >> PAGE_SHIFT, op.count);
 563         if (map) {
 564                 list_del(&map->next);
 565                 err = 0;
 566         }
 567         spin_unlock(&priv->lock);
 568         if (map)
 569                 gntdev_put_map(map);
 570         return err;
 571 }
 572
 573 static long gntdev_ioctl_get_offset_for_vaddr(struct gntdev_priv *priv,
 574                                               struct ioctl_gntdev_get_offset_for_vaddr __user *u)
 575 {
 576         struct ioctl_gntdev_get_offset_for_vaddr op;
 577         struct vm_area_struct *vma;
 578         struct grant_map *map;
 579
 580         if (copy_from_user(&op, u, sizeof(op)) != 0)
 581                 return -EFAULT;
 582         pr_debug("priv %p, offset for vaddr %lx\n", priv, (unsigned long)op.vaddr);
 583
 584         vma = find_vma(current->mm, op.vaddr);
 585         if (!vma || vma->vm_ops != &gntdev_vmops)
 586                 return -EINVAL;
 587
 588         map = vma->vm_private_data;
 589         if (!map)
 590                 return -EINVAL;
 591
 592         op.offset = map->index << PAGE_SHIFT;
 593         op.count = map->count;
 594
 595         if (copy_to_user(u, &op, sizeof(op)) != 0)
 596                 return -EFAULT;
 597         return 0;
 598 }
 599
 600 static long gntdev_ioctl_notify(struct gntdev_priv *priv, void __user *u)
 601 {
 602         struct ioctl_gntdev_unmap_notify op;
 603         struct grant_map *map;
 604         int rc;
 605         int out_flags;
 606         unsigned int out_event;
 607
 608         if (copy_from_user(&op, u, sizeof(op)))
 609                 return -EFAULT;
 610
 611         if (op.action & ~(UNMAP_NOTIFY_CLEAR_BYTE|UNMAP_NOTIFY_SEND_EVENT))
 612                 return -EINVAL;
 613
 614         /* We need to grab a reference to the event channel we are going to use
 615          * to send the notify before releasing the reference we may already have
 616          * (if someone has called this ioctl twice). This is required so that
 617          * it is possible to change the clear_byte part of the notification
 618          * without disturbing the event channel part, which may now be the last
 619          * reference to that event channel.
 620          */
 621         if (op.action & UNMAP_NOTIFY_SEND_EVENT) {
 622                 if (evtchn_get(op.event_channel_port))
 623                         return -EINVAL;
 624         }
 625
 626         out_flags = op.action;
 627         out_event = op.event_channel_port;
 628
 629         spin_lock(&priv->lock);
 630
 631         list_for_each_entry(map, &priv->maps, next) {
 632                 uint64_t begin = map->index << PAGE_SHIFT;
 633                 uint64_t end = (map->index + map->count) << PAGE_SHIFT;
 634                 if (op.index >= begin && op.index < end)
 635                         goto found;
 636         }
 637         rc = -ENOENT;
 638         goto unlock_out;
 639
 640  found:
 641         if ((op.action & UNMAP_NOTIFY_CLEAR_BYTE) &&
 642                         (map->flags & GNTMAP_readonly)) {
 643                 rc = -EINVAL;
 644                 goto unlock_out;
 645         }
 646
 647         out_flags = map->notify.flags;
 648         out_event = map->notify.event;
 649
 650         map->notify.flags = op.action;
 651         map->notify.addr = op.index - (map->index << PAGE_SHIFT);
 652         map->notify.event = op.event_channel_port;
 653
 654         rc = 0;
 655
 656  unlock_out:
 657         spin_unlock(&priv->lock);
 658
 659         /* Drop the reference to the event channel we did not save in the map */
 660         if (out_flags & UNMAP_NOTIFY_SEND_EVENT)
 661                 evtchn_put(out_event);
 662
 663         return rc;
 664 }
 665
 666 static long gntdev_ioctl(struct file *flip,
 667                          unsigned int cmd, unsigned long arg)
 668 {
 669         struct gntdev_priv *priv = flip->private_data;
 670         void __user *ptr = (void __user *)arg;
 671
 672         switch (cmd) {
 673         case IOCTL_GNTDEV_MAP_GRANT_REF:
 674                 return gntdev_ioctl_map_grant_ref(priv, ptr);
 675
 676         case IOCTL_GNTDEV_UNMAP_GRANT_REF:
 677                 return gntdev_ioctl_unmap_grant_ref(priv, ptr);
 678
 679         case IOCTL_GNTDEV_GET_OFFSET_FOR_VADDR:
 680                 return gntdev_ioctl_get_offset_for_vaddr(priv, ptr);
 681
 682         case IOCTL_GNTDEV_SET_UNMAP_NOTIFY:
 683                 return gntdev_ioctl_notify(priv, ptr);
 684
 685         default:
 686                 pr_debug("priv %p, unknown cmd %x\n", priv, cmd);
 687                 return -ENOIOCTLCMD;
 688         }
 689
 690         return 0;
 691 }
 692
 693 static int gntdev_mmap(struct file *flip, struct vm_area_struct *vma)
 694 {
 695         struct gntdev_priv *priv = flip->private_data;
 696         int index = vma->vm_pgoff;
 697         int count = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
 698         struct grant_map *map;
 699         int i, err = -EINVAL;
 700
 701         if ((vma->vm_flags & VM_WRITE) && !(vma->vm_flags & VM_SHARED))
 702                 return -EINVAL;
 703
 704         pr_debug("map %d+%d at %lx (pgoff %lx)\n",
 705                         index, count, vma->vm_start, vma->vm_pgoff);
 706
 707         spin_lock(&priv->lock);
 708         map = gntdev_find_map_index(priv, index, count);
 709         if (!map)
 710                 goto unlock_out;
 711         if (use_ptemod && map->vma)
 712                 goto unlock_out;
 713         if (use_ptemod && priv->mm != vma->vm_mm) {
 714                 printk(KERN_WARNING "Huh? Other mm?\n");
 715                 goto unlock_out;
 716         }
 717
 718         atomic_inc(&map->users);
 719
 720         vma->vm_ops = &gntdev_vmops;
 721
 722         vma->vm_flags |= VM_RESERVED|VM_DONTEXPAND;
 723
 724         if (use_ptemod)
 725                 vma->vm_flags |= VM_DONTCOPY;
 726
 727         vma->vm_private_data = map;
 728
 729         if (use_ptemod)
 730                 map->vma = vma;
 731
 732         if (map->flags) {
 733                 if ((vma->vm_flags & VM_WRITE) &&
 734                                 (map->flags & GNTMAP_readonly))
 735                         goto out_unlock_put;
 736         } else {
 737                 map->flags = GNTMAP_host_map;
 738                 if (!(vma->vm_flags & VM_WRITE))
 739                         map->flags |= GNTMAP_readonly;
 740         }
 741
 742         spin_unlock(&priv->lock);
 743
 744         if (use_ptemod) {
 745                 err = apply_to_page_range(vma->vm_mm, vma->vm_start,
 746                                           vma->vm_end - vma->vm_start,
 747                                           find_grant_ptes, map);
 748                 if (err) {
 749                         printk(KERN_WARNING "find_grant_ptes() failure.\n");
 750                         goto out_put_map;
 751                 }
 752         }
 753
 754         err = map_grant_pages(map);
 755         if (err)
 756                 goto out_put_map;
 757
 758         if (!use_ptemod) {
 759                 for (i = 0; i < count; i++) {
 760                         err = vm_insert_page(vma, vma->vm_start + i*PAGE_SIZE,
 761                                 map->pages[i]);
 762                         if (err)
 763                                 goto out_put_map;
 764                 }
 765         }
 766
 767         return 0;
 768
 769 unlock_out:
 770         spin_unlock(&priv->lock);
 771         return err;
 772
 773 out_unlock_put:
 774         spin_unlock(&priv->lock);
 775 out_put_map:
 776         if (use_ptemod)
 777                 map->vma = NULL;
 778         gntdev_put_map(map);
 779         return err;
 780 }
 781
 782 static const struct file_operations gntdev_fops = {
 783         .owner = THIS_MODULE,
 784         .open = gntdev_open,
 785         .release = gntdev_release,
 786         .mmap = gntdev_mmap,
 787         .unlocked_ioctl = gntdev_ioctl
 788 };
 789
 790 static struct miscdevice gntdev_miscdev = {
 791         .minor        = MISC_DYNAMIC_MINOR,
 792         .name         = "xen/gntdev",
 793         .fops         = &gntdev_fops,
 794 };
 795
 796 /* ------------------------------------------------------------------ */
 797
 798 static int __init gntdev_init(void)
 799 {
 800         int err;
 801
 802         if (!xen_domain())
 803                 return -ENODEV;
 804
 805         use_ptemod = xen_pv_domain();
 806
 807         err = misc_register(&gntdev_miscdev);
 808         if (err != 0) {
 809                 printk(KERN_ERR "Could not register gntdev device\n");
 810                 return err;
 811         }
 812         return 0;
 813 }
 814
 815 static void __exit gntdev_exit(void)
 816 {
 817         misc_deregister(&gntdev_miscdev);
 818 }
 819
 820 module_init(gntdev_init);
 821 module_exit(gntdev_exit);
 822
 823 /* ------------------------------------------------------------------ */