drivers/gpu/drm/i915/i915_vma.c

   1 /*
   2  * Copyright © 2016 Intel Corporation
   3  *
   4  * Permission is hereby granted, free of charge, to any person obtaining a
   5  * copy of this software and associated documentation files (the "Software"),
   6  * to deal in the Software without restriction, including without limitation
   7  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
   8  * and/or sell copies of the Software, and to permit persons to whom the
   9  * Software is furnished to do so, subject to the following conditions:
  10  *
  11  * The above copyright notice and this permission notice (including the next
  12  * paragraph) shall be included in all copies or substantial portions of the
  13  * Software.
  14  *
  15  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  16  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  17  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
  18  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  19  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  20  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
  21  * IN THE SOFTWARE.
  22  *
  23  */
  24
  25 #include "i915_vma.h"
  26
  27 #include "i915_drv.h"
  28 #include "intel_ringbuffer.h"
  29 #include "intel_frontbuffer.h"
  30
  31 #include <drm/drm_gem.h>
  32
  33 static void
  34 i915_vma_retire(struct i915_gem_active *active,
  35                 struct drm_i915_gem_request *rq)
  36 {
  37         const unsigned int idx = rq->engine->id;
  38         struct i915_vma *vma =
  39                 container_of(active, struct i915_vma, last_read[idx]);
  40         struct drm_i915_gem_object *obj = vma->obj;
  41
  42         GEM_BUG_ON(!i915_vma_has_active_engine(vma, idx));
  43
  44         i915_vma_clear_active(vma, idx);
  45         if (i915_vma_is_active(vma))
  46                 return;
  47
  48         list_move_tail(&vma->vm_link, &vma->vm->inactive_list);
  49         if (unlikely(i915_vma_is_closed(vma) && !i915_vma_is_pinned(vma)))
  50                 WARN_ON(i915_vma_unbind(vma));
  51
  52         GEM_BUG_ON(!i915_gem_object_is_active(obj));
  53         if (--obj->active_count)
  54                 return;
  55
  56         /* Bump our place on the bound list to keep it roughly in LRU order
  57          * so that we don't steal from recently used but inactive objects
  58          * (unless we are forced to ofc!)
  59          */
  60         if (obj->bind_count)
  61                 list_move_tail(&obj->global_link, &rq->i915->mm.bound_list);
  62
  63         obj->mm.dirty = true; /* be paranoid  */
  64
  65         if (i915_gem_object_has_active_reference(obj)) {
  66                 i915_gem_object_clear_active_reference(obj);
  67                 i915_gem_object_put(obj);
  68         }
  69 }
  70
  71 static struct i915_vma *
  72 __i915_vma_create(struct drm_i915_gem_object *obj,
  73                   struct i915_address_space *vm,
  74                   const struct i915_ggtt_view *view)
  75 {
  76         struct i915_vma *vma;
  77         struct rb_node *rb, **p;
  78         int i;
  79
  80         GEM_BUG_ON(vm->closed);
  81
  82         vma = kmem_cache_zalloc(to_i915(obj->base.dev)->vmas, GFP_KERNEL);
  83         if (vma == NULL)
  84                 return ERR_PTR(-ENOMEM);
  85
  86         INIT_LIST_HEAD(&vma->exec_list);
  87         for (i = 0; i < ARRAY_SIZE(vma->last_read); i++)
  88                 init_request_active(&vma->last_read[i], i915_vma_retire);
  89         init_request_active(&vma->last_fence, NULL);
  90         list_add(&vma->vm_link, &vm->unbound_list);
  91         vma->vm = vm;
  92         vma->obj = obj;
  93         vma->size = obj->base.size;
  94
  95         if (view) {
  96                 vma->ggtt_view = *view;
  97                 if (view->type == I915_GGTT_VIEW_PARTIAL) {
  98                         vma->size = view->params.partial.size;
  99                         vma->size <<= PAGE_SHIFT;
 100                 } else if (view->type == I915_GGTT_VIEW_ROTATED) {
 101                         vma->size =
 102                                 intel_rotation_info_size(&view->params.rotated);
 103                         vma->size <<= PAGE_SHIFT;
 104                 }
 105         }
 106
 107         if (i915_is_ggtt(vm)) {
 108                 vma->flags |= I915_VMA_GGTT;
 109                 list_add(&vma->obj_link, &obj->vma_list);
 110         } else {
 111                 i915_ppgtt_get(i915_vm_to_ppgtt(vm));
 112                 list_add_tail(&vma->obj_link, &obj->vma_list);
 113         }
 114
 115         rb = NULL;
 116         p = &obj->vma_tree.rb_node;
 117         while (*p) {
 118                 struct i915_vma *pos;
 119
 120                 rb = *p;
 121                 pos = rb_entry(rb, struct i915_vma, obj_node);
 122                 if (i915_vma_compare(pos, vm, view) < 0)
 123                         p = &rb->rb_right;
 124                 else
 125                         p = &rb->rb_left;
 126         }
 127         rb_link_node(&vma->obj_node, rb, p);
 128         rb_insert_color(&vma->obj_node, &obj->vma_tree);
 129
 130         return vma;
 131 }
 132
 133 struct i915_vma *
 134 i915_vma_create(struct drm_i915_gem_object *obj,
 135                 struct i915_address_space *vm,
 136                 const struct i915_ggtt_view *view)
 137 {
 138         lockdep_assert_held(&obj->base.dev->struct_mutex);
 139         GEM_BUG_ON(view && !i915_is_ggtt(vm));
 140         GEM_BUG_ON(i915_gem_obj_to_vma(obj, vm, view));
 141
 142         return __i915_vma_create(obj, vm, view);
 143 }
 144
 145 /**
 146  * i915_vma_bind - Sets up PTEs for an VMA in it's corresponding address space.
 147  * @vma: VMA to map
 148  * @cache_level: mapping cache level
 149  * @flags: flags like global or local mapping
 150  *
 151  * DMA addresses are taken from the scatter-gather table of this object (or of
 152  * this VMA in case of non-default GGTT views) and PTE entries set up.
 153  * Note that DMA addresses are also the only part of the SG table we care about.
 154  */
 155 int i915_vma_bind(struct i915_vma *vma, enum i915_cache_level cache_level,
 156                   u32 flags)
 157 {
 158         u32 bind_flags;
 159         u32 vma_flags;
 160         int ret;
 161
 162         if (WARN_ON(flags == 0))
 163                 return -EINVAL;
 164
 165         bind_flags = 0;
 166         if (flags & PIN_GLOBAL)
 167                 bind_flags |= I915_VMA_GLOBAL_BIND;
 168         if (flags & PIN_USER)
 169                 bind_flags |= I915_VMA_LOCAL_BIND;
 170
 171         vma_flags = vma->flags & (I915_VMA_GLOBAL_BIND | I915_VMA_LOCAL_BIND);
 172         if (flags & PIN_UPDATE)
 173                 bind_flags |= vma_flags;
 174         else
 175                 bind_flags &= ~vma_flags;
 176         if (bind_flags == 0)
 177                 return 0;
 178
 179         if (vma_flags == 0 && vma->vm->allocate_va_range) {
 180                 trace_i915_va_alloc(vma);
 181                 ret = vma->vm->allocate_va_range(vma->vm,
 182                                                  vma->node.start,
 183                                                  vma->node.size);
 184                 if (ret)
 185                         return ret;
 186         }
 187
 188         ret = vma->vm->bind_vma(vma, cache_level, bind_flags);
 189         if (ret)
 190                 return ret;
 191
 192         vma->flags |= bind_flags;
 193         return 0;
 194 }
 195
 196 void __iomem *i915_vma_pin_iomap(struct i915_vma *vma)
 197 {
 198         void __iomem *ptr;
 199
 200         /* Access through the GTT requires the device to be awake. */
 201         assert_rpm_wakelock_held(to_i915(vma->vm->dev));
 202
 203         lockdep_assert_held(&vma->vm->dev->struct_mutex);
 204         if (WARN_ON(!i915_vma_is_map_and_fenceable(vma)))
 205                 return IO_ERR_PTR(-ENODEV);
 206
 207         GEM_BUG_ON(!i915_vma_is_ggtt(vma));
 208         GEM_BUG_ON((vma->flags & I915_VMA_GLOBAL_BIND) == 0);
 209
 210         ptr = vma->iomap;
 211         if (ptr == NULL) {
 212                 ptr = io_mapping_map_wc(&i915_vm_to_ggtt(vma->vm)->mappable,
 213                                         vma->node.start,
 214                                         vma->node.size);
 215                 if (ptr == NULL)
 216                         return IO_ERR_PTR(-ENOMEM);
 217
 218                 vma->iomap = ptr;
 219         }
 220
 221         __i915_vma_pin(vma);
 222         return ptr;
 223 }
 224
 225 void i915_vma_unpin_and_release(struct i915_vma **p_vma)
 226 {
 227         struct i915_vma *vma;
 228         struct drm_i915_gem_object *obj;
 229
 230         vma = fetch_and_zero(p_vma);
 231         if (!vma)
 232                 return;
 233
 234         obj = vma->obj;
 235
 236         i915_vma_unpin(vma);
 237         i915_vma_close(vma);
 238
 239         __i915_gem_object_release_unless_active(obj);
 240 }
 241
 242 bool
 243 i915_vma_misplaced(struct i915_vma *vma, u64 size, u64 alignment, u64 flags)
 244 {
 245         if (!drm_mm_node_allocated(&vma->node))
 246                 return false;
 247
 248         if (vma->node.size < size)
 249                 return true;
 250
 251         if (alignment && vma->node.start & (alignment - 1))
 252                 return true;
 253
 254         if (flags & PIN_MAPPABLE && !i915_vma_is_map_and_fenceable(vma))
 255                 return true;
 256
 257         if (flags & PIN_OFFSET_BIAS &&
 258             vma->node.start < (flags & PIN_OFFSET_MASK))
 259                 return true;
 260
 261         if (flags & PIN_OFFSET_FIXED &&
 262             vma->node.start != (flags & PIN_OFFSET_MASK))
 263                 return true;
 264
 265         return false;
 266 }
 267
 268 void __i915_vma_set_map_and_fenceable(struct i915_vma *vma)
 269 {
 270         struct drm_i915_gem_object *obj = vma->obj;
 271         struct drm_i915_private *dev_priv = to_i915(obj->base.dev);
 272         bool mappable, fenceable;
 273         u32 fence_size, fence_alignment;
 274
 275         fence_size = i915_gem_get_ggtt_size(dev_priv,
 276                                             vma->size,
 277                                             i915_gem_object_get_tiling(obj));
 278         fence_alignment = i915_gem_get_ggtt_alignment(dev_priv,
 279                                                       vma->size,
 280                                                       i915_gem_object_get_tiling(obj),
 281                                                       true);
 282
 283         fenceable = (vma->node.size == fence_size &&
 284                      (vma->node.start & (fence_alignment - 1)) == 0);
 285
 286         mappable = (vma->node.start + fence_size <=
 287                     dev_priv->ggtt.mappable_end);
 288
 289         /*
 290          * Explicitly disable for rotated VMA since the display does not
 291          * need the fence and the VMA is not accessible to other users.
 292          */
 293         if (mappable && fenceable &&
 294             vma->ggtt_view.type != I915_GGTT_VIEW_ROTATED)
 295                 vma->flags |= I915_VMA_CAN_FENCE;
 296         else
 297                 vma->flags &= ~I915_VMA_CAN_FENCE;
 298 }
 299
 300 bool i915_gem_valid_gtt_space(struct i915_vma *vma,
 301                               unsigned long cache_level)
 302 {
 303         struct drm_mm_node *gtt_space = &vma->node;
 304         struct drm_mm_node *other;
 305
 306         /*
 307          * On some machines we have to be careful when putting differing types
 308          * of snoopable memory together to avoid the prefetcher crossing memory
 309          * domains and dying. During vm initialisation, we decide whether or not
 310          * these constraints apply and set the drm_mm.color_adjust
 311          * appropriately.
 312          */
 313         if (vma->vm->mm.color_adjust == NULL)
 314                 return true;
 315
 316         if (!drm_mm_node_allocated(gtt_space))
 317                 return true;
 318
 319         if (list_empty(&gtt_space->node_list))
 320                 return true;
 321
 322         other = list_entry(gtt_space->node_list.prev, struct drm_mm_node, node_list);
 323         if (other->allocated && !other->hole_follows && other->color != cache_level)
 324                 return false;
 325
 326         other = list_entry(gtt_space->node_list.next, struct drm_mm_node, node_list);
 327         if (other->allocated && !gtt_space->hole_follows && other->color != cache_level)
 328                 return false;
 329
 330         return true;
 331 }
 332
 333 /**
 334  * i915_vma_insert - finds a slot for the vma in its address space
 335  * @vma: the vma
 336  * @size: requested size in bytes (can be larger than the VMA)
 337  * @alignment: required alignment
 338  * @flags: mask of PIN_* flags to use
 339  *
 340  * First we try to allocate some free space that meets the requirements for
 341  * the VMA. Failiing that, if the flags permit, it will evict an old VMA,
 342  * preferrably the oldest idle entry to make room for the new VMA.
 343  *
 344  * Returns:
 345  * 0 on success, negative error code otherwise.
 346  */
 347 static int
 348 i915_vma_insert(struct i915_vma *vma, u64 size, u64 alignment, u64 flags)
 349 {
 350         struct drm_i915_private *dev_priv = to_i915(vma->vm->dev);
 351         struct drm_i915_gem_object *obj = vma->obj;
 352         u64 start, end;
 353         int ret;
 354
 355         GEM_BUG_ON(vma->flags & (I915_VMA_GLOBAL_BIND | I915_VMA_LOCAL_BIND));
 356         GEM_BUG_ON(drm_mm_node_allocated(&vma->node));
 357
 358         size = max(size, vma->size);
 359         if (flags & PIN_MAPPABLE)
 360                 size = i915_gem_get_ggtt_size(dev_priv, size,
 361                                               i915_gem_object_get_tiling(obj));
 362
 363         alignment = max(max(alignment, vma->display_alignment),
 364                         i915_gem_get_ggtt_alignment(dev_priv, size,
 365                                                     i915_gem_object_get_tiling(obj),
 366                                                     flags & PIN_MAPPABLE));
 367
 368         start = flags & PIN_OFFSET_BIAS ? flags & PIN_OFFSET_MASK : 0;
 369
 370         end = vma->vm->total;
 371         if (flags & PIN_MAPPABLE)
 372                 end = min_t(u64, end, dev_priv->ggtt.mappable_end);
 373         if (flags & PIN_ZONE_4G)
 374                 end = min_t(u64, end, (1ULL << 32) - PAGE_SIZE);
 375
 376         /* If binding the object/GGTT view requires more space than the entire
 377          * aperture has, reject it early before evicting everything in a vain
 378          * attempt to find space.
 379          */
 380         if (size > end) {
 381                 DRM_DEBUG("Attempting to bind an object larger than the aperture: request=%llu [object=%zd] > %s aperture=%llu\n",
 382                           size, obj->base.size,
 383                           flags & PIN_MAPPABLE ? "mappable" : "total",
 384                           end);
 385                 return -E2BIG;
 386         }
 387
 388         ret = i915_gem_object_pin_pages(obj);
 389         if (ret)
 390                 return ret;
 391
 392         if (flags & PIN_OFFSET_FIXED) {
 393                 u64 offset = flags & PIN_OFFSET_MASK;
 394                 if (offset & (alignment - 1) || offset > end - size) {
 395                         ret = -EINVAL;
 396                         goto err_unpin;
 397                 }
 398
 399                 vma->node.start = offset;
 400                 vma->node.size = size;
 401                 vma->node.color = obj->cache_level;
 402                 ret = drm_mm_reserve_node(&vma->vm->mm, &vma->node);
 403                 if (ret) {
 404                         ret = i915_gem_evict_for_vma(vma);
 405                         if (ret == 0)
 406                                 ret = drm_mm_reserve_node(&vma->vm->mm, &vma->node);
 407                         if (ret)
 408                                 goto err_unpin;
 409                 }
 410         } else {
 411                 u32 search_flag, alloc_flag;
 412
 413                 if (flags & PIN_HIGH) {
 414                         search_flag = DRM_MM_SEARCH_BELOW;
 415                         alloc_flag = DRM_MM_CREATE_TOP;
 416                 } else {
 417                         search_flag = DRM_MM_SEARCH_DEFAULT;
 418                         alloc_flag = DRM_MM_CREATE_DEFAULT;
 419                 }
 420
 421                 /* We only allocate in PAGE_SIZE/GTT_PAGE_SIZE (4096) chunks,
 422                  * so we know that we always have a minimum alignment of 4096.
 423                  * The drm_mm range manager is optimised to return results
 424                  * with zero alignment, so where possible use the optimal
 425                  * path.
 426                  */
 427                 if (alignment <= 4096)
 428                         alignment = 0;
 429
 430 search_free:
 431                 ret = drm_mm_insert_node_in_range_generic(&vma->vm->mm,
 432                                                           &vma->node,
 433                                                           size, alignment,
 434                                                           obj->cache_level,
 435                                                           start, end,
 436                                                           search_flag,
 437                                                           alloc_flag);
 438                 if (ret) {
 439                         ret = i915_gem_evict_something(vma->vm, size, alignment,
 440                                                        obj->cache_level,
 441                                                        start, end,
 442                                                        flags);
 443                         if (ret == 0)
 444                                 goto search_free;
 445
 446                         goto err_unpin;
 447                 }
 448
 449                 GEM_BUG_ON(vma->node.start < start);
 450                 GEM_BUG_ON(vma->node.start + vma->node.size > end);
 451         }
 452         GEM_BUG_ON(!i915_gem_valid_gtt_space(vma, obj->cache_level));
 453
 454         list_move_tail(&obj->global_link, &dev_priv->mm.bound_list);
 455         list_move_tail(&vma->vm_link, &vma->vm->inactive_list);
 456         obj->bind_count++;
 457         GEM_BUG_ON(atomic_read(&obj->mm.pages_pin_count) < obj->bind_count);
 458
 459         return 0;
 460
 461 err_unpin:
 462         i915_gem_object_unpin_pages(obj);
 463         return ret;
 464 }
 465
 466 int __i915_vma_do_pin(struct i915_vma *vma,
 467                       u64 size, u64 alignment, u64 flags)
 468 {
 469         unsigned int bound = vma->flags;
 470         int ret;
 471
 472         lockdep_assert_held(&vma->vm->dev->struct_mutex);
 473         GEM_BUG_ON((flags & (PIN_GLOBAL | PIN_USER)) == 0);
 474         GEM_BUG_ON((flags & PIN_GLOBAL) && !i915_vma_is_ggtt(vma));
 475
 476         if (WARN_ON(bound & I915_VMA_PIN_OVERFLOW)) {
 477                 ret = -EBUSY;
 478                 goto err;
 479         }
 480
 481         if ((bound & I915_VMA_BIND_MASK) == 0) {
 482                 ret = i915_vma_insert(vma, size, alignment, flags);
 483                 if (ret)
 484                         goto err;
 485         }
 486
 487         ret = i915_vma_bind(vma, vma->obj->cache_level, flags);
 488         if (ret)
 489                 goto err;
 490
 491         if ((bound ^ vma->flags) & I915_VMA_GLOBAL_BIND)
 492                 __i915_vma_set_map_and_fenceable(vma);
 493
 494         GEM_BUG_ON(i915_vma_misplaced(vma, size, alignment, flags));
 495         return 0;
 496
 497 err:
 498         __i915_vma_unpin(vma);
 499         return ret;
 500 }
 501
 502 void i915_vma_destroy(struct i915_vma *vma)
 503 {
 504         GEM_BUG_ON(vma->node.allocated);
 505         GEM_BUG_ON(i915_vma_is_active(vma));
 506         GEM_BUG_ON(!i915_vma_is_closed(vma));
 507         GEM_BUG_ON(vma->fence);
 508
 509         list_del(&vma->vm_link);
 510         if (!i915_vma_is_ggtt(vma))
 511                 i915_ppgtt_put(i915_vm_to_ppgtt(vma->vm));
 512
 513         kmem_cache_free(to_i915(vma->obj->base.dev)->vmas, vma);
 514 }
 515
 516 void i915_vma_close(struct i915_vma *vma)
 517 {
 518         GEM_BUG_ON(i915_vma_is_closed(vma));
 519         vma->flags |= I915_VMA_CLOSED;
 520
 521         list_del(&vma->obj_link);
 522         rb_erase(&vma->obj_node, &vma->obj->vma_tree);
 523
 524         if (!i915_vma_is_active(vma) && !i915_vma_is_pinned(vma))
 525                 WARN_ON(i915_vma_unbind(vma));
 526 }
 527
 528 static void __i915_vma_iounmap(struct i915_vma *vma)
 529 {
 530         GEM_BUG_ON(i915_vma_is_pinned(vma));
 531
 532         if (vma->iomap == NULL)
 533                 return;
 534
 535         io_mapping_unmap(vma->iomap);
 536         vma->iomap = NULL;
 537 }
 538
 539 int i915_vma_unbind(struct i915_vma *vma)
 540 {
 541         struct drm_i915_gem_object *obj = vma->obj;
 542         unsigned long active;
 543         int ret;
 544
 545         lockdep_assert_held(&obj->base.dev->struct_mutex);
 546
 547         /* First wait upon any activity as retiring the request may
 548          * have side-effects such as unpinning or even unbinding this vma.
 549          */
 550         active = i915_vma_get_active(vma);
 551         if (active) {
 552                 int idx;
 553
 554                 /* When a closed VMA is retired, it is unbound - eek.
 555                  * In order to prevent it from being recursively closed,
 556                  * take a pin on the vma so that the second unbind is
 557                  * aborted.
 558                  *
 559                  * Even more scary is that the retire callback may free
 560                  * the object (last active vma). To prevent the explosion
 561                  * we defer the actual object free to a worker that can
 562                  * only proceed once it acquires the struct_mutex (which
 563                  * we currently hold, therefore it cannot free this object
 564                  * before we are finished).
 565                  */
 566                 __i915_vma_pin(vma);
 567
 568                 for_each_active(active, idx) {
 569                         ret = i915_gem_active_retire(&vma->last_read[idx],
 570                                                    &vma->vm->dev->struct_mutex);
 571                         if (ret)
 572                                 break;
 573                 }
 574
 575                 __i915_vma_unpin(vma);
 576                 if (ret)
 577                         return ret;
 578
 579                 GEM_BUG_ON(i915_vma_is_active(vma));
 580         }
 581
 582         if (i915_vma_is_pinned(vma))
 583                 return -EBUSY;
 584
 585         if (!drm_mm_node_allocated(&vma->node))
 586                 goto destroy;
 587
 588         GEM_BUG_ON(obj->bind_count == 0);
 589         GEM_BUG_ON(!i915_gem_object_has_pinned_pages(obj));
 590
 591         if (i915_vma_is_map_and_fenceable(vma)) {
 592                 /* release the fence reg _after_ flushing */
 593                 ret = i915_vma_put_fence(vma);
 594                 if (ret)
 595                         return ret;
 596
 597                 /* Force a pagefault for domain tracking on next user access */
 598                 i915_gem_release_mmap(obj);
 599
 600                 __i915_vma_iounmap(vma);
 601                 vma->flags &= ~I915_VMA_CAN_FENCE;
 602         }
 603
 604         if (likely(!vma->vm->closed)) {
 605                 trace_i915_vma_unbind(vma);
 606                 vma->vm->unbind_vma(vma);
 607         }
 608         vma->flags &= ~(I915_VMA_GLOBAL_BIND | I915_VMA_LOCAL_BIND);
 609
 610         drm_mm_remove_node(&vma->node);
 611         list_move_tail(&vma->vm_link, &vma->vm->unbound_list);
 612
 613         if (vma->pages != obj->mm.pages) {
 614                 GEM_BUG_ON(!vma->pages);
 615                 sg_free_table(vma->pages);
 616                 kfree(vma->pages);
 617         }
 618         vma->pages = NULL;
 619
 620         /* Since the unbound list is global, only move to that list if
 621          * no more VMAs exist. */
 622         if (--obj->bind_count == 0)
 623                 list_move_tail(&obj->global_link,
 624                                &to_i915(obj->base.dev)->mm.unbound_list);
 625
 626         /* And finally now the object is completely decoupled from this vma,
 627          * we can drop its hold on the backing storage and allow it to be
 628          * reaped by the shrinker.
 629          */
 630         i915_gem_object_unpin_pages(obj);
 631
 632 destroy:
 633         if (unlikely(i915_vma_is_closed(vma)))
 634                 i915_vma_destroy(vma);
 635
 636         return 0;
 637 }
 638