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 */ 313 for (i = 0; i < map->count; i++) { 314 unsigned long address = (unsigned long) 315 pfn_to_kaddr(page_to_pfn(map->pages[i])); 316 BUG_ON(PageHighMem(map->pages[i])); 317 318 gnttab_set_map_op(&map->kmap_ops[i], address, 319 map->flags | GNTMAP_host_map, 320 map->grants[i].ref, 321 map->grants[i].domid); 322 gnttab_set_unmap_op(&map->kunmap_ops[i], address, 323 map->flags | GNTMAP_host_map, -1); 324 } 325 } 326 327 pr_debug("map %d+%d\n", map->index, map->count); 328 err = gnttab_map_refs(map->map_ops, use_ptemod ? map->kmap_ops : NULL, 329 map->pages, map->count); 330 if (err) 331 return err; 332 333 for (i = 0; i < map->count; i++) { 334 if (map->map_ops[i].status) { 335 err = -EINVAL; 336 continue; 337 } 338 339 map->unmap_ops[i].handle = map->map_ops[i].handle; 340 if (use_ptemod) 341 map->kunmap_ops[i].handle = map->kmap_ops[i].handle; 342 #ifdef CONFIG_XEN_GRANT_DMA_ALLOC 343 else if (map->dma_vaddr) { 344 unsigned long bfn; 345 346 bfn = pfn_to_bfn(page_to_pfn(map->pages[i])); 347 map->unmap_ops[i].dev_bus_addr = __pfn_to_phys(bfn); 348 } 349 #endif 350 } 351 return err; 352 } 353 354 static int __unmap_grant_pages(struct gntdev_grant_map *map, int offset, 355 int pages) 356 { 357 int i, err = 0; 358 struct gntab_unmap_queue_data unmap_data; 359 360 if (map->notify.flags & UNMAP_NOTIFY_CLEAR_BYTE) { 361 int pgno = (map->notify.addr >> PAGE_SHIFT); 362 if (pgno >= offset && pgno < offset + pages) { 363 /* No need for kmap, pages are in lowmem */ 364 uint8_t *tmp = pfn_to_kaddr(page_to_pfn(map->pages[pgno])); 365 tmp[map->notify.addr & (PAGE_SIZE-1)] = 0; 366 map->notify.flags &= ~UNMAP_NOTIFY_CLEAR_BYTE; 367 } 368 } 369 370 unmap_data.unmap_ops = map->unmap_ops + offset; 371 unmap_data.kunmap_ops = use_ptemod ? map->kunmap_ops + offset : NULL; 372 unmap_data.pages = map->pages + offset; 373 unmap_data.count = pages; 374 375 err = gnttab_unmap_refs_sync(&unmap_data); 376 if (err) 377 return err; 378 379 for (i = 0; i < pages; i++) { 380 if (map->unmap_ops[offset+i].status) 381 err = -EINVAL; 382 pr_debug("unmap handle=%d st=%d\n", 383 map->unmap_ops[offset+i].handle, 384 map->unmap_ops[offset+i].status); 385 map->unmap_ops[offset+i].handle = -1; 386 } 387 return err; 388 } 389 390 static int unmap_grant_pages(struct gntdev_grant_map *map, int offset, 391 int pages) 392 { 393 int range, err = 0; 394 395 pr_debug("unmap %d+%d [%d+%d]\n", map->index, map->count, offset, pages); 396 397 /* It is possible the requested range will have a "hole" where we 398 * already unmapped some of the grants. Only unmap valid ranges. 399 */ 400 while (pages && !err) { 401 while (pages && map->unmap_ops[offset].handle == -1) { 402 offset++; 403 pages--; 404 } 405 range = 0; 406 while (range < pages) { 407 if (map->unmap_ops[offset+range].handle == -1) 408 break; 409 range++; 410 } 411 err = __unmap_grant_pages(map, offset, range); 412 offset += range; 413 pages -= range; 414 } 415 416 return err; 417 } 418 419 /* ------------------------------------------------------------------ */ 420 421 static void gntdev_vma_open(struct vm_area_struct *vma) 422 { 423 struct gntdev_grant_map *map = vma->vm_private_data; 424 425 pr_debug("gntdev_vma_open %p\n", vma); 426 refcount_inc(&map->users); 427 } 428 429 static void gntdev_vma_close(struct vm_area_struct *vma) 430 { 431 struct gntdev_grant_map *map = vma->vm_private_data; 432 struct file *file = vma->vm_file; 433 struct gntdev_priv *priv = file->private_data; 434 435 pr_debug("gntdev_vma_close %p\n", vma); 436 if (use_ptemod) { 437 WARN_ON(map->vma != vma); 438 mmu_interval_notifier_remove(&map->notifier); 439 map->vma = NULL; 440 } 441 vma->vm_private_data = NULL; 442 gntdev_put_map(priv, map); 443 } 444 445 static struct page *gntdev_vma_find_special_page(struct vm_area_struct *vma, 446 unsigned long addr) 447 { 448 struct gntdev_grant_map *map = vma->vm_private_data; 449 450 return map->pages[(addr - map->pages_vm_start) >> PAGE_SHIFT]; 451 } 452 453 static const struct vm_operations_struct gntdev_vmops = { 454 .open = gntdev_vma_open, 455 .close = gntdev_vma_close, 456 .find_special_page = gntdev_vma_find_special_page, 457 }; 458 459 /* ------------------------------------------------------------------ */ 460 461 static bool gntdev_invalidate(struct mmu_interval_notifier *mn, 462 const struct mmu_notifier_range *range, 463 unsigned long cur_seq) 464 { 465 struct gntdev_grant_map *map = 466 container_of(mn, struct gntdev_grant_map, notifier); 467 unsigned long mstart, mend; 468 int err; 469 470 if (!mmu_notifier_range_blockable(range)) 471 return false; 472 473 /* 474 * If the VMA is split or otherwise changed the notifier is not 475 * updated, but we don't want to process VA's outside the modified 476 * VMA. FIXME: It would be much more understandable to just prevent 477 * modifying the VMA in the first place. 478 */ 479 if (map->vma->vm_start >= range->end || 480 map->vma->vm_end <= range->start) 481 return true; 482 483 mstart = max(range->start, map->vma->vm_start); 484 mend = min(range->end, map->vma->vm_end); 485 pr_debug("map %d+%d (%lx %lx), range %lx %lx, mrange %lx %lx\n", 486 map->index, map->count, 487 map->vma->vm_start, map->vma->vm_end, 488 range->start, range->end, mstart, mend); 489 err = unmap_grant_pages(map, 490 (mstart - map->vma->vm_start) >> PAGE_SHIFT, 491 (mend - mstart) >> PAGE_SHIFT); 492 WARN_ON(err); 493 494 return true; 495 } 496 497 static const struct mmu_interval_notifier_ops gntdev_mmu_ops = { 498 .invalidate = gntdev_invalidate, 499 }; 500 501 /* ------------------------------------------------------------------ */ 502 503 static int gntdev_open(struct inode *inode, struct file *flip) 504 { 505 struct gntdev_priv *priv; 506 507 priv = kzalloc(sizeof(*priv), GFP_KERNEL); 508 if (!priv) 509 return -ENOMEM; 510 511 INIT_LIST_HEAD(&priv->maps); 512 mutex_init(&priv->lock); 513 514 #ifdef CONFIG_XEN_GNTDEV_DMABUF 515 priv->dmabuf_priv = gntdev_dmabuf_init(flip); 516 if (IS_ERR(priv->dmabuf_priv)) { 517 int ret = PTR_ERR(priv->dmabuf_priv); 518 519 kfree(priv); 520 return ret; 521 } 522 #endif 523 524 flip->private_data = priv; 525 #ifdef CONFIG_XEN_GRANT_DMA_ALLOC 526 priv->dma_dev = gntdev_miscdev.this_device; 527 dma_coerce_mask_and_coherent(priv->dma_dev, DMA_BIT_MASK(64)); 528 #endif 529 pr_debug("priv %p\n", priv); 530 531 return 0; 532 } 533 534 static int gntdev_release(struct inode *inode, struct file *flip) 535 { 536 struct gntdev_priv *priv = flip->private_data; 537 struct gntdev_grant_map *map; 538 539 pr_debug("priv %p\n", priv); 540 541 mutex_lock(&priv->lock); 542 while (!list_empty(&priv->maps)) { 543 map = list_entry(priv->maps.next, 544 struct gntdev_grant_map, next); 545 list_del(&map->next); 546 gntdev_put_map(NULL /* already removed */, map); 547 } 548 mutex_unlock(&priv->lock); 549 550 #ifdef CONFIG_XEN_GNTDEV_DMABUF 551 gntdev_dmabuf_fini(priv->dmabuf_priv); 552 #endif 553 554 kfree(priv); 555 return 0; 556 } 557 558 static long gntdev_ioctl_map_grant_ref(struct gntdev_priv *priv, 559 struct ioctl_gntdev_map_grant_ref __user *u) 560 { 561 struct ioctl_gntdev_map_grant_ref op; 562 struct gntdev_grant_map *map; 563 int err; 564 565 if (copy_from_user(&op, u, sizeof(op)) != 0) 566 return -EFAULT; 567 pr_debug("priv %p, add %d\n", priv, op.count); 568 if (unlikely(gntdev_test_page_count(op.count))) 569 return -EINVAL; 570 571 err = -ENOMEM; 572 map = gntdev_alloc_map(priv, op.count, 0 /* This is not a dma-buf. */); 573 if (!map) 574 return err; 575 576 if (copy_from_user(map->grants, &u->refs, 577 sizeof(map->grants[0]) * op.count) != 0) { 578 gntdev_put_map(NULL, map); 579 return -EFAULT; 580 } 581 582 mutex_lock(&priv->lock); 583 gntdev_add_map(priv, map); 584 op.index = map->index << PAGE_SHIFT; 585 mutex_unlock(&priv->lock); 586 587 if (copy_to_user(u, &op, sizeof(op)) != 0) 588 return -EFAULT; 589 590 return 0; 591 } 592 593 static long gntdev_ioctl_unmap_grant_ref(struct gntdev_priv *priv, 594 struct ioctl_gntdev_unmap_grant_ref __user *u) 595 { 596 struct ioctl_gntdev_unmap_grant_ref op; 597 struct gntdev_grant_map *map; 598 int err = -ENOENT; 599 600 if (copy_from_user(&op, u, sizeof(op)) != 0) 601 return -EFAULT; 602 pr_debug("priv %p, del %d+%d\n", priv, (int)op.index, (int)op.count); 603 604 mutex_lock(&priv->lock); 605 map = gntdev_find_map_index(priv, op.index >> PAGE_SHIFT, op.count); 606 if (map) { 607 list_del(&map->next); 608 err = 0; 609 } 610 mutex_unlock(&priv->lock); 611 if (map) 612 gntdev_put_map(priv, map); 613 return err; 614 } 615 616 static long gntdev_ioctl_get_offset_for_vaddr(struct gntdev_priv *priv, 617 struct ioctl_gntdev_get_offset_for_vaddr __user *u) 618 { 619 struct ioctl_gntdev_get_offset_for_vaddr op; 620 struct vm_area_struct *vma; 621 struct gntdev_grant_map *map; 622 int rv = -EINVAL; 623 624 if (copy_from_user(&op, u, sizeof(op)) != 0) 625 return -EFAULT; 626 pr_debug("priv %p, offset for vaddr %lx\n", priv, (unsigned long)op.vaddr); 627 628 down_read(¤t->mm->mmap_sem); 629 vma = find_vma(current->mm, op.vaddr); 630 if (!vma || vma->vm_ops != &gntdev_vmops) 631 goto out_unlock; 632 633 map = vma->vm_private_data; 634 if (!map) 635 goto out_unlock; 636 637 op.offset = map->index << PAGE_SHIFT; 638 op.count = map->count; 639 rv = 0; 640 641 out_unlock: 642 up_read(¤t->mm->mmap_sem); 643 644 if (rv == 0 && copy_to_user(u, &op, sizeof(op)) != 0) 645 return -EFAULT; 646 return rv; 647 } 648 649 static long gntdev_ioctl_notify(struct gntdev_priv *priv, void __user *u) 650 { 651 struct ioctl_gntdev_unmap_notify op; 652 struct gntdev_grant_map *map; 653 int rc; 654 int out_flags; 655 unsigned int out_event; 656 657 if (copy_from_user(&op, u, sizeof(op))) 658 return -EFAULT; 659 660 if (op.action & ~(UNMAP_NOTIFY_CLEAR_BYTE|UNMAP_NOTIFY_SEND_EVENT)) 661 return -EINVAL; 662 663 /* We need to grab a reference to the event channel we are going to use 664 * to send the notify before releasing the reference we may already have 665 * (if someone has called this ioctl twice). This is required so that 666 * it is possible to change the clear_byte part of the notification 667 * without disturbing the event channel part, which may now be the last 668 * reference to that event channel. 669 */ 670 if (op.action & UNMAP_NOTIFY_SEND_EVENT) { 671 if (evtchn_get(op.event_channel_port)) 672 return -EINVAL; 673 } 674 675 out_flags = op.action; 676 out_event = op.event_channel_port; 677 678 mutex_lock(&priv->lock); 679 680 list_for_each_entry(map, &priv->maps, next) { 681 uint64_t begin = map->index << PAGE_SHIFT; 682 uint64_t end = (map->index + map->count) << PAGE_SHIFT; 683 if (op.index >= begin && op.index < end) 684 goto found; 685 } 686 rc = -ENOENT; 687 goto unlock_out; 688 689 found: 690 if ((op.action & UNMAP_NOTIFY_CLEAR_BYTE) && 691 (map->flags & GNTMAP_readonly)) { 692 rc = -EINVAL; 693 goto unlock_out; 694 } 695 696 out_flags = map->notify.flags; 697 out_event = map->notify.event; 698 699 map->notify.flags = op.action; 700 map->notify.addr = op.index - (map->index << PAGE_SHIFT); 701 map->notify.event = op.event_channel_port; 702 703 rc = 0; 704 705 unlock_out: 706 mutex_unlock(&priv->lock); 707 708 /* Drop the reference to the event channel we did not save in the map */ 709 if (out_flags & UNMAP_NOTIFY_SEND_EVENT) 710 evtchn_put(out_event); 711 712 return rc; 713 } 714 715 #define GNTDEV_COPY_BATCH 16 716 717 struct gntdev_copy_batch { 718 struct gnttab_copy ops[GNTDEV_COPY_BATCH]; 719 struct page *pages[GNTDEV_COPY_BATCH]; 720 s16 __user *status[GNTDEV_COPY_BATCH]; 721 unsigned int nr_ops; 722 unsigned int nr_pages; 723 }; 724 725 static int gntdev_get_page(struct gntdev_copy_batch *batch, void __user *virt, 726 bool writeable, unsigned long *gfn) 727 { 728 unsigned long addr = (unsigned long)virt; 729 struct page *page; 730 unsigned long xen_pfn; 731 int ret; 732 733 ret = get_user_pages_fast(addr, 1, writeable ? FOLL_WRITE : 0, &page); 734 if (ret < 0) 735 return ret; 736 737 batch->pages[batch->nr_pages++] = page; 738 739 xen_pfn = page_to_xen_pfn(page) + XEN_PFN_DOWN(addr & ~PAGE_MASK); 740 *gfn = pfn_to_gfn(xen_pfn); 741 742 return 0; 743 } 744 745 static void gntdev_put_pages(struct gntdev_copy_batch *batch) 746 { 747 unsigned int i; 748 749 for (i = 0; i < batch->nr_pages; i++) 750 put_page(batch->pages[i]); 751 batch->nr_pages = 0; 752 } 753 754 static int gntdev_copy(struct gntdev_copy_batch *batch) 755 { 756 unsigned int i; 757 758 gnttab_batch_copy(batch->ops, batch->nr_ops); 759 gntdev_put_pages(batch); 760 761 /* 762 * For each completed op, update the status if the op failed 763 * and all previous ops for the segment were successful. 764 */ 765 for (i = 0; i < batch->nr_ops; i++) { 766 s16 status = batch->ops[i].status; 767 s16 old_status; 768 769 if (status == GNTST_okay) 770 continue; 771 772 if (__get_user(old_status, batch->status[i])) 773 return -EFAULT; 774 775 if (old_status != GNTST_okay) 776 continue; 777 778 if (__put_user(status, batch->status[i])) 779 return -EFAULT; 780 } 781 782 batch->nr_ops = 0; 783 return 0; 784 } 785 786 static int gntdev_grant_copy_seg(struct gntdev_copy_batch *batch, 787 struct gntdev_grant_copy_segment *seg, 788 s16 __user *status) 789 { 790 uint16_t copied = 0; 791 792 /* 793 * Disallow local -> local copies since there is only space in 794 * batch->pages for one page per-op and this would be a very 795 * expensive memcpy(). 796 */ 797 if (!(seg->flags & (GNTCOPY_source_gref | GNTCOPY_dest_gref))) 798 return -EINVAL; 799 800 /* Can't cross page if source/dest is a grant ref. */ 801 if (seg->flags & GNTCOPY_source_gref) { 802 if (seg->source.foreign.offset + seg->len > XEN_PAGE_SIZE) 803 return -EINVAL; 804 } 805 if (seg->flags & GNTCOPY_dest_gref) { 806 if (seg->dest.foreign.offset + seg->len > XEN_PAGE_SIZE) 807 return -EINVAL; 808 } 809 810 if (put_user(GNTST_okay, status)) 811 return -EFAULT; 812 813 while (copied < seg->len) { 814 struct gnttab_copy *op; 815 void __user *virt; 816 size_t len, off; 817 unsigned long gfn; 818 int ret; 819 820 if (batch->nr_ops >= GNTDEV_COPY_BATCH) { 821 ret = gntdev_copy(batch); 822 if (ret < 0) 823 return ret; 824 } 825 826 len = seg->len - copied; 827 828 op = &batch->ops[batch->nr_ops]; 829 op->flags = 0; 830 831 if (seg->flags & GNTCOPY_source_gref) { 832 op->source.u.ref = seg->source.foreign.ref; 833 op->source.domid = seg->source.foreign.domid; 834 op->source.offset = seg->source.foreign.offset + copied; 835 op->flags |= GNTCOPY_source_gref; 836 } else { 837 virt = seg->source.virt + copied; 838 off = (unsigned long)virt & ~XEN_PAGE_MASK; 839 len = min(len, (size_t)XEN_PAGE_SIZE - off); 840 841 ret = gntdev_get_page(batch, virt, false, &gfn); 842 if (ret < 0) 843 return ret; 844 845 op->source.u.gmfn = gfn; 846 op->source.domid = DOMID_SELF; 847 op->source.offset = off; 848 } 849 850 if (seg->flags & GNTCOPY_dest_gref) { 851 op->dest.u.ref = seg->dest.foreign.ref; 852 op->dest.domid = seg->dest.foreign.domid; 853 op->dest.offset = seg->dest.foreign.offset + copied; 854 op->flags |= GNTCOPY_dest_gref; 855 } else { 856 virt = seg->dest.virt + copied; 857 off = (unsigned long)virt & ~XEN_PAGE_MASK; 858 len = min(len, (size_t)XEN_PAGE_SIZE - off); 859 860 ret = gntdev_get_page(batch, virt, true, &gfn); 861 if (ret < 0) 862 return ret; 863 864 op->dest.u.gmfn = gfn; 865 op->dest.domid = DOMID_SELF; 866 op->dest.offset = off; 867 } 868 869 op->len = len; 870 copied += len; 871 872 batch->status[batch->nr_ops] = status; 873 batch->nr_ops++; 874 } 875 876 return 0; 877 } 878 879 static long gntdev_ioctl_grant_copy(struct gntdev_priv *priv, void __user *u) 880 { 881 struct ioctl_gntdev_grant_copy copy; 882 struct gntdev_copy_batch batch; 883 unsigned int i; 884 int ret = 0; 885 886 if (copy_from_user(©, u, sizeof(copy))) 887 return -EFAULT; 888 889 batch.nr_ops = 0; 890 batch.nr_pages = 0; 891 892 for (i = 0; i < copy.count; i++) { 893 struct gntdev_grant_copy_segment seg; 894 895 if (copy_from_user(&seg, ©.segments[i], sizeof(seg))) { 896 ret = -EFAULT; 897 goto out; 898 } 899 900 ret = gntdev_grant_copy_seg(&batch, &seg, ©.segments[i].status); 901 if (ret < 0) 902 goto out; 903 904 cond_resched(); 905 } 906 if (batch.nr_ops) 907 ret = gntdev_copy(&batch); 908 return ret; 909 910 out: 911 gntdev_put_pages(&batch); 912 return ret; 913 } 914 915 static long gntdev_ioctl(struct file *flip, 916 unsigned int cmd, unsigned long arg) 917 { 918 struct gntdev_priv *priv = flip->private_data; 919 void __user *ptr = (void __user *)arg; 920 921 switch (cmd) { 922 case IOCTL_GNTDEV_MAP_GRANT_REF: 923 return gntdev_ioctl_map_grant_ref(priv, ptr); 924 925 case IOCTL_GNTDEV_UNMAP_GRANT_REF: 926 return gntdev_ioctl_unmap_grant_ref(priv, ptr); 927 928 case IOCTL_GNTDEV_GET_OFFSET_FOR_VADDR: 929 return gntdev_ioctl_get_offset_for_vaddr(priv, ptr); 930 931 case IOCTL_GNTDEV_SET_UNMAP_NOTIFY: 932 return gntdev_ioctl_notify(priv, ptr); 933 934 case IOCTL_GNTDEV_GRANT_COPY: 935 return gntdev_ioctl_grant_copy(priv, ptr); 936 937 #ifdef CONFIG_XEN_GNTDEV_DMABUF 938 case IOCTL_GNTDEV_DMABUF_EXP_FROM_REFS: 939 return gntdev_ioctl_dmabuf_exp_from_refs(priv, use_ptemod, ptr); 940 941 case IOCTL_GNTDEV_DMABUF_EXP_WAIT_RELEASED: 942 return gntdev_ioctl_dmabuf_exp_wait_released(priv, ptr); 943 944 case IOCTL_GNTDEV_DMABUF_IMP_TO_REFS: 945 return gntdev_ioctl_dmabuf_imp_to_refs(priv, ptr); 946 947 case IOCTL_GNTDEV_DMABUF_IMP_RELEASE: 948 return gntdev_ioctl_dmabuf_imp_release(priv, ptr); 949 #endif 950 951 default: 952 pr_debug("priv %p, unknown cmd %x\n", priv, cmd); 953 return -ENOIOCTLCMD; 954 } 955 956 return 0; 957 } 958 959 static int gntdev_mmap(struct file *flip, struct vm_area_struct *vma) 960 { 961 struct gntdev_priv *priv = flip->private_data; 962 int index = vma->vm_pgoff; 963 int count = vma_pages(vma); 964 struct gntdev_grant_map *map; 965 int err = -EINVAL; 966 967 if ((vma->vm_flags & VM_WRITE) && !(vma->vm_flags & VM_SHARED)) 968 return -EINVAL; 969 970 pr_debug("map %d+%d at %lx (pgoff %lx)\n", 971 index, count, vma->vm_start, vma->vm_pgoff); 972 973 mutex_lock(&priv->lock); 974 map = gntdev_find_map_index(priv, index, count); 975 if (!map) 976 goto unlock_out; 977 if (use_ptemod && map->vma) 978 goto unlock_out; 979 refcount_inc(&map->users); 980 981 vma->vm_ops = &gntdev_vmops; 982 983 vma->vm_flags |= VM_DONTEXPAND | VM_DONTDUMP | VM_MIXEDMAP; 984 985 if (use_ptemod) 986 vma->vm_flags |= VM_DONTCOPY; 987 988 vma->vm_private_data = map; 989 if (map->flags) { 990 if ((vma->vm_flags & VM_WRITE) && 991 (map->flags & GNTMAP_readonly)) 992 goto out_unlock_put; 993 } else { 994 map->flags = GNTMAP_host_map; 995 if (!(vma->vm_flags & VM_WRITE)) 996 map->flags |= GNTMAP_readonly; 997 } 998 999 if (use_ptemod) { 1000 map->vma = vma; 1001 err = mmu_interval_notifier_insert_locked( 1002 &map->notifier, vma->vm_mm, vma->vm_start, 1003 vma->vm_end - vma->vm_start, &gntdev_mmu_ops); 1004 if (err) 1005 goto out_unlock_put; 1006 } 1007 mutex_unlock(&priv->lock); 1008 1009 /* 1010 * gntdev takes the address of the PTE in find_grant_ptes() and passes 1011 * it to the hypervisor in gntdev_map_grant_pages(). The purpose of 1012 * the notifier is to prevent the hypervisor pointer to the PTE from 1013 * going stale. 1014 * 1015 * Since this vma's mappings can't be touched without the mmap_sem, 1016 * and we are holding it now, there is no need for the notifier_range 1017 * locking pattern. 1018 */ 1019 mmu_interval_read_begin(&map->notifier); 1020 1021 if (use_ptemod) { 1022 map->pages_vm_start = vma->vm_start; 1023 err = apply_to_page_range(vma->vm_mm, vma->vm_start, 1024 vma->vm_end - vma->vm_start, 1025 find_grant_ptes, map); 1026 if (err) { 1027 pr_warn("find_grant_ptes() failure.\n"); 1028 goto out_put_map; 1029 } 1030 } 1031 1032 err = gntdev_map_grant_pages(map); 1033 if (err) 1034 goto out_put_map; 1035 1036 if (!use_ptemod) { 1037 err = vm_map_pages_zero(vma, map->pages, map->count); 1038 if (err) 1039 goto out_put_map; 1040 } else { 1041 #ifdef CONFIG_X86 1042 /* 1043 * If the PTEs were not made special by the grant map 1044 * hypercall, do so here. 1045 * 1046 * This is racy since the mapping is already visible 1047 * to userspace but userspace should be well-behaved 1048 * enough to not touch it until the mmap() call 1049 * returns. 1050 */ 1051 if (!xen_feature(XENFEAT_gnttab_map_avail_bits)) { 1052 apply_to_page_range(vma->vm_mm, vma->vm_start, 1053 vma->vm_end - vma->vm_start, 1054 set_grant_ptes_as_special, NULL); 1055 } 1056 #endif 1057 } 1058 1059 return 0; 1060 1061 unlock_out: 1062 mutex_unlock(&priv->lock); 1063 return err; 1064 1065 out_unlock_put: 1066 mutex_unlock(&priv->lock); 1067 out_put_map: 1068 if (use_ptemod) { 1069 unmap_grant_pages(map, 0, map->count); 1070 if (map->vma) { 1071 mmu_interval_notifier_remove(&map->notifier); 1072 map->vma = NULL; 1073 } 1074 } 1075 gntdev_put_map(priv, map); 1076 return err; 1077 } 1078 1079 static const struct file_operations gntdev_fops = { 1080 .owner = THIS_MODULE, 1081 .open = gntdev_open, 1082 .release = gntdev_release, 1083 .mmap = gntdev_mmap, 1084 .unlocked_ioctl = gntdev_ioctl 1085 }; 1086 1087 static struct miscdevice gntdev_miscdev = { 1088 .minor = MISC_DYNAMIC_MINOR, 1089 .name = "xen/gntdev", 1090 .fops = &gntdev_fops, 1091 }; 1092 1093 /* ------------------------------------------------------------------ */ 1094 1095 static int __init gntdev_init(void) 1096 { 1097 int err; 1098 1099 if (!xen_domain()) 1100 return -ENODEV; 1101 1102 use_ptemod = !xen_feature(XENFEAT_auto_translated_physmap); 1103 1104 err = misc_register(&gntdev_miscdev); 1105 if (err != 0) { 1106 pr_err("Could not register gntdev device\n"); 1107 return err; 1108 } 1109 return 0; 1110 } 1111 1112 static void __exit gntdev_exit(void) 1113 { 1114 misc_deregister(&gntdev_miscdev); 1115 } 1116 1117 module_init(gntdev_init); 1118 module_exit(gntdev_exit); 1119 1120 /* ------------------------------------------------------------------ */ 1121