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 * (c) 2018 Oleksandr Andrushchenko, EPAM Systems Inc. 10 * 11 * This program is distributed in the hope that it will be useful, 12 * but WITHOUT ANY WARRANTY; without even the implied warranty of 13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 14 * GNU General Public License for more details. 15 * 16 * You should have received a copy of the GNU General Public License 17 * along with this program; if not, write to the Free Software 18 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA 19 */ 20 21 #undef DEBUG 22 23 #define pr_fmt(fmt) "xen:" KBUILD_MODNAME ": " fmt 24 25 #include <linux/dma-mapping.h> 26 #include <linux/module.h> 27 #include <linux/kernel.h> 28 #include <linux/init.h> 29 #include <linux/miscdevice.h> 30 #include <linux/fs.h> 31 #include <linux/uaccess.h> 32 #include <linux/sched.h> 33 #include <linux/sched/mm.h> 34 #include <linux/spinlock.h> 35 #include <linux/slab.h> 36 #include <linux/highmem.h> 37 #include <linux/refcount.h> 38 #include <linux/workqueue.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 #include "gntdev-common.h" 50 #ifdef CONFIG_XEN_GNTDEV_DMABUF 51 #include "gntdev-dmabuf.h" 52 #endif 53 54 MODULE_LICENSE("GPL"); 55 MODULE_AUTHOR("Derek G. Murray <Derek.Murray@cl.cam.ac.uk>, " 56 "Gerd Hoffmann <kraxel@redhat.com>"); 57 MODULE_DESCRIPTION("User-space granted page access driver"); 58 59 static unsigned int limit = 64*1024; 60 module_param(limit, uint, 0644); 61 MODULE_PARM_DESC(limit, 62 "Maximum number of grants that may be mapped by one mapping request"); 63 64 /* True in PV mode, false otherwise */ 65 static int use_ptemod; 66 67 static void unmap_grant_pages(struct gntdev_grant_map *map, 68 int offset, int pages); 69 70 static struct miscdevice gntdev_miscdev; 71 72 /* ------------------------------------------------------------------ */ 73 74 bool gntdev_test_page_count(unsigned int count) 75 { 76 return !count || count > limit; 77 } 78 79 static void gntdev_print_maps(struct gntdev_priv *priv, 80 char *text, int text_index) 81 { 82 #ifdef DEBUG 83 struct gntdev_grant_map *map; 84 85 pr_debug("%s: maps list (priv %p)\n", __func__, priv); 86 list_for_each_entry(map, &priv->maps, next) 87 pr_debug(" index %2d, count %2d %s\n", 88 map->index, map->count, 89 map->index == text_index && text ? text : ""); 90 #endif 91 } 92 93 static void gntdev_free_map(struct gntdev_grant_map *map) 94 { 95 if (map == NULL) 96 return; 97 98 #ifdef CONFIG_XEN_GRANT_DMA_ALLOC 99 if (map->dma_vaddr) { 100 struct gnttab_dma_alloc_args args; 101 102 args.dev = map->dma_dev; 103 args.coherent = !!(map->dma_flags & GNTDEV_DMA_FLAG_COHERENT); 104 args.nr_pages = map->count; 105 args.pages = map->pages; 106 args.frames = map->frames; 107 args.vaddr = map->dma_vaddr; 108 args.dev_bus_addr = map->dma_bus_addr; 109 110 gnttab_dma_free_pages(&args); 111 } else 112 #endif 113 if (map->pages) 114 gnttab_free_pages(map->count, map->pages); 115 116 #ifdef CONFIG_XEN_GRANT_DMA_ALLOC 117 kvfree(map->frames); 118 #endif 119 kvfree(map->pages); 120 kvfree(map->grants); 121 kvfree(map->map_ops); 122 kvfree(map->unmap_ops); 123 kvfree(map->kmap_ops); 124 kvfree(map->kunmap_ops); 125 kvfree(map->being_removed); 126 kfree(map); 127 } 128 129 struct gntdev_grant_map *gntdev_alloc_map(struct gntdev_priv *priv, int count, 130 int dma_flags) 131 { 132 struct gntdev_grant_map *add; 133 int i; 134 135 add = kzalloc(sizeof(*add), GFP_KERNEL); 136 if (NULL == add) 137 return NULL; 138 139 add->grants = kvmalloc_array(count, sizeof(add->grants[0]), 140 GFP_KERNEL); 141 add->map_ops = kvmalloc_array(count, sizeof(add->map_ops[0]), 142 GFP_KERNEL); 143 add->unmap_ops = kvmalloc_array(count, sizeof(add->unmap_ops[0]), 144 GFP_KERNEL); 145 add->pages = kvcalloc(count, sizeof(add->pages[0]), GFP_KERNEL); 146 add->being_removed = 147 kvcalloc(count, sizeof(add->being_removed[0]), GFP_KERNEL); 148 if (NULL == add->grants || 149 NULL == add->map_ops || 150 NULL == add->unmap_ops || 151 NULL == add->pages || 152 NULL == add->being_removed) 153 goto err; 154 if (use_ptemod) { 155 add->kmap_ops = kvmalloc_array(count, sizeof(add->kmap_ops[0]), 156 GFP_KERNEL); 157 add->kunmap_ops = kvmalloc_array(count, sizeof(add->kunmap_ops[0]), 158 GFP_KERNEL); 159 if (NULL == add->kmap_ops || NULL == add->kunmap_ops) 160 goto err; 161 } 162 163 #ifdef CONFIG_XEN_GRANT_DMA_ALLOC 164 add->dma_flags = dma_flags; 165 166 /* 167 * Check if this mapping is requested to be backed 168 * by a DMA buffer. 169 */ 170 if (dma_flags & (GNTDEV_DMA_FLAG_WC | GNTDEV_DMA_FLAG_COHERENT)) { 171 struct gnttab_dma_alloc_args args; 172 173 add->frames = kvcalloc(count, sizeof(add->frames[0]), 174 GFP_KERNEL); 175 if (!add->frames) 176 goto err; 177 178 /* Remember the device, so we can free DMA memory. */ 179 add->dma_dev = priv->dma_dev; 180 181 args.dev = priv->dma_dev; 182 args.coherent = !!(dma_flags & GNTDEV_DMA_FLAG_COHERENT); 183 args.nr_pages = count; 184 args.pages = add->pages; 185 args.frames = add->frames; 186 187 if (gnttab_dma_alloc_pages(&args)) 188 goto err; 189 190 add->dma_vaddr = args.vaddr; 191 add->dma_bus_addr = args.dev_bus_addr; 192 } else 193 #endif 194 if (gnttab_alloc_pages(count, add->pages)) 195 goto err; 196 197 for (i = 0; i < count; i++) { 198 add->grants[i].domid = DOMID_INVALID; 199 add->grants[i].ref = INVALID_GRANT_REF; 200 add->map_ops[i].handle = INVALID_GRANT_HANDLE; 201 add->unmap_ops[i].handle = INVALID_GRANT_HANDLE; 202 if (use_ptemod) { 203 add->kmap_ops[i].handle = INVALID_GRANT_HANDLE; 204 add->kunmap_ops[i].handle = INVALID_GRANT_HANDLE; 205 } 206 } 207 208 add->index = 0; 209 add->count = count; 210 refcount_set(&add->users, 1); 211 212 return add; 213 214 err: 215 gntdev_free_map(add); 216 return NULL; 217 } 218 219 void gntdev_add_map(struct gntdev_priv *priv, struct gntdev_grant_map *add) 220 { 221 struct gntdev_grant_map *map; 222 223 list_for_each_entry(map, &priv->maps, next) { 224 if (add->index + add->count < map->index) { 225 list_add_tail(&add->next, &map->next); 226 goto done; 227 } 228 add->index = map->index + map->count; 229 } 230 list_add_tail(&add->next, &priv->maps); 231 232 done: 233 gntdev_print_maps(priv, "[new]", add->index); 234 } 235 236 static struct gntdev_grant_map *gntdev_find_map_index(struct gntdev_priv *priv, 237 int index, int count) 238 { 239 struct gntdev_grant_map *map; 240 241 list_for_each_entry(map, &priv->maps, next) { 242 if (map->index != index) 243 continue; 244 if (count && map->count != count) 245 continue; 246 return map; 247 } 248 return NULL; 249 } 250 251 void gntdev_put_map(struct gntdev_priv *priv, struct gntdev_grant_map *map) 252 { 253 if (!map) 254 return; 255 256 if (!refcount_dec_and_test(&map->users)) 257 return; 258 259 if (map->pages && !use_ptemod) { 260 /* 261 * Increment the reference count. This ensures that the 262 * subsequent call to unmap_grant_pages() will not wind up 263 * re-entering itself. It *can* wind up calling 264 * gntdev_put_map() recursively, but such calls will be with a 265 * reference count greater than 1, so they will return before 266 * this code is reached. The recursion depth is thus limited to 267 * 1. Do NOT use refcount_inc() here, as it will detect that 268 * the reference count is zero and WARN(). 269 */ 270 refcount_set(&map->users, 1); 271 272 /* 273 * Unmap the grants. This may or may not be asynchronous, so it 274 * is possible that the reference count is 1 on return, but it 275 * could also be greater than 1. 276 */ 277 unmap_grant_pages(map, 0, map->count); 278 279 /* Check if the memory now needs to be freed */ 280 if (!refcount_dec_and_test(&map->users)) 281 return; 282 283 /* 284 * All pages have been returned to the hypervisor, so free the 285 * map. 286 */ 287 } 288 289 if (map->notify.flags & UNMAP_NOTIFY_SEND_EVENT) { 290 notify_remote_via_evtchn(map->notify.event); 291 evtchn_put(map->notify.event); 292 } 293 gntdev_free_map(map); 294 } 295 296 /* ------------------------------------------------------------------ */ 297 298 static int find_grant_ptes(pte_t *pte, unsigned long addr, void *data) 299 { 300 struct gntdev_grant_map *map = data; 301 unsigned int pgnr = (addr - map->vma->vm_start) >> PAGE_SHIFT; 302 int flags = map->flags | GNTMAP_application_map | GNTMAP_contains_pte | 303 (1 << _GNTMAP_guest_avail0); 304 u64 pte_maddr; 305 306 BUG_ON(pgnr >= map->count); 307 pte_maddr = arbitrary_virt_to_machine(pte).maddr; 308 309 gnttab_set_map_op(&map->map_ops[pgnr], pte_maddr, flags, 310 map->grants[pgnr].ref, 311 map->grants[pgnr].domid); 312 gnttab_set_unmap_op(&map->unmap_ops[pgnr], pte_maddr, flags, 313 INVALID_GRANT_HANDLE); 314 return 0; 315 } 316 317 int gntdev_map_grant_pages(struct gntdev_grant_map *map) 318 { 319 size_t alloced = 0; 320 int i, err = 0; 321 322 if (!use_ptemod) { 323 /* Note: it could already be mapped */ 324 if (map->map_ops[0].handle != INVALID_GRANT_HANDLE) 325 return 0; 326 for (i = 0; i < map->count; i++) { 327 unsigned long addr = (unsigned long) 328 pfn_to_kaddr(page_to_pfn(map->pages[i])); 329 gnttab_set_map_op(&map->map_ops[i], addr, map->flags, 330 map->grants[i].ref, 331 map->grants[i].domid); 332 gnttab_set_unmap_op(&map->unmap_ops[i], addr, 333 map->flags, INVALID_GRANT_HANDLE); 334 } 335 } else { 336 /* 337 * Setup the map_ops corresponding to the pte entries pointing 338 * to the kernel linear addresses of the struct pages. 339 * These ptes are completely different from the user ptes dealt 340 * with find_grant_ptes. 341 * Note that GNTMAP_device_map isn't needed here: The 342 * dev_bus_addr output field gets consumed only from ->map_ops, 343 * and by not requesting it when mapping we also avoid needing 344 * to mirror dev_bus_addr into ->unmap_ops (and holding an extra 345 * reference to the page in the hypervisor). 346 */ 347 unsigned int flags = (map->flags & ~GNTMAP_device_map) | 348 GNTMAP_host_map; 349 350 for (i = 0; i < map->count; i++) { 351 unsigned long address = (unsigned long) 352 pfn_to_kaddr(page_to_pfn(map->pages[i])); 353 BUG_ON(PageHighMem(map->pages[i])); 354 355 gnttab_set_map_op(&map->kmap_ops[i], address, flags, 356 map->grants[i].ref, 357 map->grants[i].domid); 358 gnttab_set_unmap_op(&map->kunmap_ops[i], address, 359 flags, INVALID_GRANT_HANDLE); 360 } 361 } 362 363 pr_debug("map %d+%d\n", map->index, map->count); 364 err = gnttab_map_refs(map->map_ops, map->kmap_ops, map->pages, 365 map->count); 366 367 for (i = 0; i < map->count; i++) { 368 if (map->map_ops[i].status == GNTST_okay) { 369 map->unmap_ops[i].handle = map->map_ops[i].handle; 370 if (!use_ptemod) 371 alloced++; 372 } else if (!err) 373 err = -EINVAL; 374 375 if (map->flags & GNTMAP_device_map) 376 map->unmap_ops[i].dev_bus_addr = map->map_ops[i].dev_bus_addr; 377 378 if (use_ptemod) { 379 if (map->kmap_ops[i].status == GNTST_okay) { 380 if (map->map_ops[i].status == GNTST_okay) 381 alloced++; 382 map->kunmap_ops[i].handle = map->kmap_ops[i].handle; 383 } else if (!err) 384 err = -EINVAL; 385 } 386 } 387 atomic_add(alloced, &map->live_grants); 388 return err; 389 } 390 391 static void __unmap_grant_pages_done(int result, 392 struct gntab_unmap_queue_data *data) 393 { 394 unsigned int i; 395 struct gntdev_grant_map *map = data->data; 396 unsigned int offset = data->unmap_ops - map->unmap_ops; 397 398 for (i = 0; i < data->count; i++) { 399 WARN_ON(map->unmap_ops[offset + i].status != GNTST_okay && 400 map->unmap_ops[offset + i].handle != INVALID_GRANT_HANDLE); 401 pr_debug("unmap handle=%d st=%d\n", 402 map->unmap_ops[offset+i].handle, 403 map->unmap_ops[offset+i].status); 404 map->unmap_ops[offset+i].handle = INVALID_GRANT_HANDLE; 405 if (use_ptemod) { 406 WARN_ON(map->kunmap_ops[offset + i].status != GNTST_okay && 407 map->kunmap_ops[offset + i].handle != INVALID_GRANT_HANDLE); 408 pr_debug("kunmap handle=%u st=%d\n", 409 map->kunmap_ops[offset+i].handle, 410 map->kunmap_ops[offset+i].status); 411 map->kunmap_ops[offset+i].handle = INVALID_GRANT_HANDLE; 412 } 413 } 414 /* 415 * Decrease the live-grant counter. This must happen after the loop to 416 * prevent premature reuse of the grants by gnttab_mmap(). 417 */ 418 atomic_sub(data->count, &map->live_grants); 419 420 /* Release reference taken by __unmap_grant_pages */ 421 gntdev_put_map(NULL, map); 422 } 423 424 static void __unmap_grant_pages(struct gntdev_grant_map *map, int offset, 425 int pages) 426 { 427 if (map->notify.flags & UNMAP_NOTIFY_CLEAR_BYTE) { 428 int pgno = (map->notify.addr >> PAGE_SHIFT); 429 430 if (pgno >= offset && pgno < offset + pages) { 431 /* No need for kmap, pages are in lowmem */ 432 uint8_t *tmp = pfn_to_kaddr(page_to_pfn(map->pages[pgno])); 433 434 tmp[map->notify.addr & (PAGE_SIZE-1)] = 0; 435 map->notify.flags &= ~UNMAP_NOTIFY_CLEAR_BYTE; 436 } 437 } 438 439 map->unmap_data.unmap_ops = map->unmap_ops + offset; 440 map->unmap_data.kunmap_ops = use_ptemod ? map->kunmap_ops + offset : NULL; 441 map->unmap_data.pages = map->pages + offset; 442 map->unmap_data.count = pages; 443 map->unmap_data.done = __unmap_grant_pages_done; 444 map->unmap_data.data = map; 445 refcount_inc(&map->users); /* to keep map alive during async call below */ 446 447 gnttab_unmap_refs_async(&map->unmap_data); 448 } 449 450 static void unmap_grant_pages(struct gntdev_grant_map *map, int offset, 451 int pages) 452 { 453 int range; 454 455 if (atomic_read(&map->live_grants) == 0) 456 return; /* Nothing to do */ 457 458 pr_debug("unmap %d+%d [%d+%d]\n", map->index, map->count, offset, pages); 459 460 /* It is possible the requested range will have a "hole" where we 461 * already unmapped some of the grants. Only unmap valid ranges. 462 */ 463 while (pages) { 464 while (pages && map->being_removed[offset]) { 465 offset++; 466 pages--; 467 } 468 range = 0; 469 while (range < pages) { 470 if (map->being_removed[offset + range]) 471 break; 472 map->being_removed[offset + range] = true; 473 range++; 474 } 475 if (range) 476 __unmap_grant_pages(map, offset, range); 477 offset += range; 478 pages -= range; 479 } 480 } 481 482 /* ------------------------------------------------------------------ */ 483 484 static void gntdev_vma_open(struct vm_area_struct *vma) 485 { 486 struct gntdev_grant_map *map = vma->vm_private_data; 487 488 pr_debug("gntdev_vma_open %p\n", vma); 489 refcount_inc(&map->users); 490 } 491 492 static void gntdev_vma_close(struct vm_area_struct *vma) 493 { 494 struct gntdev_grant_map *map = vma->vm_private_data; 495 struct file *file = vma->vm_file; 496 struct gntdev_priv *priv = file->private_data; 497 498 pr_debug("gntdev_vma_close %p\n", vma); 499 if (use_ptemod) { 500 WARN_ON(map->vma != vma); 501 mmu_interval_notifier_remove(&map->notifier); 502 map->vma = NULL; 503 } 504 vma->vm_private_data = NULL; 505 gntdev_put_map(priv, map); 506 } 507 508 static struct page *gntdev_vma_find_special_page(struct vm_area_struct *vma, 509 unsigned long addr) 510 { 511 struct gntdev_grant_map *map = vma->vm_private_data; 512 513 return map->pages[(addr - map->pages_vm_start) >> PAGE_SHIFT]; 514 } 515 516 static const struct vm_operations_struct gntdev_vmops = { 517 .open = gntdev_vma_open, 518 .close = gntdev_vma_close, 519 .find_special_page = gntdev_vma_find_special_page, 520 }; 521 522 /* ------------------------------------------------------------------ */ 523 524 static bool gntdev_invalidate(struct mmu_interval_notifier *mn, 525 const struct mmu_notifier_range *range, 526 unsigned long cur_seq) 527 { 528 struct gntdev_grant_map *map = 529 container_of(mn, struct gntdev_grant_map, notifier); 530 unsigned long mstart, mend; 531 532 if (!mmu_notifier_range_blockable(range)) 533 return false; 534 535 /* 536 * If the VMA is split or otherwise changed the notifier is not 537 * updated, but we don't want to process VA's outside the modified 538 * VMA. FIXME: It would be much more understandable to just prevent 539 * modifying the VMA in the first place. 540 */ 541 if (map->vma->vm_start >= range->end || 542 map->vma->vm_end <= range->start) 543 return true; 544 545 mstart = max(range->start, map->vma->vm_start); 546 mend = min(range->end, map->vma->vm_end); 547 pr_debug("map %d+%d (%lx %lx), range %lx %lx, mrange %lx %lx\n", 548 map->index, map->count, 549 map->vma->vm_start, map->vma->vm_end, 550 range->start, range->end, mstart, mend); 551 unmap_grant_pages(map, 552 (mstart - map->vma->vm_start) >> PAGE_SHIFT, 553 (mend - mstart) >> PAGE_SHIFT); 554 555 return true; 556 } 557 558 static const struct mmu_interval_notifier_ops gntdev_mmu_ops = { 559 .invalidate = gntdev_invalidate, 560 }; 561 562 /* ------------------------------------------------------------------ */ 563 564 static int gntdev_open(struct inode *inode, struct file *flip) 565 { 566 struct gntdev_priv *priv; 567 568 priv = kzalloc(sizeof(*priv), GFP_KERNEL); 569 if (!priv) 570 return -ENOMEM; 571 572 INIT_LIST_HEAD(&priv->maps); 573 mutex_init(&priv->lock); 574 575 #ifdef CONFIG_XEN_GNTDEV_DMABUF 576 priv->dmabuf_priv = gntdev_dmabuf_init(flip); 577 if (IS_ERR(priv->dmabuf_priv)) { 578 int ret = PTR_ERR(priv->dmabuf_priv); 579 580 kfree(priv); 581 return ret; 582 } 583 #endif 584 585 flip->private_data = priv; 586 #ifdef CONFIG_XEN_GRANT_DMA_ALLOC 587 priv->dma_dev = gntdev_miscdev.this_device; 588 dma_coerce_mask_and_coherent(priv->dma_dev, DMA_BIT_MASK(64)); 589 #endif 590 pr_debug("priv %p\n", priv); 591 592 return 0; 593 } 594 595 static int gntdev_release(struct inode *inode, struct file *flip) 596 { 597 struct gntdev_priv *priv = flip->private_data; 598 struct gntdev_grant_map *map; 599 600 pr_debug("priv %p\n", priv); 601 602 mutex_lock(&priv->lock); 603 while (!list_empty(&priv->maps)) { 604 map = list_entry(priv->maps.next, 605 struct gntdev_grant_map, next); 606 list_del(&map->next); 607 gntdev_put_map(NULL /* already removed */, map); 608 } 609 mutex_unlock(&priv->lock); 610 611 #ifdef CONFIG_XEN_GNTDEV_DMABUF 612 gntdev_dmabuf_fini(priv->dmabuf_priv); 613 #endif 614 615 kfree(priv); 616 return 0; 617 } 618 619 static long gntdev_ioctl_map_grant_ref(struct gntdev_priv *priv, 620 struct ioctl_gntdev_map_grant_ref __user *u) 621 { 622 struct ioctl_gntdev_map_grant_ref op; 623 struct gntdev_grant_map *map; 624 int err; 625 626 if (copy_from_user(&op, u, sizeof(op)) != 0) 627 return -EFAULT; 628 pr_debug("priv %p, add %d\n", priv, op.count); 629 if (unlikely(gntdev_test_page_count(op.count))) 630 return -EINVAL; 631 632 err = -ENOMEM; 633 map = gntdev_alloc_map(priv, op.count, 0 /* This is not a dma-buf. */); 634 if (!map) 635 return err; 636 637 if (copy_from_user(map->grants, &u->refs, 638 sizeof(map->grants[0]) * op.count) != 0) { 639 gntdev_put_map(NULL, map); 640 return -EFAULT; 641 } 642 643 mutex_lock(&priv->lock); 644 gntdev_add_map(priv, map); 645 op.index = map->index << PAGE_SHIFT; 646 mutex_unlock(&priv->lock); 647 648 if (copy_to_user(u, &op, sizeof(op)) != 0) 649 return -EFAULT; 650 651 return 0; 652 } 653 654 static long gntdev_ioctl_unmap_grant_ref(struct gntdev_priv *priv, 655 struct ioctl_gntdev_unmap_grant_ref __user *u) 656 { 657 struct ioctl_gntdev_unmap_grant_ref op; 658 struct gntdev_grant_map *map; 659 int err = -ENOENT; 660 661 if (copy_from_user(&op, u, sizeof(op)) != 0) 662 return -EFAULT; 663 pr_debug("priv %p, del %d+%d\n", priv, (int)op.index, (int)op.count); 664 665 mutex_lock(&priv->lock); 666 map = gntdev_find_map_index(priv, op.index >> PAGE_SHIFT, op.count); 667 if (map) { 668 list_del(&map->next); 669 err = 0; 670 } 671 mutex_unlock(&priv->lock); 672 if (map) 673 gntdev_put_map(priv, map); 674 return err; 675 } 676 677 static long gntdev_ioctl_get_offset_for_vaddr(struct gntdev_priv *priv, 678 struct ioctl_gntdev_get_offset_for_vaddr __user *u) 679 { 680 struct ioctl_gntdev_get_offset_for_vaddr op; 681 struct vm_area_struct *vma; 682 struct gntdev_grant_map *map; 683 int rv = -EINVAL; 684 685 if (copy_from_user(&op, u, sizeof(op)) != 0) 686 return -EFAULT; 687 pr_debug("priv %p, offset for vaddr %lx\n", priv, (unsigned long)op.vaddr); 688 689 mmap_read_lock(current->mm); 690 vma = find_vma(current->mm, op.vaddr); 691 if (!vma || vma->vm_ops != &gntdev_vmops) 692 goto out_unlock; 693 694 map = vma->vm_private_data; 695 if (!map) 696 goto out_unlock; 697 698 op.offset = map->index << PAGE_SHIFT; 699 op.count = map->count; 700 rv = 0; 701 702 out_unlock: 703 mmap_read_unlock(current->mm); 704 705 if (rv == 0 && copy_to_user(u, &op, sizeof(op)) != 0) 706 return -EFAULT; 707 return rv; 708 } 709 710 static long gntdev_ioctl_notify(struct gntdev_priv *priv, void __user *u) 711 { 712 struct ioctl_gntdev_unmap_notify op; 713 struct gntdev_grant_map *map; 714 int rc; 715 int out_flags; 716 evtchn_port_t out_event; 717 718 if (copy_from_user(&op, u, sizeof(op))) 719 return -EFAULT; 720 721 if (op.action & ~(UNMAP_NOTIFY_CLEAR_BYTE|UNMAP_NOTIFY_SEND_EVENT)) 722 return -EINVAL; 723 724 /* We need to grab a reference to the event channel we are going to use 725 * to send the notify before releasing the reference we may already have 726 * (if someone has called this ioctl twice). This is required so that 727 * it is possible to change the clear_byte part of the notification 728 * without disturbing the event channel part, which may now be the last 729 * reference to that event channel. 730 */ 731 if (op.action & UNMAP_NOTIFY_SEND_EVENT) { 732 if (evtchn_get(op.event_channel_port)) 733 return -EINVAL; 734 } 735 736 out_flags = op.action; 737 out_event = op.event_channel_port; 738 739 mutex_lock(&priv->lock); 740 741 list_for_each_entry(map, &priv->maps, next) { 742 uint64_t begin = map->index << PAGE_SHIFT; 743 uint64_t end = (map->index + map->count) << PAGE_SHIFT; 744 if (op.index >= begin && op.index < end) 745 goto found; 746 } 747 rc = -ENOENT; 748 goto unlock_out; 749 750 found: 751 if ((op.action & UNMAP_NOTIFY_CLEAR_BYTE) && 752 (map->flags & GNTMAP_readonly)) { 753 rc = -EINVAL; 754 goto unlock_out; 755 } 756 757 out_flags = map->notify.flags; 758 out_event = map->notify.event; 759 760 map->notify.flags = op.action; 761 map->notify.addr = op.index - (map->index << PAGE_SHIFT); 762 map->notify.event = op.event_channel_port; 763 764 rc = 0; 765 766 unlock_out: 767 mutex_unlock(&priv->lock); 768 769 /* Drop the reference to the event channel we did not save in the map */ 770 if (out_flags & UNMAP_NOTIFY_SEND_EVENT) 771 evtchn_put(out_event); 772 773 return rc; 774 } 775 776 #define GNTDEV_COPY_BATCH 16 777 778 struct gntdev_copy_batch { 779 struct gnttab_copy ops[GNTDEV_COPY_BATCH]; 780 struct page *pages[GNTDEV_COPY_BATCH]; 781 s16 __user *status[GNTDEV_COPY_BATCH]; 782 unsigned int nr_ops; 783 unsigned int nr_pages; 784 bool writeable; 785 }; 786 787 static int gntdev_get_page(struct gntdev_copy_batch *batch, void __user *virt, 788 unsigned long *gfn) 789 { 790 unsigned long addr = (unsigned long)virt; 791 struct page *page; 792 unsigned long xen_pfn; 793 int ret; 794 795 ret = pin_user_pages_fast(addr, 1, batch->writeable ? FOLL_WRITE : 0, &page); 796 if (ret < 0) 797 return ret; 798 799 batch->pages[batch->nr_pages++] = page; 800 801 xen_pfn = page_to_xen_pfn(page) + XEN_PFN_DOWN(addr & ~PAGE_MASK); 802 *gfn = pfn_to_gfn(xen_pfn); 803 804 return 0; 805 } 806 807 static void gntdev_put_pages(struct gntdev_copy_batch *batch) 808 { 809 unpin_user_pages_dirty_lock(batch->pages, batch->nr_pages, batch->writeable); 810 batch->nr_pages = 0; 811 batch->writeable = false; 812 } 813 814 static int gntdev_copy(struct gntdev_copy_batch *batch) 815 { 816 unsigned int i; 817 818 gnttab_batch_copy(batch->ops, batch->nr_ops); 819 gntdev_put_pages(batch); 820 821 /* 822 * For each completed op, update the status if the op failed 823 * and all previous ops for the segment were successful. 824 */ 825 for (i = 0; i < batch->nr_ops; i++) { 826 s16 status = batch->ops[i].status; 827 s16 old_status; 828 829 if (status == GNTST_okay) 830 continue; 831 832 if (__get_user(old_status, batch->status[i])) 833 return -EFAULT; 834 835 if (old_status != GNTST_okay) 836 continue; 837 838 if (__put_user(status, batch->status[i])) 839 return -EFAULT; 840 } 841 842 batch->nr_ops = 0; 843 return 0; 844 } 845 846 static int gntdev_grant_copy_seg(struct gntdev_copy_batch *batch, 847 struct gntdev_grant_copy_segment *seg, 848 s16 __user *status) 849 { 850 uint16_t copied = 0; 851 852 /* 853 * Disallow local -> local copies since there is only space in 854 * batch->pages for one page per-op and this would be a very 855 * expensive memcpy(). 856 */ 857 if (!(seg->flags & (GNTCOPY_source_gref | GNTCOPY_dest_gref))) 858 return -EINVAL; 859 860 /* Can't cross page if source/dest is a grant ref. */ 861 if (seg->flags & GNTCOPY_source_gref) { 862 if (seg->source.foreign.offset + seg->len > XEN_PAGE_SIZE) 863 return -EINVAL; 864 } 865 if (seg->flags & GNTCOPY_dest_gref) { 866 if (seg->dest.foreign.offset + seg->len > XEN_PAGE_SIZE) 867 return -EINVAL; 868 } 869 870 if (put_user(GNTST_okay, status)) 871 return -EFAULT; 872 873 while (copied < seg->len) { 874 struct gnttab_copy *op; 875 void __user *virt; 876 size_t len, off; 877 unsigned long gfn; 878 int ret; 879 880 if (batch->nr_ops >= GNTDEV_COPY_BATCH) { 881 ret = gntdev_copy(batch); 882 if (ret < 0) 883 return ret; 884 } 885 886 len = seg->len - copied; 887 888 op = &batch->ops[batch->nr_ops]; 889 op->flags = 0; 890 891 if (seg->flags & GNTCOPY_source_gref) { 892 op->source.u.ref = seg->source.foreign.ref; 893 op->source.domid = seg->source.foreign.domid; 894 op->source.offset = seg->source.foreign.offset + copied; 895 op->flags |= GNTCOPY_source_gref; 896 } else { 897 virt = seg->source.virt + copied; 898 off = (unsigned long)virt & ~XEN_PAGE_MASK; 899 len = min(len, (size_t)XEN_PAGE_SIZE - off); 900 batch->writeable = false; 901 902 ret = gntdev_get_page(batch, virt, &gfn); 903 if (ret < 0) 904 return ret; 905 906 op->source.u.gmfn = gfn; 907 op->source.domid = DOMID_SELF; 908 op->source.offset = off; 909 } 910 911 if (seg->flags & GNTCOPY_dest_gref) { 912 op->dest.u.ref = seg->dest.foreign.ref; 913 op->dest.domid = seg->dest.foreign.domid; 914 op->dest.offset = seg->dest.foreign.offset + copied; 915 op->flags |= GNTCOPY_dest_gref; 916 } else { 917 virt = seg->dest.virt + copied; 918 off = (unsigned long)virt & ~XEN_PAGE_MASK; 919 len = min(len, (size_t)XEN_PAGE_SIZE - off); 920 batch->writeable = true; 921 922 ret = gntdev_get_page(batch, virt, &gfn); 923 if (ret < 0) 924 return ret; 925 926 op->dest.u.gmfn = gfn; 927 op->dest.domid = DOMID_SELF; 928 op->dest.offset = off; 929 } 930 931 op->len = len; 932 copied += len; 933 934 batch->status[batch->nr_ops] = status; 935 batch->nr_ops++; 936 } 937 938 return 0; 939 } 940 941 static long gntdev_ioctl_grant_copy(struct gntdev_priv *priv, void __user *u) 942 { 943 struct ioctl_gntdev_grant_copy copy; 944 struct gntdev_copy_batch batch; 945 unsigned int i; 946 int ret = 0; 947 948 if (copy_from_user(©, u, sizeof(copy))) 949 return -EFAULT; 950 951 batch.nr_ops = 0; 952 batch.nr_pages = 0; 953 954 for (i = 0; i < copy.count; i++) { 955 struct gntdev_grant_copy_segment seg; 956 957 if (copy_from_user(&seg, ©.segments[i], sizeof(seg))) { 958 ret = -EFAULT; 959 goto out; 960 } 961 962 ret = gntdev_grant_copy_seg(&batch, &seg, ©.segments[i].status); 963 if (ret < 0) 964 goto out; 965 966 cond_resched(); 967 } 968 if (batch.nr_ops) 969 ret = gntdev_copy(&batch); 970 return ret; 971 972 out: 973 gntdev_put_pages(&batch); 974 return ret; 975 } 976 977 static long gntdev_ioctl(struct file *flip, 978 unsigned int cmd, unsigned long arg) 979 { 980 struct gntdev_priv *priv = flip->private_data; 981 void __user *ptr = (void __user *)arg; 982 983 switch (cmd) { 984 case IOCTL_GNTDEV_MAP_GRANT_REF: 985 return gntdev_ioctl_map_grant_ref(priv, ptr); 986 987 case IOCTL_GNTDEV_UNMAP_GRANT_REF: 988 return gntdev_ioctl_unmap_grant_ref(priv, ptr); 989 990 case IOCTL_GNTDEV_GET_OFFSET_FOR_VADDR: 991 return gntdev_ioctl_get_offset_for_vaddr(priv, ptr); 992 993 case IOCTL_GNTDEV_SET_UNMAP_NOTIFY: 994 return gntdev_ioctl_notify(priv, ptr); 995 996 case IOCTL_GNTDEV_GRANT_COPY: 997 return gntdev_ioctl_grant_copy(priv, ptr); 998 999 #ifdef CONFIG_XEN_GNTDEV_DMABUF 1000 case IOCTL_GNTDEV_DMABUF_EXP_FROM_REFS: 1001 return gntdev_ioctl_dmabuf_exp_from_refs(priv, use_ptemod, ptr); 1002 1003 case IOCTL_GNTDEV_DMABUF_EXP_WAIT_RELEASED: 1004 return gntdev_ioctl_dmabuf_exp_wait_released(priv, ptr); 1005 1006 case IOCTL_GNTDEV_DMABUF_IMP_TO_REFS: 1007 return gntdev_ioctl_dmabuf_imp_to_refs(priv, ptr); 1008 1009 case IOCTL_GNTDEV_DMABUF_IMP_RELEASE: 1010 return gntdev_ioctl_dmabuf_imp_release(priv, ptr); 1011 #endif 1012 1013 default: 1014 pr_debug("priv %p, unknown cmd %x\n", priv, cmd); 1015 return -ENOIOCTLCMD; 1016 } 1017 1018 return 0; 1019 } 1020 1021 static int gntdev_mmap(struct file *flip, struct vm_area_struct *vma) 1022 { 1023 struct gntdev_priv *priv = flip->private_data; 1024 int index = vma->vm_pgoff; 1025 int count = vma_pages(vma); 1026 struct gntdev_grant_map *map; 1027 int err = -EINVAL; 1028 1029 if ((vma->vm_flags & VM_WRITE) && !(vma->vm_flags & VM_SHARED)) 1030 return -EINVAL; 1031 1032 pr_debug("map %d+%d at %lx (pgoff %lx)\n", 1033 index, count, vma->vm_start, vma->vm_pgoff); 1034 1035 mutex_lock(&priv->lock); 1036 map = gntdev_find_map_index(priv, index, count); 1037 if (!map) 1038 goto unlock_out; 1039 if (use_ptemod && map->vma) 1040 goto unlock_out; 1041 if (atomic_read(&map->live_grants)) { 1042 err = -EAGAIN; 1043 goto unlock_out; 1044 } 1045 refcount_inc(&map->users); 1046 1047 vma->vm_ops = &gntdev_vmops; 1048 1049 vma->vm_flags |= VM_DONTEXPAND | VM_DONTDUMP | VM_MIXEDMAP; 1050 1051 if (use_ptemod) 1052 vma->vm_flags |= VM_DONTCOPY; 1053 1054 vma->vm_private_data = map; 1055 if (map->flags) { 1056 if ((vma->vm_flags & VM_WRITE) && 1057 (map->flags & GNTMAP_readonly)) 1058 goto out_unlock_put; 1059 } else { 1060 map->flags = GNTMAP_host_map; 1061 if (!(vma->vm_flags & VM_WRITE)) 1062 map->flags |= GNTMAP_readonly; 1063 } 1064 1065 if (use_ptemod) { 1066 map->vma = vma; 1067 err = mmu_interval_notifier_insert_locked( 1068 &map->notifier, vma->vm_mm, vma->vm_start, 1069 vma->vm_end - vma->vm_start, &gntdev_mmu_ops); 1070 if (err) { 1071 map->vma = NULL; 1072 goto out_unlock_put; 1073 } 1074 } 1075 mutex_unlock(&priv->lock); 1076 1077 if (use_ptemod) { 1078 /* 1079 * gntdev takes the address of the PTE in find_grant_ptes() and 1080 * passes it to the hypervisor in gntdev_map_grant_pages(). The 1081 * purpose of the notifier is to prevent the hypervisor pointer 1082 * to the PTE from going stale. 1083 * 1084 * Since this vma's mappings can't be touched without the 1085 * mmap_lock, and we are holding it now, there is no need for 1086 * the notifier_range locking pattern. 1087 */ 1088 mmu_interval_read_begin(&map->notifier); 1089 1090 map->pages_vm_start = vma->vm_start; 1091 err = apply_to_page_range(vma->vm_mm, vma->vm_start, 1092 vma->vm_end - vma->vm_start, 1093 find_grant_ptes, map); 1094 if (err) { 1095 pr_warn("find_grant_ptes() failure.\n"); 1096 goto out_put_map; 1097 } 1098 } 1099 1100 err = gntdev_map_grant_pages(map); 1101 if (err) 1102 goto out_put_map; 1103 1104 if (!use_ptemod) { 1105 err = vm_map_pages_zero(vma, map->pages, map->count); 1106 if (err) 1107 goto out_put_map; 1108 } 1109 1110 return 0; 1111 1112 unlock_out: 1113 mutex_unlock(&priv->lock); 1114 return err; 1115 1116 out_unlock_put: 1117 mutex_unlock(&priv->lock); 1118 out_put_map: 1119 if (use_ptemod) { 1120 unmap_grant_pages(map, 0, map->count); 1121 if (map->vma) { 1122 mmu_interval_notifier_remove(&map->notifier); 1123 map->vma = NULL; 1124 } 1125 } 1126 gntdev_put_map(priv, map); 1127 return err; 1128 } 1129 1130 static const struct file_operations gntdev_fops = { 1131 .owner = THIS_MODULE, 1132 .open = gntdev_open, 1133 .release = gntdev_release, 1134 .mmap = gntdev_mmap, 1135 .unlocked_ioctl = gntdev_ioctl 1136 }; 1137 1138 static struct miscdevice gntdev_miscdev = { 1139 .minor = MISC_DYNAMIC_MINOR, 1140 .name = "xen/gntdev", 1141 .fops = &gntdev_fops, 1142 }; 1143 1144 /* ------------------------------------------------------------------ */ 1145 1146 static int __init gntdev_init(void) 1147 { 1148 int err; 1149 1150 if (!xen_domain()) 1151 return -ENODEV; 1152 1153 use_ptemod = !xen_feature(XENFEAT_auto_translated_physmap); 1154 1155 err = misc_register(&gntdev_miscdev); 1156 if (err != 0) { 1157 pr_err("Could not register gntdev device\n"); 1158 return err; 1159 } 1160 return 0; 1161 } 1162 1163 static void __exit gntdev_exit(void) 1164 { 1165 misc_deregister(&gntdev_miscdev); 1166 } 1167 1168 module_init(gntdev_init); 1169 module_exit(gntdev_exit); 1170 1171 /* ------------------------------------------------------------------ */ 1172