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_driver.h>
31 #include <drm/ttm/ttm_placement.h>
32 #include <linux/wait.h>
33 #include <linux/sched.h>
34 #include <linux/module.h>
35 
36 static void ttm_eu_backoff_reservation_reverse(struct list_head *list,
37 					      struct ttm_validate_buffer *entry)
38 {
39 	list_for_each_entry_continue_reverse(entry, list, head) {
40 		struct ttm_buffer_object *bo = entry->bo;
41 
42 		dma_resv_unlock(bo->base.resv);
43 	}
44 }
45 
46 void ttm_eu_backoff_reservation(struct ww_acquire_ctx *ticket,
47 				struct list_head *list)
48 {
49 	struct ttm_validate_buffer *entry;
50 
51 	if (list_empty(list))
52 		return;
53 
54 	list_for_each_entry(entry, list, head) {
55 		struct ttm_buffer_object *bo = entry->bo;
56 
57 		ttm_bo_move_to_lru_tail_unlocked(bo);
58 		dma_resv_unlock(bo->base.resv);
59 	}
60 
61 	if (ticket)
62 		ww_acquire_fini(ticket);
63 }
64 EXPORT_SYMBOL(ttm_eu_backoff_reservation);
65 
66 /*
67  * Reserve buffers for validation.
68  *
69  * If a buffer in the list is marked for CPU access, we back off and
70  * wait for that buffer to become free for GPU access.
71  *
72  * If a buffer is reserved for another validation, the validator with
73  * the highest validation sequence backs off and waits for that buffer
74  * to become unreserved. This prevents deadlocks when validating multiple
75  * buffers in different orders.
76  */
77 
78 int ttm_eu_reserve_buffers(struct ww_acquire_ctx *ticket,
79 			   struct list_head *list, bool intr,
80 			   struct list_head *dups)
81 {
82 	struct ttm_validate_buffer *entry;
83 	int ret;
84 
85 	if (list_empty(list))
86 		return 0;
87 
88 	if (ticket)
89 		ww_acquire_init(ticket, &reservation_ww_class);
90 
91 	list_for_each_entry(entry, list, head) {
92 		struct ttm_buffer_object *bo = entry->bo;
93 		unsigned int num_fences;
94 
95 		ret = ttm_bo_reserve(bo, intr, (ticket == NULL), ticket);
96 		if (ret == -EALREADY && dups) {
97 			struct ttm_validate_buffer *safe = entry;
98 			entry = list_prev_entry(entry, head);
99 			list_del(&safe->head);
100 			list_add(&safe->head, dups);
101 			continue;
102 		}
103 
104 		num_fences = max(entry->num_shared, 1u);
105 		if (!ret) {
106 			ret = dma_resv_reserve_fences(bo->base.resv,
107 						      num_fences);
108 			if (!ret)
109 				continue;
110 		}
111 
112 		/* uh oh, we lost out, drop every reservation and try
113 		 * to only reserve this buffer, then start over if
114 		 * this succeeds.
115 		 */
116 		ttm_eu_backoff_reservation_reverse(list, entry);
117 
118 		if (ret == -EDEADLK) {
119 			ret = ttm_bo_reserve_slowpath(bo, intr, ticket);
120 		}
121 
122 		if (!ret)
123 			ret = dma_resv_reserve_fences(bo->base.resv,
124 						      num_fences);
125 
126 		if (unlikely(ret != 0)) {
127 			if (ticket) {
128 				ww_acquire_done(ticket);
129 				ww_acquire_fini(ticket);
130 			}
131 			return ret;
132 		}
133 
134 		/* move this item to the front of the list,
135 		 * forces correct iteration of the loop without keeping track
136 		 */
137 		list_del(&entry->head);
138 		list_add(&entry->head, list);
139 	}
140 
141 	return 0;
142 }
143 EXPORT_SYMBOL(ttm_eu_reserve_buffers);
144 
145 void ttm_eu_fence_buffer_objects(struct ww_acquire_ctx *ticket,
146 				 struct list_head *list,
147 				 struct dma_fence *fence)
148 {
149 	struct ttm_validate_buffer *entry;
150 
151 	if (list_empty(list))
152 		return;
153 
154 	list_for_each_entry(entry, list, head) {
155 		struct ttm_buffer_object *bo = entry->bo;
156 
157 		dma_resv_add_fence(bo->base.resv, fence, entry->num_shared ?
158 				   DMA_RESV_USAGE_READ : DMA_RESV_USAGE_WRITE);
159 		ttm_bo_move_to_lru_tail_unlocked(bo);
160 		dma_resv_unlock(bo->base.resv);
161 	}
162 	if (ticket)
163 		ww_acquire_fini(ticket);
164 }
165 EXPORT_SYMBOL(ttm_eu_fence_buffer_objects);
166