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(¤t->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(¤t->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 /* ------------------------------------------------------------------ */ 947