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 	spin_lock(&ttm_bo_glob.lru_lock);
55 	list_for_each_entry(entry, list, head) {
56 		struct ttm_buffer_object *bo = entry->bo;
57 
58 		ttm_bo_move_to_lru_tail(bo, NULL);
59 		dma_resv_unlock(bo->base.resv);
60 	}
61 	spin_unlock(&ttm_bo_glob.lru_lock);
62 
63 	if (ticket)
64 		ww_acquire_fini(ticket);
65 }
66 EXPORT_SYMBOL(ttm_eu_backoff_reservation);
67 
68 /*
69  * Reserve buffers for validation.
70  *
71  * If a buffer in the list is marked for CPU access, we back off and
72  * wait for that buffer to become free for GPU access.
73  *
74  * If a buffer is reserved for another validation, the validator with
75  * the highest validation sequence backs off and waits for that buffer
76  * to become unreserved. This prevents deadlocks when validating multiple
77  * buffers in different orders.
78  */
79 
80 int ttm_eu_reserve_buffers(struct ww_acquire_ctx *ticket,
81 			   struct list_head *list, bool intr,
82 			   struct list_head *dups)
83 {
84 	struct ttm_validate_buffer *entry;
85 	int ret;
86 
87 	if (list_empty(list))
88 		return 0;
89 
90 	if (ticket)
91 		ww_acquire_init(ticket, &reservation_ww_class);
92 
93 	list_for_each_entry(entry, list, head) {
94 		struct ttm_buffer_object *bo = entry->bo;
95 
96 		ret = __ttm_bo_reserve(bo, intr, (ticket == NULL), ticket);
97 		if (ret == -EALREADY && dups) {
98 			struct ttm_validate_buffer *safe = entry;
99 			entry = list_prev_entry(entry, head);
100 			list_del(&safe->head);
101 			list_add(&safe->head, dups);
102 			continue;
103 		}
104 
105 		if (!ret) {
106 			if (!entry->num_shared)
107 				continue;
108 
109 			ret = dma_resv_reserve_shared(bo->base.resv,
110 								entry->num_shared);
111 			if (!ret)
112 				continue;
113 		}
114 
115 		/* uh oh, we lost out, drop every reservation and try
116 		 * to only reserve this buffer, then start over if
117 		 * this succeeds.
118 		 */
119 		ttm_eu_backoff_reservation_reverse(list, entry);
120 
121 		if (ret == -EDEADLK) {
122 			if (intr) {
123 				ret = dma_resv_lock_slow_interruptible(bo->base.resv,
124 										 ticket);
125 			} else {
126 				dma_resv_lock_slow(bo->base.resv, ticket);
127 				ret = 0;
128 			}
129 		}
130 
131 		if (!ret && entry->num_shared)
132 			ret = dma_resv_reserve_shared(bo->base.resv,
133 								entry->num_shared);
134 
135 		if (unlikely(ret != 0)) {
136 			if (ret == -EINTR)
137 				ret = -ERESTARTSYS;
138 			if (ticket) {
139 				ww_acquire_done(ticket);
140 				ww_acquire_fini(ticket);
141 			}
142 			return ret;
143 		}
144 
145 		/* move this item to the front of the list,
146 		 * forces correct iteration of the loop without keeping track
147 		 */
148 		list_del(&entry->head);
149 		list_add(&entry->head, list);
150 	}
151 
152 	return 0;
153 }
154 EXPORT_SYMBOL(ttm_eu_reserve_buffers);
155 
156 void ttm_eu_fence_buffer_objects(struct ww_acquire_ctx *ticket,
157 				 struct list_head *list,
158 				 struct dma_fence *fence)
159 {
160 	struct ttm_validate_buffer *entry;
161 
162 	if (list_empty(list))
163 		return;
164 
165 	spin_lock(&ttm_bo_glob.lru_lock);
166 	list_for_each_entry(entry, list, head) {
167 		struct ttm_buffer_object *bo = entry->bo;
168 
169 		if (entry->num_shared)
170 			dma_resv_add_shared_fence(bo->base.resv, fence);
171 		else
172 			dma_resv_add_excl_fence(bo->base.resv, fence);
173 		ttm_bo_move_to_lru_tail(bo, NULL);
174 		dma_resv_unlock(bo->base.resv);
175 	}
176 	spin_unlock(&ttm_bo_glob.lru_lock);
177 	if (ticket)
178 		ww_acquire_fini(ticket);
179 }
180 EXPORT_SYMBOL(ttm_eu_fence_buffer_objects);
181