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