drivers/gpu/drm/ttm/ttm_bo_util.c

   1 /* SPDX-License-Identifier: GPL-2.0 OR MIT */
   2 /**************************************************************************
   3  *
   4  * Copyright (c) 2007-2009 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 #include <drm/ttm/ttm_bo_driver.h>
  33 #include <drm/ttm/ttm_placement.h>
  34 #include <drm/drm_cache.h>
  35 #include <drm/drm_vma_manager.h>
  36 #include <linux/dma-buf-map.h>
  37 #include <linux/io.h>
  38 #include <linux/highmem.h>
  39 #include <linux/wait.h>
  40 #include <linux/slab.h>
  41 #include <linux/vmalloc.h>
  42 #include <linux/module.h>
  43 #include <linux/dma-resv.h>
  44
  45 struct ttm_transfer_obj {
  46         struct ttm_buffer_object base;
  47         struct ttm_buffer_object *bo;
  48 };
  49
  50 int ttm_mem_io_reserve(struct ttm_device *bdev,
  51                        struct ttm_resource *mem)
  52 {
  53         if (mem->bus.offset || mem->bus.addr)
  54                 return 0;
  55
  56         mem->bus.is_iomem = false;
  57         if (!bdev->funcs->io_mem_reserve)
  58                 return 0;
  59
  60         return bdev->funcs->io_mem_reserve(bdev, mem);
  61 }
  62
  63 void ttm_mem_io_free(struct ttm_device *bdev,
  64                      struct ttm_resource *mem)
  65 {
  66         if (!mem)
  67                 return;
  68
  69         if (!mem->bus.offset && !mem->bus.addr)
  70                 return;
  71
  72         if (bdev->funcs->io_mem_free)
  73                 bdev->funcs->io_mem_free(bdev, mem);
  74
  75         mem->bus.offset = 0;
  76         mem->bus.addr = NULL;
  77 }
  78
  79 /**
  80  * ttm_move_memcpy - Helper to perform a memcpy ttm move operation.
  81  * @bo: The struct ttm_buffer_object.
  82  * @new_mem: The struct ttm_resource we're moving to (copy destination).
  83  * @new_iter: A struct ttm_kmap_iter representing the destination resource.
  84  * @src_iter: A struct ttm_kmap_iter representing the source resource.
  85  *
  86  * This function is intended to be able to move out async under a
  87  * dma-fence if desired.
  88  */
  89 void ttm_move_memcpy(struct ttm_buffer_object *bo,
  90                      u32 num_pages,
  91                      struct ttm_kmap_iter *dst_iter,
  92                      struct ttm_kmap_iter *src_iter)
  93 {
  94         const struct ttm_kmap_iter_ops *dst_ops = dst_iter->ops;
  95         const struct ttm_kmap_iter_ops *src_ops = src_iter->ops;
  96         struct ttm_tt *ttm = bo->ttm;
  97         struct dma_buf_map src_map, dst_map;
  98         pgoff_t i;
  99
 100         /* Single TTM move. NOP */
 101         if (dst_ops->maps_tt && src_ops->maps_tt)
 102                 return;
 103
 104         /* Don't move nonexistent data. Clear destination instead. */
 105         if (src_ops->maps_tt && (!ttm || !ttm_tt_is_populated(ttm))) {
 106                 if (ttm && !(ttm->page_flags & TTM_PAGE_FLAG_ZERO_ALLOC))
 107                         return;
 108
 109                 for (i = 0; i < num_pages; ++i) {
 110                         dst_ops->map_local(dst_iter, &dst_map, i);
 111                         if (dst_map.is_iomem)
 112                                 memset_io(dst_map.vaddr_iomem, 0, PAGE_SIZE);
 113                         else
 114                                 memset(dst_map.vaddr, 0, PAGE_SIZE);
 115                         if (dst_ops->unmap_local)
 116                                 dst_ops->unmap_local(dst_iter, &dst_map);
 117                 }
 118                 return;
 119         }
 120
 121         for (i = 0; i < num_pages; ++i) {
 122                 dst_ops->map_local(dst_iter, &dst_map, i);
 123                 src_ops->map_local(src_iter, &src_map, i);
 124
 125                 drm_memcpy_from_wc(&dst_map, &src_map, PAGE_SIZE);
 126
 127                 if (src_ops->unmap_local)
 128                         src_ops->unmap_local(src_iter, &src_map);
 129                 if (dst_ops->unmap_local)
 130                         dst_ops->unmap_local(dst_iter, &dst_map);
 131         }
 132 }
 133 EXPORT_SYMBOL(ttm_move_memcpy);
 134
 135 int ttm_bo_move_memcpy(struct ttm_buffer_object *bo,
 136                        struct ttm_operation_ctx *ctx,
 137                        struct ttm_resource *dst_mem)
 138 {
 139         struct ttm_device *bdev = bo->bdev;
 140         struct ttm_resource_manager *dst_man =
 141                 ttm_manager_type(bo->bdev, dst_mem->mem_type);
 142         struct ttm_tt *ttm = bo->ttm;
 143         struct ttm_resource *src_mem = bo->resource;
 144         struct ttm_resource_manager *src_man =
 145                 ttm_manager_type(bdev, src_mem->mem_type);
 146         struct ttm_resource src_copy = *src_mem;
 147         union {
 148                 struct ttm_kmap_iter_tt tt;
 149                 struct ttm_kmap_iter_linear_io io;
 150         } _dst_iter, _src_iter;
 151         struct ttm_kmap_iter *dst_iter, *src_iter;
 152         int ret = 0;
 153
 154         if (ttm && ((ttm->page_flags & TTM_PAGE_FLAG_SWAPPED) ||
 155                     dst_man->use_tt)) {
 156                 ret = ttm_tt_populate(bdev, ttm, ctx);
 157                 if (ret)
 158                         return ret;
 159         }
 160
 161         dst_iter = ttm_kmap_iter_linear_io_init(&_dst_iter.io, bdev, dst_mem);
 162         if (PTR_ERR(dst_iter) == -EINVAL && dst_man->use_tt)
 163                 dst_iter = ttm_kmap_iter_tt_init(&_dst_iter.tt, bo->ttm);
 164         if (IS_ERR(dst_iter))
 165                 return PTR_ERR(dst_iter);
 166
 167         src_iter = ttm_kmap_iter_linear_io_init(&_src_iter.io, bdev, src_mem);
 168         if (PTR_ERR(src_iter) == -EINVAL && src_man->use_tt)
 169                 src_iter = ttm_kmap_iter_tt_init(&_src_iter.tt, bo->ttm);
 170         if (IS_ERR(src_iter)) {
 171                 ret = PTR_ERR(src_iter);
 172                 goto out_src_iter;
 173         }
 174
 175         ttm_move_memcpy(bo, dst_mem->num_pages, dst_iter, src_iter);
 176         src_copy = *src_mem;
 177         ttm_bo_move_sync_cleanup(bo, dst_mem);
 178
 179         if (!src_iter->ops->maps_tt)
 180                 ttm_kmap_iter_linear_io_fini(&_src_iter.io, bdev, &src_copy);
 181 out_src_iter:
 182         if (!dst_iter->ops->maps_tt)
 183                 ttm_kmap_iter_linear_io_fini(&_dst_iter.io, bdev, dst_mem);
 184
 185         return ret;
 186 }
 187 EXPORT_SYMBOL(ttm_bo_move_memcpy);
 188
 189 static void ttm_transfered_destroy(struct ttm_buffer_object *bo)
 190 {
 191         struct ttm_transfer_obj *fbo;
 192
 193         fbo = container_of(bo, struct ttm_transfer_obj, base);
 194         ttm_bo_put(fbo->bo);
 195         kfree(fbo);
 196 }
 197
 198 /**
 199  * ttm_buffer_object_transfer
 200  *
 201  * @bo: A pointer to a struct ttm_buffer_object.
 202  * @new_obj: A pointer to a pointer to a newly created ttm_buffer_object,
 203  * holding the data of @bo with the old placement.
 204  *
 205  * This is a utility function that may be called after an accelerated move
 206  * has been scheduled. A new buffer object is created as a placeholder for
 207  * the old data while it's being copied. When that buffer object is idle,
 208  * it can be destroyed, releasing the space of the old placement.
 209  * Returns:
 210  * !0: Failure.
 211  */
 212
 213 static int ttm_buffer_object_transfer(struct ttm_buffer_object *bo,
 214                                       struct ttm_buffer_object **new_obj)
 215 {
 216         struct ttm_transfer_obj *fbo;
 217         int ret;
 218
 219         fbo = kmalloc(sizeof(*fbo), GFP_KERNEL);
 220         if (!fbo)
 221                 return -ENOMEM;
 222
 223         fbo->base = *bo;
 224
 225         ttm_bo_get(bo);
 226         fbo->bo = bo;
 227
 228         /**
 229          * Fix up members that we shouldn't copy directly:
 230          * TODO: Explicit member copy would probably be better here.
 231          */
 232
 233         atomic_inc(&ttm_glob.bo_count);
 234         INIT_LIST_HEAD(&fbo->base.ddestroy);
 235         INIT_LIST_HEAD(&fbo->base.lru);
 236         fbo->base.moving = NULL;
 237         drm_vma_node_reset(&fbo->base.base.vma_node);
 238
 239         kref_init(&fbo->base.kref);
 240         fbo->base.destroy = &ttm_transfered_destroy;
 241         fbo->base.pin_count = 0;
 242         if (bo->type != ttm_bo_type_sg)
 243                 fbo->base.base.resv = &fbo->base.base._resv;
 244
 245         dma_resv_init(&fbo->base.base._resv);
 246         fbo->base.base.dev = NULL;
 247         ret = dma_resv_trylock(&fbo->base.base._resv);
 248         WARN_ON(!ret);
 249
 250         ttm_bo_move_to_lru_tail_unlocked(&fbo->base);
 251
 252         *new_obj = &fbo->base;
 253         return 0;
 254 }
 255
 256 pgprot_t ttm_io_prot(struct ttm_buffer_object *bo, struct ttm_resource *res,
 257                      pgprot_t tmp)
 258 {
 259         struct ttm_resource_manager *man;
 260         enum ttm_caching caching;
 261
 262         man = ttm_manager_type(bo->bdev, res->mem_type);
 263         caching = man->use_tt ? bo->ttm->caching : res->bus.caching;
 264
 265         return ttm_prot_from_caching(caching, tmp);
 266 }
 267 EXPORT_SYMBOL(ttm_io_prot);
 268
 269 static int ttm_bo_ioremap(struct ttm_buffer_object *bo,
 270                           unsigned long offset,
 271                           unsigned long size,
 272                           struct ttm_bo_kmap_obj *map)
 273 {
 274         struct ttm_resource *mem = bo->resource;
 275
 276         if (bo->resource->bus.addr) {
 277                 map->bo_kmap_type = ttm_bo_map_premapped;
 278                 map->virtual = ((u8 *)bo->resource->bus.addr) + offset;
 279         } else {
 280                 resource_size_t res = bo->resource->bus.offset + offset;
 281
 282                 map->bo_kmap_type = ttm_bo_map_iomap;
 283                 if (mem->bus.caching == ttm_write_combined)
 284                         map->virtual = ioremap_wc(res, size);
 285 #ifdef CONFIG_X86
 286                 else if (mem->bus.caching == ttm_cached)
 287                         map->virtual = ioremap_cache(res, size);
 288 #endif
 289                 else
 290                         map->virtual = ioremap(res, size);
 291         }
 292         return (!map->virtual) ? -ENOMEM : 0;
 293 }
 294
 295 static int ttm_bo_kmap_ttm(struct ttm_buffer_object *bo,
 296                            unsigned long start_page,
 297                            unsigned long num_pages,
 298                            struct ttm_bo_kmap_obj *map)
 299 {
 300         struct ttm_resource *mem = bo->resource;
 301         struct ttm_operation_ctx ctx = {
 302                 .interruptible = false,
 303                 .no_wait_gpu = false
 304         };
 305         struct ttm_tt *ttm = bo->ttm;
 306         pgprot_t prot;
 307         int ret;
 308
 309         BUG_ON(!ttm);
 310
 311         ret = ttm_tt_populate(bo->bdev, ttm, &ctx);
 312         if (ret)
 313                 return ret;
 314
 315         if (num_pages == 1 && ttm->caching == ttm_cached) {
 316                 /*
 317                  * We're mapping a single page, and the desired
 318                  * page protection is consistent with the bo.
 319                  */
 320
 321                 map->bo_kmap_type = ttm_bo_map_kmap;
 322                 map->page = ttm->pages[start_page];
 323                 map->virtual = kmap(map->page);
 324         } else {
 325                 /*
 326                  * We need to use vmap to get the desired page protection
 327                  * or to make the buffer object look contiguous.
 328                  */
 329                 prot = ttm_io_prot(bo, mem, PAGE_KERNEL);
 330                 map->bo_kmap_type = ttm_bo_map_vmap;
 331                 map->virtual = vmap(ttm->pages + start_page, num_pages,
 332                                     0, prot);
 333         }
 334         return (!map->virtual) ? -ENOMEM : 0;
 335 }
 336
 337 int ttm_bo_kmap(struct ttm_buffer_object *bo,
 338                 unsigned long start_page, unsigned long num_pages,
 339                 struct ttm_bo_kmap_obj *map)
 340 {
 341         unsigned long offset, size;
 342         int ret;
 343
 344         map->virtual = NULL;
 345         map->bo = bo;
 346         if (num_pages > bo->resource->num_pages)
 347                 return -EINVAL;
 348         if ((start_page + num_pages) > bo->resource->num_pages)
 349                 return -EINVAL;
 350
 351         ret = ttm_mem_io_reserve(bo->bdev, bo->resource);
 352         if (ret)
 353                 return ret;
 354         if (!bo->resource->bus.is_iomem) {
 355                 return ttm_bo_kmap_ttm(bo, start_page, num_pages, map);
 356         } else {
 357                 offset = start_page << PAGE_SHIFT;
 358                 size = num_pages << PAGE_SHIFT;
 359                 return ttm_bo_ioremap(bo, offset, size, map);
 360         }
 361 }
 362 EXPORT_SYMBOL(ttm_bo_kmap);
 363
 364 void ttm_bo_kunmap(struct ttm_bo_kmap_obj *map)
 365 {
 366         if (!map->virtual)
 367                 return;
 368         switch (map->bo_kmap_type) {
 369         case ttm_bo_map_iomap:
 370                 iounmap(map->virtual);
 371                 break;
 372         case ttm_bo_map_vmap:
 373                 vunmap(map->virtual);
 374                 break;
 375         case ttm_bo_map_kmap:
 376                 kunmap(map->page);
 377                 break;
 378         case ttm_bo_map_premapped:
 379                 break;
 380         default:
 381                 BUG();
 382         }
 383         ttm_mem_io_free(map->bo->bdev, map->bo->resource);
 384         map->virtual = NULL;
 385         map->page = NULL;
 386 }
 387 EXPORT_SYMBOL(ttm_bo_kunmap);
 388
 389 int ttm_bo_vmap(struct ttm_buffer_object *bo, struct dma_buf_map *map)
 390 {
 391         struct ttm_resource *mem = bo->resource;
 392         int ret;
 393
 394         ret = ttm_mem_io_reserve(bo->bdev, mem);
 395         if (ret)
 396                 return ret;
 397
 398         if (mem->bus.is_iomem) {
 399                 void __iomem *vaddr_iomem;
 400
 401                 if (mem->bus.addr)
 402                         vaddr_iomem = (void __iomem *)mem->bus.addr;
 403                 else if (mem->bus.caching == ttm_write_combined)
 404                         vaddr_iomem = ioremap_wc(mem->bus.offset,
 405                                                  bo->base.size);
 406 #ifdef CONFIG_X86
 407                 else if (mem->bus.caching == ttm_cached)
 408                         vaddr_iomem = ioremap_cache(mem->bus.offset,
 409                                                   bo->base.size);
 410 #endif
 411                 else
 412                         vaddr_iomem = ioremap(mem->bus.offset, bo->base.size);
 413
 414                 if (!vaddr_iomem)
 415                         return -ENOMEM;
 416
 417                 dma_buf_map_set_vaddr_iomem(map, vaddr_iomem);
 418
 419         } else {
 420                 struct ttm_operation_ctx ctx = {
 421                         .interruptible = false,
 422                         .no_wait_gpu = false
 423                 };
 424                 struct ttm_tt *ttm = bo->ttm;
 425                 pgprot_t prot;
 426                 void *vaddr;
 427
 428                 ret = ttm_tt_populate(bo->bdev, ttm, &ctx);
 429                 if (ret)
 430                         return ret;
 431
 432                 /*
 433                  * We need to use vmap to get the desired page protection
 434                  * or to make the buffer object look contiguous.
 435                  */
 436                 prot = ttm_io_prot(bo, mem, PAGE_KERNEL);
 437                 vaddr = vmap(ttm->pages, ttm->num_pages, 0, prot);
 438                 if (!vaddr)
 439                         return -ENOMEM;
 440
 441                 dma_buf_map_set_vaddr(map, vaddr);
 442         }
 443
 444         return 0;
 445 }
 446 EXPORT_SYMBOL(ttm_bo_vmap);
 447
 448 void ttm_bo_vunmap(struct ttm_buffer_object *bo, struct dma_buf_map *map)
 449 {
 450         struct ttm_resource *mem = bo->resource;
 451
 452         if (dma_buf_map_is_null(map))
 453                 return;
 454
 455         if (!map->is_iomem)
 456                 vunmap(map->vaddr);
 457         else if (!mem->bus.addr)
 458                 iounmap(map->vaddr_iomem);
 459         dma_buf_map_clear(map);
 460
 461         ttm_mem_io_free(bo->bdev, bo->resource);
 462 }
 463 EXPORT_SYMBOL(ttm_bo_vunmap);
 464
 465 static int ttm_bo_wait_free_node(struct ttm_buffer_object *bo,
 466                                  bool dst_use_tt)
 467 {
 468         int ret;
 469         ret = ttm_bo_wait(bo, false, false);
 470         if (ret)
 471                 return ret;
 472
 473         if (!dst_use_tt)
 474                 ttm_bo_tt_destroy(bo);
 475         ttm_resource_free(bo, &bo->resource);
 476         return 0;
 477 }
 478
 479 static int ttm_bo_move_to_ghost(struct ttm_buffer_object *bo,
 480                                 struct dma_fence *fence,
 481                                 bool dst_use_tt)
 482 {
 483         struct ttm_buffer_object *ghost_obj;
 484         int ret;
 485
 486         /**
 487          * This should help pipeline ordinary buffer moves.
 488          *
 489          * Hang old buffer memory on a new buffer object,
 490          * and leave it to be released when the GPU
 491          * operation has completed.
 492          */
 493
 494         dma_fence_put(bo->moving);
 495         bo->moving = dma_fence_get(fence);
 496
 497         ret = ttm_buffer_object_transfer(bo, &ghost_obj);
 498         if (ret)
 499                 return ret;
 500
 501         dma_resv_add_excl_fence(&ghost_obj->base._resv, fence);
 502
 503         /**
 504          * If we're not moving to fixed memory, the TTM object
 505          * needs to stay alive. Otherwhise hang it on the ghost
 506          * bo to be unbound and destroyed.
 507          */
 508
 509         if (dst_use_tt)
 510                 ghost_obj->ttm = NULL;
 511         else
 512                 bo->ttm = NULL;
 513         bo->resource = NULL;
 514
 515         dma_resv_unlock(&ghost_obj->base._resv);
 516         ttm_bo_put(ghost_obj);
 517         return 0;
 518 }
 519
 520 static void ttm_bo_move_pipeline_evict(struct ttm_buffer_object *bo,
 521                                        struct dma_fence *fence)
 522 {
 523         struct ttm_device *bdev = bo->bdev;
 524         struct ttm_resource_manager *from;
 525
 526         from = ttm_manager_type(bdev, bo->resource->mem_type);
 527
 528         /**
 529          * BO doesn't have a TTM we need to bind/unbind. Just remember
 530          * this eviction and free up the allocation
 531          */
 532         spin_lock(&from->move_lock);
 533         if (!from->move || dma_fence_is_later(fence, from->move)) {
 534                 dma_fence_put(from->move);
 535                 from->move = dma_fence_get(fence);
 536         }
 537         spin_unlock(&from->move_lock);
 538
 539         ttm_resource_free(bo, &bo->resource);
 540
 541         dma_fence_put(bo->moving);
 542         bo->moving = dma_fence_get(fence);
 543 }
 544
 545 int ttm_bo_move_accel_cleanup(struct ttm_buffer_object *bo,
 546                               struct dma_fence *fence,
 547                               bool evict,
 548                               bool pipeline,
 549                               struct ttm_resource *new_mem)
 550 {
 551         struct ttm_device *bdev = bo->bdev;
 552         struct ttm_resource_manager *from = ttm_manager_type(bdev, bo->resource->mem_type);
 553         struct ttm_resource_manager *man = ttm_manager_type(bdev, new_mem->mem_type);
 554         int ret = 0;
 555
 556         dma_resv_add_excl_fence(bo->base.resv, fence);
 557         if (!evict)
 558                 ret = ttm_bo_move_to_ghost(bo, fence, man->use_tt);
 559         else if (!from->use_tt && pipeline)
 560                 ttm_bo_move_pipeline_evict(bo, fence);
 561         else
 562                 ret = ttm_bo_wait_free_node(bo, man->use_tt);
 563
 564         if (ret)
 565                 return ret;
 566
 567         ttm_bo_assign_mem(bo, new_mem);
 568
 569         return 0;
 570 }
 571 EXPORT_SYMBOL(ttm_bo_move_accel_cleanup);
 572
 573 /**
 574  * ttm_bo_pipeline_gutting - purge the contents of a bo
 575  * @bo: The buffer object
 576  *
 577  * Purge the contents of a bo, async if the bo is not idle.
 578  * After a successful call, the bo is left unpopulated in
 579  * system placement. The function may wait uninterruptible
 580  * for idle on OOM.
 581  *
 582  * Return: 0 if successful, negative error code on failure.
 583  */
 584 int ttm_bo_pipeline_gutting(struct ttm_buffer_object *bo)
 585 {
 586         static const struct ttm_place sys_mem = { .mem_type = TTM_PL_SYSTEM };
 587         struct ttm_buffer_object *ghost;
 588         struct ttm_resource *sys_res;
 589         struct ttm_tt *ttm;
 590         int ret;
 591
 592         ret = ttm_resource_alloc(bo, &sys_mem, &sys_res);
 593         if (ret)
 594                 return ret;
 595
 596         /* If already idle, no need for ghost object dance. */
 597         ret = ttm_bo_wait(bo, false, true);
 598         if (ret != -EBUSY) {
 599                 if (!bo->ttm) {
 600                         /* See comment below about clearing. */
 601                         ret = ttm_tt_create(bo, true);
 602                         if (ret)
 603                                 goto error_free_sys_mem;
 604                 } else {
 605                         ttm_tt_unpopulate(bo->bdev, bo->ttm);
 606                         if (bo->type == ttm_bo_type_device)
 607                                 ttm_tt_mark_for_clear(bo->ttm);
 608                 }
 609                 ttm_resource_free(bo, &bo->resource);
 610                 ttm_bo_assign_mem(bo, sys_res);
 611                 return 0;
 612         }
 613
 614         /*
 615          * We need an unpopulated ttm_tt after giving our current one,
 616          * if any, to the ghost object. And we can't afford to fail
 617          * creating one *after* the operation. If the bo subsequently gets
 618          * resurrected, make sure it's cleared (if ttm_bo_type_device)
 619          * to avoid leaking sensitive information to user-space.
 620          */
 621
 622         ttm = bo->ttm;
 623         bo->ttm = NULL;
 624         ret = ttm_tt_create(bo, true);
 625         swap(bo->ttm, ttm);
 626         if (ret)
 627                 goto error_free_sys_mem;
 628
 629         ret = ttm_buffer_object_transfer(bo, &ghost);
 630         if (ret)
 631                 goto error_destroy_tt;
 632
 633         ret = dma_resv_copy_fences(&ghost->base._resv, bo->base.resv);
 634         /* Last resort, wait for the BO to be idle when we are OOM */
 635         if (ret)
 636                 ttm_bo_wait(bo, false, false);
 637
 638         dma_resv_unlock(&ghost->base._resv);
 639         ttm_bo_put(ghost);
 640         bo->ttm = ttm;
 641         bo->resource = NULL;
 642         ttm_bo_assign_mem(bo, sys_res);
 643         return 0;
 644
 645 error_destroy_tt:
 646         ttm_tt_destroy(bo->bdev, ttm);
 647
 648 error_free_sys_mem:
 649         ttm_resource_free(bo, &sys_res);
 650         return ret;
 651 }