drivers/gpu/drm/i915/i915_gem_batch_pool.c

   1 /*
   2  * Copyright © 2014 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_drv.h"
  26 #include "i915_gem_batch_pool.h"
  27
  28 /**
  29  * DOC: batch pool
  30  *
  31  * In order to submit batch buffers as 'secure', the software command parser
  32  * must ensure that a batch buffer cannot be modified after parsing. It does
  33  * this by copying the user provided batch buffer contents to a kernel owned
  34  * buffer from which the hardware will actually execute, and by carefully
  35  * managing the address space bindings for such buffers.
  36  *
  37  * The batch pool framework provides a mechanism for the driver to manage a
  38  * set of scratch buffers to use for this purpose. The framework can be
  39  * extended to support other uses cases should they arise.
  40  */
  41
  42 /**
  43  * i915_gem_batch_pool_init() - initialize a batch buffer pool
  44  * @engine: the associated request submission engine
  45  * @pool: the batch buffer pool
  46  */
  47 void i915_gem_batch_pool_init(struct intel_engine_cs *engine,
  48                               struct i915_gem_batch_pool *pool)
  49 {
  50         int n;
  51
  52         pool->engine = engine;
  53
  54         for (n = 0; n < ARRAY_SIZE(pool->cache_list); n++)
  55                 INIT_LIST_HEAD(&pool->cache_list[n]);
  56 }
  57
  58 /**
  59  * i915_gem_batch_pool_fini() - clean up a batch buffer pool
  60  * @pool: the pool to clean up
  61  *
  62  * Note: Callers must hold the struct_mutex.
  63  */
  64 void i915_gem_batch_pool_fini(struct i915_gem_batch_pool *pool)
  65 {
  66         int n;
  67
  68         lockdep_assert_held(&pool->engine->i915->drm.struct_mutex);
  69
  70         for (n = 0; n < ARRAY_SIZE(pool->cache_list); n++) {
  71                 struct drm_i915_gem_object *obj, *next;
  72
  73                 list_for_each_entry_safe(obj, next,
  74                                          &pool->cache_list[n],
  75                                          batch_pool_link)
  76                         __i915_gem_object_release_unless_active(obj);
  77
  78                 INIT_LIST_HEAD(&pool->cache_list[n]);
  79         }
  80 }
  81
  82 /**
  83  * i915_gem_batch_pool_get() - allocate a buffer from the pool
  84  * @pool: the batch buffer pool
  85  * @size: the minimum desired size of the returned buffer
  86  *
  87  * Returns an inactive buffer from @pool with at least @size bytes,
  88  * with the pages pinned. The caller must i915_gem_object_unpin_pages()
  89  * on the returned object.
  90  *
  91  * Note: Callers must hold the struct_mutex
  92  *
  93  * Return: the buffer object or an error pointer
  94  */
  95 struct drm_i915_gem_object *
  96 i915_gem_batch_pool_get(struct i915_gem_batch_pool *pool,
  97                         size_t size)
  98 {
  99         struct drm_i915_gem_object *obj;
 100         struct list_head *list;
 101         int n, ret;
 102
 103         lockdep_assert_held(&pool->engine->i915->drm.struct_mutex);
 104
 105         /* Compute a power-of-two bucket, but throw everything greater than
 106          * 16KiB into the same bucket: i.e. the the buckets hold objects of
 107          * (1 page, 2 pages, 4 pages, 8+ pages).
 108          */
 109         n = fls(size >> PAGE_SHIFT) - 1;
 110         if (n >= ARRAY_SIZE(pool->cache_list))
 111                 n = ARRAY_SIZE(pool->cache_list) - 1;
 112         list = &pool->cache_list[n];
 113
 114         list_for_each_entry(obj, list, batch_pool_link) {
 115                 /* The batches are strictly LRU ordered */
 116                 if (i915_gem_object_is_active(obj)) {
 117                         struct reservation_object *resv = obj->resv;
 118
 119                         if (!reservation_object_test_signaled_rcu(resv, true))
 120                                 break;
 121
 122                         i915_gem_retire_requests(pool->engine->i915);
 123                         GEM_BUG_ON(i915_gem_object_is_active(obj));
 124
 125                         /*
 126                          * The object is now idle, clear the array of shared
 127                          * fences before we add a new request. Although, we
 128                          * remain on the same engine, we may be on a different
 129                          * timeline and so may continually grow the array,
 130                          * trapping a reference to all the old fences, rather
 131                          * than replace the existing fence.
 132                          */
 133                         if (rcu_access_pointer(resv->fence)) {
 134                                 reservation_object_lock(resv, NULL);
 135                                 reservation_object_add_excl_fence(resv, NULL);
 136                                 reservation_object_unlock(resv);
 137                         }
 138                 }
 139
 140                 GEM_BUG_ON(!reservation_object_test_signaled_rcu(obj->resv,
 141                                                                  true));
 142
 143                 if (obj->base.size >= size)
 144                         goto found;
 145         }
 146
 147         obj = i915_gem_object_create_internal(pool->engine->i915, size);
 148         if (IS_ERR(obj))
 149                 return obj;
 150
 151 found:
 152         ret = i915_gem_object_pin_pages(obj);
 153         if (ret)
 154                 return ERR_PTR(ret);
 155
 156         list_move_tail(&obj->batch_pool_link, list);
 157         return obj;
 158 }