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