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
  27 /**
  28  * DOC: batch pool
  29  *
  30  * In order to submit batch buffers as 'secure', the software command parser
  31  * must ensure that a batch buffer cannot be modified after parsing. It does
  32  * this by copying the user provided batch buffer contents to a kernel owned
  33  * buffer from which the hardware will actually execute, and by carefully
  34  * managing the address space bindings for such buffers.
  35  *
  36  * The batch pool framework provides a mechanism for the driver to manage a
  37  * set of scratch buffers to use for this purpose. The framework can be
  38  * extended to support other uses cases should they arise.
  39  */
  40
  41 /**
  42  * i915_gem_batch_pool_init() - initialize a batch buffer pool
  43  * @dev: the drm device
  44  * @pool: the batch buffer pool
  45  */
  46 void i915_gem_batch_pool_init(struct drm_device *dev,
  47                               struct i915_gem_batch_pool *pool)
  48 {
  49         pool->dev = dev;
  50         INIT_LIST_HEAD(&pool->cache_list);
  51 }
  52
  53 /**
  54  * i915_gem_batch_pool_fini() - clean up a batch buffer pool
  55  * @pool: the pool to clean up
  56  *
  57  * Note: Callers must hold the struct_mutex.
  58  */
  59 void i915_gem_batch_pool_fini(struct i915_gem_batch_pool *pool)
  60 {
  61         WARN_ON(!mutex_is_locked(&pool->dev->struct_mutex));
  62
  63         while (!list_empty(&pool->cache_list)) {
  64                 struct drm_i915_gem_object *obj =
  65                         list_first_entry(&pool->cache_list,
  66                                          struct drm_i915_gem_object,
  67                                          batch_pool_list);
  68
  69                 WARN_ON(obj->active);
  70
  71                 list_del_init(&obj->batch_pool_list);
  72                 drm_gem_object_unreference(&obj->base);
  73         }
  74 }
  75
  76 /**
  77  * i915_gem_batch_pool_get() - select a buffer from the pool
  78  * @pool: the batch buffer pool
  79  * @size: the minimum desired size of the returned buffer
  80  *
  81  * Finds or allocates a batch buffer in the pool with at least the requested
  82  * size. The caller is responsible for any domain, active/inactive, or
  83  * purgeability management for the returned buffer.
  84  *
  85  * Note: Callers must hold the struct_mutex
  86  *
  87  * Return: the selected batch buffer object
  88  */
  89 struct drm_i915_gem_object *
  90 i915_gem_batch_pool_get(struct i915_gem_batch_pool *pool,
  91                         size_t size)
  92 {
  93         struct drm_i915_gem_object *obj = NULL;
  94         struct drm_i915_gem_object *tmp, *next;
  95
  96         WARN_ON(!mutex_is_locked(&pool->dev->struct_mutex));
  97
  98         list_for_each_entry_safe(tmp, next,
  99                         &pool->cache_list, batch_pool_list) {
 100
 101                 if (tmp->active)
 102                         continue;
 103
 104                 /* While we're looping, do some clean up */
 105                 if (tmp->madv == __I915_MADV_PURGED) {
 106                         list_del(&tmp->batch_pool_list);
 107                         drm_gem_object_unreference(&tmp->base);
 108                         continue;
 109                 }
 110
 111                 /*
 112                  * Select a buffer that is at least as big as needed
 113                  * but not 'too much' bigger. A better way to do this
 114                  * might be to bucket the pool objects based on size.
 115                  */
 116                 if (tmp->base.size >= size &&
 117                     tmp->base.size <= (2 * size)) {
 118                         obj = tmp;
 119                         break;
 120                 }
 121         }
 122
 123         if (!obj) {
 124                 obj = i915_gem_alloc_object(pool->dev, size);
 125                 if (!obj)
 126                         return ERR_PTR(-ENOMEM);
 127
 128                 list_add_tail(&obj->batch_pool_list, &pool->cache_list);
 129         }
 130         else
 131                 /* Keep list in LRU order */
 132                 list_move_tail(&obj->batch_pool_list, &pool->cache_list);
 133
 134         obj->madv = I915_MADV_WILLNEED;
 135
 136         return obj;
 137 }