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 <xen/page.h>
  45 #include <asm/xen/hypervisor.h>
  46 #include <asm/xen/hypercall.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 gnttab_unmap_grant_ref *kunmap_ops;
  95         struct page **pages;
  96         unsigned long pages_vm_start;
  97 };
  98
  99 static int unmap_grant_pages(struct grant_map *map, int offset, int pages);
 100
 101 /* ------------------------------------------------------------------ */
 102
 103 static void gntdev_print_maps(struct gntdev_priv *priv,
 104                               char *text, int text_index)
 105 {
 106 #ifdef DEBUG
 107         struct grant_map *map;
 108
 109         pr_debug("%s: maps list (priv %p)\n", __func__, priv);
 110         list_for_each_entry(map, &priv->maps, next)
 111                 pr_debug("  index %2d, count %2d %s\n",
 112                        map->index, map->count,
 113                        map->index == text_index && text ? text : "");
 114 #endif
 115 }
 116
 117 static void gntdev_free_map(struct grant_map *map)
 118 {
 119         if (map == NULL)
 120                 return;
 121
 122         if (map->pages)
 123                 gnttab_free_pages(map->count, map->pages);
 124         kfree(map->pages);
 125         kfree(map->grants);
 126         kfree(map->map_ops);
 127         kfree(map->unmap_ops);
 128         kfree(map->kmap_ops);
 129         kfree(map->kunmap_ops);
 130         kfree(map);
 131 }
 132
 133 static struct grant_map *gntdev_alloc_map(struct gntdev_priv *priv, int count)
 134 {
 135         struct grant_map *add;
 136         int i;
 137
 138         add = kzalloc(sizeof(struct grant_map), GFP_KERNEL);
 139         if (NULL == add)
 140                 return NULL;
 141
 142         add->grants    = kcalloc(count, sizeof(add->grants[0]), GFP_KERNEL);
 143         add->map_ops   = kcalloc(count, sizeof(add->map_ops[0]), GFP_KERNEL);
 144         add->unmap_ops = kcalloc(count, sizeof(add->unmap_ops[0]), GFP_KERNEL);
 145         add->kmap_ops  = kcalloc(count, sizeof(add->kmap_ops[0]), GFP_KERNEL);
 146         add->kunmap_ops = kcalloc(count, sizeof(add->kunmap_ops[0]), GFP_KERNEL);
 147         add->pages     = kcalloc(count, sizeof(add->pages[0]), GFP_KERNEL);
 148         if (NULL == add->grants    ||
 149             NULL == add->map_ops   ||
 150             NULL == add->unmap_ops ||
 151             NULL == add->kmap_ops  ||
 152             NULL == add->kunmap_ops ||
 153             NULL == add->pages)
 154                 goto err;
 155
 156         if (gnttab_alloc_pages(count, add->pages))
 157                 goto err;
 158
 159         for (i = 0; i < count; i++) {
 160                 add->map_ops[i].handle = -1;
 161                 add->unmap_ops[i].handle = -1;
 162                 add->kmap_ops[i].handle = -1;
 163                 add->kunmap_ops[i].handle = -1;
 164         }
 165
 166         add->index = 0;
 167         add->count = count;
 168         atomic_set(&add->users, 1);
 169
 170         return add;
 171
 172 err:
 173         gntdev_free_map(add);
 174         return NULL;
 175 }
 176
 177 static void gntdev_add_map(struct gntdev_priv *priv, struct grant_map *add)
 178 {
 179         struct grant_map *map;
 180
 181         list_for_each_entry(map, &priv->maps, next) {
 182                 if (add->index + add->count < map->index) {
 183                         list_add_tail(&add->next, &map->next);
 184                         goto done;
 185                 }
 186                 add->index = map->index + map->count;
 187         }
 188         list_add_tail(&add->next, &priv->maps);
 189
 190 done:
 191         gntdev_print_maps(priv, "[new]", add->index);
 192 }
 193
 194 static struct grant_map *gntdev_find_map_index(struct gntdev_priv *priv,
 195                 int index, int count)
 196 {
 197         struct grant_map *map;
 198
 199         list_for_each_entry(map, &priv->maps, next) {
 200                 if (map->index != index)
 201                         continue;
 202                 if (count && map->count != count)
 203                         continue;
 204                 return map;
 205         }
 206         return NULL;
 207 }
 208
 209 static void gntdev_put_map(struct gntdev_priv *priv, struct grant_map *map)
 210 {
 211         if (!map)
 212                 return;
 213
 214         if (!atomic_dec_and_test(&map->users))
 215                 return;
 216
 217         atomic_sub(map->count, &pages_mapped);
 218
 219         if (map->notify.flags & UNMAP_NOTIFY_SEND_EVENT) {
 220                 notify_remote_via_evtchn(map->notify.event);
 221                 evtchn_put(map->notify.event);
 222         }
 223
 224         if (populate_freeable_maps && priv) {
 225                 mutex_lock(&priv->lock);
 226                 list_del(&map->next);
 227                 mutex_unlock(&priv->lock);
 228         }
 229
 230         if (map->pages && !use_ptemod)
 231                 unmap_grant_pages(map, 0, map->count);
 232         gntdev_free_map(map);
 233 }
 234
 235 /* ------------------------------------------------------------------ */
 236
 237 static int find_grant_ptes(pte_t *pte, pgtable_t token,
 238                 unsigned long addr, void *data)
 239 {
 240         struct grant_map *map = data;
 241         unsigned int pgnr = (addr - map->vma->vm_start) >> PAGE_SHIFT;
 242         int flags = map->flags | GNTMAP_application_map | GNTMAP_contains_pte;
 243         u64 pte_maddr;
 244
 245         BUG_ON(pgnr >= map->count);
 246         pte_maddr = arbitrary_virt_to_machine(pte).maddr;
 247
 248         /*
 249          * Set the PTE as special to force get_user_pages_fast() fall
 250          * back to the slow path.  If this is not supported as part of
 251          * the grant map, it will be done afterwards.
 252          */
 253         if (xen_feature(XENFEAT_gnttab_map_avail_bits))
 254                 flags |= (1 << _GNTMAP_guest_avail0);
 255
 256         gnttab_set_map_op(&map->map_ops[pgnr], pte_maddr, flags,
 257                           map->grants[pgnr].ref,
 258                           map->grants[pgnr].domid);
 259         gnttab_set_unmap_op(&map->unmap_ops[pgnr], pte_maddr, flags,
 260                             -1 /* handle */);
 261         return 0;
 262 }
 263
 264 #ifdef CONFIG_X86
 265 static int set_grant_ptes_as_special(pte_t *pte, pgtable_t token,
 266                                      unsigned long addr, void *data)
 267 {
 268         set_pte_at(current->mm, addr, pte, pte_mkspecial(*pte));
 269         return 0;
 270 }
 271 #endif
 272
 273 static int map_grant_pages(struct grant_map *map)
 274 {
 275         int i, err = 0;
 276
 277         if (!use_ptemod) {
 278                 /* Note: it could already be mapped */
 279                 if (map->map_ops[0].handle != -1)
 280                         return 0;
 281                 for (i = 0; i < map->count; i++) {
 282                         unsigned long addr = (unsigned long)
 283                                 pfn_to_kaddr(page_to_pfn(map->pages[i]));
 284                         gnttab_set_map_op(&map->map_ops[i], addr, map->flags,
 285                                 map->grants[i].ref,
 286                                 map->grants[i].domid);
 287                         gnttab_set_unmap_op(&map->unmap_ops[i], addr,
 288                                 map->flags, -1 /* handle */);
 289                 }
 290         } else {
 291                 /*
 292                  * Setup the map_ops corresponding to the pte entries pointing
 293                  * to the kernel linear addresses of the struct pages.
 294                  * These ptes are completely different from the user ptes dealt
 295                  * with find_grant_ptes.
 296                  */
 297                 for (i = 0; i < map->count; i++) {
 298                         unsigned long address = (unsigned long)
 299                                 pfn_to_kaddr(page_to_pfn(map->pages[i]));
 300                         BUG_ON(PageHighMem(map->pages[i]));
 301
 302                         gnttab_set_map_op(&map->kmap_ops[i], address,
 303                                 map->flags | GNTMAP_host_map,
 304                                 map->grants[i].ref,
 305                                 map->grants[i].domid);
 306                         gnttab_set_unmap_op(&map->kunmap_ops[i], address,
 307                                 map->flags | GNTMAP_host_map, -1);
 308                 }
 309         }
 310
 311         pr_debug("map %d+%d\n", map->index, map->count);
 312         err = gnttab_map_refs(map->map_ops, use_ptemod ? map->kmap_ops : NULL,
 313                         map->pages, map->count);
 314         if (err)
 315                 return err;
 316
 317         for (i = 0; i < map->count; i++) {
 318                 if (map->map_ops[i].status) {
 319                         err = -EINVAL;
 320                         continue;
 321                 }
 322
 323                 map->unmap_ops[i].handle = map->map_ops[i].handle;
 324                 if (use_ptemod)
 325                         map->kunmap_ops[i].handle = map->kmap_ops[i].handle;
 326         }
 327         return err;
 328 }
 329
 330 static int __unmap_grant_pages(struct grant_map *map, int offset, int pages)
 331 {
 332         int i, err = 0;
 333         struct gntab_unmap_queue_data unmap_data;
 334
 335         if (map->notify.flags & UNMAP_NOTIFY_CLEAR_BYTE) {
 336                 int pgno = (map->notify.addr >> PAGE_SHIFT);
 337                 if (pgno >= offset && pgno < offset + pages) {
 338                         /* No need for kmap, pages are in lowmem */
 339                         uint8_t *tmp = pfn_to_kaddr(page_to_pfn(map->pages[pgno]));
 340                         tmp[map->notify.addr & (PAGE_SIZE-1)] = 0;
 341                         map->notify.flags &= ~UNMAP_NOTIFY_CLEAR_BYTE;
 342                 }
 343         }
 344
 345         unmap_data.unmap_ops = map->unmap_ops + offset;
 346         unmap_data.kunmap_ops = use_ptemod ? map->kunmap_ops + offset : NULL;
 347         unmap_data.pages = map->pages + offset;
 348         unmap_data.count = pages;
 349
 350         err = gnttab_unmap_refs_sync(&unmap_data);
 351         if (err)
 352                 return err;
 353
 354         for (i = 0; i < pages; i++) {
 355                 if (map->unmap_ops[offset+i].status)
 356                         err = -EINVAL;
 357                 pr_debug("unmap handle=%d st=%d\n",
 358                         map->unmap_ops[offset+i].handle,
 359                         map->unmap_ops[offset+i].status);
 360                 map->unmap_ops[offset+i].handle = -1;
 361         }
 362         return err;
 363 }
 364
 365 static int unmap_grant_pages(struct grant_map *map, int offset, int pages)
 366 {
 367         int range, err = 0;
 368
 369         pr_debug("unmap %d+%d [%d+%d]\n", map->index, map->count, offset, pages);
 370
 371         /* It is possible the requested range will have a "hole" where we
 372          * already unmapped some of the grants. Only unmap valid ranges.
 373          */
 374         while (pages && !err) {
 375                 while (pages && map->unmap_ops[offset].handle == -1) {
 376                         offset++;
 377                         pages--;
 378                 }
 379                 range = 0;
 380                 while (range < pages) {
 381                         if (map->unmap_ops[offset+range].handle == -1) {
 382                                 range--;
 383                                 break;
 384                         }
 385                         range++;
 386                 }
 387                 err = __unmap_grant_pages(map, offset, range);
 388                 offset += range;
 389                 pages -= range;
 390         }
 391
 392         return err;
 393 }
 394
 395 /* ------------------------------------------------------------------ */
 396
 397 static void gntdev_vma_open(struct vm_area_struct *vma)
 398 {
 399         struct grant_map *map = vma->vm_private_data;
 400
 401         pr_debug("gntdev_vma_open %p\n", vma);
 402         atomic_inc(&map->users);
 403 }
 404
 405 static void gntdev_vma_close(struct vm_area_struct *vma)
 406 {
 407         struct grant_map *map = vma->vm_private_data;
 408         struct file *file = vma->vm_file;
 409         struct gntdev_priv *priv = file->private_data;
 410
 411         pr_debug("gntdev_vma_close %p\n", vma);
 412         if (use_ptemod) {
 413                 /* It is possible that an mmu notifier could be running
 414                  * concurrently, so take priv->lock to ensure that the vma won't
 415                  * vanishing during the unmap_grant_pages call, since we will
 416                  * spin here until that completes. Such a concurrent call will
 417                  * not do any unmapping, since that has been done prior to
 418                  * closing the vma, but it may still iterate the unmap_ops list.
 419                  */
 420                 mutex_lock(&priv->lock);
 421                 map->vma = NULL;
 422                 mutex_unlock(&priv->lock);
 423         }
 424         vma->vm_private_data = NULL;
 425         gntdev_put_map(priv, map);
 426 }
 427
 428 static struct page *gntdev_vma_find_special_page(struct vm_area_struct *vma,
 429                                                  unsigned long addr)
 430 {
 431         struct grant_map *map = vma->vm_private_data;
 432
 433         return map->pages[(addr - map->pages_vm_start) >> PAGE_SHIFT];
 434 }
 435
 436 static struct vm_operations_struct gntdev_vmops = {
 437         .open = gntdev_vma_open,
 438         .close = gntdev_vma_close,
 439         .find_special_page = gntdev_vma_find_special_page,
 440 };
 441
 442 /* ------------------------------------------------------------------ */
 443
 444 static void unmap_if_in_range(struct grant_map *map,
 445                               unsigned long start, unsigned long end)
 446 {
 447         unsigned long mstart, mend;
 448         int err;
 449
 450         if (!map->vma)
 451                 return;
 452         if (map->vma->vm_start >= end)
 453                 return;
 454         if (map->vma->vm_end <= start)
 455                 return;
 456         mstart = max(start, map->vma->vm_start);
 457         mend   = min(end,   map->vma->vm_end);
 458         pr_debug("map %d+%d (%lx %lx), range %lx %lx, mrange %lx %lx\n",
 459                         map->index, map->count,
 460                         map->vma->vm_start, map->vma->vm_end,
 461                         start, end, mstart, mend);
 462         err = unmap_grant_pages(map,
 463                                 (mstart - map->vma->vm_start) >> PAGE_SHIFT,
 464                                 (mend - mstart) >> PAGE_SHIFT);
 465         WARN_ON(err);
 466 }
 467
 468 static void mn_invl_range_start(struct mmu_notifier *mn,
 469                                 struct mm_struct *mm,
 470                                 unsigned long start, unsigned long end)
 471 {
 472         struct gntdev_priv *priv = container_of(mn, struct gntdev_priv, mn);
 473         struct grant_map *map;
 474
 475         mutex_lock(&priv->lock);
 476         list_for_each_entry(map, &priv->maps, next) {
 477                 unmap_if_in_range(map, start, end);
 478         }
 479         list_for_each_entry(map, &priv->freeable_maps, next) {
 480                 unmap_if_in_range(map, start, end);
 481         }
 482         mutex_unlock(&priv->lock);
 483 }
 484
 485 static void mn_invl_page(struct mmu_notifier *mn,
 486                          struct mm_struct *mm,
 487                          unsigned long address)
 488 {
 489         mn_invl_range_start(mn, mm, address, address + PAGE_SIZE);
 490 }
 491
 492 static void mn_release(struct mmu_notifier *mn,
 493                        struct mm_struct *mm)
 494 {
 495         struct gntdev_priv *priv = container_of(mn, struct gntdev_priv, mn);
 496         struct grant_map *map;
 497         int err;
 498
 499         mutex_lock(&priv->lock);
 500         list_for_each_entry(map, &priv->maps, next) {
 501                 if (!map->vma)
 502                         continue;
 503                 pr_debug("map %d+%d (%lx %lx)\n",
 504                                 map->index, map->count,
 505                                 map->vma->vm_start, map->vma->vm_end);
 506                 err = unmap_grant_pages(map, /* offset */ 0, map->count);
 507                 WARN_ON(err);
 508         }
 509         list_for_each_entry(map, &priv->freeable_maps, next) {
 510                 if (!map->vma)
 511                         continue;
 512                 pr_debug("map %d+%d (%lx %lx)\n",
 513                                 map->index, map->count,
 514                                 map->vma->vm_start, map->vma->vm_end);
 515                 err = unmap_grant_pages(map, /* offset */ 0, map->count);
 516                 WARN_ON(err);
 517         }
 518         mutex_unlock(&priv->lock);
 519 }
 520
 521 static struct mmu_notifier_ops gntdev_mmu_ops = {
 522         .release                = mn_release,
 523         .invalidate_page        = mn_invl_page,
 524         .invalidate_range_start = mn_invl_range_start,
 525 };
 526
 527 /* ------------------------------------------------------------------ */
 528
 529 static int gntdev_open(struct inode *inode, struct file *flip)
 530 {
 531         struct gntdev_priv *priv;
 532         int ret = 0;
 533
 534         priv = kzalloc(sizeof(*priv), GFP_KERNEL);
 535         if (!priv)
 536                 return -ENOMEM;
 537
 538         INIT_LIST_HEAD(&priv->maps);
 539         INIT_LIST_HEAD(&priv->freeable_maps);
 540         mutex_init(&priv->lock);
 541
 542         if (use_ptemod) {
 543                 priv->mm = get_task_mm(current);
 544                 if (!priv->mm) {
 545                         kfree(priv);
 546                         return -ENOMEM;
 547                 }
 548                 priv->mn.ops = &gntdev_mmu_ops;
 549                 ret = mmu_notifier_register(&priv->mn, priv->mm);
 550                 mmput(priv->mm);
 551         }
 552
 553         if (ret) {
 554                 kfree(priv);
 555                 return ret;
 556         }
 557
 558         flip->private_data = priv;
 559         pr_debug("priv %p\n", priv);
 560
 561         return 0;
 562 }
 563
 564 static int gntdev_release(struct inode *inode, struct file *flip)
 565 {
 566         struct gntdev_priv *priv = flip->private_data;
 567         struct grant_map *map;
 568
 569         pr_debug("priv %p\n", priv);
 570
 571         while (!list_empty(&priv->maps)) {
 572                 map = list_entry(priv->maps.next, struct grant_map, next);
 573                 list_del(&map->next);
 574                 gntdev_put_map(NULL /* already removed */, map);
 575         }
 576         WARN_ON(!list_empty(&priv->freeable_maps));
 577
 578         if (use_ptemod)
 579                 mmu_notifier_unregister(&priv->mn, priv->mm);
 580         kfree(priv);
 581         return 0;
 582 }
 583
 584 static long gntdev_ioctl_map_grant_ref(struct gntdev_priv *priv,
 585                                        struct ioctl_gntdev_map_grant_ref __user *u)
 586 {
 587         struct ioctl_gntdev_map_grant_ref op;
 588         struct grant_map *map;
 589         int err;
 590
 591         if (copy_from_user(&op, u, sizeof(op)) != 0)
 592                 return -EFAULT;
 593         pr_debug("priv %p, add %d\n", priv, op.count);
 594         if (unlikely(op.count <= 0))
 595                 return -EINVAL;
 596
 597         err = -ENOMEM;
 598         map = gntdev_alloc_map(priv, op.count);
 599         if (!map)
 600                 return err;
 601
 602         if (unlikely(atomic_add_return(op.count, &pages_mapped) > limit)) {
 603                 pr_debug("can't map: over limit\n");
 604                 gntdev_put_map(NULL, map);
 605                 return err;
 606         }
 607
 608         if (copy_from_user(map->grants, &u->refs,
 609                            sizeof(map->grants[0]) * op.count) != 0) {
 610                 gntdev_put_map(NULL, map);
 611                 return -EFAULT;
 612         }
 613
 614         mutex_lock(&priv->lock);
 615         gntdev_add_map(priv, map);
 616         op.index = map->index << PAGE_SHIFT;
 617         mutex_unlock(&priv->lock);
 618
 619         if (copy_to_user(u, &op, sizeof(op)) != 0)
 620                 return -EFAULT;
 621
 622         return 0;
 623 }
 624
 625 static long gntdev_ioctl_unmap_grant_ref(struct gntdev_priv *priv,
 626                                          struct ioctl_gntdev_unmap_grant_ref __user *u)
 627 {
 628         struct ioctl_gntdev_unmap_grant_ref op;
 629         struct grant_map *map;
 630         int err = -ENOENT;
 631
 632         if (copy_from_user(&op, u, sizeof(op)) != 0)
 633                 return -EFAULT;
 634         pr_debug("priv %p, del %d+%d\n", priv, (int)op.index, (int)op.count);
 635
 636         mutex_lock(&priv->lock);
 637         map = gntdev_find_map_index(priv, op.index >> PAGE_SHIFT, op.count);
 638         if (map) {
 639                 list_del(&map->next);
 640                 if (populate_freeable_maps)
 641                         list_add_tail(&map->next, &priv->freeable_maps);
 642                 err = 0;
 643         }
 644         mutex_unlock(&priv->lock);
 645         if (map)
 646                 gntdev_put_map(priv, map);
 647         return err;
 648 }
 649
 650 static long gntdev_ioctl_get_offset_for_vaddr(struct gntdev_priv *priv,
 651                                               struct ioctl_gntdev_get_offset_for_vaddr __user *u)
 652 {
 653         struct ioctl_gntdev_get_offset_for_vaddr op;
 654         struct vm_area_struct *vma;
 655         struct grant_map *map;
 656         int rv = -EINVAL;
 657
 658         if (copy_from_user(&op, u, sizeof(op)) != 0)
 659                 return -EFAULT;
 660         pr_debug("priv %p, offset for vaddr %lx\n", priv, (unsigned long)op.vaddr);
 661
 662         down_read(&current->mm->mmap_sem);
 663         vma = find_vma(current->mm, op.vaddr);
 664         if (!vma || vma->vm_ops != &gntdev_vmops)
 665                 goto out_unlock;
 666
 667         map = vma->vm_private_data;
 668         if (!map)
 669                 goto out_unlock;
 670
 671         op.offset = map->index << PAGE_SHIFT;
 672         op.count = map->count;
 673         rv = 0;
 674
 675  out_unlock:
 676         up_read(&current->mm->mmap_sem);
 677
 678         if (rv == 0 && copy_to_user(u, &op, sizeof(op)) != 0)
 679                 return -EFAULT;
 680         return rv;
 681 }
 682
 683 static long gntdev_ioctl_notify(struct gntdev_priv *priv, void __user *u)
 684 {
 685         struct ioctl_gntdev_unmap_notify op;
 686         struct grant_map *map;
 687         int rc;
 688         int out_flags;
 689         unsigned int out_event;
 690
 691         if (copy_from_user(&op, u, sizeof(op)))
 692                 return -EFAULT;
 693
 694         if (op.action & ~(UNMAP_NOTIFY_CLEAR_BYTE|UNMAP_NOTIFY_SEND_EVENT))
 695                 return -EINVAL;
 696
 697         /* We need to grab a reference to the event channel we are going to use
 698          * to send the notify before releasing the reference we may already have
 699          * (if someone has called this ioctl twice). This is required so that
 700          * it is possible to change the clear_byte part of the notification
 701          * without disturbing the event channel part, which may now be the last
 702          * reference to that event channel.
 703          */
 704         if (op.action & UNMAP_NOTIFY_SEND_EVENT) {
 705                 if (evtchn_get(op.event_channel_port))
 706                         return -EINVAL;
 707         }
 708
 709         out_flags = op.action;
 710         out_event = op.event_channel_port;
 711
 712         mutex_lock(&priv->lock);
 713
 714         list_for_each_entry(map, &priv->maps, next) {
 715                 uint64_t begin = map->index << PAGE_SHIFT;
 716                 uint64_t end = (map->index + map->count) << PAGE_SHIFT;
 717                 if (op.index >= begin && op.index < end)
 718                         goto found;
 719         }
 720         rc = -ENOENT;
 721         goto unlock_out;
 722
 723  found:
 724         if ((op.action & UNMAP_NOTIFY_CLEAR_BYTE) &&
 725                         (map->flags & GNTMAP_readonly)) {
 726                 rc = -EINVAL;
 727                 goto unlock_out;
 728         }
 729
 730         out_flags = map->notify.flags;
 731         out_event = map->notify.event;
 732
 733         map->notify.flags = op.action;
 734         map->notify.addr = op.index - (map->index << PAGE_SHIFT);
 735         map->notify.event = op.event_channel_port;
 736
 737         rc = 0;
 738
 739  unlock_out:
 740         mutex_unlock(&priv->lock);
 741
 742         /* Drop the reference to the event channel we did not save in the map */
 743         if (out_flags & UNMAP_NOTIFY_SEND_EVENT)
 744                 evtchn_put(out_event);
 745
 746         return rc;
 747 }
 748
 749 static long gntdev_ioctl(struct file *flip,
 750                          unsigned int cmd, unsigned long arg)
 751 {
 752         struct gntdev_priv *priv = flip->private_data;
 753         void __user *ptr = (void __user *)arg;
 754
 755         switch (cmd) {
 756         case IOCTL_GNTDEV_MAP_GRANT_REF:
 757                 return gntdev_ioctl_map_grant_ref(priv, ptr);
 758
 759         case IOCTL_GNTDEV_UNMAP_GRANT_REF:
 760                 return gntdev_ioctl_unmap_grant_ref(priv, ptr);
 761
 762         case IOCTL_GNTDEV_GET_OFFSET_FOR_VADDR:
 763                 return gntdev_ioctl_get_offset_for_vaddr(priv, ptr);
 764
 765         case IOCTL_GNTDEV_SET_UNMAP_NOTIFY:
 766                 return gntdev_ioctl_notify(priv, ptr);
 767
 768         default:
 769                 pr_debug("priv %p, unknown cmd %x\n", priv, cmd);
 770                 return -ENOIOCTLCMD;
 771         }
 772
 773         return 0;
 774 }
 775
 776 static int gntdev_mmap(struct file *flip, struct vm_area_struct *vma)
 777 {
 778         struct gntdev_priv *priv = flip->private_data;
 779         int index = vma->vm_pgoff;
 780         int count = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
 781         struct grant_map *map;
 782         int i, err = -EINVAL;
 783
 784         if ((vma->vm_flags & VM_WRITE) && !(vma->vm_flags & VM_SHARED))
 785                 return -EINVAL;
 786
 787         pr_debug("map %d+%d at %lx (pgoff %lx)\n",
 788                         index, count, vma->vm_start, vma->vm_pgoff);
 789
 790         mutex_lock(&priv->lock);
 791         map = gntdev_find_map_index(priv, index, count);
 792         if (!map)
 793                 goto unlock_out;
 794         if (use_ptemod && map->vma)
 795                 goto unlock_out;
 796         if (use_ptemod && priv->mm != vma->vm_mm) {
 797                 pr_warn("Huh? Other mm?\n");
 798                 goto unlock_out;
 799         }
 800
 801         atomic_inc(&map->users);
 802
 803         vma->vm_ops = &gntdev_vmops;
 804
 805         vma->vm_flags |= VM_DONTEXPAND | VM_DONTDUMP;
 806
 807         if (use_ptemod)
 808                 vma->vm_flags |= VM_DONTCOPY;
 809
 810         vma->vm_private_data = map;
 811
 812         if (use_ptemod)
 813                 map->vma = vma;
 814
 815         if (map->flags) {
 816                 if ((vma->vm_flags & VM_WRITE) &&
 817                                 (map->flags & GNTMAP_readonly))
 818                         goto out_unlock_put;
 819         } else {
 820                 map->flags = GNTMAP_host_map;
 821                 if (!(vma->vm_flags & VM_WRITE))
 822                         map->flags |= GNTMAP_readonly;
 823         }
 824
 825         mutex_unlock(&priv->lock);
 826
 827         if (use_ptemod) {
 828                 err = apply_to_page_range(vma->vm_mm, vma->vm_start,
 829                                           vma->vm_end - vma->vm_start,
 830                                           find_grant_ptes, map);
 831                 if (err) {
 832                         pr_warn("find_grant_ptes() failure.\n");
 833                         goto out_put_map;
 834                 }
 835         }
 836
 837         err = map_grant_pages(map);
 838         if (err)
 839                 goto out_put_map;
 840
 841         if (!use_ptemod) {
 842                 for (i = 0; i < count; i++) {
 843                         err = vm_insert_page(vma, vma->vm_start + i*PAGE_SIZE,
 844                                 map->pages[i]);
 845                         if (err)
 846                                 goto out_put_map;
 847                 }
 848         } else {
 849 #ifdef CONFIG_X86
 850                 /*
 851                  * If the PTEs were not made special by the grant map
 852                  * hypercall, do so here.
 853                  *
 854                  * This is racy since the mapping is already visible
 855                  * to userspace but userspace should be well-behaved
 856                  * enough to not touch it until the mmap() call
 857                  * returns.
 858                  */
 859                 if (!xen_feature(XENFEAT_gnttab_map_avail_bits)) {
 860                         apply_to_page_range(vma->vm_mm, vma->vm_start,
 861                                             vma->vm_end - vma->vm_start,
 862                                             set_grant_ptes_as_special, NULL);
 863                 }
 864 #endif
 865                 map->pages_vm_start = vma->vm_start;
 866         }
 867
 868         return 0;
 869
 870 unlock_out:
 871         mutex_unlock(&priv->lock);
 872         return err;
 873
 874 out_unlock_put:
 875         mutex_unlock(&priv->lock);
 876 out_put_map:
 877         if (use_ptemod)
 878                 map->vma = NULL;
 879         gntdev_put_map(priv, map);
 880         return err;
 881 }
 882
 883 static const struct file_operations gntdev_fops = {
 884         .owner = THIS_MODULE,
 885         .open = gntdev_open,
 886         .release = gntdev_release,
 887         .mmap = gntdev_mmap,
 888         .unlocked_ioctl = gntdev_ioctl
 889 };
 890
 891 static struct miscdevice gntdev_miscdev = {
 892         .minor        = MISC_DYNAMIC_MINOR,
 893         .name         = "xen/gntdev",
 894         .fops         = &gntdev_fops,
 895 };
 896
 897 /* ------------------------------------------------------------------ */
 898
 899 static int __init gntdev_init(void)
 900 {
 901         int err;
 902
 903         if (!xen_domain())
 904                 return -ENODEV;
 905
 906         use_ptemod = !xen_feature(XENFEAT_auto_translated_physmap);
 907
 908         err = misc_register(&gntdev_miscdev);
 909         if (err != 0) {
 910                 pr_err("Could not register gntdev device\n");
 911                 return err;
 912         }
 913         return 0;
 914 }
 915
 916 static void __exit gntdev_exit(void)
 917 {
 918         misc_deregister(&gntdev_miscdev);
 919 }
 920
 921 module_init(gntdev_init);
 922 module_exit(gntdev_exit);
 923
 924 /* ------------------------------------------------------------------ */