drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_fence.c

   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         .release = amdkfd_fence_release,
 177 };