drivers/gpu/drm/ttm/ttm_bo_vm.c

   1 /* SPDX-License-Identifier: GPL-2.0 OR MIT */
   2 /**************************************************************************
   3  *
   4  * Copyright (c) 2006-2009 VMware, Inc., Palo Alto, CA., USA
   5  * All Rights Reserved.
   6  *
   7  * Permission is hereby granted, free of charge, to any person obtaining a
   8  * copy of this software and associated documentation files (the
   9  * "Software"), to deal in the Software without restriction, including
  10  * without limitation the rights to use, copy, modify, merge, publish,
  11  * distribute, sub license, and/or sell copies of the Software, and to
  12  * permit persons to whom the Software is furnished to do so, subject to
  13  * the following conditions:
  14  *
  15  * The above copyright notice and this permission notice (including the
  16  * next paragraph) shall be included in all copies or substantial portions
  17  * of the Software.
  18  *
  19  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  20  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  21  * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL
  22  * THE COPYRIGHT HOLDERS, AUTHORS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM,
  23  * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
  24  * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
  25  * USE OR OTHER DEALINGS IN THE SOFTWARE.
  26  *
  27  **************************************************************************/
  28 /*
  29  * Authors: Thomas Hellstrom <thellstrom-at-vmware-dot-com>
  30  */
  31
  32 #define pr_fmt(fmt) "[TTM] " fmt
  33
  34 #include <drm/ttm/ttm_module.h>
  35 #include <drm/ttm/ttm_bo_driver.h>
  36 #include <drm/ttm/ttm_placement.h>
  37 #include <drm/drm_vma_manager.h>
  38 #include <linux/mm.h>
  39 #include <linux/pfn_t.h>
  40 #include <linux/rbtree.h>
  41 #include <linux/module.h>
  42 #include <linux/uaccess.h>
  43 #include <linux/mem_encrypt.h>
  44
  45 static vm_fault_t ttm_bo_vm_fault_idle(struct ttm_buffer_object *bo,
  46                                 struct vm_fault *vmf)
  47 {
  48         vm_fault_t ret = 0;
  49         int err = 0;
  50
  51         if (likely(!bo->moving))
  52                 goto out_unlock;
  53
  54         /*
  55          * Quick non-stalling check for idle.
  56          */
  57         if (dma_fence_is_signaled(bo->moving))
  58                 goto out_clear;
  59
  60         /*
  61          * If possible, avoid waiting for GPU with mmap_sem
  62          * held.
  63          */
  64         if (vmf->flags & FAULT_FLAG_ALLOW_RETRY) {
  65                 ret = VM_FAULT_RETRY;
  66                 if (vmf->flags & FAULT_FLAG_RETRY_NOWAIT)
  67                         goto out_unlock;
  68
  69                 ttm_bo_get(bo);
  70                 up_read(&vmf->vma->vm_mm->mmap_sem);
  71                 (void) dma_fence_wait(bo->moving, true);
  72                 dma_resv_unlock(bo->base.resv);
  73                 ttm_bo_put(bo);
  74                 goto out_unlock;
  75         }
  76
  77         /*
  78          * Ordinary wait.
  79          */
  80         err = dma_fence_wait(bo->moving, true);
  81         if (unlikely(err != 0)) {
  82                 ret = (err != -ERESTARTSYS) ? VM_FAULT_SIGBUS :
  83                         VM_FAULT_NOPAGE;
  84                 goto out_unlock;
  85         }
  86
  87 out_clear:
  88         dma_fence_put(bo->moving);
  89         bo->moving = NULL;
  90
  91 out_unlock:
  92         return ret;
  93 }
  94
  95 static unsigned long ttm_bo_io_mem_pfn(struct ttm_buffer_object *bo,
  96                                        unsigned long page_offset)
  97 {
  98         struct ttm_bo_device *bdev = bo->bdev;
  99
 100         if (bdev->driver->io_mem_pfn)
 101                 return bdev->driver->io_mem_pfn(bo, page_offset);
 102
 103         return ((bo->mem.bus.base + bo->mem.bus.offset) >> PAGE_SHIFT)
 104                 + page_offset;
 105 }
 106
 107 /**
 108  * ttm_bo_vm_reserve - Reserve a buffer object in a retryable vm callback
 109  * @bo: The buffer object
 110  * @vmf: The fault structure handed to the callback
 111  *
 112  * vm callbacks like fault() and *_mkwrite() allow for the mm_sem to be dropped
 113  * during long waits, and after the wait the callback will be restarted. This
 114  * is to allow other threads using the same virtual memory space concurrent
 115  * access to map(), unmap() completely unrelated buffer objects. TTM buffer
 116  * object reservations sometimes wait for GPU and should therefore be
 117  * considered long waits. This function reserves the buffer object interruptibly
 118  * taking this into account. Starvation is avoided by the vm system not
 119  * allowing too many repeated restarts.
 120  * This function is intended to be used in customized fault() and _mkwrite()
 121  * handlers.
 122  *
 123  * Return:
 124  *    0 on success and the bo was reserved.
 125  *    VM_FAULT_RETRY if blocking wait.
 126  *    VM_FAULT_NOPAGE if blocking wait and retrying was not allowed.
 127  */
 128 vm_fault_t ttm_bo_vm_reserve(struct ttm_buffer_object *bo,
 129                              struct vm_fault *vmf)
 130 {
 131         /*
 132          * Work around locking order reversal in fault / nopfn
 133          * between mmap_sem and bo_reserve: Perform a trylock operation
 134          * for reserve, and if it fails, retry the fault after waiting
 135          * for the buffer to become unreserved.
 136          */
 137         if (unlikely(!dma_resv_trylock(bo->base.resv))) {
 138                 if (vmf->flags & FAULT_FLAG_ALLOW_RETRY) {
 139                         if (!(vmf->flags & FAULT_FLAG_RETRY_NOWAIT)) {
 140                                 ttm_bo_get(bo);
 141                                 up_read(&vmf->vma->vm_mm->mmap_sem);
 142                                 if (!dma_resv_lock_interruptible(bo->base.resv,
 143                                                                  NULL))
 144                                         dma_resv_unlock(bo->base.resv);
 145                                 ttm_bo_put(bo);
 146                         }
 147
 148                         return VM_FAULT_RETRY;
 149                 }
 150
 151                 if (dma_resv_lock_interruptible(bo->base.resv, NULL))
 152                         return VM_FAULT_NOPAGE;
 153         }
 154
 155         return 0;
 156 }
 157 EXPORT_SYMBOL(ttm_bo_vm_reserve);
 158
 159 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
 160 /**
 161  * ttm_bo_vm_insert_huge - Insert a pfn for PUD or PMD faults
 162  * @vmf: Fault data
 163  * @bo: The buffer object
 164  * @page_offset: Page offset from bo start
 165  * @fault_page_size: The size of the fault in pages.
 166  * @pgprot: The page protections.
 167  * Does additional checking whether it's possible to insert a PUD or PMD
 168  * pfn and performs the insertion.
 169  *
 170  * Return: VM_FAULT_NOPAGE on successful insertion, VM_FAULT_FALLBACK if
 171  * a huge fault was not possible, or on insertion error.
 172  */
 173 static vm_fault_t ttm_bo_vm_insert_huge(struct vm_fault *vmf,
 174                                         struct ttm_buffer_object *bo,
 175                                         pgoff_t page_offset,
 176                                         pgoff_t fault_page_size,
 177                                         pgprot_t pgprot)
 178 {
 179         pgoff_t i;
 180         vm_fault_t ret;
 181         unsigned long pfn;
 182         pfn_t pfnt;
 183         struct ttm_tt *ttm = bo->ttm;
 184         bool write = vmf->flags & FAULT_FLAG_WRITE;
 185
 186         /* Fault should not cross bo boundary. */
 187         page_offset &= ~(fault_page_size - 1);
 188         if (page_offset + fault_page_size > bo->num_pages)
 189                 goto out_fallback;
 190
 191         if (bo->mem.bus.is_iomem)
 192                 pfn = ttm_bo_io_mem_pfn(bo, page_offset);
 193         else
 194                 pfn = page_to_pfn(ttm->pages[page_offset]);
 195
 196         /* pfn must be fault_page_size aligned. */
 197         if ((pfn & (fault_page_size - 1)) != 0)
 198                 goto out_fallback;
 199
 200         /* Check that memory is contiguous. */
 201         if (!bo->mem.bus.is_iomem) {
 202                 for (i = 1; i < fault_page_size; ++i) {
 203                         if (page_to_pfn(ttm->pages[page_offset + i]) != pfn + i)
 204                                 goto out_fallback;
 205                 }
 206         } else if (bo->bdev->driver->io_mem_pfn) {
 207                 for (i = 1; i < fault_page_size; ++i) {
 208                         if (ttm_bo_io_mem_pfn(bo, page_offset + i) != pfn + i)
 209                                 goto out_fallback;
 210                 }
 211         }
 212
 213         pfnt = __pfn_to_pfn_t(pfn, PFN_DEV);
 214         if (fault_page_size == (HPAGE_PMD_SIZE >> PAGE_SHIFT))
 215                 ret = vmf_insert_pfn_pmd_prot(vmf, pfnt, pgprot, write);
 216 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
 217         else if (fault_page_size == (HPAGE_PUD_SIZE >> PAGE_SHIFT))
 218                 ret = vmf_insert_pfn_pud_prot(vmf, pfnt, pgprot, write);
 219 #endif
 220         else
 221                 WARN_ON_ONCE(ret = VM_FAULT_FALLBACK);
 222
 223         if (ret != VM_FAULT_NOPAGE)
 224                 goto out_fallback;
 225
 226         return VM_FAULT_NOPAGE;
 227 out_fallback:
 228         count_vm_event(THP_FAULT_FALLBACK);
 229         return VM_FAULT_FALLBACK;
 230 }
 231 #else
 232 static vm_fault_t ttm_bo_vm_insert_huge(struct vm_fault *vmf,
 233                                         struct ttm_buffer_object *bo,
 234                                         pgoff_t page_offset,
 235                                         pgoff_t fault_page_size,
 236                                         pgprot_t pgprot)
 237 {
 238         return VM_FAULT_FALLBACK;
 239 }
 240 #endif
 241
 242 /**
 243  * ttm_bo_vm_fault_reserved - TTM fault helper
 244  * @vmf: The struct vm_fault given as argument to the fault callback
 245  * @prot: The page protection to be used for this memory area.
 246  * @num_prefault: Maximum number of prefault pages. The caller may want to
 247  * specify this based on madvice settings and the size of the GPU object
 248  * backed by the memory.
 249  * @fault_page_size: The size of the fault in pages.
 250  *
 251  * This function inserts one or more page table entries pointing to the
 252  * memory backing the buffer object, and then returns a return code
 253  * instructing the caller to retry the page access.
 254  *
 255  * Return:
 256  *   VM_FAULT_NOPAGE on success or pending signal
 257  *   VM_FAULT_SIGBUS on unspecified error
 258  *   VM_FAULT_OOM on out-of-memory
 259  *   VM_FAULT_RETRY if retryable wait
 260  */
 261 vm_fault_t ttm_bo_vm_fault_reserved(struct vm_fault *vmf,
 262                                     pgprot_t prot,
 263                                     pgoff_t num_prefault,
 264                                     pgoff_t fault_page_size)
 265 {
 266         struct vm_area_struct *vma = vmf->vma;
 267         struct ttm_buffer_object *bo = vma->vm_private_data;
 268         struct ttm_bo_device *bdev = bo->bdev;
 269         unsigned long page_offset;
 270         unsigned long page_last;
 271         unsigned long pfn;
 272         struct ttm_tt *ttm = NULL;
 273         struct page *page;
 274         int err;
 275         pgoff_t i;
 276         vm_fault_t ret = VM_FAULT_NOPAGE;
 277         unsigned long address = vmf->address;
 278         struct ttm_mem_type_manager *man =
 279                 &bdev->man[bo->mem.mem_type];
 280
 281         /*
 282          * Refuse to fault imported pages. This should be handled
 283          * (if at all) by redirecting mmap to the exporter.
 284          */
 285         if (bo->ttm && (bo->ttm->page_flags & TTM_PAGE_FLAG_SG))
 286                 return VM_FAULT_SIGBUS;
 287
 288         if (bdev->driver->fault_reserve_notify) {
 289                 struct dma_fence *moving = dma_fence_get(bo->moving);
 290
 291                 err = bdev->driver->fault_reserve_notify(bo);
 292                 switch (err) {
 293                 case 0:
 294                         break;
 295                 case -EBUSY:
 296                 case -ERESTARTSYS:
 297                         return VM_FAULT_NOPAGE;
 298                 default:
 299                         return VM_FAULT_SIGBUS;
 300                 }
 301
 302                 if (bo->moving != moving) {
 303                         spin_lock(&ttm_bo_glob.lru_lock);
 304                         ttm_bo_move_to_lru_tail(bo, NULL);
 305                         spin_unlock(&ttm_bo_glob.lru_lock);
 306                 }
 307                 dma_fence_put(moving);
 308         }
 309
 310         /*
 311          * Wait for buffer data in transit, due to a pipelined
 312          * move.
 313          */
 314         ret = ttm_bo_vm_fault_idle(bo, vmf);
 315         if (unlikely(ret != 0))
 316                 return ret;
 317
 318         err = ttm_mem_io_lock(man, true);
 319         if (unlikely(err != 0))
 320                 return VM_FAULT_NOPAGE;
 321         err = ttm_mem_io_reserve_vm(bo);
 322         if (unlikely(err != 0)) {
 323                 ret = VM_FAULT_SIGBUS;
 324                 goto out_io_unlock;
 325         }
 326
 327         page_offset = ((address - vma->vm_start) >> PAGE_SHIFT) +
 328                 vma->vm_pgoff - drm_vma_node_start(&bo->base.vma_node);
 329         page_last = vma_pages(vma) + vma->vm_pgoff -
 330                 drm_vma_node_start(&bo->base.vma_node);
 331
 332         if (unlikely(page_offset >= bo->num_pages)) {
 333                 ret = VM_FAULT_SIGBUS;
 334                 goto out_io_unlock;
 335         }
 336
 337         prot = ttm_io_prot(bo->mem.placement, prot);
 338         if (!bo->mem.bus.is_iomem) {
 339                 struct ttm_operation_ctx ctx = {
 340                         .interruptible = false,
 341                         .no_wait_gpu = false,
 342                         .flags = TTM_OPT_FLAG_FORCE_ALLOC
 343
 344                 };
 345
 346                 ttm = bo->ttm;
 347                 if (ttm_tt_populate(bo->ttm, &ctx)) {
 348                         ret = VM_FAULT_OOM;
 349                         goto out_io_unlock;
 350                 }
 351         } else {
 352                 /* Iomem should not be marked encrypted */
 353                 prot = pgprot_decrypted(prot);
 354         }
 355
 356         /* We don't prefault on huge faults. Yet. */
 357         if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE) && fault_page_size != 1) {
 358                 ret = ttm_bo_vm_insert_huge(vmf, bo, page_offset,
 359                                             fault_page_size, prot);
 360                 goto out_io_unlock;
 361         }
 362
 363         /*
 364          * Speculatively prefault a number of pages. Only error on
 365          * first page.
 366          */
 367         for (i = 0; i < num_prefault; ++i) {
 368                 if (bo->mem.bus.is_iomem) {
 369                         pfn = ttm_bo_io_mem_pfn(bo, page_offset);
 370                 } else {
 371                         page = ttm->pages[page_offset];
 372                         if (unlikely(!page && i == 0)) {
 373                                 ret = VM_FAULT_OOM;
 374                                 goto out_io_unlock;
 375                         } else if (unlikely(!page)) {
 376                                 break;
 377                         }
 378                         page->index = drm_vma_node_start(&bo->base.vma_node) +
 379                                 page_offset;
 380                         pfn = page_to_pfn(page);
 381                 }
 382
 383                 /*
 384                  * Note that the value of @prot at this point may differ from
 385                  * the value of @vma->vm_page_prot in the caching- and
 386                  * encryption bits. This is because the exact location of the
 387                  * data may not be known at mmap() time and may also change
 388                  * at arbitrary times while the data is mmap'ed.
 389                  * See vmf_insert_mixed_prot() for a discussion.
 390                  */
 391                 if (vma->vm_flags & VM_MIXEDMAP)
 392                         ret = vmf_insert_mixed_prot(vma, address,
 393                                                     __pfn_to_pfn_t(pfn, PFN_DEV),
 394                                                     prot);
 395                 else
 396                         ret = vmf_insert_pfn_prot(vma, address, pfn, prot);
 397
 398                 /* Never error on prefaulted PTEs */
 399                 if (unlikely((ret & VM_FAULT_ERROR))) {
 400                         if (i == 0)
 401                                 goto out_io_unlock;
 402                         else
 403                                 break;
 404                 }
 405
 406                 address += PAGE_SIZE;
 407                 if (unlikely(++page_offset >= page_last))
 408                         break;
 409         }
 410         ret = VM_FAULT_NOPAGE;
 411 out_io_unlock:
 412         ttm_mem_io_unlock(man);
 413         return ret;
 414 }
 415 EXPORT_SYMBOL(ttm_bo_vm_fault_reserved);
 416
 417 vm_fault_t ttm_bo_vm_fault(struct vm_fault *vmf)
 418 {
 419         struct vm_area_struct *vma = vmf->vma;
 420         pgprot_t prot;
 421         struct ttm_buffer_object *bo = vma->vm_private_data;
 422         vm_fault_t ret;
 423
 424         ret = ttm_bo_vm_reserve(bo, vmf);
 425         if (ret)
 426                 return ret;
 427
 428         prot = vma->vm_page_prot;
 429         ret = ttm_bo_vm_fault_reserved(vmf, prot, TTM_BO_VM_NUM_PREFAULT, 1);
 430         if (ret == VM_FAULT_RETRY && !(vmf->flags & FAULT_FLAG_RETRY_NOWAIT))
 431                 return ret;
 432
 433         dma_resv_unlock(bo->base.resv);
 434
 435         return ret;
 436 }
 437 EXPORT_SYMBOL(ttm_bo_vm_fault);
 438
 439 void ttm_bo_vm_open(struct vm_area_struct *vma)
 440 {
 441         struct ttm_buffer_object *bo = vma->vm_private_data;
 442
 443         WARN_ON(bo->bdev->dev_mapping != vma->vm_file->f_mapping);
 444
 445         ttm_bo_get(bo);
 446 }
 447 EXPORT_SYMBOL(ttm_bo_vm_open);
 448
 449 void ttm_bo_vm_close(struct vm_area_struct *vma)
 450 {
 451         struct ttm_buffer_object *bo = vma->vm_private_data;
 452
 453         ttm_bo_put(bo);
 454         vma->vm_private_data = NULL;
 455 }
 456 EXPORT_SYMBOL(ttm_bo_vm_close);
 457
 458 static int ttm_bo_vm_access_kmap(struct ttm_buffer_object *bo,
 459                                  unsigned long offset,
 460                                  uint8_t *buf, int len, int write)
 461 {
 462         unsigned long page = offset >> PAGE_SHIFT;
 463         unsigned long bytes_left = len;
 464         int ret;
 465
 466         /* Copy a page at a time, that way no extra virtual address
 467          * mapping is needed
 468          */
 469         offset -= page << PAGE_SHIFT;
 470         do {
 471                 unsigned long bytes = min(bytes_left, PAGE_SIZE - offset);
 472                 struct ttm_bo_kmap_obj map;
 473                 void *ptr;
 474                 bool is_iomem;
 475
 476                 ret = ttm_bo_kmap(bo, page, 1, &map);
 477                 if (ret)
 478                         return ret;
 479
 480                 ptr = (uint8_t *)ttm_kmap_obj_virtual(&map, &is_iomem) + offset;
 481                 WARN_ON_ONCE(is_iomem);
 482                 if (write)
 483                         memcpy(ptr, buf, bytes);
 484                 else
 485                         memcpy(buf, ptr, bytes);
 486                 ttm_bo_kunmap(&map);
 487
 488                 page++;
 489                 buf += bytes;
 490                 bytes_left -= bytes;
 491                 offset = 0;
 492         } while (bytes_left);
 493
 494         return len;
 495 }
 496
 497 int ttm_bo_vm_access(struct vm_area_struct *vma, unsigned long addr,
 498                      void *buf, int len, int write)
 499 {
 500         unsigned long offset = (addr) - vma->vm_start;
 501         struct ttm_buffer_object *bo = vma->vm_private_data;
 502         int ret;
 503
 504         if (len < 1 || (offset + len) >> PAGE_SHIFT > bo->num_pages)
 505                 return -EIO;
 506
 507         ret = ttm_bo_reserve(bo, true, false, NULL);
 508         if (ret)
 509                 return ret;
 510
 511         switch (bo->mem.mem_type) {
 512         case TTM_PL_SYSTEM:
 513                 if (unlikely(bo->ttm->page_flags & TTM_PAGE_FLAG_SWAPPED)) {
 514                         ret = ttm_tt_swapin(bo->ttm);
 515                         if (unlikely(ret != 0))
 516                                 return ret;
 517                 }
 518                 /* fall through */
 519         case TTM_PL_TT:
 520                 ret = ttm_bo_vm_access_kmap(bo, offset, buf, len, write);
 521                 break;
 522         default:
 523                 if (bo->bdev->driver->access_memory)
 524                         ret = bo->bdev->driver->access_memory(
 525                                 bo, offset, buf, len, write);
 526                 else
 527                         ret = -EIO;
 528         }
 529
 530         ttm_bo_unreserve(bo);
 531
 532         return ret;
 533 }
 534 EXPORT_SYMBOL(ttm_bo_vm_access);
 535
 536 static const struct vm_operations_struct ttm_bo_vm_ops = {
 537         .fault = ttm_bo_vm_fault,
 538         .open = ttm_bo_vm_open,
 539         .close = ttm_bo_vm_close,
 540         .access = ttm_bo_vm_access,
 541 };
 542
 543 static struct ttm_buffer_object *ttm_bo_vm_lookup(struct ttm_bo_device *bdev,
 544                                                   unsigned long offset,
 545                                                   unsigned long pages)
 546 {
 547         struct drm_vma_offset_node *node;
 548         struct ttm_buffer_object *bo = NULL;
 549
 550         drm_vma_offset_lock_lookup(bdev->vma_manager);
 551
 552         node = drm_vma_offset_lookup_locked(bdev->vma_manager, offset, pages);
 553         if (likely(node)) {
 554                 bo = container_of(node, struct ttm_buffer_object,
 555                                   base.vma_node);
 556                 bo = ttm_bo_get_unless_zero(bo);
 557         }
 558
 559         drm_vma_offset_unlock_lookup(bdev->vma_manager);
 560
 561         if (!bo)
 562                 pr_err("Could not find buffer object to map\n");
 563
 564         return bo;
 565 }
 566
 567 static void ttm_bo_mmap_vma_setup(struct ttm_buffer_object *bo, struct vm_area_struct *vma)
 568 {
 569         vma->vm_ops = &ttm_bo_vm_ops;
 570
 571         /*
 572          * Note: We're transferring the bo reference to
 573          * vma->vm_private_data here.
 574          */
 575
 576         vma->vm_private_data = bo;
 577
 578         /*
 579          * We'd like to use VM_PFNMAP on shared mappings, where
 580          * (vma->vm_flags & VM_SHARED) != 0, for performance reasons,
 581          * but for some reason VM_PFNMAP + x86 PAT + write-combine is very
 582          * bad for performance. Until that has been sorted out, use
 583          * VM_MIXEDMAP on all mappings. See freedesktop.org bug #75719
 584          */
 585         vma->vm_flags |= VM_MIXEDMAP;
 586         vma->vm_flags |= VM_IO | VM_DONTEXPAND | VM_DONTDUMP;
 587 }
 588
 589 int ttm_bo_mmap(struct file *filp, struct vm_area_struct *vma,
 590                 struct ttm_bo_device *bdev)
 591 {
 592         struct ttm_bo_driver *driver;
 593         struct ttm_buffer_object *bo;
 594         int ret;
 595
 596         if (unlikely(vma->vm_pgoff < DRM_FILE_PAGE_OFFSET_START))
 597                 return -EINVAL;
 598
 599         bo = ttm_bo_vm_lookup(bdev, vma->vm_pgoff, vma_pages(vma));
 600         if (unlikely(!bo))
 601                 return -EINVAL;
 602
 603         driver = bo->bdev->driver;
 604         if (unlikely(!driver->verify_access)) {
 605                 ret = -EPERM;
 606                 goto out_unref;
 607         }
 608         ret = driver->verify_access(bo, filp);
 609         if (unlikely(ret != 0))
 610                 goto out_unref;
 611
 612         ttm_bo_mmap_vma_setup(bo, vma);
 613         return 0;
 614 out_unref:
 615         ttm_bo_put(bo);
 616         return ret;
 617 }
 618 EXPORT_SYMBOL(ttm_bo_mmap);
 619
 620 int ttm_bo_mmap_obj(struct vm_area_struct *vma, struct ttm_buffer_object *bo)
 621 {
 622         ttm_bo_get(bo);
 623         ttm_bo_mmap_vma_setup(bo, vma);
 624         return 0;
 625 }
 626 EXPORT_SYMBOL(ttm_bo_mmap_obj);