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 = NULL;
 100         struct drm_i915_gem_object *tmp;
 101         struct list_head *list;
 102         int n, ret;
 103
 104         lockdep_assert_held(&pool->engine->i915->drm.struct_mutex);
 105
 106         /* Compute a power-of-two bucket, but throw everything greater than
 107          * 16KiB into the same bucket: i.e. the the buckets hold objects of
 108          * (1 page, 2 pages, 4 pages, 8+ pages).
 109          */
 110         n = fls(size >> PAGE_SHIFT) - 1;
 111         if (n >= ARRAY_SIZE(pool->cache_list))
 112                 n = ARRAY_SIZE(pool->cache_list) - 1;
 113         list = &pool->cache_list[n];
 114
 115         list_for_each_entry(tmp, list, batch_pool_link) {
 116                 /* The batches are strictly LRU ordered */
 117                 if (i915_gem_object_is_active(tmp))
 118                         break;
 119
 120                 GEM_BUG_ON(!reservation_object_test_signaled_rcu(tmp->resv,
 121                                                                  true));
 122
 123                 if (tmp->base.size >= size) {
 124                         /* Clear the set of shared fences early */
 125                         ww_mutex_lock(&tmp->resv->lock, NULL);
 126                         reservation_object_add_excl_fence(tmp->resv, NULL);
 127                         ww_mutex_unlock(&tmp->resv->lock);
 128
 129                         obj = tmp;
 130                         break;
 131                 }
 132         }
 133
 134         if (obj == NULL) {
 135                 obj = i915_gem_object_create_internal(pool->engine->i915, size);
 136                 if (IS_ERR(obj))
 137                         return obj;
 138         }
 139
 140         ret = i915_gem_object_pin_pages(obj);
 141         if (ret)
 142                 return ERR_PTR(ret);
 143
 144         list_move_tail(&obj->batch_pool_link, list);
 145         return obj;
 146 }