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/sched/mm.h> 36 #include <linux/spinlock.h> 37 #include <linux/slab.h> 38 #include <linux/highmem.h> 39 40 #include <xen/xen.h> 41 #include <xen/grant_table.h> 42 #include <xen/balloon.h> 43 #include <xen/gntdev.h> 44 #include <xen/events.h> 45 #include <xen/page.h> 46 #include <asm/xen/hypervisor.h> 47 #include <asm/xen/hypercall.h> 48 49 MODULE_LICENSE("GPL"); 50 MODULE_AUTHOR("Derek G. Murray <Derek.Murray@cl.cam.ac.uk>, " 51 "Gerd Hoffmann <kraxel@redhat.com>"); 52 MODULE_DESCRIPTION("User-space granted page access driver"); 53 54 static int limit = 1024*1024; 55 module_param(limit, int, 0644); 56 MODULE_PARM_DESC(limit, "Maximum number of grants that may be mapped by " 57 "the gntdev device"); 58 59 static atomic_t pages_mapped = ATOMIC_INIT(0); 60 61 static int use_ptemod; 62 #define populate_freeable_maps use_ptemod 63 64 struct gntdev_priv { 65 /* maps with visible offsets in the file descriptor */ 66 struct list_head maps; 67 /* maps that are not visible; will be freed on munmap. 68 * Only populated if populate_freeable_maps == 1 */ 69 struct list_head freeable_maps; 70 /* lock protects maps and freeable_maps */ 71 struct mutex lock; 72 struct mm_struct *mm; 73 struct mmu_notifier mn; 74 }; 75 76 struct unmap_notify { 77 int flags; 78 /* Address relative to the start of the grant_map */ 79 int addr; 80 int event; 81 }; 82 83 struct grant_map { 84 struct list_head next; 85 struct vm_area_struct *vma; 86 int index; 87 int count; 88 int flags; 89 atomic_t users; 90 struct unmap_notify notify; 91 struct ioctl_gntdev_grant_ref *grants; 92 struct gnttab_map_grant_ref *map_ops; 93 struct gnttab_unmap_grant_ref *unmap_ops; 94 struct gnttab_map_grant_ref *kmap_ops; 95 struct gnttab_unmap_grant_ref *kunmap_ops; 96 struct page **pages; 97 unsigned long pages_vm_start; 98 }; 99 100 static int unmap_grant_pages(struct grant_map *map, int offset, int pages); 101 102 /* ------------------------------------------------------------------ */ 103 104 static void gntdev_print_maps(struct gntdev_priv *priv, 105 char *text, int text_index) 106 { 107 #ifdef DEBUG 108 struct grant_map *map; 109 110 pr_debug("%s: maps list (priv %p)\n", __func__, priv); 111 list_for_each_entry(map, &priv->maps, next) 112 pr_debug(" index %2d, count %2d %s\n", 113 map->index, map->count, 114 map->index == text_index && text ? text : ""); 115 #endif 116 } 117 118 static void gntdev_free_map(struct grant_map *map) 119 { 120 if (map == NULL) 121 return; 122 123 if (map->pages) 124 gnttab_free_pages(map->count, map->pages); 125 kfree(map->pages); 126 kfree(map->grants); 127 kfree(map->map_ops); 128 kfree(map->unmap_ops); 129 kfree(map->kmap_ops); 130 kfree(map->kunmap_ops); 131 kfree(map); 132 } 133 134 static struct grant_map *gntdev_alloc_map(struct gntdev_priv *priv, int count) 135 { 136 struct grant_map *add; 137 int i; 138 139 add = kzalloc(sizeof(struct grant_map), GFP_KERNEL); 140 if (NULL == add) 141 return NULL; 142 143 add->grants = kcalloc(count, sizeof(add->grants[0]), GFP_KERNEL); 144 add->map_ops = kcalloc(count, sizeof(add->map_ops[0]), GFP_KERNEL); 145 add->unmap_ops = kcalloc(count, sizeof(add->unmap_ops[0]), GFP_KERNEL); 146 add->kmap_ops = kcalloc(count, sizeof(add->kmap_ops[0]), GFP_KERNEL); 147 add->kunmap_ops = kcalloc(count, sizeof(add->kunmap_ops[0]), GFP_KERNEL); 148 add->pages = kcalloc(count, sizeof(add->pages[0]), GFP_KERNEL); 149 if (NULL == add->grants || 150 NULL == add->map_ops || 151 NULL == add->unmap_ops || 152 NULL == add->kmap_ops || 153 NULL == add->kunmap_ops || 154 NULL == add->pages) 155 goto err; 156 157 if (gnttab_alloc_pages(count, add->pages)) 158 goto err; 159 160 for (i = 0; i < count; i++) { 161 add->map_ops[i].handle = -1; 162 add->unmap_ops[i].handle = -1; 163 add->kmap_ops[i].handle = -1; 164 add->kunmap_ops[i].handle = -1; 165 } 166 167 add->index = 0; 168 add->count = count; 169 atomic_set(&add->users, 1); 170 171 return add; 172 173 err: 174 gntdev_free_map(add); 175 return NULL; 176 } 177 178 static void gntdev_add_map(struct gntdev_priv *priv, struct grant_map *add) 179 { 180 struct grant_map *map; 181 182 list_for_each_entry(map, &priv->maps, next) { 183 if (add->index + add->count < map->index) { 184 list_add_tail(&add->next, &map->next); 185 goto done; 186 } 187 add->index = map->index + map->count; 188 } 189 list_add_tail(&add->next, &priv->maps); 190 191 done: 192 gntdev_print_maps(priv, "[new]", add->index); 193 } 194 195 static struct grant_map *gntdev_find_map_index(struct gntdev_priv *priv, 196 int index, int count) 197 { 198 struct grant_map *map; 199 200 list_for_each_entry(map, &priv->maps, next) { 201 if (map->index != index) 202 continue; 203 if (count && map->count != count) 204 continue; 205 return map; 206 } 207 return NULL; 208 } 209 210 static void gntdev_put_map(struct gntdev_priv *priv, struct grant_map *map) 211 { 212 if (!map) 213 return; 214 215 if (!atomic_dec_and_test(&map->users)) 216 return; 217 218 atomic_sub(map->count, &pages_mapped); 219 220 if (map->notify.flags & UNMAP_NOTIFY_SEND_EVENT) { 221 notify_remote_via_evtchn(map->notify.event); 222 evtchn_put(map->notify.event); 223 } 224 225 if (populate_freeable_maps && priv) { 226 mutex_lock(&priv->lock); 227 list_del(&map->next); 228 mutex_unlock(&priv->lock); 229 } 230 231 if (map->pages && !use_ptemod) 232 unmap_grant_pages(map, 0, map->count); 233 gntdev_free_map(map); 234 } 235 236 /* ------------------------------------------------------------------ */ 237 238 static int find_grant_ptes(pte_t *pte, pgtable_t token, 239 unsigned long addr, void *data) 240 { 241 struct grant_map *map = data; 242 unsigned int pgnr = (addr - map->vma->vm_start) >> PAGE_SHIFT; 243 int flags = map->flags | GNTMAP_application_map | GNTMAP_contains_pte; 244 u64 pte_maddr; 245 246 BUG_ON(pgnr >= map->count); 247 pte_maddr = arbitrary_virt_to_machine(pte).maddr; 248 249 /* 250 * Set the PTE as special to force get_user_pages_fast() fall 251 * back to the slow path. If this is not supported as part of 252 * the grant map, it will be done afterwards. 253 */ 254 if (xen_feature(XENFEAT_gnttab_map_avail_bits)) 255 flags |= (1 << _GNTMAP_guest_avail0); 256 257 gnttab_set_map_op(&map->map_ops[pgnr], pte_maddr, flags, 258 map->grants[pgnr].ref, 259 map->grants[pgnr].domid); 260 gnttab_set_unmap_op(&map->unmap_ops[pgnr], pte_maddr, flags, 261 -1 /* handle */); 262 return 0; 263 } 264 265 #ifdef CONFIG_X86 266 static int set_grant_ptes_as_special(pte_t *pte, pgtable_t token, 267 unsigned long addr, void *data) 268 { 269 set_pte_at(current->mm, addr, pte, pte_mkspecial(*pte)); 270 return 0; 271 } 272 #endif 273 274 static int map_grant_pages(struct grant_map *map) 275 { 276 int i, err = 0; 277 278 if (!use_ptemod) { 279 /* Note: it could already be mapped */ 280 if (map->map_ops[0].handle != -1) 281 return 0; 282 for (i = 0; i < map->count; i++) { 283 unsigned long addr = (unsigned long) 284 pfn_to_kaddr(page_to_pfn(map->pages[i])); 285 gnttab_set_map_op(&map->map_ops[i], addr, map->flags, 286 map->grants[i].ref, 287 map->grants[i].domid); 288 gnttab_set_unmap_op(&map->unmap_ops[i], addr, 289 map->flags, -1 /* handle */); 290 } 291 } else { 292 /* 293 * Setup the map_ops corresponding to the pte entries pointing 294 * to the kernel linear addresses of the struct pages. 295 * These ptes are completely different from the user ptes dealt 296 * with find_grant_ptes. 297 */ 298 for (i = 0; i < map->count; i++) { 299 unsigned long address = (unsigned long) 300 pfn_to_kaddr(page_to_pfn(map->pages[i])); 301 BUG_ON(PageHighMem(map->pages[i])); 302 303 gnttab_set_map_op(&map->kmap_ops[i], address, 304 map->flags | GNTMAP_host_map, 305 map->grants[i].ref, 306 map->grants[i].domid); 307 gnttab_set_unmap_op(&map->kunmap_ops[i], address, 308 map->flags | GNTMAP_host_map, -1); 309 } 310 } 311 312 pr_debug("map %d+%d\n", map->index, map->count); 313 err = gnttab_map_refs(map->map_ops, use_ptemod ? map->kmap_ops : NULL, 314 map->pages, map->count); 315 if (err) 316 return err; 317 318 for (i = 0; i < map->count; i++) { 319 if (map->map_ops[i].status) { 320 err = -EINVAL; 321 continue; 322 } 323 324 map->unmap_ops[i].handle = map->map_ops[i].handle; 325 if (use_ptemod) 326 map->kunmap_ops[i].handle = map->kmap_ops[i].handle; 327 } 328 return err; 329 } 330 331 static int __unmap_grant_pages(struct grant_map *map, int offset, int pages) 332 { 333 int i, err = 0; 334 struct gntab_unmap_queue_data unmap_data; 335 336 if (map->notify.flags & UNMAP_NOTIFY_CLEAR_BYTE) { 337 int pgno = (map->notify.addr >> PAGE_SHIFT); 338 if (pgno >= offset && pgno < offset + pages) { 339 /* No need for kmap, pages are in lowmem */ 340 uint8_t *tmp = pfn_to_kaddr(page_to_pfn(map->pages[pgno])); 341 tmp[map->notify.addr & (PAGE_SIZE-1)] = 0; 342 map->notify.flags &= ~UNMAP_NOTIFY_CLEAR_BYTE; 343 } 344 } 345 346 unmap_data.unmap_ops = map->unmap_ops + offset; 347 unmap_data.kunmap_ops = use_ptemod ? map->kunmap_ops + offset : NULL; 348 unmap_data.pages = map->pages + offset; 349 unmap_data.count = pages; 350 351 err = gnttab_unmap_refs_sync(&unmap_data); 352 if (err) 353 return err; 354 355 for (i = 0; i < pages; i++) { 356 if (map->unmap_ops[offset+i].status) 357 err = -EINVAL; 358 pr_debug("unmap handle=%d st=%d\n", 359 map->unmap_ops[offset+i].handle, 360 map->unmap_ops[offset+i].status); 361 map->unmap_ops[offset+i].handle = -1; 362 } 363 return err; 364 } 365 366 static int unmap_grant_pages(struct grant_map *map, int offset, int pages) 367 { 368 int range, err = 0; 369 370 pr_debug("unmap %d+%d [%d+%d]\n", map->index, map->count, offset, pages); 371 372 /* It is possible the requested range will have a "hole" where we 373 * already unmapped some of the grants. Only unmap valid ranges. 374 */ 375 while (pages && !err) { 376 while (pages && map->unmap_ops[offset].handle == -1) { 377 offset++; 378 pages--; 379 } 380 range = 0; 381 while (range < pages) { 382 if (map->unmap_ops[offset+range].handle == -1) { 383 range--; 384 break; 385 } 386 range++; 387 } 388 err = __unmap_grant_pages(map, offset, range); 389 offset += range; 390 pages -= range; 391 } 392 393 return err; 394 } 395 396 /* ------------------------------------------------------------------ */ 397 398 static void gntdev_vma_open(struct vm_area_struct *vma) 399 { 400 struct grant_map *map = vma->vm_private_data; 401 402 pr_debug("gntdev_vma_open %p\n", vma); 403 atomic_inc(&map->users); 404 } 405 406 static void gntdev_vma_close(struct vm_area_struct *vma) 407 { 408 struct grant_map *map = vma->vm_private_data; 409 struct file *file = vma->vm_file; 410 struct gntdev_priv *priv = file->private_data; 411 412 pr_debug("gntdev_vma_close %p\n", vma); 413 if (use_ptemod) { 414 /* It is possible that an mmu notifier could be running 415 * concurrently, so take priv->lock to ensure that the vma won't 416 * vanishing during the unmap_grant_pages call, since we will 417 * spin here until that completes. Such a concurrent call will 418 * not do any unmapping, since that has been done prior to 419 * closing the vma, but it may still iterate the unmap_ops list. 420 */ 421 mutex_lock(&priv->lock); 422 map->vma = NULL; 423 mutex_unlock(&priv->lock); 424 } 425 vma->vm_private_data = NULL; 426 gntdev_put_map(priv, map); 427 } 428 429 static struct page *gntdev_vma_find_special_page(struct vm_area_struct *vma, 430 unsigned long addr) 431 { 432 struct grant_map *map = vma->vm_private_data; 433 434 return map->pages[(addr - map->pages_vm_start) >> PAGE_SHIFT]; 435 } 436 437 static const struct vm_operations_struct gntdev_vmops = { 438 .open = gntdev_vma_open, 439 .close = gntdev_vma_close, 440 .find_special_page = gntdev_vma_find_special_page, 441 }; 442 443 /* ------------------------------------------------------------------ */ 444 445 static void unmap_if_in_range(struct grant_map *map, 446 unsigned long start, unsigned long end) 447 { 448 unsigned long mstart, mend; 449 int err; 450 451 if (!map->vma) 452 return; 453 if (map->vma->vm_start >= end) 454 return; 455 if (map->vma->vm_end <= start) 456 return; 457 mstart = max(start, map->vma->vm_start); 458 mend = min(end, map->vma->vm_end); 459 pr_debug("map %d+%d (%lx %lx), range %lx %lx, mrange %lx %lx\n", 460 map->index, map->count, 461 map->vma->vm_start, map->vma->vm_end, 462 start, end, mstart, mend); 463 err = unmap_grant_pages(map, 464 (mstart - map->vma->vm_start) >> PAGE_SHIFT, 465 (mend - mstart) >> PAGE_SHIFT); 466 WARN_ON(err); 467 } 468 469 static void mn_invl_range_start(struct mmu_notifier *mn, 470 struct mm_struct *mm, 471 unsigned long start, unsigned long end) 472 { 473 struct gntdev_priv *priv = container_of(mn, struct gntdev_priv, mn); 474 struct grant_map *map; 475 476 mutex_lock(&priv->lock); 477 list_for_each_entry(map, &priv->maps, next) { 478 unmap_if_in_range(map, start, end); 479 } 480 list_for_each_entry(map, &priv->freeable_maps, next) { 481 unmap_if_in_range(map, start, end); 482 } 483 mutex_unlock(&priv->lock); 484 } 485 486 static void mn_invl_page(struct mmu_notifier *mn, 487 struct mm_struct *mm, 488 unsigned long address) 489 { 490 mn_invl_range_start(mn, mm, address, address + PAGE_SIZE); 491 } 492 493 static void mn_release(struct mmu_notifier *mn, 494 struct mm_struct *mm) 495 { 496 struct gntdev_priv *priv = container_of(mn, struct gntdev_priv, mn); 497 struct grant_map *map; 498 int err; 499 500 mutex_lock(&priv->lock); 501 list_for_each_entry(map, &priv->maps, next) { 502 if (!map->vma) 503 continue; 504 pr_debug("map %d+%d (%lx %lx)\n", 505 map->index, map->count, 506 map->vma->vm_start, map->vma->vm_end); 507 err = unmap_grant_pages(map, /* offset */ 0, map->count); 508 WARN_ON(err); 509 } 510 list_for_each_entry(map, &priv->freeable_maps, next) { 511 if (!map->vma) 512 continue; 513 pr_debug("map %d+%d (%lx %lx)\n", 514 map->index, map->count, 515 map->vma->vm_start, map->vma->vm_end); 516 err = unmap_grant_pages(map, /* offset */ 0, map->count); 517 WARN_ON(err); 518 } 519 mutex_unlock(&priv->lock); 520 } 521 522 static const struct mmu_notifier_ops gntdev_mmu_ops = { 523 .release = mn_release, 524 .invalidate_page = mn_invl_page, 525 .invalidate_range_start = mn_invl_range_start, 526 }; 527 528 /* ------------------------------------------------------------------ */ 529 530 static int gntdev_open(struct inode *inode, struct file *flip) 531 { 532 struct gntdev_priv *priv; 533 int ret = 0; 534 535 priv = kzalloc(sizeof(*priv), GFP_KERNEL); 536 if (!priv) 537 return -ENOMEM; 538 539 INIT_LIST_HEAD(&priv->maps); 540 INIT_LIST_HEAD(&priv->freeable_maps); 541 mutex_init(&priv->lock); 542 543 if (use_ptemod) { 544 priv->mm = get_task_mm(current); 545 if (!priv->mm) { 546 kfree(priv); 547 return -ENOMEM; 548 } 549 priv->mn.ops = &gntdev_mmu_ops; 550 ret = mmu_notifier_register(&priv->mn, priv->mm); 551 mmput(priv->mm); 552 } 553 554 if (ret) { 555 kfree(priv); 556 return ret; 557 } 558 559 flip->private_data = priv; 560 pr_debug("priv %p\n", priv); 561 562 return 0; 563 } 564 565 static int gntdev_release(struct inode *inode, struct file *flip) 566 { 567 struct gntdev_priv *priv = flip->private_data; 568 struct grant_map *map; 569 570 pr_debug("priv %p\n", priv); 571 572 mutex_lock(&priv->lock); 573 while (!list_empty(&priv->maps)) { 574 map = list_entry(priv->maps.next, struct grant_map, next); 575 list_del(&map->next); 576 gntdev_put_map(NULL /* already removed */, map); 577 } 578 WARN_ON(!list_empty(&priv->freeable_maps)); 579 mutex_unlock(&priv->lock); 580 581 if (use_ptemod) 582 mmu_notifier_unregister(&priv->mn, priv->mm); 583 kfree(priv); 584 return 0; 585 } 586 587 static long gntdev_ioctl_map_grant_ref(struct gntdev_priv *priv, 588 struct ioctl_gntdev_map_grant_ref __user *u) 589 { 590 struct ioctl_gntdev_map_grant_ref op; 591 struct grant_map *map; 592 int err; 593 594 if (copy_from_user(&op, u, sizeof(op)) != 0) 595 return -EFAULT; 596 pr_debug("priv %p, add %d\n", priv, op.count); 597 if (unlikely(op.count <= 0)) 598 return -EINVAL; 599 600 err = -ENOMEM; 601 map = gntdev_alloc_map(priv, op.count); 602 if (!map) 603 return err; 604 605 if (unlikely(atomic_add_return(op.count, &pages_mapped) > limit)) { 606 pr_debug("can't map: over limit\n"); 607 gntdev_put_map(NULL, map); 608 return err; 609 } 610 611 if (copy_from_user(map->grants, &u->refs, 612 sizeof(map->grants[0]) * op.count) != 0) { 613 gntdev_put_map(NULL, map); 614 return -EFAULT; 615 } 616 617 mutex_lock(&priv->lock); 618 gntdev_add_map(priv, map); 619 op.index = map->index << PAGE_SHIFT; 620 mutex_unlock(&priv->lock); 621 622 if (copy_to_user(u, &op, sizeof(op)) != 0) 623 return -EFAULT; 624 625 return 0; 626 } 627 628 static long gntdev_ioctl_unmap_grant_ref(struct gntdev_priv *priv, 629 struct ioctl_gntdev_unmap_grant_ref __user *u) 630 { 631 struct ioctl_gntdev_unmap_grant_ref op; 632 struct grant_map *map; 633 int err = -ENOENT; 634 635 if (copy_from_user(&op, u, sizeof(op)) != 0) 636 return -EFAULT; 637 pr_debug("priv %p, del %d+%d\n", priv, (int)op.index, (int)op.count); 638 639 mutex_lock(&priv->lock); 640 map = gntdev_find_map_index(priv, op.index >> PAGE_SHIFT, op.count); 641 if (map) { 642 list_del(&map->next); 643 if (populate_freeable_maps) 644 list_add_tail(&map->next, &priv->freeable_maps); 645 err = 0; 646 } 647 mutex_unlock(&priv->lock); 648 if (map) 649 gntdev_put_map(priv, map); 650 return err; 651 } 652 653 static long gntdev_ioctl_get_offset_for_vaddr(struct gntdev_priv *priv, 654 struct ioctl_gntdev_get_offset_for_vaddr __user *u) 655 { 656 struct ioctl_gntdev_get_offset_for_vaddr op; 657 struct vm_area_struct *vma; 658 struct grant_map *map; 659 int rv = -EINVAL; 660 661 if (copy_from_user(&op, u, sizeof(op)) != 0) 662 return -EFAULT; 663 pr_debug("priv %p, offset for vaddr %lx\n", priv, (unsigned long)op.vaddr); 664 665 down_read(¤t->mm->mmap_sem); 666 vma = find_vma(current->mm, op.vaddr); 667 if (!vma || vma->vm_ops != &gntdev_vmops) 668 goto out_unlock; 669 670 map = vma->vm_private_data; 671 if (!map) 672 goto out_unlock; 673 674 op.offset = map->index << PAGE_SHIFT; 675 op.count = map->count; 676 rv = 0; 677 678 out_unlock: 679 up_read(¤t->mm->mmap_sem); 680 681 if (rv == 0 && copy_to_user(u, &op, sizeof(op)) != 0) 682 return -EFAULT; 683 return rv; 684 } 685 686 static long gntdev_ioctl_notify(struct gntdev_priv *priv, void __user *u) 687 { 688 struct ioctl_gntdev_unmap_notify op; 689 struct grant_map *map; 690 int rc; 691 int out_flags; 692 unsigned int out_event; 693 694 if (copy_from_user(&op, u, sizeof(op))) 695 return -EFAULT; 696 697 if (op.action & ~(UNMAP_NOTIFY_CLEAR_BYTE|UNMAP_NOTIFY_SEND_EVENT)) 698 return -EINVAL; 699 700 /* We need to grab a reference to the event channel we are going to use 701 * to send the notify before releasing the reference we may already have 702 * (if someone has called this ioctl twice). This is required so that 703 * it is possible to change the clear_byte part of the notification 704 * without disturbing the event channel part, which may now be the last 705 * reference to that event channel. 706 */ 707 if (op.action & UNMAP_NOTIFY_SEND_EVENT) { 708 if (evtchn_get(op.event_channel_port)) 709 return -EINVAL; 710 } 711 712 out_flags = op.action; 713 out_event = op.event_channel_port; 714 715 mutex_lock(&priv->lock); 716 717 list_for_each_entry(map, &priv->maps, next) { 718 uint64_t begin = map->index << PAGE_SHIFT; 719 uint64_t end = (map->index + map->count) << PAGE_SHIFT; 720 if (op.index >= begin && op.index < end) 721 goto found; 722 } 723 rc = -ENOENT; 724 goto unlock_out; 725 726 found: 727 if ((op.action & UNMAP_NOTIFY_CLEAR_BYTE) && 728 (map->flags & GNTMAP_readonly)) { 729 rc = -EINVAL; 730 goto unlock_out; 731 } 732 733 out_flags = map->notify.flags; 734 out_event = map->notify.event; 735 736 map->notify.flags = op.action; 737 map->notify.addr = op.index - (map->index << PAGE_SHIFT); 738 map->notify.event = op.event_channel_port; 739 740 rc = 0; 741 742 unlock_out: 743 mutex_unlock(&priv->lock); 744 745 /* Drop the reference to the event channel we did not save in the map */ 746 if (out_flags & UNMAP_NOTIFY_SEND_EVENT) 747 evtchn_put(out_event); 748 749 return rc; 750 } 751 752 #define GNTDEV_COPY_BATCH 16 753 754 struct gntdev_copy_batch { 755 struct gnttab_copy ops[GNTDEV_COPY_BATCH]; 756 struct page *pages[GNTDEV_COPY_BATCH]; 757 s16 __user *status[GNTDEV_COPY_BATCH]; 758 unsigned int nr_ops; 759 unsigned int nr_pages; 760 }; 761 762 static int gntdev_get_page(struct gntdev_copy_batch *batch, void __user *virt, 763 bool writeable, unsigned long *gfn) 764 { 765 unsigned long addr = (unsigned long)virt; 766 struct page *page; 767 unsigned long xen_pfn; 768 int ret; 769 770 ret = get_user_pages_fast(addr, 1, writeable, &page); 771 if (ret < 0) 772 return ret; 773 774 batch->pages[batch->nr_pages++] = page; 775 776 xen_pfn = page_to_xen_pfn(page) + XEN_PFN_DOWN(addr & ~PAGE_MASK); 777 *gfn = pfn_to_gfn(xen_pfn); 778 779 return 0; 780 } 781 782 static void gntdev_put_pages(struct gntdev_copy_batch *batch) 783 { 784 unsigned int i; 785 786 for (i = 0; i < batch->nr_pages; i++) 787 put_page(batch->pages[i]); 788 batch->nr_pages = 0; 789 } 790 791 static int gntdev_copy(struct gntdev_copy_batch *batch) 792 { 793 unsigned int i; 794 795 gnttab_batch_copy(batch->ops, batch->nr_ops); 796 gntdev_put_pages(batch); 797 798 /* 799 * For each completed op, update the status if the op failed 800 * and all previous ops for the segment were successful. 801 */ 802 for (i = 0; i < batch->nr_ops; i++) { 803 s16 status = batch->ops[i].status; 804 s16 old_status; 805 806 if (status == GNTST_okay) 807 continue; 808 809 if (__get_user(old_status, batch->status[i])) 810 return -EFAULT; 811 812 if (old_status != GNTST_okay) 813 continue; 814 815 if (__put_user(status, batch->status[i])) 816 return -EFAULT; 817 } 818 819 batch->nr_ops = 0; 820 return 0; 821 } 822 823 static int gntdev_grant_copy_seg(struct gntdev_copy_batch *batch, 824 struct gntdev_grant_copy_segment *seg, 825 s16 __user *status) 826 { 827 uint16_t copied = 0; 828 829 /* 830 * Disallow local -> local copies since there is only space in 831 * batch->pages for one page per-op and this would be a very 832 * expensive memcpy(). 833 */ 834 if (!(seg->flags & (GNTCOPY_source_gref | GNTCOPY_dest_gref))) 835 return -EINVAL; 836 837 /* Can't cross page if source/dest is a grant ref. */ 838 if (seg->flags & GNTCOPY_source_gref) { 839 if (seg->source.foreign.offset + seg->len > XEN_PAGE_SIZE) 840 return -EINVAL; 841 } 842 if (seg->flags & GNTCOPY_dest_gref) { 843 if (seg->dest.foreign.offset + seg->len > XEN_PAGE_SIZE) 844 return -EINVAL; 845 } 846 847 if (put_user(GNTST_okay, status)) 848 return -EFAULT; 849 850 while (copied < seg->len) { 851 struct gnttab_copy *op; 852 void __user *virt; 853 size_t len, off; 854 unsigned long gfn; 855 int ret; 856 857 if (batch->nr_ops >= GNTDEV_COPY_BATCH) { 858 ret = gntdev_copy(batch); 859 if (ret < 0) 860 return ret; 861 } 862 863 len = seg->len - copied; 864 865 op = &batch->ops[batch->nr_ops]; 866 op->flags = 0; 867 868 if (seg->flags & GNTCOPY_source_gref) { 869 op->source.u.ref = seg->source.foreign.ref; 870 op->source.domid = seg->source.foreign.domid; 871 op->source.offset = seg->source.foreign.offset + copied; 872 op->flags |= GNTCOPY_source_gref; 873 } else { 874 virt = seg->source.virt + copied; 875 off = (unsigned long)virt & ~XEN_PAGE_MASK; 876 len = min(len, (size_t)XEN_PAGE_SIZE - off); 877 878 ret = gntdev_get_page(batch, virt, false, &gfn); 879 if (ret < 0) 880 return ret; 881 882 op->source.u.gmfn = gfn; 883 op->source.domid = DOMID_SELF; 884 op->source.offset = off; 885 } 886 887 if (seg->flags & GNTCOPY_dest_gref) { 888 op->dest.u.ref = seg->dest.foreign.ref; 889 op->dest.domid = seg->dest.foreign.domid; 890 op->dest.offset = seg->dest.foreign.offset + copied; 891 op->flags |= GNTCOPY_dest_gref; 892 } else { 893 virt = seg->dest.virt + copied; 894 off = (unsigned long)virt & ~XEN_PAGE_MASK; 895 len = min(len, (size_t)XEN_PAGE_SIZE - off); 896 897 ret = gntdev_get_page(batch, virt, true, &gfn); 898 if (ret < 0) 899 return ret; 900 901 op->dest.u.gmfn = gfn; 902 op->dest.domid = DOMID_SELF; 903 op->dest.offset = off; 904 } 905 906 op->len = len; 907 copied += len; 908 909 batch->status[batch->nr_ops] = status; 910 batch->nr_ops++; 911 } 912 913 return 0; 914 } 915 916 static long gntdev_ioctl_grant_copy(struct gntdev_priv *priv, void __user *u) 917 { 918 struct ioctl_gntdev_grant_copy copy; 919 struct gntdev_copy_batch batch; 920 unsigned int i; 921 int ret = 0; 922 923 if (copy_from_user(©, u, sizeof(copy))) 924 return -EFAULT; 925 926 batch.nr_ops = 0; 927 batch.nr_pages = 0; 928 929 for (i = 0; i < copy.count; i++) { 930 struct gntdev_grant_copy_segment seg; 931 932 if (copy_from_user(&seg, ©.segments[i], sizeof(seg))) { 933 ret = -EFAULT; 934 goto out; 935 } 936 937 ret = gntdev_grant_copy_seg(&batch, &seg, ©.segments[i].status); 938 if (ret < 0) 939 goto out; 940 941 cond_resched(); 942 } 943 if (batch.nr_ops) 944 ret = gntdev_copy(&batch); 945 return ret; 946 947 out: 948 gntdev_put_pages(&batch); 949 return ret; 950 } 951 952 static long gntdev_ioctl(struct file *flip, 953 unsigned int cmd, unsigned long arg) 954 { 955 struct gntdev_priv *priv = flip->private_data; 956 void __user *ptr = (void __user *)arg; 957 958 switch (cmd) { 959 case IOCTL_GNTDEV_MAP_GRANT_REF: 960 return gntdev_ioctl_map_grant_ref(priv, ptr); 961 962 case IOCTL_GNTDEV_UNMAP_GRANT_REF: 963 return gntdev_ioctl_unmap_grant_ref(priv, ptr); 964 965 case IOCTL_GNTDEV_GET_OFFSET_FOR_VADDR: 966 return gntdev_ioctl_get_offset_for_vaddr(priv, ptr); 967 968 case IOCTL_GNTDEV_SET_UNMAP_NOTIFY: 969 return gntdev_ioctl_notify(priv, ptr); 970 971 case IOCTL_GNTDEV_GRANT_COPY: 972 return gntdev_ioctl_grant_copy(priv, ptr); 973 974 default: 975 pr_debug("priv %p, unknown cmd %x\n", priv, cmd); 976 return -ENOIOCTLCMD; 977 } 978 979 return 0; 980 } 981 982 static int gntdev_mmap(struct file *flip, struct vm_area_struct *vma) 983 { 984 struct gntdev_priv *priv = flip->private_data; 985 int index = vma->vm_pgoff; 986 int count = vma_pages(vma); 987 struct grant_map *map; 988 int i, err = -EINVAL; 989 990 if ((vma->vm_flags & VM_WRITE) && !(vma->vm_flags & VM_SHARED)) 991 return -EINVAL; 992 993 pr_debug("map %d+%d at %lx (pgoff %lx)\n", 994 index, count, vma->vm_start, vma->vm_pgoff); 995 996 mutex_lock(&priv->lock); 997 map = gntdev_find_map_index(priv, index, count); 998 if (!map) 999 goto unlock_out; 1000 if (use_ptemod && map->vma) 1001 goto unlock_out; 1002 if (use_ptemod && priv->mm != vma->vm_mm) { 1003 pr_warn("Huh? Other mm?\n"); 1004 goto unlock_out; 1005 } 1006 1007 atomic_inc(&map->users); 1008 1009 vma->vm_ops = &gntdev_vmops; 1010 1011 vma->vm_flags |= VM_DONTEXPAND | VM_DONTDUMP | VM_MIXEDMAP; 1012 1013 if (use_ptemod) 1014 vma->vm_flags |= VM_DONTCOPY; 1015 1016 vma->vm_private_data = map; 1017 1018 if (use_ptemod) 1019 map->vma = vma; 1020 1021 if (map->flags) { 1022 if ((vma->vm_flags & VM_WRITE) && 1023 (map->flags & GNTMAP_readonly)) 1024 goto out_unlock_put; 1025 } else { 1026 map->flags = GNTMAP_host_map; 1027 if (!(vma->vm_flags & VM_WRITE)) 1028 map->flags |= GNTMAP_readonly; 1029 } 1030 1031 mutex_unlock(&priv->lock); 1032 1033 if (use_ptemod) { 1034 err = apply_to_page_range(vma->vm_mm, vma->vm_start, 1035 vma->vm_end - vma->vm_start, 1036 find_grant_ptes, map); 1037 if (err) { 1038 pr_warn("find_grant_ptes() failure.\n"); 1039 goto out_put_map; 1040 } 1041 } 1042 1043 err = map_grant_pages(map); 1044 if (err) 1045 goto out_put_map; 1046 1047 if (!use_ptemod) { 1048 for (i = 0; i < count; i++) { 1049 err = vm_insert_page(vma, vma->vm_start + i*PAGE_SIZE, 1050 map->pages[i]); 1051 if (err) 1052 goto out_put_map; 1053 } 1054 } else { 1055 #ifdef CONFIG_X86 1056 /* 1057 * If the PTEs were not made special by the grant map 1058 * hypercall, do so here. 1059 * 1060 * This is racy since the mapping is already visible 1061 * to userspace but userspace should be well-behaved 1062 * enough to not touch it until the mmap() call 1063 * returns. 1064 */ 1065 if (!xen_feature(XENFEAT_gnttab_map_avail_bits)) { 1066 apply_to_page_range(vma->vm_mm, vma->vm_start, 1067 vma->vm_end - vma->vm_start, 1068 set_grant_ptes_as_special, NULL); 1069 } 1070 #endif 1071 map->pages_vm_start = vma->vm_start; 1072 } 1073 1074 return 0; 1075 1076 unlock_out: 1077 mutex_unlock(&priv->lock); 1078 return err; 1079 1080 out_unlock_put: 1081 mutex_unlock(&priv->lock); 1082 out_put_map: 1083 if (use_ptemod) 1084 map->vma = NULL; 1085 gntdev_put_map(priv, map); 1086 return err; 1087 } 1088 1089 static const struct file_operations gntdev_fops = { 1090 .owner = THIS_MODULE, 1091 .open = gntdev_open, 1092 .release = gntdev_release, 1093 .mmap = gntdev_mmap, 1094 .unlocked_ioctl = gntdev_ioctl 1095 }; 1096 1097 static struct miscdevice gntdev_miscdev = { 1098 .minor = MISC_DYNAMIC_MINOR, 1099 .name = "xen/gntdev", 1100 .fops = &gntdev_fops, 1101 }; 1102 1103 /* ------------------------------------------------------------------ */ 1104 1105 static int __init gntdev_init(void) 1106 { 1107 int err; 1108 1109 if (!xen_domain()) 1110 return -ENODEV; 1111 1112 use_ptemod = !xen_feature(XENFEAT_auto_translated_physmap); 1113 1114 err = misc_register(&gntdev_miscdev); 1115 if (err != 0) { 1116 pr_err("Could not register gntdev device\n"); 1117 return err; 1118 } 1119 return 0; 1120 } 1121 1122 static void __exit gntdev_exit(void) 1123 { 1124 misc_deregister(&gntdev_miscdev); 1125 } 1126 1127 module_init(gntdev_init); 1128 module_exit(gntdev_exit); 1129 1130 /* ------------------------------------------------------------------ */ 1131