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 const 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 const 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 mutex_lock(&priv->lock); 572 while (!list_empty(&priv->maps)) { 573 map = list_entry(priv->maps.next, struct grant_map, next); 574 list_del(&map->next); 575 gntdev_put_map(NULL /* already removed */, map); 576 } 577 WARN_ON(!list_empty(&priv->freeable_maps)); 578 mutex_unlock(&priv->lock); 579 580 if (use_ptemod) 581 mmu_notifier_unregister(&priv->mn, priv->mm); 582 kfree(priv); 583 return 0; 584 } 585 586 static long gntdev_ioctl_map_grant_ref(struct gntdev_priv *priv, 587 struct ioctl_gntdev_map_grant_ref __user *u) 588 { 589 struct ioctl_gntdev_map_grant_ref op; 590 struct grant_map *map; 591 int err; 592 593 if (copy_from_user(&op, u, sizeof(op)) != 0) 594 return -EFAULT; 595 pr_debug("priv %p, add %d\n", priv, op.count); 596 if (unlikely(op.count <= 0)) 597 return -EINVAL; 598 599 err = -ENOMEM; 600 map = gntdev_alloc_map(priv, op.count); 601 if (!map) 602 return err; 603 604 if (unlikely(atomic_add_return(op.count, &pages_mapped) > limit)) { 605 pr_debug("can't map: over limit\n"); 606 gntdev_put_map(NULL, map); 607 return err; 608 } 609 610 if (copy_from_user(map->grants, &u->refs, 611 sizeof(map->grants[0]) * op.count) != 0) { 612 gntdev_put_map(NULL, map); 613 return -EFAULT; 614 } 615 616 mutex_lock(&priv->lock); 617 gntdev_add_map(priv, map); 618 op.index = map->index << PAGE_SHIFT; 619 mutex_unlock(&priv->lock); 620 621 if (copy_to_user(u, &op, sizeof(op)) != 0) 622 return -EFAULT; 623 624 return 0; 625 } 626 627 static long gntdev_ioctl_unmap_grant_ref(struct gntdev_priv *priv, 628 struct ioctl_gntdev_unmap_grant_ref __user *u) 629 { 630 struct ioctl_gntdev_unmap_grant_ref op; 631 struct grant_map *map; 632 int err = -ENOENT; 633 634 if (copy_from_user(&op, u, sizeof(op)) != 0) 635 return -EFAULT; 636 pr_debug("priv %p, del %d+%d\n", priv, (int)op.index, (int)op.count); 637 638 mutex_lock(&priv->lock); 639 map = gntdev_find_map_index(priv, op.index >> PAGE_SHIFT, op.count); 640 if (map) { 641 list_del(&map->next); 642 if (populate_freeable_maps) 643 list_add_tail(&map->next, &priv->freeable_maps); 644 err = 0; 645 } 646 mutex_unlock(&priv->lock); 647 if (map) 648 gntdev_put_map(priv, map); 649 return err; 650 } 651 652 static long gntdev_ioctl_get_offset_for_vaddr(struct gntdev_priv *priv, 653 struct ioctl_gntdev_get_offset_for_vaddr __user *u) 654 { 655 struct ioctl_gntdev_get_offset_for_vaddr op; 656 struct vm_area_struct *vma; 657 struct grant_map *map; 658 int rv = -EINVAL; 659 660 if (copy_from_user(&op, u, sizeof(op)) != 0) 661 return -EFAULT; 662 pr_debug("priv %p, offset for vaddr %lx\n", priv, (unsigned long)op.vaddr); 663 664 down_read(¤t->mm->mmap_sem); 665 vma = find_vma(current->mm, op.vaddr); 666 if (!vma || vma->vm_ops != &gntdev_vmops) 667 goto out_unlock; 668 669 map = vma->vm_private_data; 670 if (!map) 671 goto out_unlock; 672 673 op.offset = map->index << PAGE_SHIFT; 674 op.count = map->count; 675 rv = 0; 676 677 out_unlock: 678 up_read(¤t->mm->mmap_sem); 679 680 if (rv == 0 && copy_to_user(u, &op, sizeof(op)) != 0) 681 return -EFAULT; 682 return rv; 683 } 684 685 static long gntdev_ioctl_notify(struct gntdev_priv *priv, void __user *u) 686 { 687 struct ioctl_gntdev_unmap_notify op; 688 struct grant_map *map; 689 int rc; 690 int out_flags; 691 unsigned int out_event; 692 693 if (copy_from_user(&op, u, sizeof(op))) 694 return -EFAULT; 695 696 if (op.action & ~(UNMAP_NOTIFY_CLEAR_BYTE|UNMAP_NOTIFY_SEND_EVENT)) 697 return -EINVAL; 698 699 /* We need to grab a reference to the event channel we are going to use 700 * to send the notify before releasing the reference we may already have 701 * (if someone has called this ioctl twice). This is required so that 702 * it is possible to change the clear_byte part of the notification 703 * without disturbing the event channel part, which may now be the last 704 * reference to that event channel. 705 */ 706 if (op.action & UNMAP_NOTIFY_SEND_EVENT) { 707 if (evtchn_get(op.event_channel_port)) 708 return -EINVAL; 709 } 710 711 out_flags = op.action; 712 out_event = op.event_channel_port; 713 714 mutex_lock(&priv->lock); 715 716 list_for_each_entry(map, &priv->maps, next) { 717 uint64_t begin = map->index << PAGE_SHIFT; 718 uint64_t end = (map->index + map->count) << PAGE_SHIFT; 719 if (op.index >= begin && op.index < end) 720 goto found; 721 } 722 rc = -ENOENT; 723 goto unlock_out; 724 725 found: 726 if ((op.action & UNMAP_NOTIFY_CLEAR_BYTE) && 727 (map->flags & GNTMAP_readonly)) { 728 rc = -EINVAL; 729 goto unlock_out; 730 } 731 732 out_flags = map->notify.flags; 733 out_event = map->notify.event; 734 735 map->notify.flags = op.action; 736 map->notify.addr = op.index - (map->index << PAGE_SHIFT); 737 map->notify.event = op.event_channel_port; 738 739 rc = 0; 740 741 unlock_out: 742 mutex_unlock(&priv->lock); 743 744 /* Drop the reference to the event channel we did not save in the map */ 745 if (out_flags & UNMAP_NOTIFY_SEND_EVENT) 746 evtchn_put(out_event); 747 748 return rc; 749 } 750 751 #define GNTDEV_COPY_BATCH 16 752 753 struct gntdev_copy_batch { 754 struct gnttab_copy ops[GNTDEV_COPY_BATCH]; 755 struct page *pages[GNTDEV_COPY_BATCH]; 756 s16 __user *status[GNTDEV_COPY_BATCH]; 757 unsigned int nr_ops; 758 unsigned int nr_pages; 759 }; 760 761 static int gntdev_get_page(struct gntdev_copy_batch *batch, void __user *virt, 762 bool writeable, unsigned long *gfn) 763 { 764 unsigned long addr = (unsigned long)virt; 765 struct page *page; 766 unsigned long xen_pfn; 767 int ret; 768 769 ret = get_user_pages_fast(addr, 1, writeable, &page); 770 if (ret < 0) 771 return ret; 772 773 batch->pages[batch->nr_pages++] = page; 774 775 xen_pfn = page_to_xen_pfn(page) + XEN_PFN_DOWN(addr & ~PAGE_MASK); 776 *gfn = pfn_to_gfn(xen_pfn); 777 778 return 0; 779 } 780 781 static void gntdev_put_pages(struct gntdev_copy_batch *batch) 782 { 783 unsigned int i; 784 785 for (i = 0; i < batch->nr_pages; i++) 786 put_page(batch->pages[i]); 787 batch->nr_pages = 0; 788 } 789 790 static int gntdev_copy(struct gntdev_copy_batch *batch) 791 { 792 unsigned int i; 793 794 gnttab_batch_copy(batch->ops, batch->nr_ops); 795 gntdev_put_pages(batch); 796 797 /* 798 * For each completed op, update the status if the op failed 799 * and all previous ops for the segment were successful. 800 */ 801 for (i = 0; i < batch->nr_ops; i++) { 802 s16 status = batch->ops[i].status; 803 s16 old_status; 804 805 if (status == GNTST_okay) 806 continue; 807 808 if (__get_user(old_status, batch->status[i])) 809 return -EFAULT; 810 811 if (old_status != GNTST_okay) 812 continue; 813 814 if (__put_user(status, batch->status[i])) 815 return -EFAULT; 816 } 817 818 batch->nr_ops = 0; 819 return 0; 820 } 821 822 static int gntdev_grant_copy_seg(struct gntdev_copy_batch *batch, 823 struct gntdev_grant_copy_segment *seg, 824 s16 __user *status) 825 { 826 uint16_t copied = 0; 827 828 /* 829 * Disallow local -> local copies since there is only space in 830 * batch->pages for one page per-op and this would be a very 831 * expensive memcpy(). 832 */ 833 if (!(seg->flags & (GNTCOPY_source_gref | GNTCOPY_dest_gref))) 834 return -EINVAL; 835 836 /* Can't cross page if source/dest is a grant ref. */ 837 if (seg->flags & GNTCOPY_source_gref) { 838 if (seg->source.foreign.offset + seg->len > XEN_PAGE_SIZE) 839 return -EINVAL; 840 } 841 if (seg->flags & GNTCOPY_dest_gref) { 842 if (seg->dest.foreign.offset + seg->len > XEN_PAGE_SIZE) 843 return -EINVAL; 844 } 845 846 if (put_user(GNTST_okay, status)) 847 return -EFAULT; 848 849 while (copied < seg->len) { 850 struct gnttab_copy *op; 851 void __user *virt; 852 size_t len, off; 853 unsigned long gfn; 854 int ret; 855 856 if (batch->nr_ops >= GNTDEV_COPY_BATCH) { 857 ret = gntdev_copy(batch); 858 if (ret < 0) 859 return ret; 860 } 861 862 len = seg->len - copied; 863 864 op = &batch->ops[batch->nr_ops]; 865 op->flags = 0; 866 867 if (seg->flags & GNTCOPY_source_gref) { 868 op->source.u.ref = seg->source.foreign.ref; 869 op->source.domid = seg->source.foreign.domid; 870 op->source.offset = seg->source.foreign.offset + copied; 871 op->flags |= GNTCOPY_source_gref; 872 } else { 873 virt = seg->source.virt + copied; 874 off = (unsigned long)virt & ~XEN_PAGE_MASK; 875 len = min(len, (size_t)XEN_PAGE_SIZE - off); 876 877 ret = gntdev_get_page(batch, virt, false, &gfn); 878 if (ret < 0) 879 return ret; 880 881 op->source.u.gmfn = gfn; 882 op->source.domid = DOMID_SELF; 883 op->source.offset = off; 884 } 885 886 if (seg->flags & GNTCOPY_dest_gref) { 887 op->dest.u.ref = seg->dest.foreign.ref; 888 op->dest.domid = seg->dest.foreign.domid; 889 op->dest.offset = seg->dest.foreign.offset + copied; 890 op->flags |= GNTCOPY_dest_gref; 891 } else { 892 virt = seg->dest.virt + copied; 893 off = (unsigned long)virt & ~XEN_PAGE_MASK; 894 len = min(len, (size_t)XEN_PAGE_SIZE - off); 895 896 ret = gntdev_get_page(batch, virt, true, &gfn); 897 if (ret < 0) 898 return ret; 899 900 op->dest.u.gmfn = gfn; 901 op->dest.domid = DOMID_SELF; 902 op->dest.offset = off; 903 } 904 905 op->len = len; 906 copied += len; 907 908 batch->status[batch->nr_ops] = status; 909 batch->nr_ops++; 910 } 911 912 return 0; 913 } 914 915 static long gntdev_ioctl_grant_copy(struct gntdev_priv *priv, void __user *u) 916 { 917 struct ioctl_gntdev_grant_copy copy; 918 struct gntdev_copy_batch batch; 919 unsigned int i; 920 int ret = 0; 921 922 if (copy_from_user(©, u, sizeof(copy))) 923 return -EFAULT; 924 925 batch.nr_ops = 0; 926 batch.nr_pages = 0; 927 928 for (i = 0; i < copy.count; i++) { 929 struct gntdev_grant_copy_segment seg; 930 931 if (copy_from_user(&seg, ©.segments[i], sizeof(seg))) { 932 ret = -EFAULT; 933 goto out; 934 } 935 936 ret = gntdev_grant_copy_seg(&batch, &seg, ©.segments[i].status); 937 if (ret < 0) 938 goto out; 939 940 cond_resched(); 941 } 942 if (batch.nr_ops) 943 ret = gntdev_copy(&batch); 944 return ret; 945 946 out: 947 gntdev_put_pages(&batch); 948 return ret; 949 } 950 951 static long gntdev_ioctl(struct file *flip, 952 unsigned int cmd, unsigned long arg) 953 { 954 struct gntdev_priv *priv = flip->private_data; 955 void __user *ptr = (void __user *)arg; 956 957 switch (cmd) { 958 case IOCTL_GNTDEV_MAP_GRANT_REF: 959 return gntdev_ioctl_map_grant_ref(priv, ptr); 960 961 case IOCTL_GNTDEV_UNMAP_GRANT_REF: 962 return gntdev_ioctl_unmap_grant_ref(priv, ptr); 963 964 case IOCTL_GNTDEV_GET_OFFSET_FOR_VADDR: 965 return gntdev_ioctl_get_offset_for_vaddr(priv, ptr); 966 967 case IOCTL_GNTDEV_SET_UNMAP_NOTIFY: 968 return gntdev_ioctl_notify(priv, ptr); 969 970 case IOCTL_GNTDEV_GRANT_COPY: 971 return gntdev_ioctl_grant_copy(priv, ptr); 972 973 default: 974 pr_debug("priv %p, unknown cmd %x\n", priv, cmd); 975 return -ENOIOCTLCMD; 976 } 977 978 return 0; 979 } 980 981 static int gntdev_mmap(struct file *flip, struct vm_area_struct *vma) 982 { 983 struct gntdev_priv *priv = flip->private_data; 984 int index = vma->vm_pgoff; 985 int count = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT; 986 struct grant_map *map; 987 int i, err = -EINVAL; 988 989 if ((vma->vm_flags & VM_WRITE) && !(vma->vm_flags & VM_SHARED)) 990 return -EINVAL; 991 992 pr_debug("map %d+%d at %lx (pgoff %lx)\n", 993 index, count, vma->vm_start, vma->vm_pgoff); 994 995 mutex_lock(&priv->lock); 996 map = gntdev_find_map_index(priv, index, count); 997 if (!map) 998 goto unlock_out; 999 if (use_ptemod && map->vma) 1000 goto unlock_out; 1001 if (use_ptemod && priv->mm != vma->vm_mm) { 1002 pr_warn("Huh? Other mm?\n"); 1003 goto unlock_out; 1004 } 1005 1006 atomic_inc(&map->users); 1007 1008 vma->vm_ops = &gntdev_vmops; 1009 1010 vma->vm_flags |= VM_DONTEXPAND | VM_DONTDUMP | VM_IO; 1011 1012 if (use_ptemod) 1013 vma->vm_flags |= VM_DONTCOPY; 1014 1015 vma->vm_private_data = map; 1016 1017 if (use_ptemod) 1018 map->vma = vma; 1019 1020 if (map->flags) { 1021 if ((vma->vm_flags & VM_WRITE) && 1022 (map->flags & GNTMAP_readonly)) 1023 goto out_unlock_put; 1024 } else { 1025 map->flags = GNTMAP_host_map; 1026 if (!(vma->vm_flags & VM_WRITE)) 1027 map->flags |= GNTMAP_readonly; 1028 } 1029 1030 mutex_unlock(&priv->lock); 1031 1032 if (use_ptemod) { 1033 err = apply_to_page_range(vma->vm_mm, vma->vm_start, 1034 vma->vm_end - vma->vm_start, 1035 find_grant_ptes, map); 1036 if (err) { 1037 pr_warn("find_grant_ptes() failure.\n"); 1038 goto out_put_map; 1039 } 1040 } 1041 1042 err = map_grant_pages(map); 1043 if (err) 1044 goto out_put_map; 1045 1046 if (!use_ptemod) { 1047 for (i = 0; i < count; i++) { 1048 err = vm_insert_page(vma, vma->vm_start + i*PAGE_SIZE, 1049 map->pages[i]); 1050 if (err) 1051 goto out_put_map; 1052 } 1053 } else { 1054 #ifdef CONFIG_X86 1055 /* 1056 * If the PTEs were not made special by the grant map 1057 * hypercall, do so here. 1058 * 1059 * This is racy since the mapping is already visible 1060 * to userspace but userspace should be well-behaved 1061 * enough to not touch it until the mmap() call 1062 * returns. 1063 */ 1064 if (!xen_feature(XENFEAT_gnttab_map_avail_bits)) { 1065 apply_to_page_range(vma->vm_mm, vma->vm_start, 1066 vma->vm_end - vma->vm_start, 1067 set_grant_ptes_as_special, NULL); 1068 } 1069 #endif 1070 map->pages_vm_start = vma->vm_start; 1071 } 1072 1073 return 0; 1074 1075 unlock_out: 1076 mutex_unlock(&priv->lock); 1077 return err; 1078 1079 out_unlock_put: 1080 mutex_unlock(&priv->lock); 1081 out_put_map: 1082 if (use_ptemod) 1083 map->vma = NULL; 1084 gntdev_put_map(priv, map); 1085 return err; 1086 } 1087 1088 static const struct file_operations gntdev_fops = { 1089 .owner = THIS_MODULE, 1090 .open = gntdev_open, 1091 .release = gntdev_release, 1092 .mmap = gntdev_mmap, 1093 .unlocked_ioctl = gntdev_ioctl 1094 }; 1095 1096 static struct miscdevice gntdev_miscdev = { 1097 .minor = MISC_DYNAMIC_MINOR, 1098 .name = "xen/gntdev", 1099 .fops = &gntdev_fops, 1100 }; 1101 1102 /* ------------------------------------------------------------------ */ 1103 1104 static int __init gntdev_init(void) 1105 { 1106 int err; 1107 1108 if (!xen_domain()) 1109 return -ENODEV; 1110 1111 use_ptemod = !xen_feature(XENFEAT_auto_translated_physmap); 1112 1113 err = misc_register(&gntdev_miscdev); 1114 if (err != 0) { 1115 pr_err("Could not register gntdev device\n"); 1116 return err; 1117 } 1118 return 0; 1119 } 1120 1121 static void __exit gntdev_exit(void) 1122 { 1123 misc_deregister(&gntdev_miscdev); 1124 } 1125 1126 module_init(gntdev_init); 1127 module_exit(gntdev_exit); 1128 1129 /* ------------------------------------------------------------------ */ 1130