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 32 static const struct dma_fence_ops amdkfd_fence_ops; 33 static atomic_t fence_seq = ATOMIC_INIT(0); 34 35 /* Eviction Fence 36 * Fence helper functions to deal with KFD memory eviction. 37 * Big Idea - Since KFD submissions are done by user queues, a BO cannot be 38 * evicted unless all the user queues for that process are evicted. 39 * 40 * All the BOs in a process share an eviction fence. When process X wants 41 * to map VRAM memory but TTM can't find enough space, TTM will attempt to 42 * evict BOs from its LRU list. TTM checks if the BO is valuable to evict 43 * by calling ttm_bo_driver->eviction_valuable(). 44 * 45 * ttm_bo_driver->eviction_valuable() - will return false if the BO belongs 46 * to process X. Otherwise, it will return true to indicate BO can be 47 * evicted by TTM. 48 * 49 * If ttm_bo_driver->eviction_valuable returns true, then TTM will continue 50 * the evcition process for that BO by calling ttm_bo_evict --> amdgpu_bo_move 51 * --> amdgpu_copy_buffer(). This sets up job in GPU scheduler. 52 * 53 * GPU Scheduler (amd_sched_main) - sets up a cb (fence_add_callback) to 54 * nofity when the BO is free to move. fence_add_callback --> enable_signaling 55 * --> amdgpu_amdkfd_fence.enable_signaling 56 * 57 * amdgpu_amdkfd_fence.enable_signaling - Start a work item that will quiesce 58 * user queues and signal fence. The work item will also start another delayed 59 * work item to restore BOs 60 */ 61 62 struct amdgpu_amdkfd_fence *amdgpu_amdkfd_fence_create(u64 context, 63 struct mm_struct *mm) 64 { 65 struct amdgpu_amdkfd_fence *fence; 66 67 fence = kzalloc(sizeof(*fence), GFP_KERNEL); 68 if (fence == NULL) 69 return NULL; 70 71 /* This reference gets released in amdkfd_fence_release */ 72 mmgrab(mm); 73 fence->mm = mm; 74 get_task_comm(fence->timeline_name, current); 75 spin_lock_init(&fence->lock); 76 77 dma_fence_init(&fence->base, &amdkfd_fence_ops, &fence->lock, 78 context, atomic_inc_return(&fence_seq)); 79 80 return fence; 81 } 82 83 struct amdgpu_amdkfd_fence *to_amdgpu_amdkfd_fence(struct dma_fence *f) 84 { 85 struct amdgpu_amdkfd_fence *fence; 86 87 if (!f) 88 return NULL; 89 90 fence = container_of(f, struct amdgpu_amdkfd_fence, base); 91 if (fence && f->ops == &amdkfd_fence_ops) 92 return fence; 93 94 return NULL; 95 } 96 97 static const char *amdkfd_fence_get_driver_name(struct dma_fence *f) 98 { 99 return "amdgpu_amdkfd_fence"; 100 } 101 102 static const char *amdkfd_fence_get_timeline_name(struct dma_fence *f) 103 { 104 struct amdgpu_amdkfd_fence *fence = to_amdgpu_amdkfd_fence(f); 105 106 return fence->timeline_name; 107 } 108 109 /** 110 * amdkfd_fence_enable_signaling - This gets called when TTM wants to evict 111 * a KFD BO and schedules a job to move the BO. 112 * If fence is already signaled return true. 113 * If fence is not signaled schedule a evict KFD process work item. 114 */ 115 static bool amdkfd_fence_enable_signaling(struct dma_fence *f) 116 { 117 struct amdgpu_amdkfd_fence *fence = to_amdgpu_amdkfd_fence(f); 118 119 if (!fence) 120 return false; 121 122 if (dma_fence_is_signaled(f)) 123 return true; 124 125 if (!kgd2kfd->schedule_evict_and_restore_process(fence->mm, f)) 126 return true; 127 128 return false; 129 } 130 131 /** 132 * amdkfd_fence_release - callback that fence can be freed 133 * 134 * @fence: fence 135 * 136 * This function is called when the reference count becomes zero. 137 * Drops the mm_struct reference and RCU schedules freeing up the fence. 138 */ 139 static void amdkfd_fence_release(struct dma_fence *f) 140 { 141 struct amdgpu_amdkfd_fence *fence = to_amdgpu_amdkfd_fence(f); 142 143 /* Unconditionally signal the fence. The process is getting 144 * terminated. 145 */ 146 if (WARN_ON(!fence)) 147 return; /* Not an amdgpu_amdkfd_fence */ 148 149 mmdrop(fence->mm); 150 kfree_rcu(f, rcu); 151 } 152 153 /** 154 * amdkfd_fence_check_mm - Check if @mm is same as that of the fence @f 155 * if same return TRUE else return FALSE. 156 * 157 * @f: [IN] fence 158 * @mm: [IN] mm that needs to be verified 159 */ 160 bool amdkfd_fence_check_mm(struct dma_fence *f, struct mm_struct *mm) 161 { 162 struct amdgpu_amdkfd_fence *fence = to_amdgpu_amdkfd_fence(f); 163 164 if (!fence) 165 return false; 166 else if (fence->mm == mm) 167 return true; 168 169 return false; 170 } 171 172 static const struct dma_fence_ops amdkfd_fence_ops = { 173 .get_driver_name = amdkfd_fence_get_driver_name, 174 .get_timeline_name = amdkfd_fence_get_timeline_name, 175 .enable_signaling = amdkfd_fence_enable_signaling, 176 .signaled = NULL, 177 .wait = dma_fence_default_wait, 178 .release = amdkfd_fence_release, 179 }; 180