141 lines
3.8 KiB
C
141 lines
3.8 KiB
C
/*
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* SPDX-License-Identifier: MIT
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*
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* Copyright © 2014-2018 Intel Corporation
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*/
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#include "i915_gem_batch_pool.h"
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#include "i915_drv.h"
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/**
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* DOC: batch pool
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*
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* In order to submit batch buffers as 'secure', the software command parser
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* must ensure that a batch buffer cannot be modified after parsing. It does
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* this by copying the user provided batch buffer contents to a kernel owned
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* buffer from which the hardware will actually execute, and by carefully
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* managing the address space bindings for such buffers.
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*
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* The batch pool framework provides a mechanism for the driver to manage a
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* set of scratch buffers to use for this purpose. The framework can be
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* extended to support other uses cases should they arise.
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*/
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/**
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* i915_gem_batch_pool_init() - initialize a batch buffer pool
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* @pool: the batch buffer pool
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* @engine: the associated request submission engine
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*/
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void i915_gem_batch_pool_init(struct i915_gem_batch_pool *pool,
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struct intel_engine_cs *engine)
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{
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int n;
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pool->engine = engine;
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for (n = 0; n < ARRAY_SIZE(pool->cache_list); n++)
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INIT_LIST_HEAD(&pool->cache_list[n]);
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}
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/**
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* i915_gem_batch_pool_fini() - clean up a batch buffer pool
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* @pool: the pool to clean up
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*
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* Note: Callers must hold the struct_mutex.
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*/
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void i915_gem_batch_pool_fini(struct i915_gem_batch_pool *pool)
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{
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int n;
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lockdep_assert_held(&pool->engine->i915->drm.struct_mutex);
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for (n = 0; n < ARRAY_SIZE(pool->cache_list); n++) {
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struct drm_i915_gem_object *obj, *next;
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list_for_each_entry_safe(obj, next,
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&pool->cache_list[n],
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batch_pool_link)
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i915_gem_object_put(obj);
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INIT_LIST_HEAD(&pool->cache_list[n]);
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}
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}
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/**
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* i915_gem_batch_pool_get() - allocate a buffer from the pool
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* @pool: the batch buffer pool
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* @size: the minimum desired size of the returned buffer
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*
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* Returns an inactive buffer from @pool with at least @size bytes,
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* with the pages pinned. The caller must i915_gem_object_unpin_pages()
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* on the returned object.
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*
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* Note: Callers must hold the struct_mutex
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*
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* Return: the buffer object or an error pointer
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*/
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struct drm_i915_gem_object *
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i915_gem_batch_pool_get(struct i915_gem_batch_pool *pool,
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size_t size)
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{
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struct drm_i915_gem_object *obj;
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struct list_head *list;
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int n, ret;
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lockdep_assert_held(&pool->engine->i915->drm.struct_mutex);
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/* Compute a power-of-two bucket, but throw everything greater than
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* 16KiB into the same bucket: i.e. the the buckets hold objects of
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* (1 page, 2 pages, 4 pages, 8+ pages).
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*/
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n = fls(size >> PAGE_SHIFT) - 1;
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if (n >= ARRAY_SIZE(pool->cache_list))
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n = ARRAY_SIZE(pool->cache_list) - 1;
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list = &pool->cache_list[n];
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list_for_each_entry(obj, list, batch_pool_link) {
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/* The batches are strictly LRU ordered */
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if (i915_gem_object_is_active(obj)) {
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struct reservation_object *resv = obj->base.resv;
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if (!reservation_object_test_signaled_rcu(resv, true))
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break;
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i915_retire_requests(pool->engine->i915);
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GEM_BUG_ON(i915_gem_object_is_active(obj));
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/*
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* The object is now idle, clear the array of shared
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* fences before we add a new request. Although, we
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* remain on the same engine, we may be on a different
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* timeline and so may continually grow the array,
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* trapping a reference to all the old fences, rather
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* than replace the existing fence.
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*/
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if (rcu_access_pointer(resv->fence)) {
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reservation_object_lock(resv, NULL);
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reservation_object_add_excl_fence(resv, NULL);
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reservation_object_unlock(resv);
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}
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}
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GEM_BUG_ON(!reservation_object_test_signaled_rcu(obj->base.resv,
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true));
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if (obj->base.size >= size)
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goto found;
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}
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obj = i915_gem_object_create_internal(pool->engine->i915, size);
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if (IS_ERR(obj))
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return obj;
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found:
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ret = i915_gem_object_pin_pages(obj);
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if (ret)
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return ERR_PTR(ret);
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list_move_tail(&obj->batch_pool_link, list);
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return obj;
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}
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