1 /*
2  * SPDX-License-Identifier: MIT
3  *
4  * Copyright © 2016 Intel Corporation
5  */
6 
7 #include "display/intel_frontbuffer.h"
8 
9 #include "i915_drv.h"
10 #include "i915_gem_clflush.h"
11 #include "i915_sw_fence_work.h"
12 #include "i915_trace.h"
13 
14 struct clflush {
15 	struct dma_fence_work base;
16 	struct drm_i915_gem_object *obj;
17 };
18 
19 static void __do_clflush(struct drm_i915_gem_object *obj)
20 {
21 	GEM_BUG_ON(!i915_gem_object_has_pages(obj));
22 	drm_clflush_sg(obj->mm.pages);
23 
24 	i915_gem_object_flush_frontbuffer(obj, ORIGIN_CPU);
25 }
26 
27 static int clflush_work(struct dma_fence_work *base)
28 {
29 	struct clflush *clflush = container_of(base, typeof(*clflush), base);
30 	struct drm_i915_gem_object *obj = clflush->obj;
31 	int err;
32 
33 	err = i915_gem_object_pin_pages(obj);
34 	if (err)
35 		return err;
36 
37 	__do_clflush(obj);
38 	i915_gem_object_unpin_pages(obj);
39 
40 	return 0;
41 }
42 
43 static void clflush_release(struct dma_fence_work *base)
44 {
45 	struct clflush *clflush = container_of(base, typeof(*clflush), base);
46 
47 	i915_gem_object_put(clflush->obj);
48 }
49 
50 static const struct dma_fence_work_ops clflush_ops = {
51 	.name = "clflush",
52 	.work = clflush_work,
53 	.release = clflush_release,
54 };
55 
56 static struct clflush *clflush_work_create(struct drm_i915_gem_object *obj)
57 {
58 	struct clflush *clflush;
59 
60 	GEM_BUG_ON(!obj->cache_dirty);
61 
62 	clflush = kmalloc(sizeof(*clflush), GFP_KERNEL);
63 	if (!clflush)
64 		return NULL;
65 
66 	dma_fence_work_init(&clflush->base, &clflush_ops);
67 	clflush->obj = i915_gem_object_get(obj); /* obj <-> clflush cycle */
68 
69 	return clflush;
70 }
71 
72 bool i915_gem_clflush_object(struct drm_i915_gem_object *obj,
73 			     unsigned int flags)
74 {
75 	struct clflush *clflush;
76 
77 	assert_object_held(obj);
78 
79 	/*
80 	 * Stolen memory is always coherent with the GPU as it is explicitly
81 	 * marked as wc by the system, or the system is cache-coherent.
82 	 * Similarly, we only access struct pages through the CPU cache, so
83 	 * anything not backed by physical memory we consider to be always
84 	 * coherent and not need clflushing.
85 	 */
86 	if (!i915_gem_object_has_struct_page(obj)) {
87 		obj->cache_dirty = false;
88 		return false;
89 	}
90 
91 	/* If the GPU is snooping the contents of the CPU cache,
92 	 * we do not need to manually clear the CPU cache lines.  However,
93 	 * the caches are only snooped when the render cache is
94 	 * flushed/invalidated.  As we always have to emit invalidations
95 	 * and flushes when moving into and out of the RENDER domain, correct
96 	 * snooping behaviour occurs naturally as the result of our domain
97 	 * tracking.
98 	 */
99 	if (!(flags & I915_CLFLUSH_FORCE) &&
100 	    obj->cache_coherent & I915_BO_CACHE_COHERENT_FOR_READ)
101 		return false;
102 
103 	trace_i915_gem_object_clflush(obj);
104 
105 	clflush = NULL;
106 	if (!(flags & I915_CLFLUSH_SYNC))
107 		clflush = clflush_work_create(obj);
108 	if (clflush) {
109 		i915_sw_fence_await_reservation(&clflush->base.chain,
110 						obj->base.resv, NULL, true,
111 						I915_FENCE_TIMEOUT,
112 						I915_FENCE_GFP);
113 		dma_resv_add_excl_fence(obj->base.resv, &clflush->base.dma);
114 		dma_fence_work_commit(&clflush->base);
115 	} else if (obj->mm.pages) {
116 		__do_clflush(obj);
117 	} else {
118 		GEM_BUG_ON(obj->write_domain != I915_GEM_DOMAIN_CPU);
119 	}
120 
121 	obj->cache_dirty = false;
122 	return true;
123 }
124