1 /*
2  * Copyright 2016-2018 Advanced Micro Devices, Inc.
3  *
4  * Permission is hereby granted, free of charge, to any person obtaining a
5  * copy of this software and associated documentation files (the "Software"),
6  * to deal in the Software without restriction, including without limitation
7  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
8  * and/or sell copies of the Software, and to permit persons to whom the
9  * Software is furnished to do so, subject to the following conditions:
10  *
11  * The above copyright notice and this permission notice shall be included in
12  * all copies or substantial portions of the Software.
13  *
14  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
15  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
16  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
17  * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR
18  * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
19  * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
20  * OTHER DEALINGS IN THE SOFTWARE.
21  */
22 
23 #include <linux/dma-fence.h>
24 #include <linux/spinlock.h>
25 #include <linux/atomic.h>
26 #include <linux/stacktrace.h>
27 #include <linux/sched.h>
28 #include <linux/slab.h>
29 #include <linux/sched/mm.h>
30 #include "amdgpu_amdkfd.h"
31 #include "kfd_svm.h"
32 
33 static const struct dma_fence_ops amdkfd_fence_ops;
34 static atomic_t fence_seq = ATOMIC_INIT(0);
35 
36 /* Eviction Fence
37  * Fence helper functions to deal with KFD memory eviction.
38  * Big Idea - Since KFD submissions are done by user queues, a BO cannot be
39  *  evicted unless all the user queues for that process are evicted.
40  *
41  * All the BOs in a process share an eviction fence. When process X wants
42  * to map VRAM memory but TTM can't find enough space, TTM will attempt to
43  * evict BOs from its LRU list. TTM checks if the BO is valuable to evict
44  * by calling ttm_device_funcs->eviction_valuable().
45  *
46  * ttm_device_funcs->eviction_valuable() - will return false if the BO belongs
47  *  to process X. Otherwise, it will return true to indicate BO can be
48  *  evicted by TTM.
49  *
50  * If ttm_device_funcs->eviction_valuable returns true, then TTM will continue
51  * the evcition process for that BO by calling ttm_bo_evict --> amdgpu_bo_move
52  * --> amdgpu_copy_buffer(). This sets up job in GPU scheduler.
53  *
54  * GPU Scheduler (amd_sched_main) - sets up a cb (fence_add_callback) to
55  *  nofity when the BO is free to move. fence_add_callback --> enable_signaling
56  *  --> amdgpu_amdkfd_fence.enable_signaling
57  *
58  * amdgpu_amdkfd_fence.enable_signaling - Start a work item that will quiesce
59  * user queues and signal fence. The work item will also start another delayed
60  * work item to restore BOs
61  */
62 
63 struct amdgpu_amdkfd_fence *amdgpu_amdkfd_fence_create(u64 context,
64 				struct mm_struct *mm,
65 				struct svm_range_bo *svm_bo)
66 {
67 	struct amdgpu_amdkfd_fence *fence;
68 
69 	fence = kzalloc(sizeof(*fence), GFP_KERNEL);
70 	if (fence == NULL)
71 		return NULL;
72 
73 	/* This reference gets released in amdkfd_fence_release */
74 	mmgrab(mm);
75 	fence->mm = mm;
76 	get_task_comm(fence->timeline_name, current);
77 	spin_lock_init(&fence->lock);
78 	fence->svm_bo = svm_bo;
79 	dma_fence_init(&fence->base, &amdkfd_fence_ops, &fence->lock,
80 		   context, atomic_inc_return(&fence_seq));
81 
82 	return fence;
83 }
84 
85 struct amdgpu_amdkfd_fence *to_amdgpu_amdkfd_fence(struct dma_fence *f)
86 {
87 	struct amdgpu_amdkfd_fence *fence;
88 
89 	if (!f)
90 		return NULL;
91 
92 	fence = container_of(f, struct amdgpu_amdkfd_fence, base);
93 	if (fence && f->ops == &amdkfd_fence_ops)
94 		return fence;
95 
96 	return NULL;
97 }
98 
99 static const char *amdkfd_fence_get_driver_name(struct dma_fence *f)
100 {
101 	return "amdgpu_amdkfd_fence";
102 }
103 
104 static const char *amdkfd_fence_get_timeline_name(struct dma_fence *f)
105 {
106 	struct amdgpu_amdkfd_fence *fence = to_amdgpu_amdkfd_fence(f);
107 
108 	return fence->timeline_name;
109 }
110 
111 /**
112  * amdkfd_fence_enable_signaling - This gets called when TTM wants to evict
113  *  a KFD BO and schedules a job to move the BO.
114  *  If fence is already signaled return true.
115  *  If fence is not signaled schedule a evict KFD process work item.
116  *
117  *  @f: dma_fence
118  */
119 static bool amdkfd_fence_enable_signaling(struct dma_fence *f)
120 {
121 	struct amdgpu_amdkfd_fence *fence = to_amdgpu_amdkfd_fence(f);
122 
123 	if (!fence)
124 		return false;
125 
126 	if (dma_fence_is_signaled(f))
127 		return true;
128 
129 	if (!fence->svm_bo) {
130 		if (!kgd2kfd_schedule_evict_and_restore_process(fence->mm, f))
131 			return true;
132 	} else {
133 		if (!svm_range_schedule_evict_svm_bo(fence))
134 			return true;
135 	}
136 	return false;
137 }
138 
139 /**
140  * amdkfd_fence_release - callback that fence can be freed
141  *
142  * @f: dma_fence
143  *
144  * This function is called when the reference count becomes zero.
145  * Drops the mm_struct reference and RCU schedules freeing up the fence.
146  */
147 static void amdkfd_fence_release(struct dma_fence *f)
148 {
149 	struct amdgpu_amdkfd_fence *fence = to_amdgpu_amdkfd_fence(f);
150 
151 	/* Unconditionally signal the fence. The process is getting
152 	 * terminated.
153 	 */
154 	if (WARN_ON(!fence))
155 		return; /* Not an amdgpu_amdkfd_fence */
156 
157 	mmdrop(fence->mm);
158 	kfree_rcu(f, rcu);
159 }
160 
161 /**
162  * amdkfd_fence_check_mm - Check whether to prevent eviction of @f by @mm
163  *
164  * @f: [IN] fence
165  * @mm: [IN] mm that needs to be verified
166  *
167  * Check if @mm is same as that of the fence @f, if same return TRUE else
168  * return FALSE.
169  * For svm bo, which support vram overcommitment, always return FALSE.
170  */
171 bool amdkfd_fence_check_mm(struct dma_fence *f, struct mm_struct *mm)
172 {
173 	struct amdgpu_amdkfd_fence *fence = to_amdgpu_amdkfd_fence(f);
174 
175 	if (!fence)
176 		return false;
177 	else if (fence->mm == mm  && !fence->svm_bo)
178 		return true;
179 
180 	return false;
181 }
182 
183 static const struct dma_fence_ops amdkfd_fence_ops = {
184 	.get_driver_name = amdkfd_fence_get_driver_name,
185 	.get_timeline_name = amdkfd_fence_get_timeline_name,
186 	.enable_signaling = amdkfd_fence_enable_signaling,
187 	.release = amdkfd_fence_release,
188 };
189