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         vma->display_alignment = I915_GTT_MIN_ALIGNMENT;
  95
  96         if (view) {
  97                 vma->ggtt_view = *view;
  98                 if (view->type == I915_GGTT_VIEW_PARTIAL) {
  99                         GEM_BUG_ON(range_overflows_t(u64,
 100                                                      view->params.partial.offset,
 101                                                      view->params.partial.size,
 102                                                      obj->base.size >> PAGE_SHIFT));
 103                         vma->size = view->params.partial.size;
 104                         vma->size <<= PAGE_SHIFT;
 105                         GEM_BUG_ON(vma->size >= obj->base.size);
 106                 } else if (view->type == I915_GGTT_VIEW_ROTATED) {
 107                         vma->size =
 108                                 intel_rotation_info_size(&view->params.rotated);
 109                         vma->size <<= PAGE_SHIFT;
 110                 }
 111         }
 112
 113         if (i915_is_ggtt(vm)) {
 114                 GEM_BUG_ON(overflows_type(vma->size, u32));
 115                 vma->fence_size = i915_gem_fence_size(vm->i915, vma->size,
 116                                                       i915_gem_object_get_tiling(obj),
 117                                                       i915_gem_object_get_stride(obj));
 118                 GEM_BUG_ON(!IS_ALIGNED(vma->fence_size, I915_GTT_MIN_ALIGNMENT));
 119
 120                 vma->fence_alignment = i915_gem_fence_alignment(vm->i915, vma->size,
 121                                                                 i915_gem_object_get_tiling(obj),
 122                                                                 i915_gem_object_get_stride(obj));
 123                 GEM_BUG_ON(!is_power_of_2(vma->fence_alignment));
 124
 125                 vma->flags |= I915_VMA_GGTT;
 126                 list_add(&vma->obj_link, &obj->vma_list);
 127         } else {
 128                 i915_ppgtt_get(i915_vm_to_ppgtt(vm));
 129                 list_add_tail(&vma->obj_link, &obj->vma_list);
 130         }
 131
 132         rb = NULL;
 133         p = &obj->vma_tree.rb_node;
 134         while (*p) {
 135                 struct i915_vma *pos;
 136
 137                 rb = *p;
 138                 pos = rb_entry(rb, struct i915_vma, obj_node);
 139                 if (i915_vma_compare(pos, vm, view) < 0)
 140                         p = &rb->rb_right;
 141                 else
 142                         p = &rb->rb_left;
 143         }
 144         rb_link_node(&vma->obj_node, rb, p);
 145         rb_insert_color(&vma->obj_node, &obj->vma_tree);
 146
 147         return vma;
 148 }
 149
 150 struct i915_vma *
 151 i915_vma_create(struct drm_i915_gem_object *obj,
 152                 struct i915_address_space *vm,
 153                 const struct i915_ggtt_view *view)
 154 {
 155         lockdep_assert_held(&obj->base.dev->struct_mutex);
 156         GEM_BUG_ON(view && !i915_is_ggtt(vm));
 157         GEM_BUG_ON(i915_gem_obj_to_vma(obj, vm, view));
 158
 159         return __i915_vma_create(obj, vm, view);
 160 }
 161
 162 /**
 163  * i915_vma_bind - Sets up PTEs for an VMA in it's corresponding address space.
 164  * @vma: VMA to map
 165  * @cache_level: mapping cache level
 166  * @flags: flags like global or local mapping
 167  *
 168  * DMA addresses are taken from the scatter-gather table of this object (or of
 169  * this VMA in case of non-default GGTT views) and PTE entries set up.
 170  * Note that DMA addresses are also the only part of the SG table we care about.
 171  */
 172 int i915_vma_bind(struct i915_vma *vma, enum i915_cache_level cache_level,
 173                   u32 flags)
 174 {
 175         u32 bind_flags;
 176         u32 vma_flags;
 177         int ret;
 178
 179         if (WARN_ON(flags == 0))
 180                 return -EINVAL;
 181
 182         bind_flags = 0;
 183         if (flags & PIN_GLOBAL)
 184                 bind_flags |= I915_VMA_GLOBAL_BIND;
 185         if (flags & PIN_USER)
 186                 bind_flags |= I915_VMA_LOCAL_BIND;
 187
 188         vma_flags = vma->flags & (I915_VMA_GLOBAL_BIND | I915_VMA_LOCAL_BIND);
 189         if (flags & PIN_UPDATE)
 190                 bind_flags |= vma_flags;
 191         else
 192                 bind_flags &= ~vma_flags;
 193         if (bind_flags == 0)
 194                 return 0;
 195
 196         if (GEM_WARN_ON(range_overflows(vma->node.start,
 197                                         vma->node.size,
 198                                         vma->vm->total)))
 199                 return -ENODEV;
 200
 201         if (vma_flags == 0 && vma->vm->allocate_va_range) {
 202                 trace_i915_va_alloc(vma);
 203                 ret = vma->vm->allocate_va_range(vma->vm,
 204                                                  vma->node.start,
 205                                                  vma->node.size);
 206                 if (ret)
 207                         return ret;
 208         }
 209
 210         ret = vma->vm->bind_vma(vma, cache_level, bind_flags);
 211         if (ret)
 212                 return ret;
 213
 214         vma->flags |= bind_flags;
 215         return 0;
 216 }
 217
 218 void __iomem *i915_vma_pin_iomap(struct i915_vma *vma)
 219 {
 220         void __iomem *ptr;
 221
 222         /* Access through the GTT requires the device to be awake. */
 223         assert_rpm_wakelock_held(vma->vm->i915);
 224
 225         lockdep_assert_held(&vma->vm->i915->drm.struct_mutex);
 226         if (WARN_ON(!i915_vma_is_map_and_fenceable(vma)))
 227                 return IO_ERR_PTR(-ENODEV);
 228
 229         GEM_BUG_ON(!i915_vma_is_ggtt(vma));
 230         GEM_BUG_ON((vma->flags & I915_VMA_GLOBAL_BIND) == 0);
 231
 232         ptr = vma->iomap;
 233         if (ptr == NULL) {
 234                 ptr = io_mapping_map_wc(&i915_vm_to_ggtt(vma->vm)->mappable,
 235                                         vma->node.start,
 236                                         vma->node.size);
 237                 if (ptr == NULL)
 238                         return IO_ERR_PTR(-ENOMEM);
 239
 240                 vma->iomap = ptr;
 241         }
 242
 243         __i915_vma_pin(vma);
 244         return ptr;
 245 }
 246
 247 void i915_vma_unpin_and_release(struct i915_vma **p_vma)
 248 {
 249         struct i915_vma *vma;
 250         struct drm_i915_gem_object *obj;
 251
 252         vma = fetch_and_zero(p_vma);
 253         if (!vma)
 254                 return;
 255
 256         obj = vma->obj;
 257
 258         i915_vma_unpin(vma);
 259         i915_vma_close(vma);
 260
 261         __i915_gem_object_release_unless_active(obj);
 262 }
 263
 264 bool
 265 i915_vma_misplaced(struct i915_vma *vma, u64 size, u64 alignment, u64 flags)
 266 {
 267         if (!drm_mm_node_allocated(&vma->node))
 268                 return false;
 269
 270         if (vma->node.size < size)
 271                 return true;
 272
 273         GEM_BUG_ON(alignment && !is_power_of_2(alignment));
 274         if (alignment && !IS_ALIGNED(vma->node.start, alignment))
 275                 return true;
 276
 277         if (flags & PIN_MAPPABLE && !i915_vma_is_map_and_fenceable(vma))
 278                 return true;
 279
 280         if (flags & PIN_OFFSET_BIAS &&
 281             vma->node.start < (flags & PIN_OFFSET_MASK))
 282                 return true;
 283
 284         if (flags & PIN_OFFSET_FIXED &&
 285             vma->node.start != (flags & PIN_OFFSET_MASK))
 286                 return true;
 287
 288         return false;
 289 }
 290
 291 void __i915_vma_set_map_and_fenceable(struct i915_vma *vma)
 292 {
 293         bool mappable, fenceable;
 294
 295         GEM_BUG_ON(!i915_vma_is_ggtt(vma));
 296         GEM_BUG_ON(!vma->fence_size);
 297
 298         /*
 299          * Explicitly disable for rotated VMA since the display does not
 300          * need the fence and the VMA is not accessible to other users.
 301          */
 302         if (vma->ggtt_view.type == I915_GGTT_VIEW_ROTATED)
 303                 return;
 304
 305         fenceable = (vma->node.size >= vma->fence_size &&
 306                      IS_ALIGNED(vma->node.start, vma->fence_alignment));
 307
 308         mappable = vma->node.start + vma->fence_size <= i915_vm_to_ggtt(vma->vm)->mappable_end;
 309
 310         if (mappable && fenceable)
 311                 vma->flags |= I915_VMA_CAN_FENCE;
 312         else
 313                 vma->flags &= ~I915_VMA_CAN_FENCE;
 314 }
 315
 316 static bool color_differs(struct drm_mm_node *node, unsigned long color)
 317 {
 318         return node->allocated && node->color != color;
 319 }
 320
 321 bool i915_gem_valid_gtt_space(struct i915_vma *vma, unsigned long cache_level)
 322 {
 323         struct drm_mm_node *node = &vma->node;
 324         struct drm_mm_node *other;
 325
 326         /*
 327          * On some machines we have to be careful when putting differing types
 328          * of snoopable memory together to avoid the prefetcher crossing memory
 329          * domains and dying. During vm initialisation, we decide whether or not
 330          * these constraints apply and set the drm_mm.color_adjust
 331          * appropriately.
 332          */
 333         if (vma->vm->mm.color_adjust == NULL)
 334                 return true;
 335
 336         /* Only valid to be called on an already inserted vma */
 337         GEM_BUG_ON(!drm_mm_node_allocated(node));
 338         GEM_BUG_ON(list_empty(&node->node_list));
 339
 340         other = list_prev_entry(node, node_list);
 341         if (color_differs(other, cache_level) && !drm_mm_hole_follows(other))
 342                 return false;
 343
 344         other = list_next_entry(node, node_list);
 345         if (color_differs(other, cache_level) && !drm_mm_hole_follows(node))
 346                 return false;
 347
 348         return true;
 349 }
 350
 351 /**
 352  * i915_vma_insert - finds a slot for the vma in its address space
 353  * @vma: the vma
 354  * @size: requested size in bytes (can be larger than the VMA)
 355  * @alignment: required alignment
 356  * @flags: mask of PIN_* flags to use
 357  *
 358  * First we try to allocate some free space that meets the requirements for
 359  * the VMA. Failiing that, if the flags permit, it will evict an old VMA,
 360  * preferrably the oldest idle entry to make room for the new VMA.
 361  *
 362  * Returns:
 363  * 0 on success, negative error code otherwise.
 364  */
 365 static int
 366 i915_vma_insert(struct i915_vma *vma, u64 size, u64 alignment, u64 flags)
 367 {
 368         struct drm_i915_private *dev_priv = vma->vm->i915;
 369         struct drm_i915_gem_object *obj = vma->obj;
 370         u64 start, end;
 371         int ret;
 372
 373         GEM_BUG_ON(vma->flags & (I915_VMA_GLOBAL_BIND | I915_VMA_LOCAL_BIND));
 374         GEM_BUG_ON(drm_mm_node_allocated(&vma->node));
 375
 376         size = max(size, vma->size);
 377         alignment = max(alignment, vma->display_alignment);
 378         if (flags & PIN_MAPPABLE) {
 379                 size = max_t(typeof(size), size, vma->fence_size);
 380                 alignment = max_t(typeof(alignment),
 381                                   alignment, vma->fence_alignment);
 382         }
 383
 384         GEM_BUG_ON(!IS_ALIGNED(size, I915_GTT_PAGE_SIZE));
 385         GEM_BUG_ON(!IS_ALIGNED(alignment, I915_GTT_MIN_ALIGNMENT));
 386         GEM_BUG_ON(!is_power_of_2(alignment));
 387
 388         start = flags & PIN_OFFSET_BIAS ? flags & PIN_OFFSET_MASK : 0;
 389         GEM_BUG_ON(!IS_ALIGNED(start, I915_GTT_PAGE_SIZE));
 390
 391         end = vma->vm->total;
 392         if (flags & PIN_MAPPABLE)
 393                 end = min_t(u64, end, dev_priv->ggtt.mappable_end);
 394         if (flags & PIN_ZONE_4G)
 395                 end = min_t(u64, end, (1ULL << 32) - I915_GTT_PAGE_SIZE);
 396         GEM_BUG_ON(!IS_ALIGNED(end, I915_GTT_PAGE_SIZE));
 397
 398         /* If binding the object/GGTT view requires more space than the entire
 399          * aperture has, reject it early before evicting everything in a vain
 400          * attempt to find space.
 401          */
 402         if (size > end) {
 403                 DRM_DEBUG("Attempting to bind an object larger than the aperture: request=%llu [object=%zd] > %s aperture=%llu\n",
 404                           size, obj->base.size,
 405                           flags & PIN_MAPPABLE ? "mappable" : "total",
 406                           end);
 407                 return -E2BIG;
 408         }
 409
 410         ret = i915_gem_object_pin_pages(obj);
 411         if (ret)
 412                 return ret;
 413
 414         if (flags & PIN_OFFSET_FIXED) {
 415                 u64 offset = flags & PIN_OFFSET_MASK;
 416                 if (!IS_ALIGNED(offset, alignment) ||
 417                     range_overflows(offset, size, end)) {
 418                         ret = -EINVAL;
 419                         goto err_unpin;
 420                 }
 421
 422                 ret = i915_gem_gtt_reserve(vma->vm, &vma->node,
 423                                            size, offset, obj->cache_level,
 424                                            flags);
 425                 if (ret)
 426                         goto err_unpin;
 427         } else {
 428                 ret = i915_gem_gtt_insert(vma->vm, &vma->node,
 429                                           size, alignment, obj->cache_level,
 430                                           start, end, flags);
 431                 if (ret)
 432                         goto err_unpin;
 433
 434                 GEM_BUG_ON(vma->node.start < start);
 435                 GEM_BUG_ON(vma->node.start + vma->node.size > end);
 436         }
 437         GEM_BUG_ON(!i915_gem_valid_gtt_space(vma, obj->cache_level));
 438
 439         list_move_tail(&obj->global_link, &dev_priv->mm.bound_list);
 440         list_move_tail(&vma->vm_link, &vma->vm->inactive_list);
 441         obj->bind_count++;
 442         GEM_BUG_ON(atomic_read(&obj->mm.pages_pin_count) < obj->bind_count);
 443
 444         return 0;
 445
 446 err_unpin:
 447         i915_gem_object_unpin_pages(obj);
 448         return ret;
 449 }
 450
 451 int __i915_vma_do_pin(struct i915_vma *vma,
 452                       u64 size, u64 alignment, u64 flags)
 453 {
 454         unsigned int bound = vma->flags;
 455         int ret;
 456
 457         lockdep_assert_held(&vma->vm->i915->drm.struct_mutex);
 458         GEM_BUG_ON((flags & (PIN_GLOBAL | PIN_USER)) == 0);
 459         GEM_BUG_ON((flags & PIN_GLOBAL) && !i915_vma_is_ggtt(vma));
 460
 461         if (WARN_ON(bound & I915_VMA_PIN_OVERFLOW)) {
 462                 ret = -EBUSY;
 463                 goto err;
 464         }
 465
 466         if ((bound & I915_VMA_BIND_MASK) == 0) {
 467                 ret = i915_vma_insert(vma, size, alignment, flags);
 468                 if (ret)
 469                         goto err;
 470         }
 471
 472         ret = i915_vma_bind(vma, vma->obj->cache_level, flags);
 473         if (ret)
 474                 goto err;
 475
 476         if ((bound ^ vma->flags) & I915_VMA_GLOBAL_BIND)
 477                 __i915_vma_set_map_and_fenceable(vma);
 478
 479         GEM_BUG_ON(i915_vma_misplaced(vma, size, alignment, flags));
 480         return 0;
 481
 482 err:
 483         __i915_vma_unpin(vma);
 484         return ret;
 485 }
 486
 487 void i915_vma_destroy(struct i915_vma *vma)
 488 {
 489         GEM_BUG_ON(vma->node.allocated);
 490         GEM_BUG_ON(i915_vma_is_active(vma));
 491         GEM_BUG_ON(!i915_vma_is_closed(vma));
 492         GEM_BUG_ON(vma->fence);
 493
 494         list_del(&vma->vm_link);
 495         if (!i915_vma_is_ggtt(vma))
 496                 i915_ppgtt_put(i915_vm_to_ppgtt(vma->vm));
 497
 498         kmem_cache_free(to_i915(vma->obj->base.dev)->vmas, vma);
 499 }
 500
 501 void i915_vma_close(struct i915_vma *vma)
 502 {
 503         GEM_BUG_ON(i915_vma_is_closed(vma));
 504         vma->flags |= I915_VMA_CLOSED;
 505
 506         list_del(&vma->obj_link);
 507         rb_erase(&vma->obj_node, &vma->obj->vma_tree);
 508
 509         if (!i915_vma_is_active(vma) && !i915_vma_is_pinned(vma))
 510                 WARN_ON(i915_vma_unbind(vma));
 511 }
 512
 513 static void __i915_vma_iounmap(struct i915_vma *vma)
 514 {
 515         GEM_BUG_ON(i915_vma_is_pinned(vma));
 516
 517         if (vma->iomap == NULL)
 518                 return;
 519
 520         io_mapping_unmap(vma->iomap);
 521         vma->iomap = NULL;
 522 }
 523
 524 int i915_vma_unbind(struct i915_vma *vma)
 525 {
 526         struct drm_i915_gem_object *obj = vma->obj;
 527         unsigned long active;
 528         int ret;
 529
 530         lockdep_assert_held(&obj->base.dev->struct_mutex);
 531
 532         /* First wait upon any activity as retiring the request may
 533          * have side-effects such as unpinning or even unbinding this vma.
 534          */
 535         active = i915_vma_get_active(vma);
 536         if (active) {
 537                 int idx;
 538
 539                 /* When a closed VMA is retired, it is unbound - eek.
 540                  * In order to prevent it from being recursively closed,
 541                  * take a pin on the vma so that the second unbind is
 542                  * aborted.
 543                  *
 544                  * Even more scary is that the retire callback may free
 545                  * the object (last active vma). To prevent the explosion
 546                  * we defer the actual object free to a worker that can
 547                  * only proceed once it acquires the struct_mutex (which
 548                  * we currently hold, therefore it cannot free this object
 549                  * before we are finished).
 550                  */
 551                 __i915_vma_pin(vma);
 552
 553                 for_each_active(active, idx) {
 554                         ret = i915_gem_active_retire(&vma->last_read[idx],
 555                                                      &vma->vm->i915->drm.struct_mutex);
 556                         if (ret)
 557                                 break;
 558                 }
 559
 560                 __i915_vma_unpin(vma);
 561                 if (ret)
 562                         return ret;
 563
 564                 GEM_BUG_ON(i915_vma_is_active(vma));
 565         }
 566
 567         if (i915_vma_is_pinned(vma))
 568                 return -EBUSY;
 569
 570         if (!drm_mm_node_allocated(&vma->node))
 571                 goto destroy;
 572
 573         GEM_BUG_ON(obj->bind_count == 0);
 574         GEM_BUG_ON(!i915_gem_object_has_pinned_pages(obj));
 575
 576         if (i915_vma_is_map_and_fenceable(vma)) {
 577                 /* release the fence reg _after_ flushing */
 578                 ret = i915_vma_put_fence(vma);
 579                 if (ret)
 580                         return ret;
 581
 582                 /* Force a pagefault for domain tracking on next user access */
 583                 i915_gem_release_mmap(obj);
 584
 585                 __i915_vma_iounmap(vma);
 586                 vma->flags &= ~I915_VMA_CAN_FENCE;
 587         }
 588
 589         if (likely(!vma->vm->closed)) {
 590                 trace_i915_vma_unbind(vma);
 591                 vma->vm->unbind_vma(vma);
 592         }
 593         vma->flags &= ~(I915_VMA_GLOBAL_BIND | I915_VMA_LOCAL_BIND);
 594
 595         drm_mm_remove_node(&vma->node);
 596         list_move_tail(&vma->vm_link, &vma->vm->unbound_list);
 597
 598         if (vma->pages != obj->mm.pages) {
 599                 GEM_BUG_ON(!vma->pages);
 600                 sg_free_table(vma->pages);
 601                 kfree(vma->pages);
 602         }
 603         vma->pages = NULL;
 604
 605         /* Since the unbound list is global, only move to that list if
 606          * no more VMAs exist. */
 607         if (--obj->bind_count == 0)
 608                 list_move_tail(&obj->global_link,
 609                                &to_i915(obj->base.dev)->mm.unbound_list);
 610
 611         /* And finally now the object is completely decoupled from this vma,
 612          * we can drop its hold on the backing storage and allow it to be
 613          * reaped by the shrinker.
 614          */
 615         i915_gem_object_unpin_pages(obj);
 616         GEM_BUG_ON(atomic_read(&obj->mm.pages_pin_count) < obj->bind_count);
 617
 618 destroy:
 619         if (unlikely(i915_vma_is_closed(vma)))
 620                 i915_vma_destroy(vma);
 621
 622         return 0;
 623 }
 624