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 #define GNTDEV_COPY_BATCH 16 60 61 struct gntdev_copy_batch { 62 struct gnttab_copy ops[GNTDEV_COPY_BATCH]; 63 struct page *pages[GNTDEV_COPY_BATCH]; 64 s16 __user *status[GNTDEV_COPY_BATCH]; 65 unsigned int nr_ops; 66 unsigned int nr_pages; 67 bool writeable; 68 struct gntdev_copy_batch *next; 69 }; 70 71 static unsigned int limit = 64*1024; 72 module_param(limit, uint, 0644); 73 MODULE_PARM_DESC(limit, 74 "Maximum number of grants that may be mapped by one mapping request"); 75 76 /* True in PV mode, false otherwise */ 77 static int use_ptemod; 78 79 static void unmap_grant_pages(struct gntdev_grant_map *map, 80 int offset, int pages); 81 82 static struct miscdevice gntdev_miscdev; 83 84 /* ------------------------------------------------------------------ */ 85 86 bool gntdev_test_page_count(unsigned int count) 87 { 88 return !count || count > limit; 89 } 90 91 static void gntdev_print_maps(struct gntdev_priv *priv, 92 char *text, int text_index) 93 { 94 #ifdef DEBUG 95 struct gntdev_grant_map *map; 96 97 pr_debug("%s: maps list (priv %p)\n", __func__, priv); 98 list_for_each_entry(map, &priv->maps, next) 99 pr_debug(" index %2d, count %2d %s\n", 100 map->index, map->count, 101 map->index == text_index && text ? text : ""); 102 #endif 103 } 104 105 static void gntdev_free_map(struct gntdev_grant_map *map) 106 { 107 if (map == NULL) 108 return; 109 110 #ifdef CONFIG_XEN_GRANT_DMA_ALLOC 111 if (map->dma_vaddr) { 112 struct gnttab_dma_alloc_args args; 113 114 args.dev = map->dma_dev; 115 args.coherent = !!(map->dma_flags & GNTDEV_DMA_FLAG_COHERENT); 116 args.nr_pages = map->count; 117 args.pages = map->pages; 118 args.frames = map->frames; 119 args.vaddr = map->dma_vaddr; 120 args.dev_bus_addr = map->dma_bus_addr; 121 122 gnttab_dma_free_pages(&args); 123 } else 124 #endif 125 if (map->pages) 126 gnttab_free_pages(map->count, map->pages); 127 128 #ifdef CONFIG_XEN_GRANT_DMA_ALLOC 129 kvfree(map->frames); 130 #endif 131 kvfree(map->pages); 132 kvfree(map->grants); 133 kvfree(map->map_ops); 134 kvfree(map->unmap_ops); 135 kvfree(map->kmap_ops); 136 kvfree(map->kunmap_ops); 137 kvfree(map->being_removed); 138 kfree(map); 139 } 140 141 struct gntdev_grant_map *gntdev_alloc_map(struct gntdev_priv *priv, int count, 142 int dma_flags) 143 { 144 struct gntdev_grant_map *add; 145 int i; 146 147 add = kzalloc(sizeof(*add), GFP_KERNEL); 148 if (NULL == add) 149 return NULL; 150 151 add->grants = kvmalloc_array(count, sizeof(add->grants[0]), 152 GFP_KERNEL); 153 add->map_ops = kvmalloc_array(count, sizeof(add->map_ops[0]), 154 GFP_KERNEL); 155 add->unmap_ops = kvmalloc_array(count, sizeof(add->unmap_ops[0]), 156 GFP_KERNEL); 157 add->pages = kvcalloc(count, sizeof(add->pages[0]), GFP_KERNEL); 158 add->being_removed = 159 kvcalloc(count, sizeof(add->being_removed[0]), GFP_KERNEL); 160 if (NULL == add->grants || 161 NULL == add->map_ops || 162 NULL == add->unmap_ops || 163 NULL == add->pages || 164 NULL == add->being_removed) 165 goto err; 166 if (use_ptemod) { 167 add->kmap_ops = kvmalloc_array(count, sizeof(add->kmap_ops[0]), 168 GFP_KERNEL); 169 add->kunmap_ops = kvmalloc_array(count, sizeof(add->kunmap_ops[0]), 170 GFP_KERNEL); 171 if (NULL == add->kmap_ops || NULL == add->kunmap_ops) 172 goto err; 173 } 174 175 #ifdef CONFIG_XEN_GRANT_DMA_ALLOC 176 add->dma_flags = dma_flags; 177 178 /* 179 * Check if this mapping is requested to be backed 180 * by a DMA buffer. 181 */ 182 if (dma_flags & (GNTDEV_DMA_FLAG_WC | GNTDEV_DMA_FLAG_COHERENT)) { 183 struct gnttab_dma_alloc_args args; 184 185 add->frames = kvcalloc(count, sizeof(add->frames[0]), 186 GFP_KERNEL); 187 if (!add->frames) 188 goto err; 189 190 /* Remember the device, so we can free DMA memory. */ 191 add->dma_dev = priv->dma_dev; 192 193 args.dev = priv->dma_dev; 194 args.coherent = !!(dma_flags & GNTDEV_DMA_FLAG_COHERENT); 195 args.nr_pages = count; 196 args.pages = add->pages; 197 args.frames = add->frames; 198 199 if (gnttab_dma_alloc_pages(&args)) 200 goto err; 201 202 add->dma_vaddr = args.vaddr; 203 add->dma_bus_addr = args.dev_bus_addr; 204 } else 205 #endif 206 if (gnttab_alloc_pages(count, add->pages)) 207 goto err; 208 209 for (i = 0; i < count; i++) { 210 add->grants[i].domid = DOMID_INVALID; 211 add->grants[i].ref = INVALID_GRANT_REF; 212 add->map_ops[i].handle = INVALID_GRANT_HANDLE; 213 add->unmap_ops[i].handle = INVALID_GRANT_HANDLE; 214 if (use_ptemod) { 215 add->kmap_ops[i].handle = INVALID_GRANT_HANDLE; 216 add->kunmap_ops[i].handle = INVALID_GRANT_HANDLE; 217 } 218 } 219 220 add->index = 0; 221 add->count = count; 222 refcount_set(&add->users, 1); 223 224 return add; 225 226 err: 227 gntdev_free_map(add); 228 return NULL; 229 } 230 231 void gntdev_add_map(struct gntdev_priv *priv, struct gntdev_grant_map *add) 232 { 233 struct gntdev_grant_map *map; 234 235 list_for_each_entry(map, &priv->maps, next) { 236 if (add->index + add->count < map->index) { 237 list_add_tail(&add->next, &map->next); 238 goto done; 239 } 240 add->index = map->index + map->count; 241 } 242 list_add_tail(&add->next, &priv->maps); 243 244 done: 245 gntdev_print_maps(priv, "[new]", add->index); 246 } 247 248 static struct gntdev_grant_map *gntdev_find_map_index(struct gntdev_priv *priv, 249 int index, int count) 250 { 251 struct gntdev_grant_map *map; 252 253 list_for_each_entry(map, &priv->maps, next) { 254 if (map->index != index) 255 continue; 256 if (count && map->count != count) 257 continue; 258 return map; 259 } 260 return NULL; 261 } 262 263 void gntdev_put_map(struct gntdev_priv *priv, struct gntdev_grant_map *map) 264 { 265 if (!map) 266 return; 267 268 if (!refcount_dec_and_test(&map->users)) 269 return; 270 271 if (map->pages && !use_ptemod) { 272 /* 273 * Increment the reference count. This ensures that the 274 * subsequent call to unmap_grant_pages() will not wind up 275 * re-entering itself. It *can* wind up calling 276 * gntdev_put_map() recursively, but such calls will be with a 277 * reference count greater than 1, so they will return before 278 * this code is reached. The recursion depth is thus limited to 279 * 1. Do NOT use refcount_inc() here, as it will detect that 280 * the reference count is zero and WARN(). 281 */ 282 refcount_set(&map->users, 1); 283 284 /* 285 * Unmap the grants. This may or may not be asynchronous, so it 286 * is possible that the reference count is 1 on return, but it 287 * could also be greater than 1. 288 */ 289 unmap_grant_pages(map, 0, map->count); 290 291 /* Check if the memory now needs to be freed */ 292 if (!refcount_dec_and_test(&map->users)) 293 return; 294 295 /* 296 * All pages have been returned to the hypervisor, so free the 297 * map. 298 */ 299 } 300 301 if (use_ptemod && map->notifier_init) 302 mmu_interval_notifier_remove(&map->notifier); 303 304 if (map->notify.flags & UNMAP_NOTIFY_SEND_EVENT) { 305 notify_remote_via_evtchn(map->notify.event); 306 evtchn_put(map->notify.event); 307 } 308 gntdev_free_map(map); 309 } 310 311 /* ------------------------------------------------------------------ */ 312 313 static int find_grant_ptes(pte_t *pte, unsigned long addr, void *data) 314 { 315 struct gntdev_grant_map *map = data; 316 unsigned int pgnr = (addr - map->pages_vm_start) >> PAGE_SHIFT; 317 int flags = map->flags | GNTMAP_application_map | GNTMAP_contains_pte | 318 (1 << _GNTMAP_guest_avail0); 319 u64 pte_maddr; 320 321 BUG_ON(pgnr >= map->count); 322 pte_maddr = arbitrary_virt_to_machine(pte).maddr; 323 324 gnttab_set_map_op(&map->map_ops[pgnr], pte_maddr, flags, 325 map->grants[pgnr].ref, 326 map->grants[pgnr].domid); 327 gnttab_set_unmap_op(&map->unmap_ops[pgnr], pte_maddr, flags, 328 INVALID_GRANT_HANDLE); 329 return 0; 330 } 331 332 int gntdev_map_grant_pages(struct gntdev_grant_map *map) 333 { 334 size_t alloced = 0; 335 int i, err = 0; 336 337 if (!use_ptemod) { 338 /* Note: it could already be mapped */ 339 if (map->map_ops[0].handle != INVALID_GRANT_HANDLE) 340 return 0; 341 for (i = 0; i < map->count; i++) { 342 unsigned long addr = (unsigned long) 343 pfn_to_kaddr(page_to_pfn(map->pages[i])); 344 gnttab_set_map_op(&map->map_ops[i], addr, map->flags, 345 map->grants[i].ref, 346 map->grants[i].domid); 347 gnttab_set_unmap_op(&map->unmap_ops[i], addr, 348 map->flags, INVALID_GRANT_HANDLE); 349 } 350 } else { 351 /* 352 * Setup the map_ops corresponding to the pte entries pointing 353 * to the kernel linear addresses of the struct pages. 354 * These ptes are completely different from the user ptes dealt 355 * with find_grant_ptes. 356 * Note that GNTMAP_device_map isn't needed here: The 357 * dev_bus_addr output field gets consumed only from ->map_ops, 358 * and by not requesting it when mapping we also avoid needing 359 * to mirror dev_bus_addr into ->unmap_ops (and holding an extra 360 * reference to the page in the hypervisor). 361 */ 362 unsigned int flags = (map->flags & ~GNTMAP_device_map) | 363 GNTMAP_host_map; 364 365 for (i = 0; i < map->count; i++) { 366 unsigned long address = (unsigned long) 367 pfn_to_kaddr(page_to_pfn(map->pages[i])); 368 BUG_ON(PageHighMem(map->pages[i])); 369 370 gnttab_set_map_op(&map->kmap_ops[i], address, flags, 371 map->grants[i].ref, 372 map->grants[i].domid); 373 gnttab_set_unmap_op(&map->kunmap_ops[i], address, 374 flags, INVALID_GRANT_HANDLE); 375 } 376 } 377 378 pr_debug("map %d+%d\n", map->index, map->count); 379 err = gnttab_map_refs(map->map_ops, map->kmap_ops, map->pages, 380 map->count); 381 382 for (i = 0; i < map->count; i++) { 383 if (map->map_ops[i].status == GNTST_okay) { 384 map->unmap_ops[i].handle = map->map_ops[i].handle; 385 alloced++; 386 } else if (!err) 387 err = -EINVAL; 388 389 if (map->flags & GNTMAP_device_map) 390 map->unmap_ops[i].dev_bus_addr = map->map_ops[i].dev_bus_addr; 391 392 if (use_ptemod) { 393 if (map->kmap_ops[i].status == GNTST_okay) { 394 alloced++; 395 map->kunmap_ops[i].handle = map->kmap_ops[i].handle; 396 } else if (!err) 397 err = -EINVAL; 398 } 399 } 400 atomic_add(alloced, &map->live_grants); 401 return err; 402 } 403 404 static void __unmap_grant_pages_done(int result, 405 struct gntab_unmap_queue_data *data) 406 { 407 unsigned int i; 408 struct gntdev_grant_map *map = data->data; 409 unsigned int offset = data->unmap_ops - map->unmap_ops; 410 int successful_unmaps = 0; 411 int live_grants; 412 413 for (i = 0; i < data->count; i++) { 414 if (map->unmap_ops[offset + i].status == GNTST_okay && 415 map->unmap_ops[offset + i].handle != INVALID_GRANT_HANDLE) 416 successful_unmaps++; 417 418 WARN_ON(map->unmap_ops[offset + i].status != GNTST_okay && 419 map->unmap_ops[offset + i].handle != INVALID_GRANT_HANDLE); 420 pr_debug("unmap handle=%d st=%d\n", 421 map->unmap_ops[offset+i].handle, 422 map->unmap_ops[offset+i].status); 423 map->unmap_ops[offset+i].handle = INVALID_GRANT_HANDLE; 424 if (use_ptemod) { 425 if (map->kunmap_ops[offset + i].status == GNTST_okay && 426 map->kunmap_ops[offset + i].handle != INVALID_GRANT_HANDLE) 427 successful_unmaps++; 428 429 WARN_ON(map->kunmap_ops[offset + i].status != GNTST_okay && 430 map->kunmap_ops[offset + i].handle != INVALID_GRANT_HANDLE); 431 pr_debug("kunmap handle=%u st=%d\n", 432 map->kunmap_ops[offset+i].handle, 433 map->kunmap_ops[offset+i].status); 434 map->kunmap_ops[offset+i].handle = INVALID_GRANT_HANDLE; 435 } 436 } 437 438 /* 439 * Decrease the live-grant counter. This must happen after the loop to 440 * prevent premature reuse of the grants by gnttab_mmap(). 441 */ 442 live_grants = atomic_sub_return(successful_unmaps, &map->live_grants); 443 if (WARN_ON(live_grants < 0)) 444 pr_err("%s: live_grants became negative (%d) after unmapping %d pages!\n", 445 __func__, live_grants, successful_unmaps); 446 447 /* Release reference taken by __unmap_grant_pages */ 448 gntdev_put_map(NULL, map); 449 } 450 451 static void __unmap_grant_pages(struct gntdev_grant_map *map, int offset, 452 int pages) 453 { 454 if (map->notify.flags & UNMAP_NOTIFY_CLEAR_BYTE) { 455 int pgno = (map->notify.addr >> PAGE_SHIFT); 456 457 if (pgno >= offset && pgno < offset + pages) { 458 /* No need for kmap, pages are in lowmem */ 459 uint8_t *tmp = pfn_to_kaddr(page_to_pfn(map->pages[pgno])); 460 461 tmp[map->notify.addr & (PAGE_SIZE-1)] = 0; 462 map->notify.flags &= ~UNMAP_NOTIFY_CLEAR_BYTE; 463 } 464 } 465 466 map->unmap_data.unmap_ops = map->unmap_ops + offset; 467 map->unmap_data.kunmap_ops = use_ptemod ? map->kunmap_ops + offset : NULL; 468 map->unmap_data.pages = map->pages + offset; 469 map->unmap_data.count = pages; 470 map->unmap_data.done = __unmap_grant_pages_done; 471 map->unmap_data.data = map; 472 refcount_inc(&map->users); /* to keep map alive during async call below */ 473 474 gnttab_unmap_refs_async(&map->unmap_data); 475 } 476 477 static void unmap_grant_pages(struct gntdev_grant_map *map, int offset, 478 int pages) 479 { 480 int range; 481 482 if (atomic_read(&map->live_grants) == 0) 483 return; /* Nothing to do */ 484 485 pr_debug("unmap %d+%d [%d+%d]\n", map->index, map->count, offset, pages); 486 487 /* It is possible the requested range will have a "hole" where we 488 * already unmapped some of the grants. Only unmap valid ranges. 489 */ 490 while (pages) { 491 while (pages && map->being_removed[offset]) { 492 offset++; 493 pages--; 494 } 495 range = 0; 496 while (range < pages) { 497 if (map->being_removed[offset + range]) 498 break; 499 map->being_removed[offset + range] = true; 500 range++; 501 } 502 if (range) 503 __unmap_grant_pages(map, offset, range); 504 offset += range; 505 pages -= range; 506 } 507 } 508 509 /* ------------------------------------------------------------------ */ 510 511 static void gntdev_vma_open(struct vm_area_struct *vma) 512 { 513 struct gntdev_grant_map *map = vma->vm_private_data; 514 515 pr_debug("gntdev_vma_open %p\n", vma); 516 refcount_inc(&map->users); 517 } 518 519 static void gntdev_vma_close(struct vm_area_struct *vma) 520 { 521 struct gntdev_grant_map *map = vma->vm_private_data; 522 struct file *file = vma->vm_file; 523 struct gntdev_priv *priv = file->private_data; 524 525 pr_debug("gntdev_vma_close %p\n", vma); 526 527 vma->vm_private_data = NULL; 528 gntdev_put_map(priv, map); 529 } 530 531 static struct page *gntdev_vma_find_special_page(struct vm_area_struct *vma, 532 unsigned long addr) 533 { 534 struct gntdev_grant_map *map = vma->vm_private_data; 535 536 return map->pages[(addr - map->pages_vm_start) >> PAGE_SHIFT]; 537 } 538 539 static const struct vm_operations_struct gntdev_vmops = { 540 .open = gntdev_vma_open, 541 .close = gntdev_vma_close, 542 .find_special_page = gntdev_vma_find_special_page, 543 }; 544 545 /* ------------------------------------------------------------------ */ 546 547 static bool gntdev_invalidate(struct mmu_interval_notifier *mn, 548 const struct mmu_notifier_range *range, 549 unsigned long cur_seq) 550 { 551 struct gntdev_grant_map *map = 552 container_of(mn, struct gntdev_grant_map, notifier); 553 unsigned long mstart, mend; 554 unsigned long map_start, map_end; 555 556 if (!mmu_notifier_range_blockable(range)) 557 return false; 558 559 map_start = map->pages_vm_start; 560 map_end = map->pages_vm_start + (map->count << PAGE_SHIFT); 561 562 /* 563 * If the VMA is split or otherwise changed the notifier is not 564 * updated, but we don't want to process VA's outside the modified 565 * VMA. FIXME: It would be much more understandable to just prevent 566 * modifying the VMA in the first place. 567 */ 568 if (map_start >= range->end || map_end <= range->start) 569 return true; 570 571 mstart = max(range->start, map_start); 572 mend = min(range->end, map_end); 573 pr_debug("map %d+%d (%lx %lx), range %lx %lx, mrange %lx %lx\n", 574 map->index, map->count, map_start, map_end, 575 range->start, range->end, mstart, mend); 576 unmap_grant_pages(map, (mstart - map_start) >> PAGE_SHIFT, 577 (mend - mstart) >> PAGE_SHIFT); 578 579 return true; 580 } 581 582 static const struct mmu_interval_notifier_ops gntdev_mmu_ops = { 583 .invalidate = gntdev_invalidate, 584 }; 585 586 /* ------------------------------------------------------------------ */ 587 588 static int gntdev_open(struct inode *inode, struct file *flip) 589 { 590 struct gntdev_priv *priv; 591 592 priv = kzalloc(sizeof(*priv), GFP_KERNEL); 593 if (!priv) 594 return -ENOMEM; 595 596 INIT_LIST_HEAD(&priv->maps); 597 mutex_init(&priv->lock); 598 599 mutex_init(&priv->batch_lock); 600 601 #ifdef CONFIG_XEN_GNTDEV_DMABUF 602 priv->dmabuf_priv = gntdev_dmabuf_init(flip); 603 if (IS_ERR(priv->dmabuf_priv)) { 604 int ret = PTR_ERR(priv->dmabuf_priv); 605 606 kfree(priv); 607 return ret; 608 } 609 #endif 610 611 flip->private_data = priv; 612 #ifdef CONFIG_XEN_GRANT_DMA_ALLOC 613 priv->dma_dev = gntdev_miscdev.this_device; 614 dma_coerce_mask_and_coherent(priv->dma_dev, DMA_BIT_MASK(64)); 615 #endif 616 pr_debug("priv %p\n", priv); 617 618 return 0; 619 } 620 621 static int gntdev_release(struct inode *inode, struct file *flip) 622 { 623 struct gntdev_priv *priv = flip->private_data; 624 struct gntdev_grant_map *map; 625 struct gntdev_copy_batch *batch; 626 627 pr_debug("priv %p\n", priv); 628 629 mutex_lock(&priv->lock); 630 while (!list_empty(&priv->maps)) { 631 map = list_entry(priv->maps.next, 632 struct gntdev_grant_map, next); 633 list_del(&map->next); 634 gntdev_put_map(NULL /* already removed */, map); 635 } 636 mutex_unlock(&priv->lock); 637 638 mutex_lock(&priv->batch_lock); 639 while (priv->batch) { 640 batch = priv->batch; 641 priv->batch = batch->next; 642 kfree(batch); 643 } 644 mutex_unlock(&priv->batch_lock); 645 646 #ifdef CONFIG_XEN_GNTDEV_DMABUF 647 gntdev_dmabuf_fini(priv->dmabuf_priv); 648 #endif 649 650 kfree(priv); 651 return 0; 652 } 653 654 static long gntdev_ioctl_map_grant_ref(struct gntdev_priv *priv, 655 struct ioctl_gntdev_map_grant_ref __user *u) 656 { 657 struct ioctl_gntdev_map_grant_ref op; 658 struct gntdev_grant_map *map; 659 int err; 660 661 if (copy_from_user(&op, u, sizeof(op)) != 0) 662 return -EFAULT; 663 pr_debug("priv %p, add %d\n", priv, op.count); 664 if (unlikely(gntdev_test_page_count(op.count))) 665 return -EINVAL; 666 667 err = -ENOMEM; 668 map = gntdev_alloc_map(priv, op.count, 0 /* This is not a dma-buf. */); 669 if (!map) 670 return err; 671 672 if (copy_from_user(map->grants, &u->refs, 673 sizeof(map->grants[0]) * op.count) != 0) { 674 gntdev_put_map(NULL, map); 675 return -EFAULT; 676 } 677 678 mutex_lock(&priv->lock); 679 gntdev_add_map(priv, map); 680 op.index = map->index << PAGE_SHIFT; 681 mutex_unlock(&priv->lock); 682 683 if (copy_to_user(u, &op, sizeof(op)) != 0) 684 return -EFAULT; 685 686 return 0; 687 } 688 689 static long gntdev_ioctl_unmap_grant_ref(struct gntdev_priv *priv, 690 struct ioctl_gntdev_unmap_grant_ref __user *u) 691 { 692 struct ioctl_gntdev_unmap_grant_ref op; 693 struct gntdev_grant_map *map; 694 int err = -ENOENT; 695 696 if (copy_from_user(&op, u, sizeof(op)) != 0) 697 return -EFAULT; 698 pr_debug("priv %p, del %d+%d\n", priv, (int)op.index, (int)op.count); 699 700 mutex_lock(&priv->lock); 701 map = gntdev_find_map_index(priv, op.index >> PAGE_SHIFT, op.count); 702 if (map) { 703 list_del(&map->next); 704 err = 0; 705 } 706 mutex_unlock(&priv->lock); 707 if (map) 708 gntdev_put_map(priv, map); 709 return err; 710 } 711 712 static long gntdev_ioctl_get_offset_for_vaddr(struct gntdev_priv *priv, 713 struct ioctl_gntdev_get_offset_for_vaddr __user *u) 714 { 715 struct ioctl_gntdev_get_offset_for_vaddr op; 716 struct vm_area_struct *vma; 717 struct gntdev_grant_map *map; 718 int rv = -EINVAL; 719 720 if (copy_from_user(&op, u, sizeof(op)) != 0) 721 return -EFAULT; 722 pr_debug("priv %p, offset for vaddr %lx\n", priv, (unsigned long)op.vaddr); 723 724 mmap_read_lock(current->mm); 725 vma = find_vma(current->mm, op.vaddr); 726 if (!vma || vma->vm_ops != &gntdev_vmops) 727 goto out_unlock; 728 729 map = vma->vm_private_data; 730 if (!map) 731 goto out_unlock; 732 733 op.offset = map->index << PAGE_SHIFT; 734 op.count = map->count; 735 rv = 0; 736 737 out_unlock: 738 mmap_read_unlock(current->mm); 739 740 if (rv == 0 && copy_to_user(u, &op, sizeof(op)) != 0) 741 return -EFAULT; 742 return rv; 743 } 744 745 static long gntdev_ioctl_notify(struct gntdev_priv *priv, void __user *u) 746 { 747 struct ioctl_gntdev_unmap_notify op; 748 struct gntdev_grant_map *map; 749 int rc; 750 int out_flags; 751 evtchn_port_t out_event; 752 753 if (copy_from_user(&op, u, sizeof(op))) 754 return -EFAULT; 755 756 if (op.action & ~(UNMAP_NOTIFY_CLEAR_BYTE|UNMAP_NOTIFY_SEND_EVENT)) 757 return -EINVAL; 758 759 /* We need to grab a reference to the event channel we are going to use 760 * to send the notify before releasing the reference we may already have 761 * (if someone has called this ioctl twice). This is required so that 762 * it is possible to change the clear_byte part of the notification 763 * without disturbing the event channel part, which may now be the last 764 * reference to that event channel. 765 */ 766 if (op.action & UNMAP_NOTIFY_SEND_EVENT) { 767 if (evtchn_get(op.event_channel_port)) 768 return -EINVAL; 769 } 770 771 out_flags = op.action; 772 out_event = op.event_channel_port; 773 774 mutex_lock(&priv->lock); 775 776 list_for_each_entry(map, &priv->maps, next) { 777 uint64_t begin = map->index << PAGE_SHIFT; 778 uint64_t end = (map->index + map->count) << PAGE_SHIFT; 779 if (op.index >= begin && op.index < end) 780 goto found; 781 } 782 rc = -ENOENT; 783 goto unlock_out; 784 785 found: 786 if ((op.action & UNMAP_NOTIFY_CLEAR_BYTE) && 787 (map->flags & GNTMAP_readonly)) { 788 rc = -EINVAL; 789 goto unlock_out; 790 } 791 792 out_flags = map->notify.flags; 793 out_event = map->notify.event; 794 795 map->notify.flags = op.action; 796 map->notify.addr = op.index - (map->index << PAGE_SHIFT); 797 map->notify.event = op.event_channel_port; 798 799 rc = 0; 800 801 unlock_out: 802 mutex_unlock(&priv->lock); 803 804 /* Drop the reference to the event channel we did not save in the map */ 805 if (out_flags & UNMAP_NOTIFY_SEND_EVENT) 806 evtchn_put(out_event); 807 808 return rc; 809 } 810 811 static int gntdev_get_page(struct gntdev_copy_batch *batch, void __user *virt, 812 unsigned long *gfn) 813 { 814 unsigned long addr = (unsigned long)virt; 815 struct page *page; 816 unsigned long xen_pfn; 817 int ret; 818 819 ret = pin_user_pages_fast(addr, 1, batch->writeable ? FOLL_WRITE : 0, &page); 820 if (ret < 0) 821 return ret; 822 823 batch->pages[batch->nr_pages++] = page; 824 825 xen_pfn = page_to_xen_pfn(page) + XEN_PFN_DOWN(addr & ~PAGE_MASK); 826 *gfn = pfn_to_gfn(xen_pfn); 827 828 return 0; 829 } 830 831 static void gntdev_put_pages(struct gntdev_copy_batch *batch) 832 { 833 unpin_user_pages_dirty_lock(batch->pages, batch->nr_pages, batch->writeable); 834 batch->nr_pages = 0; 835 batch->writeable = false; 836 } 837 838 static int gntdev_copy(struct gntdev_copy_batch *batch) 839 { 840 unsigned int i; 841 842 gnttab_batch_copy(batch->ops, batch->nr_ops); 843 gntdev_put_pages(batch); 844 845 /* 846 * For each completed op, update the status if the op failed 847 * and all previous ops for the segment were successful. 848 */ 849 for (i = 0; i < batch->nr_ops; i++) { 850 s16 status = batch->ops[i].status; 851 s16 old_status; 852 853 if (status == GNTST_okay) 854 continue; 855 856 if (__get_user(old_status, batch->status[i])) 857 return -EFAULT; 858 859 if (old_status != GNTST_okay) 860 continue; 861 862 if (__put_user(status, batch->status[i])) 863 return -EFAULT; 864 } 865 866 batch->nr_ops = 0; 867 return 0; 868 } 869 870 static int gntdev_grant_copy_seg(struct gntdev_copy_batch *batch, 871 struct gntdev_grant_copy_segment *seg, 872 s16 __user *status) 873 { 874 uint16_t copied = 0; 875 876 /* 877 * Disallow local -> local copies since there is only space in 878 * batch->pages for one page per-op and this would be a very 879 * expensive memcpy(). 880 */ 881 if (!(seg->flags & (GNTCOPY_source_gref | GNTCOPY_dest_gref))) 882 return -EINVAL; 883 884 /* Can't cross page if source/dest is a grant ref. */ 885 if (seg->flags & GNTCOPY_source_gref) { 886 if (seg->source.foreign.offset + seg->len > XEN_PAGE_SIZE) 887 return -EINVAL; 888 } 889 if (seg->flags & GNTCOPY_dest_gref) { 890 if (seg->dest.foreign.offset + seg->len > XEN_PAGE_SIZE) 891 return -EINVAL; 892 } 893 894 if (put_user(GNTST_okay, status)) 895 return -EFAULT; 896 897 while (copied < seg->len) { 898 struct gnttab_copy *op; 899 void __user *virt; 900 size_t len, off; 901 unsigned long gfn; 902 int ret; 903 904 if (batch->nr_ops >= GNTDEV_COPY_BATCH) { 905 ret = gntdev_copy(batch); 906 if (ret < 0) 907 return ret; 908 } 909 910 len = seg->len - copied; 911 912 op = &batch->ops[batch->nr_ops]; 913 op->flags = 0; 914 915 if (seg->flags & GNTCOPY_source_gref) { 916 op->source.u.ref = seg->source.foreign.ref; 917 op->source.domid = seg->source.foreign.domid; 918 op->source.offset = seg->source.foreign.offset + copied; 919 op->flags |= GNTCOPY_source_gref; 920 } else { 921 virt = seg->source.virt + copied; 922 off = (unsigned long)virt & ~XEN_PAGE_MASK; 923 len = min(len, (size_t)XEN_PAGE_SIZE - off); 924 batch->writeable = false; 925 926 ret = gntdev_get_page(batch, virt, &gfn); 927 if (ret < 0) 928 return ret; 929 930 op->source.u.gmfn = gfn; 931 op->source.domid = DOMID_SELF; 932 op->source.offset = off; 933 } 934 935 if (seg->flags & GNTCOPY_dest_gref) { 936 op->dest.u.ref = seg->dest.foreign.ref; 937 op->dest.domid = seg->dest.foreign.domid; 938 op->dest.offset = seg->dest.foreign.offset + copied; 939 op->flags |= GNTCOPY_dest_gref; 940 } else { 941 virt = seg->dest.virt + copied; 942 off = (unsigned long)virt & ~XEN_PAGE_MASK; 943 len = min(len, (size_t)XEN_PAGE_SIZE - off); 944 batch->writeable = true; 945 946 ret = gntdev_get_page(batch, virt, &gfn); 947 if (ret < 0) 948 return ret; 949 950 op->dest.u.gmfn = gfn; 951 op->dest.domid = DOMID_SELF; 952 op->dest.offset = off; 953 } 954 955 op->len = len; 956 copied += len; 957 958 batch->status[batch->nr_ops] = status; 959 batch->nr_ops++; 960 } 961 962 return 0; 963 } 964 965 static long gntdev_ioctl_grant_copy(struct gntdev_priv *priv, void __user *u) 966 { 967 struct ioctl_gntdev_grant_copy copy; 968 struct gntdev_copy_batch *batch; 969 unsigned int i; 970 int ret = 0; 971 972 if (copy_from_user(©, u, sizeof(copy))) 973 return -EFAULT; 974 975 mutex_lock(&priv->batch_lock); 976 if (!priv->batch) { 977 batch = kmalloc(sizeof(*batch), GFP_KERNEL); 978 } else { 979 batch = priv->batch; 980 priv->batch = batch->next; 981 } 982 mutex_unlock(&priv->batch_lock); 983 if (!batch) 984 return -ENOMEM; 985 986 batch->nr_ops = 0; 987 batch->nr_pages = 0; 988 989 for (i = 0; i < copy.count; i++) { 990 struct gntdev_grant_copy_segment seg; 991 992 if (copy_from_user(&seg, ©.segments[i], sizeof(seg))) { 993 ret = -EFAULT; 994 gntdev_put_pages(batch); 995 goto out; 996 } 997 998 ret = gntdev_grant_copy_seg(batch, &seg, ©.segments[i].status); 999 if (ret < 0) { 1000 gntdev_put_pages(batch); 1001 goto out; 1002 } 1003 1004 cond_resched(); 1005 } 1006 if (batch->nr_ops) 1007 ret = gntdev_copy(batch); 1008 1009 out: 1010 mutex_lock(&priv->batch_lock); 1011 batch->next = priv->batch; 1012 priv->batch = batch; 1013 mutex_unlock(&priv->batch_lock); 1014 1015 return ret; 1016 } 1017 1018 static long gntdev_ioctl(struct file *flip, 1019 unsigned int cmd, unsigned long arg) 1020 { 1021 struct gntdev_priv *priv = flip->private_data; 1022 void __user *ptr = (void __user *)arg; 1023 1024 switch (cmd) { 1025 case IOCTL_GNTDEV_MAP_GRANT_REF: 1026 return gntdev_ioctl_map_grant_ref(priv, ptr); 1027 1028 case IOCTL_GNTDEV_UNMAP_GRANT_REF: 1029 return gntdev_ioctl_unmap_grant_ref(priv, ptr); 1030 1031 case IOCTL_GNTDEV_GET_OFFSET_FOR_VADDR: 1032 return gntdev_ioctl_get_offset_for_vaddr(priv, ptr); 1033 1034 case IOCTL_GNTDEV_SET_UNMAP_NOTIFY: 1035 return gntdev_ioctl_notify(priv, ptr); 1036 1037 case IOCTL_GNTDEV_GRANT_COPY: 1038 return gntdev_ioctl_grant_copy(priv, ptr); 1039 1040 #ifdef CONFIG_XEN_GNTDEV_DMABUF 1041 case IOCTL_GNTDEV_DMABUF_EXP_FROM_REFS: 1042 return gntdev_ioctl_dmabuf_exp_from_refs(priv, use_ptemod, ptr); 1043 1044 case IOCTL_GNTDEV_DMABUF_EXP_WAIT_RELEASED: 1045 return gntdev_ioctl_dmabuf_exp_wait_released(priv, ptr); 1046 1047 case IOCTL_GNTDEV_DMABUF_IMP_TO_REFS: 1048 return gntdev_ioctl_dmabuf_imp_to_refs(priv, ptr); 1049 1050 case IOCTL_GNTDEV_DMABUF_IMP_RELEASE: 1051 return gntdev_ioctl_dmabuf_imp_release(priv, ptr); 1052 #endif 1053 1054 default: 1055 pr_debug("priv %p, unknown cmd %x\n", priv, cmd); 1056 return -ENOIOCTLCMD; 1057 } 1058 1059 return 0; 1060 } 1061 1062 static int gntdev_mmap(struct file *flip, struct vm_area_struct *vma) 1063 { 1064 struct gntdev_priv *priv = flip->private_data; 1065 int index = vma->vm_pgoff; 1066 int count = vma_pages(vma); 1067 struct gntdev_grant_map *map; 1068 int err = -EINVAL; 1069 1070 if ((vma->vm_flags & VM_WRITE) && !(vma->vm_flags & VM_SHARED)) 1071 return -EINVAL; 1072 1073 pr_debug("map %d+%d at %lx (pgoff %lx)\n", 1074 index, count, vma->vm_start, vma->vm_pgoff); 1075 1076 mutex_lock(&priv->lock); 1077 map = gntdev_find_map_index(priv, index, count); 1078 if (!map) 1079 goto unlock_out; 1080 if (!atomic_add_unless(&map->in_use, 1, 1)) 1081 goto unlock_out; 1082 1083 refcount_inc(&map->users); 1084 1085 vma->vm_ops = &gntdev_vmops; 1086 1087 vm_flags_set(vma, VM_DONTEXPAND | VM_DONTDUMP | VM_MIXEDMAP); 1088 1089 if (use_ptemod) 1090 vm_flags_set(vma, VM_DONTCOPY); 1091 1092 vma->vm_private_data = map; 1093 if (map->flags) { 1094 if ((vma->vm_flags & VM_WRITE) && 1095 (map->flags & GNTMAP_readonly)) 1096 goto out_unlock_put; 1097 } else { 1098 map->flags = GNTMAP_host_map; 1099 if (!(vma->vm_flags & VM_WRITE)) 1100 map->flags |= GNTMAP_readonly; 1101 } 1102 1103 map->pages_vm_start = vma->vm_start; 1104 1105 if (use_ptemod) { 1106 err = mmu_interval_notifier_insert_locked( 1107 &map->notifier, vma->vm_mm, vma->vm_start, 1108 vma->vm_end - vma->vm_start, &gntdev_mmu_ops); 1109 if (err) 1110 goto out_unlock_put; 1111 1112 map->notifier_init = true; 1113 } 1114 mutex_unlock(&priv->lock); 1115 1116 if (use_ptemod) { 1117 /* 1118 * gntdev takes the address of the PTE in find_grant_ptes() and 1119 * passes it to the hypervisor in gntdev_map_grant_pages(). The 1120 * purpose of the notifier is to prevent the hypervisor pointer 1121 * to the PTE from going stale. 1122 * 1123 * Since this vma's mappings can't be touched without the 1124 * mmap_lock, and we are holding it now, there is no need for 1125 * the notifier_range locking pattern. 1126 */ 1127 mmu_interval_read_begin(&map->notifier); 1128 1129 err = apply_to_page_range(vma->vm_mm, vma->vm_start, 1130 vma->vm_end - vma->vm_start, 1131 find_grant_ptes, map); 1132 if (err) { 1133 pr_warn("find_grant_ptes() failure.\n"); 1134 goto out_put_map; 1135 } 1136 } 1137 1138 err = gntdev_map_grant_pages(map); 1139 if (err) 1140 goto out_put_map; 1141 1142 if (!use_ptemod) { 1143 err = vm_map_pages_zero(vma, map->pages, map->count); 1144 if (err) 1145 goto out_put_map; 1146 } 1147 1148 return 0; 1149 1150 unlock_out: 1151 mutex_unlock(&priv->lock); 1152 return err; 1153 1154 out_unlock_put: 1155 mutex_unlock(&priv->lock); 1156 out_put_map: 1157 if (use_ptemod) 1158 unmap_grant_pages(map, 0, map->count); 1159 gntdev_put_map(priv, map); 1160 return err; 1161 } 1162 1163 static const struct file_operations gntdev_fops = { 1164 .owner = THIS_MODULE, 1165 .open = gntdev_open, 1166 .release = gntdev_release, 1167 .mmap = gntdev_mmap, 1168 .unlocked_ioctl = gntdev_ioctl 1169 }; 1170 1171 static struct miscdevice gntdev_miscdev = { 1172 .minor = MISC_DYNAMIC_MINOR, 1173 .name = "xen/gntdev", 1174 .fops = &gntdev_fops, 1175 }; 1176 1177 /* ------------------------------------------------------------------ */ 1178 1179 static int __init gntdev_init(void) 1180 { 1181 int err; 1182 1183 if (!xen_domain()) 1184 return -ENODEV; 1185 1186 use_ptemod = !xen_feature(XENFEAT_auto_translated_physmap); 1187 1188 err = misc_register(&gntdev_miscdev); 1189 if (err != 0) { 1190 pr_err("Could not register gntdev device\n"); 1191 return err; 1192 } 1193 return 0; 1194 } 1195 1196 static void __exit gntdev_exit(void) 1197 { 1198 misc_deregister(&gntdev_miscdev); 1199 } 1200 1201 module_init(gntdev_init); 1202 module_exit(gntdev_exit); 1203 1204 /* ------------------------------------------------------------------ */ 1205