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 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 struct unmap_grant_pages_callback_data
 331 {
 332         struct completion completion;
 333         int result;
 334 };
 335
 336 static void unmap_grant_callback(int result,
 337                                  struct gntab_unmap_queue_data *data)
 338 {
 339         struct unmap_grant_pages_callback_data* d = data->data;
 340
 341         d->result = result;
 342         complete(&d->completion);
 343 }
 344
 345 static int __unmap_grant_pages(struct grant_map *map, int offset, int pages)
 346 {
 347         int i, err = 0;
 348         struct gntab_unmap_queue_data unmap_data;
 349         struct unmap_grant_pages_callback_data data;
 350
 351         init_completion(&data.completion);
 352         unmap_data.data = &data;
 353         unmap_data.done= &unmap_grant_callback;
 354
 355         if (map->notify.flags & UNMAP_NOTIFY_CLEAR_BYTE) {
 356                 int pgno = (map->notify.addr >> PAGE_SHIFT);
 357                 if (pgno >= offset && pgno < offset + pages) {
 358                         /* No need for kmap, pages are in lowmem */
 359                         uint8_t *tmp = pfn_to_kaddr(page_to_pfn(map->pages[pgno]));
 360                         tmp[map->notify.addr & (PAGE_SIZE-1)] = 0;
 361                         map->notify.flags &= ~UNMAP_NOTIFY_CLEAR_BYTE;
 362                 }
 363         }
 364
 365         unmap_data.unmap_ops = map->unmap_ops + offset;
 366         unmap_data.kunmap_ops = use_ptemod ? map->kunmap_ops + offset : NULL;
 367         unmap_data.pages = map->pages + offset;
 368         unmap_data.count = pages;
 369
 370         gnttab_unmap_refs_async(&unmap_data);
 371
 372         wait_for_completion(&data.completion);
 373         if (data.result)
 374                 return data.result;
 375
 376         for (i = 0; i < pages; i++) {
 377                 if (map->unmap_ops[offset+i].status)
 378                         err = -EINVAL;
 379                 pr_debug("unmap handle=%d st=%d\n",
 380                         map->unmap_ops[offset+i].handle,
 381                         map->unmap_ops[offset+i].status);
 382                 map->unmap_ops[offset+i].handle = -1;
 383         }
 384         return err;
 385 }
 386
 387 static int unmap_grant_pages(struct grant_map *map, int offset, int pages)
 388 {
 389         int range, err = 0;
 390
 391         pr_debug("unmap %d+%d [%d+%d]\n", map->index, map->count, offset, pages);
 392
 393         /* It is possible the requested range will have a "hole" where we
 394          * already unmapped some of the grants. Only unmap valid ranges.
 395          */
 396         while (pages && !err) {
 397                 while (pages && map->unmap_ops[offset].handle == -1) {
 398                         offset++;
 399                         pages--;
 400                 }
 401                 range = 0;
 402                 while (range < pages) {
 403                         if (map->unmap_ops[offset+range].handle == -1) {
 404                                 range--;
 405                                 break;
 406                         }
 407                         range++;
 408                 }
 409                 err = __unmap_grant_pages(map, offset, range);
 410                 offset += range;
 411                 pages -= range;
 412         }
 413
 414         return err;
 415 }
 416
 417 /* ------------------------------------------------------------------ */
 418
 419 static void gntdev_vma_open(struct vm_area_struct *vma)
 420 {
 421         struct grant_map *map = vma->vm_private_data;
 422
 423         pr_debug("gntdev_vma_open %p\n", vma);
 424         atomic_inc(&map->users);
 425 }
 426
 427 static void gntdev_vma_close(struct vm_area_struct *vma)
 428 {
 429         struct grant_map *map = vma->vm_private_data;
 430         struct file *file = vma->vm_file;
 431         struct gntdev_priv *priv = file->private_data;
 432
 433         pr_debug("gntdev_vma_close %p\n", vma);
 434         if (use_ptemod) {
 435                 /* It is possible that an mmu notifier could be running
 436                  * concurrently, so take priv->lock to ensure that the vma won't
 437                  * vanishing during the unmap_grant_pages call, since we will
 438                  * spin here until that completes. Such a concurrent call will
 439                  * not do any unmapping, since that has been done prior to
 440                  * closing the vma, but it may still iterate the unmap_ops list.
 441                  */
 442                 mutex_lock(&priv->lock);
 443                 map->vma = NULL;
 444                 mutex_unlock(&priv->lock);
 445         }
 446         vma->vm_private_data = NULL;
 447         gntdev_put_map(priv, map);
 448 }
 449
 450 static struct page *gntdev_vma_find_special_page(struct vm_area_struct *vma,
 451                                                  unsigned long addr)
 452 {
 453         struct grant_map *map = vma->vm_private_data;
 454
 455         return map->pages[(addr - map->pages_vm_start) >> PAGE_SHIFT];
 456 }
 457
 458 static struct vm_operations_struct gntdev_vmops = {
 459         .open = gntdev_vma_open,
 460         .close = gntdev_vma_close,
 461         .find_special_page = gntdev_vma_find_special_page,
 462 };
 463
 464 /* ------------------------------------------------------------------ */
 465
 466 static void unmap_if_in_range(struct grant_map *map,
 467                               unsigned long start, unsigned long end)
 468 {
 469         unsigned long mstart, mend;
 470         int err;
 471
 472         if (!map->vma)
 473                 return;
 474         if (map->vma->vm_start >= end)
 475                 return;
 476         if (map->vma->vm_end <= start)
 477                 return;
 478         mstart = max(start, map->vma->vm_start);
 479         mend   = min(end,   map->vma->vm_end);
 480         pr_debug("map %d+%d (%lx %lx), range %lx %lx, mrange %lx %lx\n",
 481                         map->index, map->count,
 482                         map->vma->vm_start, map->vma->vm_end,
 483                         start, end, mstart, mend);
 484         err = unmap_grant_pages(map,
 485                                 (mstart - map->vma->vm_start) >> PAGE_SHIFT,
 486                                 (mend - mstart) >> PAGE_SHIFT);
 487         WARN_ON(err);
 488 }
 489
 490 static void mn_invl_range_start(struct mmu_notifier *mn,
 491                                 struct mm_struct *mm,
 492                                 unsigned long start, unsigned long end)
 493 {
 494         struct gntdev_priv *priv = container_of(mn, struct gntdev_priv, mn);
 495         struct grant_map *map;
 496
 497         mutex_lock(&priv->lock);
 498         list_for_each_entry(map, &priv->maps, next) {
 499                 unmap_if_in_range(map, start, end);
 500         }
 501         list_for_each_entry(map, &priv->freeable_maps, next) {
 502                 unmap_if_in_range(map, start, end);
 503         }
 504         mutex_unlock(&priv->lock);
 505 }
 506
 507 static void mn_invl_page(struct mmu_notifier *mn,
 508                          struct mm_struct *mm,
 509                          unsigned long address)
 510 {
 511         mn_invl_range_start(mn, mm, address, address + PAGE_SIZE);
 512 }
 513
 514 static void mn_release(struct mmu_notifier *mn,
 515                        struct mm_struct *mm)
 516 {
 517         struct gntdev_priv *priv = container_of(mn, struct gntdev_priv, mn);
 518         struct grant_map *map;
 519         int err;
 520
 521         mutex_lock(&priv->lock);
 522         list_for_each_entry(map, &priv->maps, next) {
 523                 if (!map->vma)
 524                         continue;
 525                 pr_debug("map %d+%d (%lx %lx)\n",
 526                                 map->index, map->count,
 527                                 map->vma->vm_start, map->vma->vm_end);
 528                 err = unmap_grant_pages(map, /* offset */ 0, map->count);
 529                 WARN_ON(err);
 530         }
 531         list_for_each_entry(map, &priv->freeable_maps, next) {
 532                 if (!map->vma)
 533                         continue;
 534                 pr_debug("map %d+%d (%lx %lx)\n",
 535                                 map->index, map->count,
 536                                 map->vma->vm_start, map->vma->vm_end);
 537                 err = unmap_grant_pages(map, /* offset */ 0, map->count);
 538                 WARN_ON(err);
 539         }
 540         mutex_unlock(&priv->lock);
 541 }
 542
 543 static struct mmu_notifier_ops gntdev_mmu_ops = {
 544         .release                = mn_release,
 545         .invalidate_page        = mn_invl_page,
 546         .invalidate_range_start = mn_invl_range_start,
 547 };
 548
 549 /* ------------------------------------------------------------------ */
 550
 551 static int gntdev_open(struct inode *inode, struct file *flip)
 552 {
 553         struct gntdev_priv *priv;
 554         int ret = 0;
 555
 556         priv = kzalloc(sizeof(*priv), GFP_KERNEL);
 557         if (!priv)
 558                 return -ENOMEM;
 559
 560         INIT_LIST_HEAD(&priv->maps);
 561         INIT_LIST_HEAD(&priv->freeable_maps);
 562         mutex_init(&priv->lock);
 563
 564         if (use_ptemod) {
 565                 priv->mm = get_task_mm(current);
 566                 if (!priv->mm) {
 567                         kfree(priv);
 568                         return -ENOMEM;
 569                 }
 570                 priv->mn.ops = &gntdev_mmu_ops;
 571                 ret = mmu_notifier_register(&priv->mn, priv->mm);
 572                 mmput(priv->mm);
 573         }
 574
 575         if (ret) {
 576                 kfree(priv);
 577                 return ret;
 578         }
 579
 580         flip->private_data = priv;
 581         pr_debug("priv %p\n", priv);
 582
 583         return 0;
 584 }
 585
 586 static int gntdev_release(struct inode *inode, struct file *flip)
 587 {
 588         struct gntdev_priv *priv = flip->private_data;
 589         struct grant_map *map;
 590
 591         pr_debug("priv %p\n", priv);
 592
 593         while (!list_empty(&priv->maps)) {
 594                 map = list_entry(priv->maps.next, struct grant_map, next);
 595                 list_del(&map->next);
 596                 gntdev_put_map(NULL /* already removed */, map);
 597         }
 598         WARN_ON(!list_empty(&priv->freeable_maps));
 599
 600         if (use_ptemod)
 601                 mmu_notifier_unregister(&priv->mn, priv->mm);
 602         kfree(priv);
 603         return 0;
 604 }
 605
 606 static long gntdev_ioctl_map_grant_ref(struct gntdev_priv *priv,
 607                                        struct ioctl_gntdev_map_grant_ref __user *u)
 608 {
 609         struct ioctl_gntdev_map_grant_ref op;
 610         struct grant_map *map;
 611         int err;
 612
 613         if (copy_from_user(&op, u, sizeof(op)) != 0)
 614                 return -EFAULT;
 615         pr_debug("priv %p, add %d\n", priv, op.count);
 616         if (unlikely(op.count <= 0))
 617                 return -EINVAL;
 618
 619         err = -ENOMEM;
 620         map = gntdev_alloc_map(priv, op.count);
 621         if (!map)
 622                 return err;
 623
 624         if (unlikely(atomic_add_return(op.count, &pages_mapped) > limit)) {
 625                 pr_debug("can't map: over limit\n");
 626                 gntdev_put_map(NULL, map);
 627                 return err;
 628         }
 629
 630         if (copy_from_user(map->grants, &u->refs,
 631                            sizeof(map->grants[0]) * op.count) != 0) {
 632                 gntdev_put_map(NULL, map);
 633                 return -EFAULT;
 634         }
 635
 636         mutex_lock(&priv->lock);
 637         gntdev_add_map(priv, map);
 638         op.index = map->index << PAGE_SHIFT;
 639         mutex_unlock(&priv->lock);
 640
 641         if (copy_to_user(u, &op, sizeof(op)) != 0)
 642                 return -EFAULT;
 643
 644         return 0;
 645 }
 646
 647 static long gntdev_ioctl_unmap_grant_ref(struct gntdev_priv *priv,
 648                                          struct ioctl_gntdev_unmap_grant_ref __user *u)
 649 {
 650         struct ioctl_gntdev_unmap_grant_ref op;
 651         struct grant_map *map;
 652         int err = -ENOENT;
 653
 654         if (copy_from_user(&op, u, sizeof(op)) != 0)
 655                 return -EFAULT;
 656         pr_debug("priv %p, del %d+%d\n", priv, (int)op.index, (int)op.count);
 657
 658         mutex_lock(&priv->lock);
 659         map = gntdev_find_map_index(priv, op.index >> PAGE_SHIFT, op.count);
 660         if (map) {
 661                 list_del(&map->next);
 662                 if (populate_freeable_maps)
 663                         list_add_tail(&map->next, &priv->freeable_maps);
 664                 err = 0;
 665         }
 666         mutex_unlock(&priv->lock);
 667         if (map)
 668                 gntdev_put_map(priv, map);
 669         return err;
 670 }
 671
 672 static long gntdev_ioctl_get_offset_for_vaddr(struct gntdev_priv *priv,
 673                                               struct ioctl_gntdev_get_offset_for_vaddr __user *u)
 674 {
 675         struct ioctl_gntdev_get_offset_for_vaddr op;
 676         struct vm_area_struct *vma;
 677         struct grant_map *map;
 678         int rv = -EINVAL;
 679
 680         if (copy_from_user(&op, u, sizeof(op)) != 0)
 681                 return -EFAULT;
 682         pr_debug("priv %p, offset for vaddr %lx\n", priv, (unsigned long)op.vaddr);
 683
 684         down_read(&current->mm->mmap_sem);
 685         vma = find_vma(current->mm, op.vaddr);
 686         if (!vma || vma->vm_ops != &gntdev_vmops)
 687                 goto out_unlock;
 688
 689         map = vma->vm_private_data;
 690         if (!map)
 691                 goto out_unlock;
 692
 693         op.offset = map->index << PAGE_SHIFT;
 694         op.count = map->count;
 695         rv = 0;
 696
 697  out_unlock:
 698         up_read(&current->mm->mmap_sem);
 699
 700         if (rv == 0 && copy_to_user(u, &op, sizeof(op)) != 0)
 701                 return -EFAULT;
 702         return rv;
 703 }
 704
 705 static long gntdev_ioctl_notify(struct gntdev_priv *priv, void __user *u)
 706 {
 707         struct ioctl_gntdev_unmap_notify op;
 708         struct grant_map *map;
 709         int rc;
 710         int out_flags;
 711         unsigned int out_event;
 712
 713         if (copy_from_user(&op, u, sizeof(op)))
 714                 return -EFAULT;
 715
 716         if (op.action & ~(UNMAP_NOTIFY_CLEAR_BYTE|UNMAP_NOTIFY_SEND_EVENT))
 717                 return -EINVAL;
 718
 719         /* We need to grab a reference to the event channel we are going to use
 720          * to send the notify before releasing the reference we may already have
 721          * (if someone has called this ioctl twice). This is required so that
 722          * it is possible to change the clear_byte part of the notification
 723          * without disturbing the event channel part, which may now be the last
 724          * reference to that event channel.
 725          */
 726         if (op.action & UNMAP_NOTIFY_SEND_EVENT) {
 727                 if (evtchn_get(op.event_channel_port))
 728                         return -EINVAL;
 729         }
 730
 731         out_flags = op.action;
 732         out_event = op.event_channel_port;
 733
 734         mutex_lock(&priv->lock);
 735
 736         list_for_each_entry(map, &priv->maps, next) {
 737                 uint64_t begin = map->index << PAGE_SHIFT;
 738                 uint64_t end = (map->index + map->count) << PAGE_SHIFT;
 739                 if (op.index >= begin && op.index < end)
 740                         goto found;
 741         }
 742         rc = -ENOENT;
 743         goto unlock_out;
 744
 745  found:
 746         if ((op.action & UNMAP_NOTIFY_CLEAR_BYTE) &&
 747                         (map->flags & GNTMAP_readonly)) {
 748                 rc = -EINVAL;
 749                 goto unlock_out;
 750         }
 751
 752         out_flags = map->notify.flags;
 753         out_event = map->notify.event;
 754
 755         map->notify.flags = op.action;
 756         map->notify.addr = op.index - (map->index << PAGE_SHIFT);
 757         map->notify.event = op.event_channel_port;
 758
 759         rc = 0;
 760
 761  unlock_out:
 762         mutex_unlock(&priv->lock);
 763
 764         /* Drop the reference to the event channel we did not save in the map */
 765         if (out_flags & UNMAP_NOTIFY_SEND_EVENT)
 766                 evtchn_put(out_event);
 767
 768         return rc;
 769 }
 770
 771 static long gntdev_ioctl(struct file *flip,
 772                          unsigned int cmd, unsigned long arg)
 773 {
 774         struct gntdev_priv *priv = flip->private_data;
 775         void __user *ptr = (void __user *)arg;
 776
 777         switch (cmd) {
 778         case IOCTL_GNTDEV_MAP_GRANT_REF:
 779                 return gntdev_ioctl_map_grant_ref(priv, ptr);
 780
 781         case IOCTL_GNTDEV_UNMAP_GRANT_REF:
 782                 return gntdev_ioctl_unmap_grant_ref(priv, ptr);
 783
 784         case IOCTL_GNTDEV_GET_OFFSET_FOR_VADDR:
 785                 return gntdev_ioctl_get_offset_for_vaddr(priv, ptr);
 786
 787         case IOCTL_GNTDEV_SET_UNMAP_NOTIFY:
 788                 return gntdev_ioctl_notify(priv, ptr);
 789
 790         default:
 791                 pr_debug("priv %p, unknown cmd %x\n", priv, cmd);
 792                 return -ENOIOCTLCMD;
 793         }
 794
 795         return 0;
 796 }
 797
 798 static int gntdev_mmap(struct file *flip, struct vm_area_struct *vma)
 799 {
 800         struct gntdev_priv *priv = flip->private_data;
 801         int index = vma->vm_pgoff;
 802         int count = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
 803         struct grant_map *map;
 804         int i, err = -EINVAL;
 805
 806         if ((vma->vm_flags & VM_WRITE) && !(vma->vm_flags & VM_SHARED))
 807                 return -EINVAL;
 808
 809         pr_debug("map %d+%d at %lx (pgoff %lx)\n",
 810                         index, count, vma->vm_start, vma->vm_pgoff);
 811
 812         mutex_lock(&priv->lock);
 813         map = gntdev_find_map_index(priv, index, count);
 814         if (!map)
 815                 goto unlock_out;
 816         if (use_ptemod && map->vma)
 817                 goto unlock_out;
 818         if (use_ptemod && priv->mm != vma->vm_mm) {
 819                 pr_warn("Huh? Other mm?\n");
 820                 goto unlock_out;
 821         }
 822
 823         atomic_inc(&map->users);
 824
 825         vma->vm_ops = &gntdev_vmops;
 826
 827         vma->vm_flags |= VM_DONTEXPAND | VM_DONTDUMP;
 828
 829         if (use_ptemod)
 830                 vma->vm_flags |= VM_DONTCOPY;
 831
 832         vma->vm_private_data = map;
 833
 834         if (use_ptemod)
 835                 map->vma = vma;
 836
 837         if (map->flags) {
 838                 if ((vma->vm_flags & VM_WRITE) &&
 839                                 (map->flags & GNTMAP_readonly))
 840                         goto out_unlock_put;
 841         } else {
 842                 map->flags = GNTMAP_host_map;
 843                 if (!(vma->vm_flags & VM_WRITE))
 844                         map->flags |= GNTMAP_readonly;
 845         }
 846
 847         mutex_unlock(&priv->lock);
 848
 849         if (use_ptemod) {
 850                 err = apply_to_page_range(vma->vm_mm, vma->vm_start,
 851                                           vma->vm_end - vma->vm_start,
 852                                           find_grant_ptes, map);
 853                 if (err) {
 854                         pr_warn("find_grant_ptes() failure.\n");
 855                         goto out_put_map;
 856                 }
 857         }
 858
 859         err = map_grant_pages(map);
 860         if (err)
 861                 goto out_put_map;
 862
 863         if (!use_ptemod) {
 864                 for (i = 0; i < count; i++) {
 865                         err = vm_insert_page(vma, vma->vm_start + i*PAGE_SIZE,
 866                                 map->pages[i]);
 867                         if (err)
 868                                 goto out_put_map;
 869                 }
 870         } else {
 871 #ifdef CONFIG_X86
 872                 /*
 873                  * If the PTEs were not made special by the grant map
 874                  * hypercall, do so here.
 875                  *
 876                  * This is racy since the mapping is already visible
 877                  * to userspace but userspace should be well-behaved
 878                  * enough to not touch it until the mmap() call
 879                  * returns.
 880                  */
 881                 if (!xen_feature(XENFEAT_gnttab_map_avail_bits)) {
 882                         apply_to_page_range(vma->vm_mm, vma->vm_start,
 883                                             vma->vm_end - vma->vm_start,
 884                                             set_grant_ptes_as_special, NULL);
 885                 }
 886 #endif
 887                 map->pages_vm_start = vma->vm_start;
 888         }
 889
 890         return 0;
 891
 892 unlock_out:
 893         mutex_unlock(&priv->lock);
 894         return err;
 895
 896 out_unlock_put:
 897         mutex_unlock(&priv->lock);
 898 out_put_map:
 899         if (use_ptemod)
 900                 map->vma = NULL;
 901         gntdev_put_map(priv, map);
 902         return err;
 903 }
 904
 905 static const struct file_operations gntdev_fops = {
 906         .owner = THIS_MODULE,
 907         .open = gntdev_open,
 908         .release = gntdev_release,
 909         .mmap = gntdev_mmap,
 910         .unlocked_ioctl = gntdev_ioctl
 911 };
 912
 913 static struct miscdevice gntdev_miscdev = {
 914         .minor        = MISC_DYNAMIC_MINOR,
 915         .name         = "xen/gntdev",
 916         .fops         = &gntdev_fops,
 917 };
 918
 919 /* ------------------------------------------------------------------ */
 920
 921 static int __init gntdev_init(void)
 922 {
 923         int err;
 924
 925         if (!xen_domain())
 926                 return -ENODEV;
 927
 928         use_ptemod = !xen_feature(XENFEAT_auto_translated_physmap);
 929
 930         err = misc_register(&gntdev_miscdev);
 931         if (err != 0) {
 932                 pr_err("Could not register gntdev device\n");
 933                 return err;
 934         }
 935         return 0;
 936 }
 937
 938 static void __exit gntdev_exit(void)
 939 {
 940         misc_deregister(&gntdev_miscdev);
 941 }
 942
 943 module_init(gntdev_init);
 944 module_exit(gntdev_exit);
 945
 946 /* ------------------------------------------------------------------ */