1 /* SPDX-License-Identifier: GPL-2.0 OR MIT */
2 /**************************************************************************
3  *
4  * Copyright (c) 2006-2009 VMware, Inc., Palo Alto, CA., USA
5  * All Rights Reserved.
6  *
7  * Permission is hereby granted, free of charge, to any person obtaining a
8  * copy of this software and associated documentation files (the
9  * "Software"), to deal in the Software without restriction, including
10  * without limitation the rights to use, copy, modify, merge, publish,
11  * distribute, sub license, and/or sell copies of the Software, and to
12  * permit persons to whom the Software is furnished to do so, subject to
13  * the following conditions:
14  *
15  * The above copyright notice and this permission notice (including the
16  * next paragraph) shall be included in all copies or substantial portions
17  * of the Software.
18  *
19  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
20  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
21  * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL
22  * THE COPYRIGHT HOLDERS, AUTHORS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM,
23  * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
24  * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
25  * USE OR OTHER DEALINGS IN THE SOFTWARE.
26  *
27  **************************************************************************/
28 
29 #include <drm/ttm/ttm_execbuf_util.h>
30 #include <drm/ttm/ttm_bo.h>
31 
32 static void ttm_eu_backoff_reservation_reverse(struct list_head *list,
33 					      struct ttm_validate_buffer *entry)
34 {
35 	list_for_each_entry_continue_reverse(entry, list, head) {
36 		struct ttm_buffer_object *bo = entry->bo;
37 
38 		dma_resv_unlock(bo->base.resv);
39 	}
40 }
41 
42 void ttm_eu_backoff_reservation(struct ww_acquire_ctx *ticket,
43 				struct list_head *list)
44 {
45 	struct ttm_validate_buffer *entry;
46 
47 	if (list_empty(list))
48 		return;
49 
50 	list_for_each_entry(entry, list, head) {
51 		struct ttm_buffer_object *bo = entry->bo;
52 
53 		ttm_bo_move_to_lru_tail_unlocked(bo);
54 		dma_resv_unlock(bo->base.resv);
55 	}
56 
57 	if (ticket)
58 		ww_acquire_fini(ticket);
59 }
60 EXPORT_SYMBOL(ttm_eu_backoff_reservation);
61 
62 /*
63  * Reserve buffers for validation.
64  *
65  * If a buffer in the list is marked for CPU access, we back off and
66  * wait for that buffer to become free for GPU access.
67  *
68  * If a buffer is reserved for another validation, the validator with
69  * the highest validation sequence backs off and waits for that buffer
70  * to become unreserved. This prevents deadlocks when validating multiple
71  * buffers in different orders.
72  */
73 
74 int ttm_eu_reserve_buffers(struct ww_acquire_ctx *ticket,
75 			   struct list_head *list, bool intr,
76 			   struct list_head *dups)
77 {
78 	struct ttm_validate_buffer *entry;
79 	int ret;
80 
81 	if (list_empty(list))
82 		return 0;
83 
84 	if (ticket)
85 		ww_acquire_init(ticket, &reservation_ww_class);
86 
87 	list_for_each_entry(entry, list, head) {
88 		struct ttm_buffer_object *bo = entry->bo;
89 		unsigned int num_fences;
90 
91 		ret = ttm_bo_reserve(bo, intr, (ticket == NULL), ticket);
92 		if (ret == -EALREADY && dups) {
93 			struct ttm_validate_buffer *safe = entry;
94 			entry = list_prev_entry(entry, head);
95 			list_del(&safe->head);
96 			list_add(&safe->head, dups);
97 			continue;
98 		}
99 
100 		num_fences = max(entry->num_shared, 1u);
101 		if (!ret) {
102 			ret = dma_resv_reserve_fences(bo->base.resv,
103 						      num_fences);
104 			if (!ret)
105 				continue;
106 		}
107 
108 		/* uh oh, we lost out, drop every reservation and try
109 		 * to only reserve this buffer, then start over if
110 		 * this succeeds.
111 		 */
112 		ttm_eu_backoff_reservation_reverse(list, entry);
113 
114 		if (ret == -EDEADLK) {
115 			ret = ttm_bo_reserve_slowpath(bo, intr, ticket);
116 		}
117 
118 		if (!ret)
119 			ret = dma_resv_reserve_fences(bo->base.resv,
120 						      num_fences);
121 
122 		if (unlikely(ret != 0)) {
123 			if (ticket) {
124 				ww_acquire_done(ticket);
125 				ww_acquire_fini(ticket);
126 			}
127 			return ret;
128 		}
129 
130 		/* move this item to the front of the list,
131 		 * forces correct iteration of the loop without keeping track
132 		 */
133 		list_del(&entry->head);
134 		list_add(&entry->head, list);
135 	}
136 
137 	return 0;
138 }
139 EXPORT_SYMBOL(ttm_eu_reserve_buffers);
140 
141 void ttm_eu_fence_buffer_objects(struct ww_acquire_ctx *ticket,
142 				 struct list_head *list,
143 				 struct dma_fence *fence)
144 {
145 	struct ttm_validate_buffer *entry;
146 
147 	if (list_empty(list))
148 		return;
149 
150 	list_for_each_entry(entry, list, head) {
151 		struct ttm_buffer_object *bo = entry->bo;
152 
153 		dma_resv_add_fence(bo->base.resv, fence, entry->num_shared ?
154 				   DMA_RESV_USAGE_READ : DMA_RESV_USAGE_WRITE);
155 		ttm_bo_move_to_lru_tail_unlocked(bo);
156 		dma_resv_unlock(bo->base.resv);
157 	}
158 	if (ticket)
159 		ww_acquire_fini(ticket);
160 }
161 EXPORT_SYMBOL(ttm_eu_fence_buffer_objects);
162