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 #define pr_fmt(fmt) "xen:" KBUILD_MODNAME ": " fmt
  23
  24 #include <linux/module.h>
  25 #include <linux/kernel.h>
  26 #include <linux/init.h>
  27 #include <linux/miscdevice.h>
  28 #include <linux/fs.h>
  29 #include <linux/mm.h>
  30 #include <linux/mman.h>
  31 #include <linux/mmu_notifier.h>
  32 #include <linux/types.h>
  33 #include <linux/uaccess.h>
  34 #include <linux/sched.h>
  35 #include <linux/spinlock.h>
  36 #include <linux/slab.h>
  37 #include <linux/highmem.h>
  38
  39 #include <xen/xen.h>
  40 #include <xen/grant_table.h>
  41 #include <xen/balloon.h>
  42 #include <xen/gntdev.h>
  43 #include <xen/events.h>
  44 #include <asm/xen/hypervisor.h>
  45 #include <asm/xen/hypercall.h>
  46 #include <asm/xen/page.h>
  47
  48 MODULE_LICENSE("GPL");
  49 MODULE_AUTHOR("Derek G. Murray <Derek.Murray@cl.cam.ac.uk>, "
  50               "Gerd Hoffmann <kraxel@redhat.com>");
  51 MODULE_DESCRIPTION("User-space granted page access driver");
  52
  53 static int limit = 1024*1024;
  54 module_param(limit, int, 0644);
  55 MODULE_PARM_DESC(limit, "Maximum number of grants that may be mapped by "
  56                 "the gntdev device");
  57
  58 static atomic_t pages_mapped = ATOMIC_INIT(0);
  59
  60 static int use_ptemod;
  61 #define populate_freeable_maps use_ptemod
  62
  63 struct gntdev_priv {
  64         /* maps with visible offsets in the file descriptor */
  65         struct list_head maps;
  66         /* maps that are not visible; will be freed on munmap.
  67          * Only populated if populate_freeable_maps == 1 */
  68         struct list_head freeable_maps;
  69         /* lock protects maps and freeable_maps */
  70         struct mutex lock;
  71         struct mm_struct *mm;
  72         struct mmu_notifier mn;
  73 };
  74
  75 struct unmap_notify {
  76         int flags;
  77         /* Address relative to the start of the grant_map */
  78         int addr;
  79         int event;
  80 };
  81
  82 struct grant_map {
  83         struct list_head next;
  84         struct vm_area_struct *vma;
  85         int index;
  86         int count;
  87         int flags;
  88         atomic_t users;
  89         struct unmap_notify notify;
  90         struct ioctl_gntdev_grant_ref *grants;
  91         struct gnttab_map_grant_ref   *map_ops;
  92         struct gnttab_unmap_grant_ref *unmap_ops;
  93         struct gnttab_map_grant_ref   *kmap_ops;
  94         struct page **pages;
  95 };
  96
  97 static int unmap_grant_pages(struct grant_map *map, int offset, int pages);
  98
  99 /* ------------------------------------------------------------------ */
 100
 101 static void gntdev_print_maps(struct gntdev_priv *priv,
 102                               char *text, int text_index)
 103 {
 104 #ifdef DEBUG
 105         struct grant_map *map;
 106
 107         pr_debug("%s: maps list (priv %p)\n", __func__, priv);
 108         list_for_each_entry(map, &priv->maps, next)
 109                 pr_debug("  index %2d, count %2d %s\n",
 110                        map->index, map->count,
 111                        map->index == text_index && text ? text : "");
 112 #endif
 113 }
 114
 115 static void gntdev_free_map(struct grant_map *map)
 116 {
 117         if (map == NULL)
 118                 return;
 119
 120         if (map->pages)
 121                 free_xenballooned_pages(map->count, map->pages);
 122         kfree(map->pages);
 123         kfree(map->grants);
 124         kfree(map->map_ops);
 125         kfree(map->unmap_ops);
 126         kfree(map->kmap_ops);
 127         kfree(map);
 128 }
 129
 130 static struct grant_map *gntdev_alloc_map(struct gntdev_priv *priv, int count)
 131 {
 132         struct grant_map *add;
 133         int i;
 134
 135         add = kzalloc(sizeof(struct grant_map), GFP_KERNEL);
 136         if (NULL == add)
 137                 return NULL;
 138
 139         add->grants    = kcalloc(count, sizeof(add->grants[0]), GFP_KERNEL);
 140         add->map_ops   = kcalloc(count, sizeof(add->map_ops[0]), GFP_KERNEL);
 141         add->unmap_ops = kcalloc(count, sizeof(add->unmap_ops[0]), GFP_KERNEL);
 142         add->kmap_ops  = kcalloc(count, sizeof(add->kmap_ops[0]), GFP_KERNEL);
 143         add->pages     = kcalloc(count, sizeof(add->pages[0]), GFP_KERNEL);
 144         if (NULL == add->grants    ||
 145             NULL == add->map_ops   ||
 146             NULL == add->unmap_ops ||
 147             NULL == add->kmap_ops  ||
 148             NULL == add->pages)
 149                 goto err;
 150
 151         if (alloc_xenballooned_pages(count, add->pages, false /* lowmem */))
 152                 goto err;
 153
 154         for (i = 0; i < count; i++) {
 155                 add->map_ops[i].handle = -1;
 156                 add->unmap_ops[i].handle = -1;
 157                 add->kmap_ops[i].handle = -1;
 158         }
 159
 160         add->index = 0;
 161         add->count = count;
 162         atomic_set(&add->users, 1);
 163
 164         return add;
 165
 166 err:
 167         gntdev_free_map(add);
 168         return NULL;
 169 }
 170
 171 static void gntdev_add_map(struct gntdev_priv *priv, struct grant_map *add)
 172 {
 173         struct grant_map *map;
 174
 175         list_for_each_entry(map, &priv->maps, next) {
 176                 if (add->index + add->count < map->index) {
 177                         list_add_tail(&add->next, &map->next);
 178                         goto done;
 179                 }
 180                 add->index = map->index + map->count;
 181         }
 182         list_add_tail(&add->next, &priv->maps);
 183
 184 done:
 185         gntdev_print_maps(priv, "[new]", add->index);
 186 }
 187
 188 static struct grant_map *gntdev_find_map_index(struct gntdev_priv *priv,
 189                 int index, int count)
 190 {
 191         struct grant_map *map;
 192
 193         list_for_each_entry(map, &priv->maps, next) {
 194                 if (map->index != index)
 195                         continue;
 196                 if (count && map->count != count)
 197                         continue;
 198                 return map;
 199         }
 200         return NULL;
 201 }
 202
 203 static void gntdev_put_map(struct gntdev_priv *priv, struct grant_map *map)
 204 {
 205         if (!map)
 206                 return;
 207
 208         if (!atomic_dec_and_test(&map->users))
 209                 return;
 210
 211         atomic_sub(map->count, &pages_mapped);
 212
 213         if (map->notify.flags & UNMAP_NOTIFY_SEND_EVENT) {
 214                 notify_remote_via_evtchn(map->notify.event);
 215                 evtchn_put(map->notify.event);
 216         }
 217
 218         if (populate_freeable_maps && priv) {
 219                 mutex_lock(&priv->lock);
 220                 list_del(&map->next);
 221                 mutex_unlock(&priv->lock);
 222         }
 223
 224         if (map->pages && !use_ptemod)
 225                 unmap_grant_pages(map, 0, map->count);
 226         gntdev_free_map(map);
 227 }
 228
 229 /* ------------------------------------------------------------------ */
 230
 231 static int find_grant_ptes(pte_t *pte, pgtable_t token,
 232                 unsigned long addr, void *data)
 233 {
 234         struct grant_map *map = data;
 235         unsigned int pgnr = (addr - map->vma->vm_start) >> PAGE_SHIFT;
 236         int flags = map->flags | GNTMAP_application_map | GNTMAP_contains_pte;
 237         u64 pte_maddr;
 238
 239         BUG_ON(pgnr >= map->count);
 240         pte_maddr = arbitrary_virt_to_machine(pte).maddr;
 241
 242         gnttab_set_map_op(&map->map_ops[pgnr], pte_maddr, flags,
 243                           map->grants[pgnr].ref,
 244                           map->grants[pgnr].domid);
 245         gnttab_set_unmap_op(&map->unmap_ops[pgnr], pte_maddr, flags,
 246                             -1 /* handle */);
 247         return 0;
 248 }
 249
 250 static int map_grant_pages(struct grant_map *map)
 251 {
 252         int i, err = 0;
 253
 254         if (!use_ptemod) {
 255                 /* Note: it could already be mapped */
 256                 if (map->map_ops[0].handle != -1)
 257                         return 0;
 258                 for (i = 0; i < map->count; i++) {
 259                         unsigned long addr = (unsigned long)
 260                                 pfn_to_kaddr(page_to_pfn(map->pages[i]));
 261                         gnttab_set_map_op(&map->map_ops[i], addr, map->flags,
 262                                 map->grants[i].ref,
 263                                 map->grants[i].domid);
 264                         gnttab_set_unmap_op(&map->unmap_ops[i], addr,
 265                                 map->flags, -1 /* handle */);
 266                 }
 267         } else {
 268                 /*
 269                  * Setup the map_ops corresponding to the pte entries pointing
 270                  * to the kernel linear addresses of the struct pages.
 271                  * These ptes are completely different from the user ptes dealt
 272                  * with find_grant_ptes.
 273                  */
 274                 for (i = 0; i < map->count; i++) {
 275                         unsigned long address = (unsigned long)
 276                                 pfn_to_kaddr(page_to_pfn(map->pages[i]));
 277                         BUG_ON(PageHighMem(map->pages[i]));
 278
 279                         gnttab_set_map_op(&map->kmap_ops[i], address,
 280                                 map->flags | GNTMAP_host_map,
 281                                 map->grants[i].ref,
 282                                 map->grants[i].domid);
 283                 }
 284         }
 285
 286         pr_debug("map %d+%d\n", map->index, map->count);
 287         err = gnttab_map_refs(map->map_ops, use_ptemod ? map->kmap_ops : NULL,
 288                         map->pages, map->count);
 289         if (err)
 290                 return err;
 291
 292         for (i = 0; i < map->count; i++) {
 293                 if (map->map_ops[i].status)
 294                         err = -EINVAL;
 295                 else {
 296                         BUG_ON(map->map_ops[i].handle == -1);
 297                         map->unmap_ops[i].handle = map->map_ops[i].handle;
 298                         pr_debug("map handle=%d\n", map->map_ops[i].handle);
 299                 }
 300         }
 301         return err;
 302 }
 303
 304 static int __unmap_grant_pages(struct grant_map *map, int offset, int pages)
 305 {
 306         int i, err = 0;
 307
 308         if (map->notify.flags & UNMAP_NOTIFY_CLEAR_BYTE) {
 309                 int pgno = (map->notify.addr >> PAGE_SHIFT);
 310                 if (pgno >= offset && pgno < offset + pages) {
 311                         /* No need for kmap, pages are in lowmem */
 312                         uint8_t *tmp = pfn_to_kaddr(page_to_pfn(map->pages[pgno]));
 313                         tmp[map->notify.addr & (PAGE_SIZE-1)] = 0;
 314                         map->notify.flags &= ~UNMAP_NOTIFY_CLEAR_BYTE;
 315                 }
 316         }
 317
 318         err = gnttab_unmap_refs(map->unmap_ops + offset,
 319                         use_ptemod ? map->kmap_ops + offset : NULL, map->pages + offset,
 320                         pages);
 321         if (err)
 322                 return err;
 323
 324         for (i = 0; i < pages; i++) {
 325                 if (map->unmap_ops[offset+i].status)
 326                         err = -EINVAL;
 327                 pr_debug("unmap handle=%d st=%d\n",
 328                         map->unmap_ops[offset+i].handle,
 329                         map->unmap_ops[offset+i].status);
 330                 map->unmap_ops[offset+i].handle = -1;
 331         }
 332         return err;
 333 }
 334
 335 static int unmap_grant_pages(struct grant_map *map, int offset, int pages)
 336 {
 337         int range, err = 0;
 338
 339         pr_debug("unmap %d+%d [%d+%d]\n", map->index, map->count, offset, pages);
 340
 341         /* It is possible the requested range will have a "hole" where we
 342          * already unmapped some of the grants. Only unmap valid ranges.
 343          */
 344         while (pages && !err) {
 345                 while (pages && map->unmap_ops[offset].handle == -1) {
 346                         offset++;
 347                         pages--;
 348                 }
 349                 range = 0;
 350                 while (range < pages) {
 351                         if (map->unmap_ops[offset+range].handle == -1) {
 352                                 range--;
 353                                 break;
 354                         }
 355                         range++;
 356                 }
 357                 err = __unmap_grant_pages(map, offset, range);
 358                 offset += range;
 359                 pages -= range;
 360         }
 361
 362         return err;
 363 }
 364
 365 /* ------------------------------------------------------------------ */
 366
 367 static void gntdev_vma_open(struct vm_area_struct *vma)
 368 {
 369         struct grant_map *map = vma->vm_private_data;
 370
 371         pr_debug("gntdev_vma_open %p\n", vma);
 372         atomic_inc(&map->users);
 373 }
 374
 375 static void gntdev_vma_close(struct vm_area_struct *vma)
 376 {
 377         struct grant_map *map = vma->vm_private_data;
 378         struct file *file = vma->vm_file;
 379         struct gntdev_priv *priv = file->private_data;
 380
 381         pr_debug("gntdev_vma_close %p\n", vma);
 382         if (use_ptemod) {
 383                 /* It is possible that an mmu notifier could be running
 384                  * concurrently, so take priv->lock to ensure that the vma won't
 385                  * vanishing during the unmap_grant_pages call, since we will
 386                  * spin here until that completes. Such a concurrent call will
 387                  * not do any unmapping, since that has been done prior to
 388                  * closing the vma, but it may still iterate the unmap_ops list.
 389                  */
 390                 mutex_lock(&priv->lock);
 391                 map->vma = NULL;
 392                 mutex_unlock(&priv->lock);
 393         }
 394         vma->vm_private_data = NULL;
 395         gntdev_put_map(priv, map);
 396 }
 397
 398 static struct vm_operations_struct gntdev_vmops = {
 399         .open = gntdev_vma_open,
 400         .close = gntdev_vma_close,
 401 };
 402
 403 /* ------------------------------------------------------------------ */
 404
 405 static void unmap_if_in_range(struct grant_map *map,
 406                               unsigned long start, unsigned long end)
 407 {
 408         unsigned long mstart, mend;
 409         int err;
 410
 411         if (!map->vma)
 412                 return;
 413         if (map->vma->vm_start >= end)
 414                 return;
 415         if (map->vma->vm_end <= start)
 416                 return;
 417         mstart = max(start, map->vma->vm_start);
 418         mend   = min(end,   map->vma->vm_end);
 419         pr_debug("map %d+%d (%lx %lx), range %lx %lx, mrange %lx %lx\n",
 420                         map->index, map->count,
 421                         map->vma->vm_start, map->vma->vm_end,
 422                         start, end, mstart, mend);
 423         err = unmap_grant_pages(map,
 424                                 (mstart - map->vma->vm_start) >> PAGE_SHIFT,
 425                                 (mend - mstart) >> PAGE_SHIFT);
 426         WARN_ON(err);
 427 }
 428
 429 static void mn_invl_range_start(struct mmu_notifier *mn,
 430                                 struct mm_struct *mm,
 431                                 unsigned long start, unsigned long end)
 432 {
 433         struct gntdev_priv *priv = container_of(mn, struct gntdev_priv, mn);
 434         struct grant_map *map;
 435
 436         mutex_lock(&priv->lock);
 437         list_for_each_entry(map, &priv->maps, next) {
 438                 unmap_if_in_range(map, start, end);
 439         }
 440         list_for_each_entry(map, &priv->freeable_maps, next) {
 441                 unmap_if_in_range(map, start, end);
 442         }
 443         mutex_unlock(&priv->lock);
 444 }
 445
 446 static void mn_invl_page(struct mmu_notifier *mn,
 447                          struct mm_struct *mm,
 448                          unsigned long address)
 449 {
 450         mn_invl_range_start(mn, mm, address, address + PAGE_SIZE);
 451 }
 452
 453 static void mn_release(struct mmu_notifier *mn,
 454                        struct mm_struct *mm)
 455 {
 456         struct gntdev_priv *priv = container_of(mn, struct gntdev_priv, mn);
 457         struct grant_map *map;
 458         int err;
 459
 460         mutex_lock(&priv->lock);
 461         list_for_each_entry(map, &priv->maps, next) {
 462                 if (!map->vma)
 463                         continue;
 464                 pr_debug("map %d+%d (%lx %lx)\n",
 465                                 map->index, map->count,
 466                                 map->vma->vm_start, map->vma->vm_end);
 467                 err = unmap_grant_pages(map, /* offset */ 0, map->count);
 468                 WARN_ON(err);
 469         }
 470         list_for_each_entry(map, &priv->freeable_maps, next) {
 471                 if (!map->vma)
 472                         continue;
 473                 pr_debug("map %d+%d (%lx %lx)\n",
 474                                 map->index, map->count,
 475                                 map->vma->vm_start, map->vma->vm_end);
 476                 err = unmap_grant_pages(map, /* offset */ 0, map->count);
 477                 WARN_ON(err);
 478         }
 479         mutex_unlock(&priv->lock);
 480 }
 481
 482 static struct mmu_notifier_ops gntdev_mmu_ops = {
 483         .release                = mn_release,
 484         .invalidate_page        = mn_invl_page,
 485         .invalidate_range_start = mn_invl_range_start,
 486 };
 487
 488 /* ------------------------------------------------------------------ */
 489
 490 static int gntdev_open(struct inode *inode, struct file *flip)
 491 {
 492         struct gntdev_priv *priv;
 493         int ret = 0;
 494
 495         priv = kzalloc(sizeof(*priv), GFP_KERNEL);
 496         if (!priv)
 497                 return -ENOMEM;
 498
 499         INIT_LIST_HEAD(&priv->maps);
 500         INIT_LIST_HEAD(&priv->freeable_maps);
 501         mutex_init(&priv->lock);
 502
 503         if (use_ptemod) {
 504                 priv->mm = get_task_mm(current);
 505                 if (!priv->mm) {
 506                         kfree(priv);
 507                         return -ENOMEM;
 508                 }
 509                 priv->mn.ops = &gntdev_mmu_ops;
 510                 ret = mmu_notifier_register(&priv->mn, priv->mm);
 511                 mmput(priv->mm);
 512         }
 513
 514         if (ret) {
 515                 kfree(priv);
 516                 return ret;
 517         }
 518
 519         flip->private_data = priv;
 520         pr_debug("priv %p\n", priv);
 521
 522         return 0;
 523 }
 524
 525 static int gntdev_release(struct inode *inode, struct file *flip)
 526 {
 527         struct gntdev_priv *priv = flip->private_data;
 528         struct grant_map *map;
 529
 530         pr_debug("priv %p\n", priv);
 531
 532         mutex_lock(&priv->lock);
 533         while (!list_empty(&priv->maps)) {
 534                 map = list_entry(priv->maps.next, struct grant_map, next);
 535                 list_del(&map->next);
 536                 gntdev_put_map(NULL /* already removed */, map);
 537         }
 538         WARN_ON(!list_empty(&priv->freeable_maps));
 539         mutex_unlock(&priv->lock);
 540
 541         if (use_ptemod)
 542                 mmu_notifier_unregister(&priv->mn, priv->mm);
 543         kfree(priv);
 544         return 0;
 545 }
 546
 547 static long gntdev_ioctl_map_grant_ref(struct gntdev_priv *priv,
 548                                        struct ioctl_gntdev_map_grant_ref __user *u)
 549 {
 550         struct ioctl_gntdev_map_grant_ref op;
 551         struct grant_map *map;
 552         int err;
 553
 554         if (copy_from_user(&op, u, sizeof(op)) != 0)
 555                 return -EFAULT;
 556         pr_debug("priv %p, add %d\n", priv, op.count);
 557         if (unlikely(op.count <= 0))
 558                 return -EINVAL;
 559
 560         err = -ENOMEM;
 561         map = gntdev_alloc_map(priv, op.count);
 562         if (!map)
 563                 return err;
 564
 565         if (unlikely(atomic_add_return(op.count, &pages_mapped) > limit)) {
 566                 pr_debug("can't map: over limit\n");
 567                 gntdev_put_map(NULL, map);
 568                 return err;
 569         }
 570
 571         if (copy_from_user(map->grants, &u->refs,
 572                            sizeof(map->grants[0]) * op.count) != 0) {
 573                 gntdev_put_map(NULL, map);
 574                 return -EFAULT;
 575         }
 576
 577         mutex_lock(&priv->lock);
 578         gntdev_add_map(priv, map);
 579         op.index = map->index << PAGE_SHIFT;
 580         mutex_unlock(&priv->lock);
 581
 582         if (copy_to_user(u, &op, sizeof(op)) != 0)
 583                 return -EFAULT;
 584
 585         return 0;
 586 }
 587
 588 static long gntdev_ioctl_unmap_grant_ref(struct gntdev_priv *priv,
 589                                          struct ioctl_gntdev_unmap_grant_ref __user *u)
 590 {
 591         struct ioctl_gntdev_unmap_grant_ref op;
 592         struct grant_map *map;
 593         int err = -ENOENT;
 594
 595         if (copy_from_user(&op, u, sizeof(op)) != 0)
 596                 return -EFAULT;
 597         pr_debug("priv %p, del %d+%d\n", priv, (int)op.index, (int)op.count);
 598
 599         mutex_lock(&priv->lock);
 600         map = gntdev_find_map_index(priv, op.index >> PAGE_SHIFT, op.count);
 601         if (map) {
 602                 list_del(&map->next);
 603                 if (populate_freeable_maps)
 604                         list_add_tail(&map->next, &priv->freeable_maps);
 605                 err = 0;
 606         }
 607         mutex_unlock(&priv->lock);
 608         if (map)
 609                 gntdev_put_map(priv, map);
 610         return err;
 611 }
 612
 613 static long gntdev_ioctl_get_offset_for_vaddr(struct gntdev_priv *priv,
 614                                               struct ioctl_gntdev_get_offset_for_vaddr __user *u)
 615 {
 616         struct ioctl_gntdev_get_offset_for_vaddr op;
 617         struct vm_area_struct *vma;
 618         struct grant_map *map;
 619         int rv = -EINVAL;
 620
 621         if (copy_from_user(&op, u, sizeof(op)) != 0)
 622                 return -EFAULT;
 623         pr_debug("priv %p, offset for vaddr %lx\n", priv, (unsigned long)op.vaddr);
 624
 625         down_read(&current->mm->mmap_sem);
 626         vma = find_vma(current->mm, op.vaddr);
 627         if (!vma || vma->vm_ops != &gntdev_vmops)
 628                 goto out_unlock;
 629
 630         map = vma->vm_private_data;
 631         if (!map)
 632                 goto out_unlock;
 633
 634         op.offset = map->index << PAGE_SHIFT;
 635         op.count = map->count;
 636         rv = 0;
 637
 638  out_unlock:
 639         up_read(&current->mm->mmap_sem);
 640
 641         if (rv == 0 && copy_to_user(u, &op, sizeof(op)) != 0)
 642                 return -EFAULT;
 643         return rv;
 644 }
 645
 646 static long gntdev_ioctl_notify(struct gntdev_priv *priv, void __user *u)
 647 {
 648         struct ioctl_gntdev_unmap_notify op;
 649         struct grant_map *map;
 650         int rc;
 651         int out_flags;
 652         unsigned int out_event;
 653
 654         if (copy_from_user(&op, u, sizeof(op)))
 655                 return -EFAULT;
 656
 657         if (op.action & ~(UNMAP_NOTIFY_CLEAR_BYTE|UNMAP_NOTIFY_SEND_EVENT))
 658                 return -EINVAL;
 659
 660         /* We need to grab a reference to the event channel we are going to use
 661          * to send the notify before releasing the reference we may already have
 662          * (if someone has called this ioctl twice). This is required so that
 663          * it is possible to change the clear_byte part of the notification
 664          * without disturbing the event channel part, which may now be the last
 665          * reference to that event channel.
 666          */
 667         if (op.action & UNMAP_NOTIFY_SEND_EVENT) {
 668                 if (evtchn_get(op.event_channel_port))
 669                         return -EINVAL;
 670         }
 671
 672         out_flags = op.action;
 673         out_event = op.event_channel_port;
 674
 675         mutex_lock(&priv->lock);
 676
 677         list_for_each_entry(map, &priv->maps, next) {
 678                 uint64_t begin = map->index << PAGE_SHIFT;
 679                 uint64_t end = (map->index + map->count) << PAGE_SHIFT;
 680                 if (op.index >= begin && op.index < end)
 681                         goto found;
 682         }
 683         rc = -ENOENT;
 684         goto unlock_out;
 685
 686  found:
 687         if ((op.action & UNMAP_NOTIFY_CLEAR_BYTE) &&
 688                         (map->flags & GNTMAP_readonly)) {
 689                 rc = -EINVAL;
 690                 goto unlock_out;
 691         }
 692
 693         out_flags = map->notify.flags;
 694         out_event = map->notify.event;
 695
 696         map->notify.flags = op.action;
 697         map->notify.addr = op.index - (map->index << PAGE_SHIFT);
 698         map->notify.event = op.event_channel_port;
 699
 700         rc = 0;
 701
 702  unlock_out:
 703         mutex_unlock(&priv->lock);
 704
 705         /* Drop the reference to the event channel we did not save in the map */
 706         if (out_flags & UNMAP_NOTIFY_SEND_EVENT)
 707                 evtchn_put(out_event);
 708
 709         return rc;
 710 }
 711
 712 static long gntdev_ioctl(struct file *flip,
 713                          unsigned int cmd, unsigned long arg)
 714 {
 715         struct gntdev_priv *priv = flip->private_data;
 716         void __user *ptr = (void __user *)arg;
 717
 718         switch (cmd) {
 719         case IOCTL_GNTDEV_MAP_GRANT_REF:
 720                 return gntdev_ioctl_map_grant_ref(priv, ptr);
 721
 722         case IOCTL_GNTDEV_UNMAP_GRANT_REF:
 723                 return gntdev_ioctl_unmap_grant_ref(priv, ptr);
 724
 725         case IOCTL_GNTDEV_GET_OFFSET_FOR_VADDR:
 726                 return gntdev_ioctl_get_offset_for_vaddr(priv, ptr);
 727
 728         case IOCTL_GNTDEV_SET_UNMAP_NOTIFY:
 729                 return gntdev_ioctl_notify(priv, ptr);
 730
 731         default:
 732                 pr_debug("priv %p, unknown cmd %x\n", priv, cmd);
 733                 return -ENOIOCTLCMD;
 734         }
 735
 736         return 0;
 737 }
 738
 739 static int gntdev_mmap(struct file *flip, struct vm_area_struct *vma)
 740 {
 741         struct gntdev_priv *priv = flip->private_data;
 742         int index = vma->vm_pgoff;
 743         int count = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
 744         struct grant_map *map;
 745         int i, err = -EINVAL;
 746
 747         if ((vma->vm_flags & VM_WRITE) && !(vma->vm_flags & VM_SHARED))
 748                 return -EINVAL;
 749
 750         pr_debug("map %d+%d at %lx (pgoff %lx)\n",
 751                         index, count, vma->vm_start, vma->vm_pgoff);
 752
 753         mutex_lock(&priv->lock);
 754         map = gntdev_find_map_index(priv, index, count);
 755         if (!map)
 756                 goto unlock_out;
 757         if (use_ptemod && map->vma)
 758                 goto unlock_out;
 759         if (use_ptemod && priv->mm != vma->vm_mm) {
 760                 pr_warn("Huh? Other mm?\n");
 761                 goto unlock_out;
 762         }
 763
 764         atomic_inc(&map->users);
 765
 766         vma->vm_ops = &gntdev_vmops;
 767
 768         vma->vm_flags |= VM_DONTEXPAND | VM_DONTDUMP;
 769
 770         if (use_ptemod)
 771                 vma->vm_flags |= VM_DONTCOPY;
 772
 773         vma->vm_private_data = map;
 774
 775         if (use_ptemod)
 776                 map->vma = vma;
 777
 778         if (map->flags) {
 779                 if ((vma->vm_flags & VM_WRITE) &&
 780                                 (map->flags & GNTMAP_readonly))
 781                         goto out_unlock_put;
 782         } else {
 783                 map->flags = GNTMAP_host_map;
 784                 if (!(vma->vm_flags & VM_WRITE))
 785                         map->flags |= GNTMAP_readonly;
 786         }
 787
 788         mutex_unlock(&priv->lock);
 789
 790         if (use_ptemod) {
 791                 err = apply_to_page_range(vma->vm_mm, vma->vm_start,
 792                                           vma->vm_end - vma->vm_start,
 793                                           find_grant_ptes, map);
 794                 if (err) {
 795                         pr_warn("find_grant_ptes() failure.\n");
 796                         goto out_put_map;
 797                 }
 798         }
 799
 800         err = map_grant_pages(map);
 801         if (err)
 802                 goto out_put_map;
 803
 804         if (!use_ptemod) {
 805                 for (i = 0; i < count; i++) {
 806                         err = vm_insert_page(vma, vma->vm_start + i*PAGE_SIZE,
 807                                 map->pages[i]);
 808                         if (err)
 809                                 goto out_put_map;
 810                 }
 811         }
 812
 813         return 0;
 814
 815 unlock_out:
 816         mutex_unlock(&priv->lock);
 817         return err;
 818
 819 out_unlock_put:
 820         mutex_unlock(&priv->lock);
 821 out_put_map:
 822         if (use_ptemod)
 823                 map->vma = NULL;
 824         gntdev_put_map(priv, map);
 825         return err;
 826 }
 827
 828 static const struct file_operations gntdev_fops = {
 829         .owner = THIS_MODULE,
 830         .open = gntdev_open,
 831         .release = gntdev_release,
 832         .mmap = gntdev_mmap,
 833         .unlocked_ioctl = gntdev_ioctl
 834 };
 835
 836 static struct miscdevice gntdev_miscdev = {
 837         .minor        = MISC_DYNAMIC_MINOR,
 838         .name         = "xen/gntdev",
 839         .fops         = &gntdev_fops,
 840 };
 841
 842 /* ------------------------------------------------------------------ */
 843
 844 static int __init gntdev_init(void)
 845 {
 846         int err;
 847
 848         if (!xen_domain())
 849                 return -ENODEV;
 850
 851         use_ptemod = !xen_feature(XENFEAT_auto_translated_physmap);
 852
 853         err = misc_register(&gntdev_miscdev);
 854         if (err != 0) {
 855                 pr_err("Could not register gntdev device\n");
 856                 return err;
 857         }
 858         return 0;
 859 }
 860
 861 static void __exit gntdev_exit(void)
 862 {
 863         misc_deregister(&gntdev_miscdev);
 864 }
 865
 866 module_init(gntdev_init);
 867 module_exit(gntdev_exit);
 868
 869 /* ------------------------------------------------------------------ */