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/module.h> 26 #include <linux/kernel.h> 27 #include <linux/init.h> 28 #include <linux/miscdevice.h> 29 #include <linux/fs.h> 30 #include <linux/uaccess.h> 31 #include <linux/sched.h> 32 #include <linux/sched/mm.h> 33 #include <linux/spinlock.h> 34 #include <linux/slab.h> 35 #include <linux/highmem.h> 36 #include <linux/refcount.h> 37 #ifdef CONFIG_XEN_GRANT_DMA_ALLOC 38 #include <linux/of_device.h> 39 #endif 40 41 #include <xen/xen.h> 42 #include <xen/grant_table.h> 43 #include <xen/balloon.h> 44 #include <xen/gntdev.h> 45 #include <xen/events.h> 46 #include <xen/page.h> 47 #include <asm/xen/hypervisor.h> 48 #include <asm/xen/hypercall.h> 49 50 #include "gntdev-common.h" 51 #ifdef CONFIG_XEN_GNTDEV_DMABUF 52 #include "gntdev-dmabuf.h" 53 #endif 54 55 MODULE_LICENSE("GPL"); 56 MODULE_AUTHOR("Derek G. Murray <Derek.Murray@cl.cam.ac.uk>, " 57 "Gerd Hoffmann <kraxel@redhat.com>"); 58 MODULE_DESCRIPTION("User-space granted page access driver"); 59 60 static int limit = 1024*1024; 61 module_param(limit, int, 0644); 62 MODULE_PARM_DESC(limit, "Maximum number of grants that may be mapped by " 63 "the gntdev device"); 64 65 static atomic_t pages_mapped = ATOMIC_INIT(0); 66 67 static int use_ptemod; 68 #define populate_freeable_maps use_ptemod 69 70 static int unmap_grant_pages(struct gntdev_grant_map *map, 71 int offset, int pages); 72 73 static struct miscdevice gntdev_miscdev; 74 75 /* ------------------------------------------------------------------ */ 76 77 bool gntdev_account_mapped_pages(int count) 78 { 79 return atomic_add_return(count, &pages_mapped) > limit; 80 } 81 82 static void gntdev_print_maps(struct gntdev_priv *priv, 83 char *text, int text_index) 84 { 85 #ifdef DEBUG 86 struct gntdev_grant_map *map; 87 88 pr_debug("%s: maps list (priv %p)\n", __func__, priv); 89 list_for_each_entry(map, &priv->maps, next) 90 pr_debug(" index %2d, count %2d %s\n", 91 map->index, map->count, 92 map->index == text_index && text ? text : ""); 93 #endif 94 } 95 96 static void gntdev_free_map(struct gntdev_grant_map *map) 97 { 98 if (map == NULL) 99 return; 100 101 #ifdef CONFIG_XEN_GRANT_DMA_ALLOC 102 if (map->dma_vaddr) { 103 struct gnttab_dma_alloc_args args; 104 105 args.dev = map->dma_dev; 106 args.coherent = !!(map->dma_flags & GNTDEV_DMA_FLAG_COHERENT); 107 args.nr_pages = map->count; 108 args.pages = map->pages; 109 args.frames = map->frames; 110 args.vaddr = map->dma_vaddr; 111 args.dev_bus_addr = map->dma_bus_addr; 112 113 gnttab_dma_free_pages(&args); 114 } else 115 #endif 116 if (map->pages) 117 gnttab_free_pages(map->count, map->pages); 118 119 #ifdef CONFIG_XEN_GRANT_DMA_ALLOC 120 kfree(map->frames); 121 #endif 122 kfree(map->pages); 123 kfree(map->grants); 124 kfree(map->map_ops); 125 kfree(map->unmap_ops); 126 kfree(map->kmap_ops); 127 kfree(map->kunmap_ops); 128 kfree(map); 129 } 130 131 struct gntdev_grant_map *gntdev_alloc_map(struct gntdev_priv *priv, int count, 132 int dma_flags) 133 { 134 struct gntdev_grant_map *add; 135 int i; 136 137 add = kzalloc(sizeof(*add), GFP_KERNEL); 138 if (NULL == add) 139 return NULL; 140 141 add->grants = kcalloc(count, sizeof(add->grants[0]), GFP_KERNEL); 142 add->map_ops = kcalloc(count, sizeof(add->map_ops[0]), GFP_KERNEL); 143 add->unmap_ops = kcalloc(count, sizeof(add->unmap_ops[0]), GFP_KERNEL); 144 add->kmap_ops = kcalloc(count, sizeof(add->kmap_ops[0]), GFP_KERNEL); 145 add->kunmap_ops = kcalloc(count, sizeof(add->kunmap_ops[0]), GFP_KERNEL); 146 add->pages = kcalloc(count, sizeof(add->pages[0]), GFP_KERNEL); 147 if (NULL == add->grants || 148 NULL == add->map_ops || 149 NULL == add->unmap_ops || 150 NULL == add->kmap_ops || 151 NULL == add->kunmap_ops || 152 NULL == add->pages) 153 goto err; 154 155 #ifdef CONFIG_XEN_GRANT_DMA_ALLOC 156 add->dma_flags = dma_flags; 157 158 /* 159 * Check if this mapping is requested to be backed 160 * by a DMA buffer. 161 */ 162 if (dma_flags & (GNTDEV_DMA_FLAG_WC | GNTDEV_DMA_FLAG_COHERENT)) { 163 struct gnttab_dma_alloc_args args; 164 165 add->frames = kcalloc(count, sizeof(add->frames[0]), 166 GFP_KERNEL); 167 if (!add->frames) 168 goto err; 169 170 /* Remember the device, so we can free DMA memory. */ 171 add->dma_dev = priv->dma_dev; 172 173 args.dev = priv->dma_dev; 174 args.coherent = !!(dma_flags & GNTDEV_DMA_FLAG_COHERENT); 175 args.nr_pages = count; 176 args.pages = add->pages; 177 args.frames = add->frames; 178 179 if (gnttab_dma_alloc_pages(&args)) 180 goto err; 181 182 add->dma_vaddr = args.vaddr; 183 add->dma_bus_addr = args.dev_bus_addr; 184 } else 185 #endif 186 if (gnttab_alloc_pages(count, add->pages)) 187 goto err; 188 189 for (i = 0; i < count; i++) { 190 add->map_ops[i].handle = -1; 191 add->unmap_ops[i].handle = -1; 192 add->kmap_ops[i].handle = -1; 193 add->kunmap_ops[i].handle = -1; 194 } 195 196 add->index = 0; 197 add->count = count; 198 refcount_set(&add->users, 1); 199 200 return add; 201 202 err: 203 gntdev_free_map(add); 204 return NULL; 205 } 206 207 void gntdev_add_map(struct gntdev_priv *priv, struct gntdev_grant_map *add) 208 { 209 struct gntdev_grant_map *map; 210 211 list_for_each_entry(map, &priv->maps, next) { 212 if (add->index + add->count < map->index) { 213 list_add_tail(&add->next, &map->next); 214 goto done; 215 } 216 add->index = map->index + map->count; 217 } 218 list_add_tail(&add->next, &priv->maps); 219 220 done: 221 gntdev_print_maps(priv, "[new]", add->index); 222 } 223 224 static struct gntdev_grant_map *gntdev_find_map_index(struct gntdev_priv *priv, 225 int index, int count) 226 { 227 struct gntdev_grant_map *map; 228 229 list_for_each_entry(map, &priv->maps, next) { 230 if (map->index != index) 231 continue; 232 if (count && map->count != count) 233 continue; 234 return map; 235 } 236 return NULL; 237 } 238 239 void gntdev_put_map(struct gntdev_priv *priv, struct gntdev_grant_map *map) 240 { 241 if (!map) 242 return; 243 244 if (!refcount_dec_and_test(&map->users)) 245 return; 246 247 atomic_sub(map->count, &pages_mapped); 248 249 if (map->notify.flags & UNMAP_NOTIFY_SEND_EVENT) { 250 notify_remote_via_evtchn(map->notify.event); 251 evtchn_put(map->notify.event); 252 } 253 254 if (populate_freeable_maps && priv) { 255 mutex_lock(&priv->lock); 256 list_del(&map->next); 257 mutex_unlock(&priv->lock); 258 } 259 260 if (map->pages && !use_ptemod) 261 unmap_grant_pages(map, 0, map->count); 262 gntdev_free_map(map); 263 } 264 265 /* ------------------------------------------------------------------ */ 266 267 static int find_grant_ptes(pte_t *pte, unsigned long addr, void *data) 268 { 269 struct gntdev_grant_map *map = data; 270 unsigned int pgnr = (addr - map->vma->vm_start) >> PAGE_SHIFT; 271 int flags = map->flags | GNTMAP_application_map | GNTMAP_contains_pte; 272 u64 pte_maddr; 273 274 BUG_ON(pgnr >= map->count); 275 pte_maddr = arbitrary_virt_to_machine(pte).maddr; 276 277 /* 278 * Set the PTE as special to force get_user_pages_fast() fall 279 * back to the slow path. If this is not supported as part of 280 * the grant map, it will be done afterwards. 281 */ 282 if (xen_feature(XENFEAT_gnttab_map_avail_bits)) 283 flags |= (1 << _GNTMAP_guest_avail0); 284 285 gnttab_set_map_op(&map->map_ops[pgnr], pte_maddr, flags, 286 map->grants[pgnr].ref, 287 map->grants[pgnr].domid); 288 gnttab_set_unmap_op(&map->unmap_ops[pgnr], pte_maddr, flags, 289 -1 /* handle */); 290 return 0; 291 } 292 293 #ifdef CONFIG_X86 294 static int set_grant_ptes_as_special(pte_t *pte, unsigned long addr, void *data) 295 { 296 set_pte_at(current->mm, addr, pte, pte_mkspecial(*pte)); 297 return 0; 298 } 299 #endif 300 301 int gntdev_map_grant_pages(struct gntdev_grant_map *map) 302 { 303 int i, err = 0; 304 305 if (!use_ptemod) { 306 /* Note: it could already be mapped */ 307 if (map->map_ops[0].handle != -1) 308 return 0; 309 for (i = 0; i < map->count; i++) { 310 unsigned long addr = (unsigned long) 311 pfn_to_kaddr(page_to_pfn(map->pages[i])); 312 gnttab_set_map_op(&map->map_ops[i], addr, map->flags, 313 map->grants[i].ref, 314 map->grants[i].domid); 315 gnttab_set_unmap_op(&map->unmap_ops[i], addr, 316 map->flags, -1 /* handle */); 317 } 318 } else { 319 /* 320 * Setup the map_ops corresponding to the pte entries pointing 321 * to the kernel linear addresses of the struct pages. 322 * These ptes are completely different from the user ptes dealt 323 * with find_grant_ptes. 324 */ 325 for (i = 0; i < map->count; i++) { 326 unsigned long address = (unsigned long) 327 pfn_to_kaddr(page_to_pfn(map->pages[i])); 328 BUG_ON(PageHighMem(map->pages[i])); 329 330 gnttab_set_map_op(&map->kmap_ops[i], address, 331 map->flags | GNTMAP_host_map, 332 map->grants[i].ref, 333 map->grants[i].domid); 334 gnttab_set_unmap_op(&map->kunmap_ops[i], address, 335 map->flags | GNTMAP_host_map, -1); 336 } 337 } 338 339 pr_debug("map %d+%d\n", map->index, map->count); 340 err = gnttab_map_refs(map->map_ops, use_ptemod ? map->kmap_ops : NULL, 341 map->pages, map->count); 342 if (err) 343 return err; 344 345 for (i = 0; i < map->count; i++) { 346 if (map->map_ops[i].status) { 347 err = -EINVAL; 348 continue; 349 } 350 351 map->unmap_ops[i].handle = map->map_ops[i].handle; 352 if (use_ptemod) 353 map->kunmap_ops[i].handle = map->kmap_ops[i].handle; 354 #ifdef CONFIG_XEN_GRANT_DMA_ALLOC 355 else if (map->dma_vaddr) { 356 unsigned long bfn; 357 358 bfn = pfn_to_bfn(page_to_pfn(map->pages[i])); 359 map->unmap_ops[i].dev_bus_addr = __pfn_to_phys(bfn); 360 } 361 #endif 362 } 363 return err; 364 } 365 366 static int __unmap_grant_pages(struct gntdev_grant_map *map, int offset, 367 int pages) 368 { 369 int i, err = 0; 370 struct gntab_unmap_queue_data unmap_data; 371 372 if (map->notify.flags & UNMAP_NOTIFY_CLEAR_BYTE) { 373 int pgno = (map->notify.addr >> PAGE_SHIFT); 374 if (pgno >= offset && pgno < offset + pages) { 375 /* No need for kmap, pages are in lowmem */ 376 uint8_t *tmp = pfn_to_kaddr(page_to_pfn(map->pages[pgno])); 377 tmp[map->notify.addr & (PAGE_SIZE-1)] = 0; 378 map->notify.flags &= ~UNMAP_NOTIFY_CLEAR_BYTE; 379 } 380 } 381 382 unmap_data.unmap_ops = map->unmap_ops + offset; 383 unmap_data.kunmap_ops = use_ptemod ? map->kunmap_ops + offset : NULL; 384 unmap_data.pages = map->pages + offset; 385 unmap_data.count = pages; 386 387 err = gnttab_unmap_refs_sync(&unmap_data); 388 if (err) 389 return err; 390 391 for (i = 0; i < pages; i++) { 392 if (map->unmap_ops[offset+i].status) 393 err = -EINVAL; 394 pr_debug("unmap handle=%d st=%d\n", 395 map->unmap_ops[offset+i].handle, 396 map->unmap_ops[offset+i].status); 397 map->unmap_ops[offset+i].handle = -1; 398 } 399 return err; 400 } 401 402 static int unmap_grant_pages(struct gntdev_grant_map *map, int offset, 403 int pages) 404 { 405 int range, err = 0; 406 407 pr_debug("unmap %d+%d [%d+%d]\n", map->index, map->count, offset, pages); 408 409 /* It is possible the requested range will have a "hole" where we 410 * already unmapped some of the grants. Only unmap valid ranges. 411 */ 412 while (pages && !err) { 413 while (pages && map->unmap_ops[offset].handle == -1) { 414 offset++; 415 pages--; 416 } 417 range = 0; 418 while (range < pages) { 419 if (map->unmap_ops[offset+range].handle == -1) 420 break; 421 range++; 422 } 423 err = __unmap_grant_pages(map, offset, range); 424 offset += range; 425 pages -= range; 426 } 427 428 return err; 429 } 430 431 /* ------------------------------------------------------------------ */ 432 433 static void gntdev_vma_open(struct vm_area_struct *vma) 434 { 435 struct gntdev_grant_map *map = vma->vm_private_data; 436 437 pr_debug("gntdev_vma_open %p\n", vma); 438 refcount_inc(&map->users); 439 } 440 441 static void gntdev_vma_close(struct vm_area_struct *vma) 442 { 443 struct gntdev_grant_map *map = vma->vm_private_data; 444 struct file *file = vma->vm_file; 445 struct gntdev_priv *priv = file->private_data; 446 447 pr_debug("gntdev_vma_close %p\n", vma); 448 if (use_ptemod) { 449 /* It is possible that an mmu notifier could be running 450 * concurrently, so take priv->lock to ensure that the vma won't 451 * vanishing during the unmap_grant_pages call, since we will 452 * spin here until that completes. Such a concurrent call will 453 * not do any unmapping, since that has been done prior to 454 * closing the vma, but it may still iterate the unmap_ops list. 455 */ 456 mutex_lock(&priv->lock); 457 map->vma = NULL; 458 mutex_unlock(&priv->lock); 459 } 460 vma->vm_private_data = NULL; 461 gntdev_put_map(priv, map); 462 } 463 464 static struct page *gntdev_vma_find_special_page(struct vm_area_struct *vma, 465 unsigned long addr) 466 { 467 struct gntdev_grant_map *map = vma->vm_private_data; 468 469 return map->pages[(addr - map->pages_vm_start) >> PAGE_SHIFT]; 470 } 471 472 static const struct vm_operations_struct gntdev_vmops = { 473 .open = gntdev_vma_open, 474 .close = gntdev_vma_close, 475 .find_special_page = gntdev_vma_find_special_page, 476 }; 477 478 /* ------------------------------------------------------------------ */ 479 480 static bool in_range(struct gntdev_grant_map *map, 481 unsigned long start, unsigned long end) 482 { 483 if (!map->vma) 484 return false; 485 if (map->vma->vm_start >= end) 486 return false; 487 if (map->vma->vm_end <= start) 488 return false; 489 490 return true; 491 } 492 493 static int unmap_if_in_range(struct gntdev_grant_map *map, 494 unsigned long start, unsigned long end, 495 bool blockable) 496 { 497 unsigned long mstart, mend; 498 int err; 499 500 if (!in_range(map, start, end)) 501 return 0; 502 503 if (!blockable) 504 return -EAGAIN; 505 506 mstart = max(start, map->vma->vm_start); 507 mend = min(end, map->vma->vm_end); 508 pr_debug("map %d+%d (%lx %lx), range %lx %lx, mrange %lx %lx\n", 509 map->index, map->count, 510 map->vma->vm_start, map->vma->vm_end, 511 start, end, mstart, mend); 512 err = unmap_grant_pages(map, 513 (mstart - map->vma->vm_start) >> PAGE_SHIFT, 514 (mend - mstart) >> PAGE_SHIFT); 515 WARN_ON(err); 516 517 return 0; 518 } 519 520 static int mn_invl_range_start(struct mmu_notifier *mn, 521 const struct mmu_notifier_range *range) 522 { 523 struct gntdev_priv *priv = container_of(mn, struct gntdev_priv, mn); 524 struct gntdev_grant_map *map; 525 int ret = 0; 526 527 if (mmu_notifier_range_blockable(range)) 528 mutex_lock(&priv->lock); 529 else if (!mutex_trylock(&priv->lock)) 530 return -EAGAIN; 531 532 list_for_each_entry(map, &priv->maps, next) { 533 ret = unmap_if_in_range(map, range->start, range->end, 534 mmu_notifier_range_blockable(range)); 535 if (ret) 536 goto out_unlock; 537 } 538 list_for_each_entry(map, &priv->freeable_maps, next) { 539 ret = unmap_if_in_range(map, range->start, range->end, 540 mmu_notifier_range_blockable(range)); 541 if (ret) 542 goto out_unlock; 543 } 544 545 out_unlock: 546 mutex_unlock(&priv->lock); 547 548 return ret; 549 } 550 551 static void mn_release(struct mmu_notifier *mn, 552 struct mm_struct *mm) 553 { 554 struct gntdev_priv *priv = container_of(mn, struct gntdev_priv, mn); 555 struct gntdev_grant_map *map; 556 int err; 557 558 mutex_lock(&priv->lock); 559 list_for_each_entry(map, &priv->maps, next) { 560 if (!map->vma) 561 continue; 562 pr_debug("map %d+%d (%lx %lx)\n", 563 map->index, map->count, 564 map->vma->vm_start, map->vma->vm_end); 565 err = unmap_grant_pages(map, /* offset */ 0, map->count); 566 WARN_ON(err); 567 } 568 list_for_each_entry(map, &priv->freeable_maps, next) { 569 if (!map->vma) 570 continue; 571 pr_debug("map %d+%d (%lx %lx)\n", 572 map->index, map->count, 573 map->vma->vm_start, map->vma->vm_end); 574 err = unmap_grant_pages(map, /* offset */ 0, map->count); 575 WARN_ON(err); 576 } 577 mutex_unlock(&priv->lock); 578 } 579 580 static const struct mmu_notifier_ops gntdev_mmu_ops = { 581 .release = mn_release, 582 .invalidate_range_start = mn_invl_range_start, 583 }; 584 585 /* ------------------------------------------------------------------ */ 586 587 static int gntdev_open(struct inode *inode, struct file *flip) 588 { 589 struct gntdev_priv *priv; 590 int ret = 0; 591 592 priv = kzalloc(sizeof(*priv), GFP_KERNEL); 593 if (!priv) 594 return -ENOMEM; 595 596 INIT_LIST_HEAD(&priv->maps); 597 INIT_LIST_HEAD(&priv->freeable_maps); 598 mutex_init(&priv->lock); 599 600 #ifdef CONFIG_XEN_GNTDEV_DMABUF 601 priv->dmabuf_priv = gntdev_dmabuf_init(flip); 602 if (IS_ERR(priv->dmabuf_priv)) { 603 ret = PTR_ERR(priv->dmabuf_priv); 604 kfree(priv); 605 return ret; 606 } 607 #endif 608 609 if (use_ptemod) { 610 priv->mm = get_task_mm(current); 611 if (!priv->mm) { 612 kfree(priv); 613 return -ENOMEM; 614 } 615 priv->mn.ops = &gntdev_mmu_ops; 616 ret = mmu_notifier_register(&priv->mn, priv->mm); 617 mmput(priv->mm); 618 } 619 620 if (ret) { 621 kfree(priv); 622 return ret; 623 } 624 625 flip->private_data = priv; 626 #ifdef CONFIG_XEN_GRANT_DMA_ALLOC 627 priv->dma_dev = gntdev_miscdev.this_device; 628 629 /* 630 * The device is not spawn from a device tree, so arch_setup_dma_ops 631 * is not called, thus leaving the device with dummy DMA ops. 632 * Fix this by calling of_dma_configure() with a NULL node to set 633 * default DMA ops. 634 */ 635 of_dma_configure(priv->dma_dev, NULL, true); 636 #endif 637 pr_debug("priv %p\n", priv); 638 639 return 0; 640 } 641 642 static int gntdev_release(struct inode *inode, struct file *flip) 643 { 644 struct gntdev_priv *priv = flip->private_data; 645 struct gntdev_grant_map *map; 646 647 pr_debug("priv %p\n", priv); 648 649 mutex_lock(&priv->lock); 650 while (!list_empty(&priv->maps)) { 651 map = list_entry(priv->maps.next, 652 struct gntdev_grant_map, next); 653 list_del(&map->next); 654 gntdev_put_map(NULL /* already removed */, map); 655 } 656 WARN_ON(!list_empty(&priv->freeable_maps)); 657 mutex_unlock(&priv->lock); 658 659 #ifdef CONFIG_XEN_GNTDEV_DMABUF 660 gntdev_dmabuf_fini(priv->dmabuf_priv); 661 #endif 662 663 if (use_ptemod) 664 mmu_notifier_unregister(&priv->mn, priv->mm); 665 666 kfree(priv); 667 return 0; 668 } 669 670 static long gntdev_ioctl_map_grant_ref(struct gntdev_priv *priv, 671 struct ioctl_gntdev_map_grant_ref __user *u) 672 { 673 struct ioctl_gntdev_map_grant_ref op; 674 struct gntdev_grant_map *map; 675 int err; 676 677 if (copy_from_user(&op, u, sizeof(op)) != 0) 678 return -EFAULT; 679 pr_debug("priv %p, add %d\n", priv, op.count); 680 if (unlikely(op.count <= 0)) 681 return -EINVAL; 682 683 err = -ENOMEM; 684 map = gntdev_alloc_map(priv, op.count, 0 /* This is not a dma-buf. */); 685 if (!map) 686 return err; 687 688 if (unlikely(gntdev_account_mapped_pages(op.count))) { 689 pr_debug("can't map: over limit\n"); 690 gntdev_put_map(NULL, map); 691 return err; 692 } 693 694 if (copy_from_user(map->grants, &u->refs, 695 sizeof(map->grants[0]) * op.count) != 0) { 696 gntdev_put_map(NULL, map); 697 return -EFAULT; 698 } 699 700 mutex_lock(&priv->lock); 701 gntdev_add_map(priv, map); 702 op.index = map->index << PAGE_SHIFT; 703 mutex_unlock(&priv->lock); 704 705 if (copy_to_user(u, &op, sizeof(op)) != 0) 706 return -EFAULT; 707 708 return 0; 709 } 710 711 static long gntdev_ioctl_unmap_grant_ref(struct gntdev_priv *priv, 712 struct ioctl_gntdev_unmap_grant_ref __user *u) 713 { 714 struct ioctl_gntdev_unmap_grant_ref op; 715 struct gntdev_grant_map *map; 716 int err = -ENOENT; 717 718 if (copy_from_user(&op, u, sizeof(op)) != 0) 719 return -EFAULT; 720 pr_debug("priv %p, del %d+%d\n", priv, (int)op.index, (int)op.count); 721 722 mutex_lock(&priv->lock); 723 map = gntdev_find_map_index(priv, op.index >> PAGE_SHIFT, op.count); 724 if (map) { 725 list_del(&map->next); 726 if (populate_freeable_maps) 727 list_add_tail(&map->next, &priv->freeable_maps); 728 err = 0; 729 } 730 mutex_unlock(&priv->lock); 731 if (map) 732 gntdev_put_map(priv, map); 733 return err; 734 } 735 736 static long gntdev_ioctl_get_offset_for_vaddr(struct gntdev_priv *priv, 737 struct ioctl_gntdev_get_offset_for_vaddr __user *u) 738 { 739 struct ioctl_gntdev_get_offset_for_vaddr op; 740 struct vm_area_struct *vma; 741 struct gntdev_grant_map *map; 742 int rv = -EINVAL; 743 744 if (copy_from_user(&op, u, sizeof(op)) != 0) 745 return -EFAULT; 746 pr_debug("priv %p, offset for vaddr %lx\n", priv, (unsigned long)op.vaddr); 747 748 down_read(¤t->mm->mmap_sem); 749 vma = find_vma(current->mm, op.vaddr); 750 if (!vma || vma->vm_ops != &gntdev_vmops) 751 goto out_unlock; 752 753 map = vma->vm_private_data; 754 if (!map) 755 goto out_unlock; 756 757 op.offset = map->index << PAGE_SHIFT; 758 op.count = map->count; 759 rv = 0; 760 761 out_unlock: 762 up_read(¤t->mm->mmap_sem); 763 764 if (rv == 0 && copy_to_user(u, &op, sizeof(op)) != 0) 765 return -EFAULT; 766 return rv; 767 } 768 769 static long gntdev_ioctl_notify(struct gntdev_priv *priv, void __user *u) 770 { 771 struct ioctl_gntdev_unmap_notify op; 772 struct gntdev_grant_map *map; 773 int rc; 774 int out_flags; 775 unsigned int out_event; 776 777 if (copy_from_user(&op, u, sizeof(op))) 778 return -EFAULT; 779 780 if (op.action & ~(UNMAP_NOTIFY_CLEAR_BYTE|UNMAP_NOTIFY_SEND_EVENT)) 781 return -EINVAL; 782 783 /* We need to grab a reference to the event channel we are going to use 784 * to send the notify before releasing the reference we may already have 785 * (if someone has called this ioctl twice). This is required so that 786 * it is possible to change the clear_byte part of the notification 787 * without disturbing the event channel part, which may now be the last 788 * reference to that event channel. 789 */ 790 if (op.action & UNMAP_NOTIFY_SEND_EVENT) { 791 if (evtchn_get(op.event_channel_port)) 792 return -EINVAL; 793 } 794 795 out_flags = op.action; 796 out_event = op.event_channel_port; 797 798 mutex_lock(&priv->lock); 799 800 list_for_each_entry(map, &priv->maps, next) { 801 uint64_t begin = map->index << PAGE_SHIFT; 802 uint64_t end = (map->index + map->count) << PAGE_SHIFT; 803 if (op.index >= begin && op.index < end) 804 goto found; 805 } 806 rc = -ENOENT; 807 goto unlock_out; 808 809 found: 810 if ((op.action & UNMAP_NOTIFY_CLEAR_BYTE) && 811 (map->flags & GNTMAP_readonly)) { 812 rc = -EINVAL; 813 goto unlock_out; 814 } 815 816 out_flags = map->notify.flags; 817 out_event = map->notify.event; 818 819 map->notify.flags = op.action; 820 map->notify.addr = op.index - (map->index << PAGE_SHIFT); 821 map->notify.event = op.event_channel_port; 822 823 rc = 0; 824 825 unlock_out: 826 mutex_unlock(&priv->lock); 827 828 /* Drop the reference to the event channel we did not save in the map */ 829 if (out_flags & UNMAP_NOTIFY_SEND_EVENT) 830 evtchn_put(out_event); 831 832 return rc; 833 } 834 835 #define GNTDEV_COPY_BATCH 16 836 837 struct gntdev_copy_batch { 838 struct gnttab_copy ops[GNTDEV_COPY_BATCH]; 839 struct page *pages[GNTDEV_COPY_BATCH]; 840 s16 __user *status[GNTDEV_COPY_BATCH]; 841 unsigned int nr_ops; 842 unsigned int nr_pages; 843 }; 844 845 static int gntdev_get_page(struct gntdev_copy_batch *batch, void __user *virt, 846 bool writeable, unsigned long *gfn) 847 { 848 unsigned long addr = (unsigned long)virt; 849 struct page *page; 850 unsigned long xen_pfn; 851 int ret; 852 853 ret = get_user_pages_fast(addr, 1, writeable ? FOLL_WRITE : 0, &page); 854 if (ret < 0) 855 return ret; 856 857 batch->pages[batch->nr_pages++] = page; 858 859 xen_pfn = page_to_xen_pfn(page) + XEN_PFN_DOWN(addr & ~PAGE_MASK); 860 *gfn = pfn_to_gfn(xen_pfn); 861 862 return 0; 863 } 864 865 static void gntdev_put_pages(struct gntdev_copy_batch *batch) 866 { 867 unsigned int i; 868 869 for (i = 0; i < batch->nr_pages; i++) 870 put_page(batch->pages[i]); 871 batch->nr_pages = 0; 872 } 873 874 static int gntdev_copy(struct gntdev_copy_batch *batch) 875 { 876 unsigned int i; 877 878 gnttab_batch_copy(batch->ops, batch->nr_ops); 879 gntdev_put_pages(batch); 880 881 /* 882 * For each completed op, update the status if the op failed 883 * and all previous ops for the segment were successful. 884 */ 885 for (i = 0; i < batch->nr_ops; i++) { 886 s16 status = batch->ops[i].status; 887 s16 old_status; 888 889 if (status == GNTST_okay) 890 continue; 891 892 if (__get_user(old_status, batch->status[i])) 893 return -EFAULT; 894 895 if (old_status != GNTST_okay) 896 continue; 897 898 if (__put_user(status, batch->status[i])) 899 return -EFAULT; 900 } 901 902 batch->nr_ops = 0; 903 return 0; 904 } 905 906 static int gntdev_grant_copy_seg(struct gntdev_copy_batch *batch, 907 struct gntdev_grant_copy_segment *seg, 908 s16 __user *status) 909 { 910 uint16_t copied = 0; 911 912 /* 913 * Disallow local -> local copies since there is only space in 914 * batch->pages for one page per-op and this would be a very 915 * expensive memcpy(). 916 */ 917 if (!(seg->flags & (GNTCOPY_source_gref | GNTCOPY_dest_gref))) 918 return -EINVAL; 919 920 /* Can't cross page if source/dest is a grant ref. */ 921 if (seg->flags & GNTCOPY_source_gref) { 922 if (seg->source.foreign.offset + seg->len > XEN_PAGE_SIZE) 923 return -EINVAL; 924 } 925 if (seg->flags & GNTCOPY_dest_gref) { 926 if (seg->dest.foreign.offset + seg->len > XEN_PAGE_SIZE) 927 return -EINVAL; 928 } 929 930 if (put_user(GNTST_okay, status)) 931 return -EFAULT; 932 933 while (copied < seg->len) { 934 struct gnttab_copy *op; 935 void __user *virt; 936 size_t len, off; 937 unsigned long gfn; 938 int ret; 939 940 if (batch->nr_ops >= GNTDEV_COPY_BATCH) { 941 ret = gntdev_copy(batch); 942 if (ret < 0) 943 return ret; 944 } 945 946 len = seg->len - copied; 947 948 op = &batch->ops[batch->nr_ops]; 949 op->flags = 0; 950 951 if (seg->flags & GNTCOPY_source_gref) { 952 op->source.u.ref = seg->source.foreign.ref; 953 op->source.domid = seg->source.foreign.domid; 954 op->source.offset = seg->source.foreign.offset + copied; 955 op->flags |= GNTCOPY_source_gref; 956 } else { 957 virt = seg->source.virt + copied; 958 off = (unsigned long)virt & ~XEN_PAGE_MASK; 959 len = min(len, (size_t)XEN_PAGE_SIZE - off); 960 961 ret = gntdev_get_page(batch, virt, false, &gfn); 962 if (ret < 0) 963 return ret; 964 965 op->source.u.gmfn = gfn; 966 op->source.domid = DOMID_SELF; 967 op->source.offset = off; 968 } 969 970 if (seg->flags & GNTCOPY_dest_gref) { 971 op->dest.u.ref = seg->dest.foreign.ref; 972 op->dest.domid = seg->dest.foreign.domid; 973 op->dest.offset = seg->dest.foreign.offset + copied; 974 op->flags |= GNTCOPY_dest_gref; 975 } else { 976 virt = seg->dest.virt + copied; 977 off = (unsigned long)virt & ~XEN_PAGE_MASK; 978 len = min(len, (size_t)XEN_PAGE_SIZE - off); 979 980 ret = gntdev_get_page(batch, virt, true, &gfn); 981 if (ret < 0) 982 return ret; 983 984 op->dest.u.gmfn = gfn; 985 op->dest.domid = DOMID_SELF; 986 op->dest.offset = off; 987 } 988 989 op->len = len; 990 copied += len; 991 992 batch->status[batch->nr_ops] = status; 993 batch->nr_ops++; 994 } 995 996 return 0; 997 } 998 999 static long gntdev_ioctl_grant_copy(struct gntdev_priv *priv, void __user *u) 1000 { 1001 struct ioctl_gntdev_grant_copy copy; 1002 struct gntdev_copy_batch batch; 1003 unsigned int i; 1004 int ret = 0; 1005 1006 if (copy_from_user(©, u, sizeof(copy))) 1007 return -EFAULT; 1008 1009 batch.nr_ops = 0; 1010 batch.nr_pages = 0; 1011 1012 for (i = 0; i < copy.count; i++) { 1013 struct gntdev_grant_copy_segment seg; 1014 1015 if (copy_from_user(&seg, ©.segments[i], sizeof(seg))) { 1016 ret = -EFAULT; 1017 goto out; 1018 } 1019 1020 ret = gntdev_grant_copy_seg(&batch, &seg, ©.segments[i].status); 1021 if (ret < 0) 1022 goto out; 1023 1024 cond_resched(); 1025 } 1026 if (batch.nr_ops) 1027 ret = gntdev_copy(&batch); 1028 return ret; 1029 1030 out: 1031 gntdev_put_pages(&batch); 1032 return ret; 1033 } 1034 1035 static long gntdev_ioctl(struct file *flip, 1036 unsigned int cmd, unsigned long arg) 1037 { 1038 struct gntdev_priv *priv = flip->private_data; 1039 void __user *ptr = (void __user *)arg; 1040 1041 switch (cmd) { 1042 case IOCTL_GNTDEV_MAP_GRANT_REF: 1043 return gntdev_ioctl_map_grant_ref(priv, ptr); 1044 1045 case IOCTL_GNTDEV_UNMAP_GRANT_REF: 1046 return gntdev_ioctl_unmap_grant_ref(priv, ptr); 1047 1048 case IOCTL_GNTDEV_GET_OFFSET_FOR_VADDR: 1049 return gntdev_ioctl_get_offset_for_vaddr(priv, ptr); 1050 1051 case IOCTL_GNTDEV_SET_UNMAP_NOTIFY: 1052 return gntdev_ioctl_notify(priv, ptr); 1053 1054 case IOCTL_GNTDEV_GRANT_COPY: 1055 return gntdev_ioctl_grant_copy(priv, ptr); 1056 1057 #ifdef CONFIG_XEN_GNTDEV_DMABUF 1058 case IOCTL_GNTDEV_DMABUF_EXP_FROM_REFS: 1059 return gntdev_ioctl_dmabuf_exp_from_refs(priv, use_ptemod, ptr); 1060 1061 case IOCTL_GNTDEV_DMABUF_EXP_WAIT_RELEASED: 1062 return gntdev_ioctl_dmabuf_exp_wait_released(priv, ptr); 1063 1064 case IOCTL_GNTDEV_DMABUF_IMP_TO_REFS: 1065 return gntdev_ioctl_dmabuf_imp_to_refs(priv, ptr); 1066 1067 case IOCTL_GNTDEV_DMABUF_IMP_RELEASE: 1068 return gntdev_ioctl_dmabuf_imp_release(priv, ptr); 1069 #endif 1070 1071 default: 1072 pr_debug("priv %p, unknown cmd %x\n", priv, cmd); 1073 return -ENOIOCTLCMD; 1074 } 1075 1076 return 0; 1077 } 1078 1079 static int gntdev_mmap(struct file *flip, struct vm_area_struct *vma) 1080 { 1081 struct gntdev_priv *priv = flip->private_data; 1082 int index = vma->vm_pgoff; 1083 int count = vma_pages(vma); 1084 struct gntdev_grant_map *map; 1085 int err = -EINVAL; 1086 1087 if ((vma->vm_flags & VM_WRITE) && !(vma->vm_flags & VM_SHARED)) 1088 return -EINVAL; 1089 1090 pr_debug("map %d+%d at %lx (pgoff %lx)\n", 1091 index, count, vma->vm_start, vma->vm_pgoff); 1092 1093 mutex_lock(&priv->lock); 1094 map = gntdev_find_map_index(priv, index, count); 1095 if (!map) 1096 goto unlock_out; 1097 if (use_ptemod && map->vma) 1098 goto unlock_out; 1099 if (use_ptemod && priv->mm != vma->vm_mm) { 1100 pr_warn("Huh? Other mm?\n"); 1101 goto unlock_out; 1102 } 1103 1104 refcount_inc(&map->users); 1105 1106 vma->vm_ops = &gntdev_vmops; 1107 1108 vma->vm_flags |= VM_DONTEXPAND | VM_DONTDUMP | VM_MIXEDMAP; 1109 1110 if (use_ptemod) 1111 vma->vm_flags |= VM_DONTCOPY; 1112 1113 vma->vm_private_data = map; 1114 1115 if (use_ptemod) 1116 map->vma = vma; 1117 1118 if (map->flags) { 1119 if ((vma->vm_flags & VM_WRITE) && 1120 (map->flags & GNTMAP_readonly)) 1121 goto out_unlock_put; 1122 } else { 1123 map->flags = GNTMAP_host_map; 1124 if (!(vma->vm_flags & VM_WRITE)) 1125 map->flags |= GNTMAP_readonly; 1126 } 1127 1128 mutex_unlock(&priv->lock); 1129 1130 if (use_ptemod) { 1131 map->pages_vm_start = vma->vm_start; 1132 err = apply_to_page_range(vma->vm_mm, vma->vm_start, 1133 vma->vm_end - vma->vm_start, 1134 find_grant_ptes, map); 1135 if (err) { 1136 pr_warn("find_grant_ptes() failure.\n"); 1137 goto out_put_map; 1138 } 1139 } 1140 1141 err = gntdev_map_grant_pages(map); 1142 if (err) 1143 goto out_put_map; 1144 1145 if (!use_ptemod) { 1146 err = vm_map_pages_zero(vma, map->pages, map->count); 1147 if (err) 1148 goto out_put_map; 1149 } else { 1150 #ifdef CONFIG_X86 1151 /* 1152 * If the PTEs were not made special by the grant map 1153 * hypercall, do so here. 1154 * 1155 * This is racy since the mapping is already visible 1156 * to userspace but userspace should be well-behaved 1157 * enough to not touch it until the mmap() call 1158 * returns. 1159 */ 1160 if (!xen_feature(XENFEAT_gnttab_map_avail_bits)) { 1161 apply_to_page_range(vma->vm_mm, vma->vm_start, 1162 vma->vm_end - vma->vm_start, 1163 set_grant_ptes_as_special, NULL); 1164 } 1165 #endif 1166 } 1167 1168 return 0; 1169 1170 unlock_out: 1171 mutex_unlock(&priv->lock); 1172 return err; 1173 1174 out_unlock_put: 1175 mutex_unlock(&priv->lock); 1176 out_put_map: 1177 if (use_ptemod) { 1178 map->vma = NULL; 1179 unmap_grant_pages(map, 0, map->count); 1180 } 1181 gntdev_put_map(priv, map); 1182 return err; 1183 } 1184 1185 static const struct file_operations gntdev_fops = { 1186 .owner = THIS_MODULE, 1187 .open = gntdev_open, 1188 .release = gntdev_release, 1189 .mmap = gntdev_mmap, 1190 .unlocked_ioctl = gntdev_ioctl 1191 }; 1192 1193 static struct miscdevice gntdev_miscdev = { 1194 .minor = MISC_DYNAMIC_MINOR, 1195 .name = "xen/gntdev", 1196 .fops = &gntdev_fops, 1197 }; 1198 1199 /* ------------------------------------------------------------------ */ 1200 1201 static int __init gntdev_init(void) 1202 { 1203 int err; 1204 1205 if (!xen_domain()) 1206 return -ENODEV; 1207 1208 use_ptemod = !xen_feature(XENFEAT_auto_translated_physmap); 1209 1210 err = misc_register(&gntdev_miscdev); 1211 if (err != 0) { 1212 pr_err("Could not register gntdev device\n"); 1213 return err; 1214 } 1215 return 0; 1216 } 1217 1218 static void __exit gntdev_exit(void) 1219 { 1220 misc_deregister(&gntdev_miscdev); 1221 } 1222 1223 module_init(gntdev_init); 1224 module_exit(gntdev_exit); 1225 1226 /* ------------------------------------------------------------------ */ 1227