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         GEM_BUG_ON(!drm_mm_node_allocated(&vma->node));
  49         list_move_tail(&vma->vm_link, &vma->vm->inactive_list);
  50         if (unlikely(i915_vma_is_closed(vma) && !i915_vma_is_pinned(vma)))
  51                 WARN_ON(i915_vma_unbind(vma));
  52
  53         GEM_BUG_ON(!i915_gem_object_is_active(obj));
  54         if (--obj->active_count)
  55                 return;
  56
  57         /* Bump our place on the bound list to keep it roughly in LRU order
  58          * so that we don't steal from recently used but inactive objects
  59          * (unless we are forced to ofc!)
  60          */
  61         if (obj->bind_count)
  62                 list_move_tail(&obj->global_link, &rq->i915->mm.bound_list);
  63
  64         obj->mm.dirty = true; /* be paranoid  */
  65
  66         if (i915_gem_object_has_active_reference(obj)) {
  67                 i915_gem_object_clear_active_reference(obj);
  68                 i915_gem_object_put(obj);
  69         }
  70 }
  71
  72 static struct i915_vma *
  73 vma_create(struct drm_i915_gem_object *obj,
  74            struct i915_address_space *vm,
  75            const struct i915_ggtt_view *view)
  76 {
  77         struct i915_vma *vma;
  78         struct rb_node *rb, **p;
  79         int i;
  80
  81         vma = kmem_cache_zalloc(vm->i915->vmas, GFP_KERNEL);
  82         if (vma == NULL)
  83                 return ERR_PTR(-ENOMEM);
  84
  85         INIT_LIST_HEAD(&vma->exec_list);
  86         for (i = 0; i < ARRAY_SIZE(vma->last_read); i++)
  87                 init_request_active(&vma->last_read[i], i915_vma_retire);
  88         init_request_active(&vma->last_fence, NULL);
  89         vma->vm = vm;
  90         vma->obj = obj;
  91         vma->size = obj->base.size;
  92         vma->display_alignment = I915_GTT_MIN_ALIGNMENT;
  93
  94         if (view) {
  95                 vma->ggtt_view = *view;
  96                 if (view->type == I915_GGTT_VIEW_PARTIAL) {
  97                         GEM_BUG_ON(range_overflows_t(u64,
  98                                                      view->partial.offset,
  99                                                      view->partial.size,
 100                                                      obj->base.size >> PAGE_SHIFT));
 101                         vma->size = view->partial.size;
 102                         vma->size <<= PAGE_SHIFT;
 103                         GEM_BUG_ON(vma->size >= obj->base.size);
 104                 } else if (view->type == I915_GGTT_VIEW_ROTATED) {
 105                         vma->size = intel_rotation_info_size(&view->rotated);
 106                         vma->size <<= PAGE_SHIFT;
 107                 }
 108         }
 109
 110         if (unlikely(vma->size > vm->total))
 111                 goto err_vma;
 112
 113         GEM_BUG_ON(!IS_ALIGNED(vma->size, I915_GTT_PAGE_SIZE));
 114
 115         if (i915_is_ggtt(vm)) {
 116                 if (unlikely(overflows_type(vma->size, u32)))
 117                         goto err_vma;
 118
 119                 vma->fence_size = i915_gem_fence_size(vm->i915, vma->size,
 120                                                       i915_gem_object_get_tiling(obj),
 121                                                       i915_gem_object_get_stride(obj));
 122                 if (unlikely(vma->fence_size < vma->size || /* overflow */
 123                              vma->fence_size > vm->total))
 124                         goto err_vma;
 125
 126                 GEM_BUG_ON(!IS_ALIGNED(vma->fence_size, I915_GTT_MIN_ALIGNMENT));
 127
 128                 vma->fence_alignment = i915_gem_fence_alignment(vm->i915, vma->size,
 129                                                                 i915_gem_object_get_tiling(obj),
 130                                                                 i915_gem_object_get_stride(obj));
 131                 GEM_BUG_ON(!is_power_of_2(vma->fence_alignment));
 132
 133                 vma->flags |= I915_VMA_GGTT;
 134                 list_add(&vma->obj_link, &obj->vma_list);
 135         } else {
 136                 i915_ppgtt_get(i915_vm_to_ppgtt(vm));
 137                 list_add_tail(&vma->obj_link, &obj->vma_list);
 138         }
 139
 140         rb = NULL;
 141         p = &obj->vma_tree.rb_node;
 142         while (*p) {
 143                 struct i915_vma *pos;
 144
 145                 rb = *p;
 146                 pos = rb_entry(rb, struct i915_vma, obj_node);
 147                 if (i915_vma_compare(pos, vm, view) < 0)
 148                         p = &rb->rb_right;
 149                 else
 150                         p = &rb->rb_left;
 151         }
 152         rb_link_node(&vma->obj_node, rb, p);
 153         rb_insert_color(&vma->obj_node, &obj->vma_tree);
 154         list_add(&vma->vm_link, &vm->unbound_list);
 155
 156         return vma;
 157
 158 err_vma:
 159         kmem_cache_free(vm->i915->vmas, vma);
 160         return ERR_PTR(-E2BIG);
 161 }
 162
 163 static struct i915_vma *
 164 vma_lookup(struct drm_i915_gem_object *obj,
 165            struct i915_address_space *vm,
 166            const struct i915_ggtt_view *view)
 167 {
 168         struct rb_node *rb;
 169
 170         rb = obj->vma_tree.rb_node;
 171         while (rb) {
 172                 struct i915_vma *vma = rb_entry(rb, struct i915_vma, obj_node);
 173                 long cmp;
 174
 175                 cmp = i915_vma_compare(vma, vm, view);
 176                 if (cmp == 0)
 177                         return vma;
 178
 179                 if (cmp < 0)
 180                         rb = rb->rb_right;
 181                 else
 182                         rb = rb->rb_left;
 183         }
 184
 185         return NULL;
 186 }
 187
 188 /**
 189  * i915_vma_instance - return the singleton instance of the VMA
 190  * @obj: parent &struct drm_i915_gem_object to be mapped
 191  * @vm: address space in which the mapping is located
 192  * @view: additional mapping requirements
 193  *
 194  * i915_vma_instance() looks up an existing VMA of the @obj in the @vm with
 195  * the same @view characteristics. If a match is not found, one is created.
 196  * Once created, the VMA is kept until either the object is freed, or the
 197  * address space is closed.
 198  *
 199  * Must be called with struct_mutex held.
 200  *
 201  * Returns the vma, or an error pointer.
 202  */
 203 struct i915_vma *
 204 i915_vma_instance(struct drm_i915_gem_object *obj,
 205                   struct i915_address_space *vm,
 206                   const struct i915_ggtt_view *view)
 207 {
 208         struct i915_vma *vma;
 209
 210         lockdep_assert_held(&obj->base.dev->struct_mutex);
 211         GEM_BUG_ON(view && !i915_is_ggtt(vm));
 212         GEM_BUG_ON(vm->closed);
 213
 214         vma = vma_lookup(obj, vm, view);
 215         if (!vma)
 216                 vma = vma_create(obj, vm, view);
 217
 218         GEM_BUG_ON(!IS_ERR(vma) && i915_vma_is_closed(vma));
 219         GEM_BUG_ON(!IS_ERR(vma) && i915_vma_compare(vma, vm, view));
 220         GEM_BUG_ON(!IS_ERR(vma) && vma_lookup(obj, vm, view) != vma);
 221         return vma;
 222 }
 223
 224 /**
 225  * i915_vma_bind - Sets up PTEs for an VMA in it's corresponding address space.
 226  * @vma: VMA to map
 227  * @cache_level: mapping cache level
 228  * @flags: flags like global or local mapping
 229  *
 230  * DMA addresses are taken from the scatter-gather table of this object (or of
 231  * this VMA in case of non-default GGTT views) and PTE entries set up.
 232  * Note that DMA addresses are also the only part of the SG table we care about.
 233  */
 234 int i915_vma_bind(struct i915_vma *vma, enum i915_cache_level cache_level,
 235                   u32 flags)
 236 {
 237         u32 bind_flags;
 238         u32 vma_flags;
 239         int ret;
 240
 241         if (WARN_ON(flags == 0))
 242                 return -EINVAL;
 243
 244         bind_flags = 0;
 245         if (flags & PIN_GLOBAL)
 246                 bind_flags |= I915_VMA_GLOBAL_BIND;
 247         if (flags & PIN_USER)
 248                 bind_flags |= I915_VMA_LOCAL_BIND;
 249
 250         vma_flags = vma->flags & (I915_VMA_GLOBAL_BIND | I915_VMA_LOCAL_BIND);
 251         if (flags & PIN_UPDATE)
 252                 bind_flags |= vma_flags;
 253         else
 254                 bind_flags &= ~vma_flags;
 255         if (bind_flags == 0)
 256                 return 0;
 257
 258         if (GEM_WARN_ON(range_overflows(vma->node.start,
 259                                         vma->node.size,
 260                                         vma->vm->total)))
 261                 return -ENODEV;
 262
 263         if (vma_flags == 0 && vma->vm->allocate_va_range) {
 264                 trace_i915_va_alloc(vma);
 265                 ret = vma->vm->allocate_va_range(vma->vm,
 266                                                  vma->node.start,
 267                                                  vma->node.size);
 268                 if (ret)
 269                         return ret;
 270         }
 271
 272         trace_i915_vma_bind(vma, bind_flags);
 273         ret = vma->vm->bind_vma(vma, cache_level, bind_flags);
 274         if (ret)
 275                 return ret;
 276
 277         vma->flags |= bind_flags;
 278         return 0;
 279 }
 280
 281 void __iomem *i915_vma_pin_iomap(struct i915_vma *vma)
 282 {
 283         void __iomem *ptr;
 284
 285         /* Access through the GTT requires the device to be awake. */
 286         assert_rpm_wakelock_held(vma->vm->i915);
 287
 288         lockdep_assert_held(&vma->vm->i915->drm.struct_mutex);
 289         if (WARN_ON(!i915_vma_is_map_and_fenceable(vma)))
 290                 return IO_ERR_PTR(-ENODEV);
 291
 292         GEM_BUG_ON(!i915_vma_is_ggtt(vma));
 293         GEM_BUG_ON((vma->flags & I915_VMA_GLOBAL_BIND) == 0);
 294
 295         ptr = vma->iomap;
 296         if (ptr == NULL) {
 297                 ptr = io_mapping_map_wc(&i915_vm_to_ggtt(vma->vm)->mappable,
 298                                         vma->node.start,
 299                                         vma->node.size);
 300                 if (ptr == NULL)
 301                         return IO_ERR_PTR(-ENOMEM);
 302
 303                 vma->iomap = ptr;
 304         }
 305
 306         __i915_vma_pin(vma);
 307         return ptr;
 308 }
 309
 310 void i915_vma_unpin_and_release(struct i915_vma **p_vma)
 311 {
 312         struct i915_vma *vma;
 313         struct drm_i915_gem_object *obj;
 314
 315         vma = fetch_and_zero(p_vma);
 316         if (!vma)
 317                 return;
 318
 319         obj = vma->obj;
 320
 321         i915_vma_unpin(vma);
 322         i915_vma_close(vma);
 323
 324         __i915_gem_object_release_unless_active(obj);
 325 }
 326
 327 bool
 328 i915_vma_misplaced(struct i915_vma *vma, u64 size, u64 alignment, u64 flags)
 329 {
 330         if (!drm_mm_node_allocated(&vma->node))
 331                 return false;
 332
 333         if (vma->node.size < size)
 334                 return true;
 335
 336         GEM_BUG_ON(alignment && !is_power_of_2(alignment));
 337         if (alignment && !IS_ALIGNED(vma->node.start, alignment))
 338                 return true;
 339
 340         if (flags & PIN_MAPPABLE && !i915_vma_is_map_and_fenceable(vma))
 341                 return true;
 342
 343         if (flags & PIN_OFFSET_BIAS &&
 344             vma->node.start < (flags & PIN_OFFSET_MASK))
 345                 return true;
 346
 347         if (flags & PIN_OFFSET_FIXED &&
 348             vma->node.start != (flags & PIN_OFFSET_MASK))
 349                 return true;
 350
 351         return false;
 352 }
 353
 354 void __i915_vma_set_map_and_fenceable(struct i915_vma *vma)
 355 {
 356         bool mappable, fenceable;
 357
 358         GEM_BUG_ON(!i915_vma_is_ggtt(vma));
 359         GEM_BUG_ON(!vma->fence_size);
 360
 361         /*
 362          * Explicitly disable for rotated VMA since the display does not
 363          * need the fence and the VMA is not accessible to other users.
 364          */
 365         if (vma->ggtt_view.type == I915_GGTT_VIEW_ROTATED)
 366                 return;
 367
 368         fenceable = (vma->node.size >= vma->fence_size &&
 369                      IS_ALIGNED(vma->node.start, vma->fence_alignment));
 370
 371         mappable = vma->node.start + vma->fence_size <= i915_vm_to_ggtt(vma->vm)->mappable_end;
 372
 373         if (mappable && fenceable)
 374                 vma->flags |= I915_VMA_CAN_FENCE;
 375         else
 376                 vma->flags &= ~I915_VMA_CAN_FENCE;
 377 }
 378
 379 static bool color_differs(struct drm_mm_node *node, unsigned long color)
 380 {
 381         return node->allocated && node->color != color;
 382 }
 383
 384 bool i915_gem_valid_gtt_space(struct i915_vma *vma, unsigned long cache_level)
 385 {
 386         struct drm_mm_node *node = &vma->node;
 387         struct drm_mm_node *other;
 388
 389         /*
 390          * On some machines we have to be careful when putting differing types
 391          * of snoopable memory together to avoid the prefetcher crossing memory
 392          * domains and dying. During vm initialisation, we decide whether or not
 393          * these constraints apply and set the drm_mm.color_adjust
 394          * appropriately.
 395          */
 396         if (vma->vm->mm.color_adjust == NULL)
 397                 return true;
 398
 399         /* Only valid to be called on an already inserted vma */
 400         GEM_BUG_ON(!drm_mm_node_allocated(node));
 401         GEM_BUG_ON(list_empty(&node->node_list));
 402
 403         other = list_prev_entry(node, node_list);
 404         if (color_differs(other, cache_level) && !drm_mm_hole_follows(other))
 405                 return false;
 406
 407         other = list_next_entry(node, node_list);
 408         if (color_differs(other, cache_level) && !drm_mm_hole_follows(node))
 409                 return false;
 410
 411         return true;
 412 }
 413
 414 /**
 415  * i915_vma_insert - finds a slot for the vma in its address space
 416  * @vma: the vma
 417  * @size: requested size in bytes (can be larger than the VMA)
 418  * @alignment: required alignment
 419  * @flags: mask of PIN_* flags to use
 420  *
 421  * First we try to allocate some free space that meets the requirements for
 422  * the VMA. Failiing that, if the flags permit, it will evict an old VMA,
 423  * preferrably the oldest idle entry to make room for the new VMA.
 424  *
 425  * Returns:
 426  * 0 on success, negative error code otherwise.
 427  */
 428 static int
 429 i915_vma_insert(struct i915_vma *vma, u64 size, u64 alignment, u64 flags)
 430 {
 431         struct drm_i915_private *dev_priv = vma->vm->i915;
 432         struct drm_i915_gem_object *obj = vma->obj;
 433         u64 start, end;
 434         int ret;
 435
 436         GEM_BUG_ON(vma->flags & (I915_VMA_GLOBAL_BIND | I915_VMA_LOCAL_BIND));
 437         GEM_BUG_ON(drm_mm_node_allocated(&vma->node));
 438
 439         size = max(size, vma->size);
 440         alignment = max(alignment, vma->display_alignment);
 441         if (flags & PIN_MAPPABLE) {
 442                 size = max_t(typeof(size), size, vma->fence_size);
 443                 alignment = max_t(typeof(alignment),
 444                                   alignment, vma->fence_alignment);
 445         }
 446
 447         GEM_BUG_ON(!IS_ALIGNED(size, I915_GTT_PAGE_SIZE));
 448         GEM_BUG_ON(!IS_ALIGNED(alignment, I915_GTT_MIN_ALIGNMENT));
 449         GEM_BUG_ON(!is_power_of_2(alignment));
 450
 451         start = flags & PIN_OFFSET_BIAS ? flags & PIN_OFFSET_MASK : 0;
 452         GEM_BUG_ON(!IS_ALIGNED(start, I915_GTT_PAGE_SIZE));
 453
 454         end = vma->vm->total;
 455         if (flags & PIN_MAPPABLE)
 456                 end = min_t(u64, end, dev_priv->ggtt.mappable_end);
 457         if (flags & PIN_ZONE_4G)
 458                 end = min_t(u64, end, (1ULL << 32) - I915_GTT_PAGE_SIZE);
 459         GEM_BUG_ON(!IS_ALIGNED(end, I915_GTT_PAGE_SIZE));
 460
 461         /* If binding the object/GGTT view requires more space than the entire
 462          * aperture has, reject it early before evicting everything in a vain
 463          * attempt to find space.
 464          */
 465         if (size > end) {
 466                 DRM_DEBUG("Attempting to bind an object larger than the aperture: request=%llu [object=%zd] > %s aperture=%llu\n",
 467                           size, obj->base.size,
 468                           flags & PIN_MAPPABLE ? "mappable" : "total",
 469                           end);
 470                 return -E2BIG;
 471         }
 472
 473         ret = i915_gem_object_pin_pages(obj);
 474         if (ret)
 475                 return ret;
 476
 477         if (flags & PIN_OFFSET_FIXED) {
 478                 u64 offset = flags & PIN_OFFSET_MASK;
 479                 if (!IS_ALIGNED(offset, alignment) ||
 480                     range_overflows(offset, size, end)) {
 481                         ret = -EINVAL;
 482                         goto err_unpin;
 483                 }
 484
 485                 ret = i915_gem_gtt_reserve(vma->vm, &vma->node,
 486                                            size, offset, obj->cache_level,
 487                                            flags);
 488                 if (ret)
 489                         goto err_unpin;
 490         } else {
 491                 ret = i915_gem_gtt_insert(vma->vm, &vma->node,
 492                                           size, alignment, obj->cache_level,
 493                                           start, end, flags);
 494                 if (ret)
 495                         goto err_unpin;
 496
 497                 GEM_BUG_ON(vma->node.start < start);
 498                 GEM_BUG_ON(vma->node.start + vma->node.size > end);
 499         }
 500         GEM_BUG_ON(!drm_mm_node_allocated(&vma->node));
 501         GEM_BUG_ON(!i915_gem_valid_gtt_space(vma, obj->cache_level));
 502
 503         list_move_tail(&obj->global_link, &dev_priv->mm.bound_list);
 504         list_move_tail(&vma->vm_link, &vma->vm->inactive_list);
 505         obj->bind_count++;
 506         GEM_BUG_ON(atomic_read(&obj->mm.pages_pin_count) < obj->bind_count);
 507
 508         return 0;
 509
 510 err_unpin:
 511         i915_gem_object_unpin_pages(obj);
 512         return ret;
 513 }
 514
 515 int __i915_vma_do_pin(struct i915_vma *vma,
 516                       u64 size, u64 alignment, u64 flags)
 517 {
 518         unsigned int bound = vma->flags;
 519         int ret;
 520
 521         lockdep_assert_held(&vma->vm->i915->drm.struct_mutex);
 522         GEM_BUG_ON((flags & (PIN_GLOBAL | PIN_USER)) == 0);
 523         GEM_BUG_ON((flags & PIN_GLOBAL) && !i915_vma_is_ggtt(vma));
 524
 525         if (WARN_ON(bound & I915_VMA_PIN_OVERFLOW)) {
 526                 ret = -EBUSY;
 527                 goto err;
 528         }
 529
 530         if ((bound & I915_VMA_BIND_MASK) == 0) {
 531                 ret = i915_vma_insert(vma, size, alignment, flags);
 532                 if (ret)
 533                         goto err;
 534         }
 535
 536         ret = i915_vma_bind(vma, vma->obj->cache_level, flags);
 537         if (ret)
 538                 goto err;
 539
 540         if ((bound ^ vma->flags) & I915_VMA_GLOBAL_BIND)
 541                 __i915_vma_set_map_and_fenceable(vma);
 542
 543         GEM_BUG_ON(!drm_mm_node_allocated(&vma->node));
 544         GEM_BUG_ON(i915_vma_misplaced(vma, size, alignment, flags));
 545         return 0;
 546
 547 err:
 548         __i915_vma_unpin(vma);
 549         return ret;
 550 }
 551
 552 void i915_vma_destroy(struct i915_vma *vma)
 553 {
 554         GEM_BUG_ON(vma->node.allocated);
 555         GEM_BUG_ON(i915_vma_is_active(vma));
 556         GEM_BUG_ON(!i915_vma_is_closed(vma));
 557         GEM_BUG_ON(vma->fence);
 558
 559         list_del(&vma->vm_link);
 560         if (!i915_vma_is_ggtt(vma))
 561                 i915_ppgtt_put(i915_vm_to_ppgtt(vma->vm));
 562
 563         kmem_cache_free(to_i915(vma->obj->base.dev)->vmas, vma);
 564 }
 565
 566 void i915_vma_close(struct i915_vma *vma)
 567 {
 568         GEM_BUG_ON(i915_vma_is_closed(vma));
 569         vma->flags |= I915_VMA_CLOSED;
 570
 571         list_del(&vma->obj_link);
 572         rb_erase(&vma->obj_node, &vma->obj->vma_tree);
 573
 574         if (!i915_vma_is_active(vma) && !i915_vma_is_pinned(vma))
 575                 WARN_ON(i915_vma_unbind(vma));
 576 }
 577
 578 static void __i915_vma_iounmap(struct i915_vma *vma)
 579 {
 580         GEM_BUG_ON(i915_vma_is_pinned(vma));
 581
 582         if (vma->iomap == NULL)
 583                 return;
 584
 585         io_mapping_unmap(vma->iomap);
 586         vma->iomap = NULL;
 587 }
 588
 589 int i915_vma_unbind(struct i915_vma *vma)
 590 {
 591         struct drm_i915_gem_object *obj = vma->obj;
 592         unsigned long active;
 593         int ret;
 594
 595         lockdep_assert_held(&obj->base.dev->struct_mutex);
 596
 597         /* First wait upon any activity as retiring the request may
 598          * have side-effects such as unpinning or even unbinding this vma.
 599          */
 600         active = i915_vma_get_active(vma);
 601         if (active) {
 602                 int idx;
 603
 604                 /* When a closed VMA is retired, it is unbound - eek.
 605                  * In order to prevent it from being recursively closed,
 606                  * take a pin on the vma so that the second unbind is
 607                  * aborted.
 608                  *
 609                  * Even more scary is that the retire callback may free
 610                  * the object (last active vma). To prevent the explosion
 611                  * we defer the actual object free to a worker that can
 612                  * only proceed once it acquires the struct_mutex (which
 613                  * we currently hold, therefore it cannot free this object
 614                  * before we are finished).
 615                  */
 616                 __i915_vma_pin(vma);
 617
 618                 for_each_active(active, idx) {
 619                         ret = i915_gem_active_retire(&vma->last_read[idx],
 620                                                      &vma->vm->i915->drm.struct_mutex);
 621                         if (ret)
 622                                 break;
 623                 }
 624
 625                 __i915_vma_unpin(vma);
 626                 if (ret)
 627                         return ret;
 628
 629                 GEM_BUG_ON(i915_vma_is_active(vma));
 630         }
 631
 632         if (i915_vma_is_pinned(vma))
 633                 return -EBUSY;
 634
 635         if (!drm_mm_node_allocated(&vma->node))
 636                 goto destroy;
 637
 638         GEM_BUG_ON(obj->bind_count == 0);
 639         GEM_BUG_ON(!i915_gem_object_has_pinned_pages(obj));
 640
 641         if (i915_vma_is_map_and_fenceable(vma)) {
 642                 /* release the fence reg _after_ flushing */
 643                 ret = i915_vma_put_fence(vma);
 644                 if (ret)
 645                         return ret;
 646
 647                 /* Force a pagefault for domain tracking on next user access */
 648                 i915_gem_release_mmap(obj);
 649
 650                 __i915_vma_iounmap(vma);
 651                 vma->flags &= ~I915_VMA_CAN_FENCE;
 652         }
 653
 654         if (likely(!vma->vm->closed)) {
 655                 trace_i915_vma_unbind(vma);
 656                 vma->vm->unbind_vma(vma);
 657         }
 658         vma->flags &= ~(I915_VMA_GLOBAL_BIND | I915_VMA_LOCAL_BIND);
 659
 660         drm_mm_remove_node(&vma->node);
 661         list_move_tail(&vma->vm_link, &vma->vm->unbound_list);
 662
 663         if (vma->pages != obj->mm.pages) {
 664                 GEM_BUG_ON(!vma->pages);
 665                 sg_free_table(vma->pages);
 666                 kfree(vma->pages);
 667         }
 668         vma->pages = NULL;
 669
 670         /* Since the unbound list is global, only move to that list if
 671          * no more VMAs exist. */
 672         if (--obj->bind_count == 0)
 673                 list_move_tail(&obj->global_link,
 674                                &to_i915(obj->base.dev)->mm.unbound_list);
 675
 676         /* And finally now the object is completely decoupled from this vma,
 677          * we can drop its hold on the backing storage and allow it to be
 678          * reaped by the shrinker.
 679          */
 680         i915_gem_object_unpin_pages(obj);
 681         GEM_BUG_ON(atomic_read(&obj->mm.pages_pin_count) < obj->bind_count);
 682
 683 destroy:
 684         if (unlikely(i915_vma_is_closed(vma)))
 685                 i915_vma_destroy(vma);
 686
 687         return 0;
 688 }
 689