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