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