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 void gntdev_free_map(struct grant_map *map)
 109 {
 110         if (map == NULL)
 111                 return;
 112
 113         if (map->pages)
 114                 free_xenballooned_pages(map->count, map->pages);
 115         kfree(map->pages);
 116         kfree(map->grants);
 117         kfree(map->map_ops);
 118         kfree(map->unmap_ops);
 119         kfree(map->kmap_ops);
 120         kfree(map);
 121 }
 122
 123 static struct grant_map *gntdev_alloc_map(struct gntdev_priv *priv, int count)
 124 {
 125         struct grant_map *add;
 126         int i;
 127
 128         add = kzalloc(sizeof(struct grant_map), GFP_KERNEL);
 129         if (NULL == add)
 130                 return NULL;
 131
 132         add->grants    = kcalloc(count, sizeof(add->grants[0]), GFP_KERNEL);
 133         add->map_ops   = kcalloc(count, sizeof(add->map_ops[0]), GFP_KERNEL);
 134         add->unmap_ops = kcalloc(count, sizeof(add->unmap_ops[0]), GFP_KERNEL);
 135         add->kmap_ops  = kcalloc(count, sizeof(add->kmap_ops[0]), GFP_KERNEL);
 136         add->pages     = kcalloc(count, sizeof(add->pages[0]), GFP_KERNEL);
 137         if (NULL == add->grants    ||
 138             NULL == add->map_ops   ||
 139             NULL == add->unmap_ops ||
 140             NULL == add->kmap_ops  ||
 141             NULL == add->pages)
 142                 goto err;
 143
 144         if (alloc_xenballooned_pages(count, add->pages, false /* lowmem */))
 145                 goto err;
 146
 147         for (i = 0; i < count; i++) {
 148                 add->map_ops[i].handle = -1;
 149                 add->unmap_ops[i].handle = -1;
 150                 add->kmap_ops[i].handle = -1;
 151         }
 152
 153         add->index = 0;
 154         add->count = count;
 155         atomic_set(&add->users, 1);
 156
 157         return add;
 158
 159 err:
 160         gntdev_free_map(add);
 161         return NULL;
 162 }
 163
 164 static void gntdev_add_map(struct gntdev_priv *priv, struct grant_map *add)
 165 {
 166         struct grant_map *map;
 167
 168         list_for_each_entry(map, &priv->maps, next) {
 169                 if (add->index + add->count < map->index) {
 170                         list_add_tail(&add->next, &map->next);
 171                         goto done;
 172                 }
 173                 add->index = map->index + map->count;
 174         }
 175         list_add_tail(&add->next, &priv->maps);
 176
 177 done:
 178         gntdev_print_maps(priv, "[new]", add->index);
 179 }
 180
 181 static struct grant_map *gntdev_find_map_index(struct gntdev_priv *priv,
 182                 int index, int count)
 183 {
 184         struct grant_map *map;
 185
 186         list_for_each_entry(map, &priv->maps, next) {
 187                 if (map->index != index)
 188                         continue;
 189                 if (count && map->count != count)
 190                         continue;
 191                 return map;
 192         }
 193         return NULL;
 194 }
 195
 196 static void gntdev_put_map(struct grant_map *map)
 197 {
 198         if (!map)
 199                 return;
 200
 201         if (!atomic_dec_and_test(&map->users))
 202                 return;
 203
 204         atomic_sub(map->count, &pages_mapped);
 205
 206         if (map->notify.flags & UNMAP_NOTIFY_SEND_EVENT) {
 207                 notify_remote_via_evtchn(map->notify.event);
 208                 evtchn_put(map->notify.event);
 209         }
 210
 211         if (map->pages && !use_ptemod)
 212                 unmap_grant_pages(map, 0, map->count);
 213         gntdev_free_map(map);
 214 }
 215
 216 /* ------------------------------------------------------------------ */
 217
 218 static int find_grant_ptes(pte_t *pte, pgtable_t token,
 219                 unsigned long addr, void *data)
 220 {
 221         struct grant_map *map = data;
 222         unsigned int pgnr = (addr - map->vma->vm_start) >> PAGE_SHIFT;
 223         int flags = map->flags | GNTMAP_application_map | GNTMAP_contains_pte;
 224         u64 pte_maddr;
 225
 226         BUG_ON(pgnr >= map->count);
 227         pte_maddr = arbitrary_virt_to_machine(pte).maddr;
 228
 229         gnttab_set_map_op(&map->map_ops[pgnr], pte_maddr, flags,
 230                           map->grants[pgnr].ref,
 231                           map->grants[pgnr].domid);
 232         gnttab_set_unmap_op(&map->unmap_ops[pgnr], pte_maddr, flags,
 233                             -1 /* handle */);
 234         return 0;
 235 }
 236
 237 static int map_grant_pages(struct grant_map *map)
 238 {
 239         int i, err = 0;
 240
 241         if (!use_ptemod) {
 242                 /* Note: it could already be mapped */
 243                 if (map->map_ops[0].handle != -1)
 244                         return 0;
 245                 for (i = 0; i < map->count; i++) {
 246                         unsigned long addr = (unsigned long)
 247                                 pfn_to_kaddr(page_to_pfn(map->pages[i]));
 248                         gnttab_set_map_op(&map->map_ops[i], addr, map->flags,
 249                                 map->grants[i].ref,
 250                                 map->grants[i].domid);
 251                         gnttab_set_unmap_op(&map->unmap_ops[i], addr,
 252                                 map->flags, -1 /* handle */);
 253                 }
 254         } else {
 255                 /*
 256                  * Setup the map_ops corresponding to the pte entries pointing
 257                  * to the kernel linear addresses of the struct pages.
 258                  * These ptes are completely different from the user ptes dealt
 259                  * with find_grant_ptes.
 260                  */
 261                 for (i = 0; i < map->count; i++) {
 262                         unsigned level;
 263                         unsigned long address = (unsigned long)
 264                                 pfn_to_kaddr(page_to_pfn(map->pages[i]));
 265                         pte_t *ptep;
 266                         u64 pte_maddr = 0;
 267                         BUG_ON(PageHighMem(map->pages[i]));
 268
 269                         ptep = lookup_address(address, &level);
 270                         pte_maddr = arbitrary_virt_to_machine(ptep).maddr;
 271                         gnttab_set_map_op(&map->kmap_ops[i], pte_maddr,
 272                                 map->flags |
 273                                 GNTMAP_host_map |
 274                                 GNTMAP_contains_pte,
 275                                 map->grants[i].ref,
 276                                 map->grants[i].domid);
 277                 }
 278         }
 279
 280         pr_debug("map %d+%d\n", map->index, map->count);
 281         err = gnttab_map_refs(map->map_ops, use_ptemod ? map->kmap_ops : NULL,
 282                         map->pages, map->count);
 283         if (err)
 284                 return err;
 285
 286         for (i = 0; i < map->count; i++) {
 287                 if (map->map_ops[i].status)
 288                         err = -EINVAL;
 289                 else {
 290                         BUG_ON(map->map_ops[i].handle == -1);
 291                         map->unmap_ops[i].handle = map->map_ops[i].handle;
 292                         pr_debug("map handle=%d\n", map->map_ops[i].handle);
 293                 }
 294         }
 295         return err;
 296 }
 297
 298 static int __unmap_grant_pages(struct grant_map *map, int offset, int pages)
 299 {
 300         int i, err = 0;
 301
 302         if (map->notify.flags & UNMAP_NOTIFY_CLEAR_BYTE) {
 303                 int pgno = (map->notify.addr >> PAGE_SHIFT);
 304                 if (pgno >= offset && pgno < offset + pages && use_ptemod) {
 305                         void __user *tmp = (void __user *)
 306                                 map->vma->vm_start + map->notify.addr;
 307                         err = copy_to_user(tmp, &err, 1);
 308                         if (err)
 309                                 return -EFAULT;
 310                         map->notify.flags &= ~UNMAP_NOTIFY_CLEAR_BYTE;
 311                 } else if (pgno >= offset && pgno < offset + pages) {
 312                         uint8_t *tmp = kmap(map->pages[pgno]);
 313                         tmp[map->notify.addr & (PAGE_SIZE-1)] = 0;
 314                         kunmap(map->pages[pgno]);
 315                         map->notify.flags &= ~UNMAP_NOTIFY_CLEAR_BYTE;
 316                 }
 317         }
 318
 319         err = gnttab_unmap_refs(map->unmap_ops + offset,
 320                         use_ptemod ? map->kmap_ops + offset : NULL, map->pages + offset,
 321                         pages);
 322         if (err)
 323                 return err;
 324
 325         for (i = 0; i < pages; i++) {
 326                 if (map->unmap_ops[offset+i].status)
 327                         err = -EINVAL;
 328                 pr_debug("unmap handle=%d st=%d\n",
 329                         map->unmap_ops[offset+i].handle,
 330                         map->unmap_ops[offset+i].status);
 331                 map->unmap_ops[offset+i].handle = -1;
 332         }
 333         return err;
 334 }
 335
 336 static int unmap_grant_pages(struct grant_map *map, int offset, int pages)
 337 {
 338         int range, err = 0;
 339
 340         pr_debug("unmap %d+%d [%d+%d]\n", map->index, map->count, offset, pages);
 341
 342         /* It is possible the requested range will have a "hole" where we
 343          * already unmapped some of the grants. Only unmap valid ranges.
 344          */
 345         while (pages && !err) {
 346                 while (pages && map->unmap_ops[offset].handle == -1) {
 347                         offset++;
 348                         pages--;
 349                 }
 350                 range = 0;
 351                 while (range < pages) {
 352                         if (map->unmap_ops[offset+range].handle == -1) {
 353                                 range--;
 354                                 break;
 355                         }
 356                         range++;
 357                 }
 358                 err = __unmap_grant_pages(map, offset, range);
 359                 offset += range;
 360                 pages -= range;
 361         }
 362
 363         return err;
 364 }
 365
 366 /* ------------------------------------------------------------------ */
 367
 368 static void gntdev_vma_open(struct vm_area_struct *vma)
 369 {
 370         struct grant_map *map = vma->vm_private_data;
 371
 372         pr_debug("gntdev_vma_open %p\n", vma);
 373         atomic_inc(&map->users);
 374 }
 375
 376 static void gntdev_vma_close(struct vm_area_struct *vma)
 377 {
 378         struct grant_map *map = vma->vm_private_data;
 379
 380         pr_debug("gntdev_vma_close %p\n", vma);
 381         map->vma = NULL;
 382         vma->vm_private_data = NULL;
 383         gntdev_put_map(map);
 384 }
 385
 386 static struct vm_operations_struct gntdev_vmops = {
 387         .open = gntdev_vma_open,
 388         .close = gntdev_vma_close,
 389 };
 390
 391 /* ------------------------------------------------------------------ */
 392
 393 static void mn_invl_range_start(struct mmu_notifier *mn,
 394                                 struct mm_struct *mm,
 395                                 unsigned long start, unsigned long end)
 396 {
 397         struct gntdev_priv *priv = container_of(mn, struct gntdev_priv, mn);
 398         struct grant_map *map;
 399         unsigned long mstart, mend;
 400         int err;
 401
 402         spin_lock(&priv->lock);
 403         list_for_each_entry(map, &priv->maps, next) {
 404                 if (!map->vma)
 405                         continue;
 406                 if (map->vma->vm_start >= end)
 407                         continue;
 408                 if (map->vma->vm_end <= start)
 409                         continue;
 410                 mstart = max(start, map->vma->vm_start);
 411                 mend   = min(end,   map->vma->vm_end);
 412                 pr_debug("map %d+%d (%lx %lx), range %lx %lx, mrange %lx %lx\n",
 413                                 map->index, map->count,
 414                                 map->vma->vm_start, map->vma->vm_end,
 415                                 start, end, mstart, mend);
 416                 err = unmap_grant_pages(map,
 417                                         (mstart - map->vma->vm_start) >> PAGE_SHIFT,
 418                                         (mend - mstart) >> PAGE_SHIFT);
 419                 WARN_ON(err);
 420         }
 421         spin_unlock(&priv->lock);
 422 }
 423
 424 static void mn_invl_page(struct mmu_notifier *mn,
 425                          struct mm_struct *mm,
 426                          unsigned long address)
 427 {
 428         mn_invl_range_start(mn, mm, address, address + PAGE_SIZE);
 429 }
 430
 431 static void mn_release(struct mmu_notifier *mn,
 432                        struct mm_struct *mm)
 433 {
 434         struct gntdev_priv *priv = container_of(mn, struct gntdev_priv, mn);
 435         struct grant_map *map;
 436         int err;
 437
 438         spin_lock(&priv->lock);
 439         list_for_each_entry(map, &priv->maps, next) {
 440                 if (!map->vma)
 441                         continue;
 442                 pr_debug("map %d+%d (%lx %lx)\n",
 443                                 map->index, map->count,
 444                                 map->vma->vm_start, map->vma->vm_end);
 445                 err = unmap_grant_pages(map, /* offset */ 0, map->count);
 446                 WARN_ON(err);
 447         }
 448         spin_unlock(&priv->lock);
 449 }
 450
 451 static struct mmu_notifier_ops gntdev_mmu_ops = {
 452         .release                = mn_release,
 453         .invalidate_page        = mn_invl_page,
 454         .invalidate_range_start = mn_invl_range_start,
 455 };
 456
 457 /* ------------------------------------------------------------------ */
 458
 459 static int gntdev_open(struct inode *inode, struct file *flip)
 460 {
 461         struct gntdev_priv *priv;
 462         int ret = 0;
 463
 464         priv = kzalloc(sizeof(*priv), GFP_KERNEL);
 465         if (!priv)
 466                 return -ENOMEM;
 467
 468         INIT_LIST_HEAD(&priv->maps);
 469         spin_lock_init(&priv->lock);
 470
 471         if (use_ptemod) {
 472                 priv->mm = get_task_mm(current);
 473                 if (!priv->mm) {
 474                         kfree(priv);
 475                         return -ENOMEM;
 476                 }
 477                 priv->mn.ops = &gntdev_mmu_ops;
 478                 ret = mmu_notifier_register(&priv->mn, priv->mm);
 479                 mmput(priv->mm);
 480         }
 481
 482         if (ret) {
 483                 kfree(priv);
 484                 return ret;
 485         }
 486
 487         flip->private_data = priv;
 488         pr_debug("priv %p\n", priv);
 489
 490         return 0;
 491 }
 492
 493 static int gntdev_release(struct inode *inode, struct file *flip)
 494 {
 495         struct gntdev_priv *priv = flip->private_data;
 496         struct grant_map *map;
 497
 498         pr_debug("priv %p\n", priv);
 499
 500         while (!list_empty(&priv->maps)) {
 501                 map = list_entry(priv->maps.next, struct grant_map, next);
 502                 list_del(&map->next);
 503                 gntdev_put_map(map);
 504         }
 505
 506         if (use_ptemod)
 507                 mmu_notifier_unregister(&priv->mn, priv->mm);
 508         kfree(priv);
 509         return 0;
 510 }
 511
 512 static long gntdev_ioctl_map_grant_ref(struct gntdev_priv *priv,
 513                                        struct ioctl_gntdev_map_grant_ref __user *u)
 514 {
 515         struct ioctl_gntdev_map_grant_ref op;
 516         struct grant_map *map;
 517         int err;
 518
 519         if (copy_from_user(&op, u, sizeof(op)) != 0)
 520                 return -EFAULT;
 521         pr_debug("priv %p, add %d\n", priv, op.count);
 522         if (unlikely(op.count <= 0))
 523                 return -EINVAL;
 524
 525         err = -ENOMEM;
 526         map = gntdev_alloc_map(priv, op.count);
 527         if (!map)
 528                 return err;
 529
 530         if (unlikely(atomic_add_return(op.count, &pages_mapped) > limit)) {
 531                 pr_debug("can't map: over limit\n");
 532                 gntdev_put_map(map);
 533                 return err;
 534         }
 535
 536         if (copy_from_user(map->grants, &u->refs,
 537                            sizeof(map->grants[0]) * op.count) != 0) {
 538                 gntdev_put_map(map);
 539                 return err;
 540         }
 541
 542         spin_lock(&priv->lock);
 543         gntdev_add_map(priv, map);
 544         op.index = map->index << PAGE_SHIFT;
 545         spin_unlock(&priv->lock);
 546
 547         if (copy_to_user(u, &op, sizeof(op)) != 0)
 548                 return -EFAULT;
 549
 550         return 0;
 551 }
 552
 553 static long gntdev_ioctl_unmap_grant_ref(struct gntdev_priv *priv,
 554                                          struct ioctl_gntdev_unmap_grant_ref __user *u)
 555 {
 556         struct ioctl_gntdev_unmap_grant_ref op;
 557         struct grant_map *map;
 558         int err = -ENOENT;
 559
 560         if (copy_from_user(&op, u, sizeof(op)) != 0)
 561                 return -EFAULT;
 562         pr_debug("priv %p, del %d+%d\n", priv, (int)op.index, (int)op.count);
 563
 564         spin_lock(&priv->lock);
 565         map = gntdev_find_map_index(priv, op.index >> PAGE_SHIFT, op.count);
 566         if (map) {
 567                 list_del(&map->next);
 568                 err = 0;
 569         }
 570         spin_unlock(&priv->lock);
 571         if (map)
 572                 gntdev_put_map(map);
 573         return err;
 574 }
 575
 576 static long gntdev_ioctl_get_offset_for_vaddr(struct gntdev_priv *priv,
 577                                               struct ioctl_gntdev_get_offset_for_vaddr __user *u)
 578 {
 579         struct ioctl_gntdev_get_offset_for_vaddr op;
 580         struct vm_area_struct *vma;
 581         struct grant_map *map;
 582
 583         if (copy_from_user(&op, u, sizeof(op)) != 0)
 584                 return -EFAULT;
 585         pr_debug("priv %p, offset for vaddr %lx\n", priv, (unsigned long)op.vaddr);
 586
 587         vma = find_vma(current->mm, op.vaddr);
 588         if (!vma || vma->vm_ops != &gntdev_vmops)
 589                 return -EINVAL;
 590
 591         map = vma->vm_private_data;
 592         if (!map)
 593                 return -EINVAL;
 594
 595         op.offset = map->index << PAGE_SHIFT;
 596         op.count = map->count;
 597
 598         if (copy_to_user(u, &op, sizeof(op)) != 0)
 599                 return -EFAULT;
 600         return 0;
 601 }
 602
 603 static long gntdev_ioctl_notify(struct gntdev_priv *priv, void __user *u)
 604 {
 605         struct ioctl_gntdev_unmap_notify op;
 606         struct grant_map *map;
 607         int rc;
 608         int out_flags;
 609         unsigned int out_event;
 610
 611         if (copy_from_user(&op, u, sizeof(op)))
 612                 return -EFAULT;
 613
 614         if (op.action & ~(UNMAP_NOTIFY_CLEAR_BYTE|UNMAP_NOTIFY_SEND_EVENT))
 615                 return -EINVAL;
 616
 617         /* We need to grab a reference to the event channel we are going to use
 618          * to send the notify before releasing the reference we may already have
 619          * (if someone has called this ioctl twice). This is required so that
 620          * it is possible to change the clear_byte part of the notification
 621          * without disturbing the event channel part, which may now be the last
 622          * reference to that event channel.
 623          */
 624         if (op.action & UNMAP_NOTIFY_SEND_EVENT) {
 625                 if (evtchn_get(op.event_channel_port))
 626                         return -EINVAL;
 627         }
 628
 629         out_flags = op.action;
 630         out_event = op.event_channel_port;
 631
 632         spin_lock(&priv->lock);
 633
 634         list_for_each_entry(map, &priv->maps, next) {
 635                 uint64_t begin = map->index << PAGE_SHIFT;
 636                 uint64_t end = (map->index + map->count) << PAGE_SHIFT;
 637                 if (op.index >= begin && op.index < end)
 638                         goto found;
 639         }
 640         rc = -ENOENT;
 641         goto unlock_out;
 642
 643  found:
 644         if ((op.action & UNMAP_NOTIFY_CLEAR_BYTE) &&
 645                         (map->flags & GNTMAP_readonly)) {
 646                 rc = -EINVAL;
 647                 goto unlock_out;
 648         }
 649
 650         out_flags = map->notify.flags;
 651         out_event = map->notify.event;
 652
 653         map->notify.flags = op.action;
 654         map->notify.addr = op.index - (map->index << PAGE_SHIFT);
 655         map->notify.event = op.event_channel_port;
 656
 657         rc = 0;
 658
 659  unlock_out:
 660         spin_unlock(&priv->lock);
 661
 662         /* Drop the reference to the event channel we did not save in the map */
 663         if (out_flags & UNMAP_NOTIFY_SEND_EVENT)
 664                 evtchn_put(out_event);
 665
 666         return rc;
 667 }
 668
 669 static long gntdev_ioctl(struct file *flip,
 670                          unsigned int cmd, unsigned long arg)
 671 {
 672         struct gntdev_priv *priv = flip->private_data;
 673         void __user *ptr = (void __user *)arg;
 674
 675         switch (cmd) {
 676         case IOCTL_GNTDEV_MAP_GRANT_REF:
 677                 return gntdev_ioctl_map_grant_ref(priv, ptr);
 678
 679         case IOCTL_GNTDEV_UNMAP_GRANT_REF:
 680                 return gntdev_ioctl_unmap_grant_ref(priv, ptr);
 681
 682         case IOCTL_GNTDEV_GET_OFFSET_FOR_VADDR:
 683                 return gntdev_ioctl_get_offset_for_vaddr(priv, ptr);
 684
 685         case IOCTL_GNTDEV_SET_UNMAP_NOTIFY:
 686                 return gntdev_ioctl_notify(priv, ptr);
 687
 688         default:
 689                 pr_debug("priv %p, unknown cmd %x\n", priv, cmd);
 690                 return -ENOIOCTLCMD;
 691         }
 692
 693         return 0;
 694 }
 695
 696 static int gntdev_mmap(struct file *flip, struct vm_area_struct *vma)
 697 {
 698         struct gntdev_priv *priv = flip->private_data;
 699         int index = vma->vm_pgoff;
 700         int count = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
 701         struct grant_map *map;
 702         int i, err = -EINVAL;
 703
 704         if ((vma->vm_flags & VM_WRITE) && !(vma->vm_flags & VM_SHARED))
 705                 return -EINVAL;
 706
 707         pr_debug("map %d+%d at %lx (pgoff %lx)\n",
 708                         index, count, vma->vm_start, vma->vm_pgoff);
 709
 710         spin_lock(&priv->lock);
 711         map = gntdev_find_map_index(priv, index, count);
 712         if (!map)
 713                 goto unlock_out;
 714         if (use_ptemod && map->vma)
 715                 goto unlock_out;
 716         if (use_ptemod && priv->mm != vma->vm_mm) {
 717                 printk(KERN_WARNING "Huh? Other mm?\n");
 718                 goto unlock_out;
 719         }
 720
 721         atomic_inc(&map->users);
 722
 723         vma->vm_ops = &gntdev_vmops;
 724
 725         vma->vm_flags |= VM_DONTEXPAND | VM_DONTDUMP;
 726
 727         if (use_ptemod)
 728                 vma->vm_flags |= VM_DONTCOPY;
 729
 730         vma->vm_private_data = map;
 731
 732         if (use_ptemod)
 733                 map->vma = vma;
 734
 735         if (map->flags) {
 736                 if ((vma->vm_flags & VM_WRITE) &&
 737                                 (map->flags & GNTMAP_readonly))
 738                         goto out_unlock_put;
 739         } else {
 740                 map->flags = GNTMAP_host_map;
 741                 if (!(vma->vm_flags & VM_WRITE))
 742                         map->flags |= GNTMAP_readonly;
 743         }
 744
 745         spin_unlock(&priv->lock);
 746
 747         if (use_ptemod) {
 748                 err = apply_to_page_range(vma->vm_mm, vma->vm_start,
 749                                           vma->vm_end - vma->vm_start,
 750                                           find_grant_ptes, map);
 751                 if (err) {
 752                         printk(KERN_WARNING "find_grant_ptes() failure.\n");
 753                         goto out_put_map;
 754                 }
 755         }
 756
 757         err = map_grant_pages(map);
 758         if (err)
 759                 goto out_put_map;
 760
 761         if (!use_ptemod) {
 762                 for (i = 0; i < count; i++) {
 763                         err = vm_insert_page(vma, vma->vm_start + i*PAGE_SIZE,
 764                                 map->pages[i]);
 765                         if (err)
 766                                 goto out_put_map;
 767                 }
 768         }
 769
 770         return 0;
 771
 772 unlock_out:
 773         spin_unlock(&priv->lock);
 774         return err;
 775
 776 out_unlock_put:
 777         spin_unlock(&priv->lock);
 778 out_put_map:
 779         if (use_ptemod)
 780                 map->vma = NULL;
 781         gntdev_put_map(map);
 782         return err;
 783 }
 784
 785 static const struct file_operations gntdev_fops = {
 786         .owner = THIS_MODULE,
 787         .open = gntdev_open,
 788         .release = gntdev_release,
 789         .mmap = gntdev_mmap,
 790         .unlocked_ioctl = gntdev_ioctl
 791 };
 792
 793 static struct miscdevice gntdev_miscdev = {
 794         .minor        = MISC_DYNAMIC_MINOR,
 795         .name         = "xen/gntdev",
 796         .fops         = &gntdev_fops,
 797 };
 798
 799 /* ------------------------------------------------------------------ */
 800
 801 static int __init gntdev_init(void)
 802 {
 803         int err;
 804
 805         if (!xen_domain())
 806                 return -ENODEV;
 807
 808         use_ptemod = xen_pv_domain();
 809
 810         err = misc_register(&gntdev_miscdev);
 811         if (err != 0) {
 812                 printk(KERN_ERR "Could not register gntdev device\n");
 813                 return err;
 814         }
 815         return 0;
 816 }
 817
 818 static void __exit gntdev_exit(void)
 819 {
 820         misc_deregister(&gntdev_miscdev);
 821 }
 822
 823 module_init(gntdev_init);
 824 module_exit(gntdev_exit);
 825
 826 /* ------------------------------------------------------------------ */