drm/amdgpu: reuse VMIDs already assigned to a process

If we don't need to flush we can easily use another VMID
already assigned to the process.

Signed-off-by: Christian König <christian.koenig@amd.com>
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Reviewed-by: Chunming Zhou <david1.zhou@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

1 files changed, 46 insertions, 31 deletions

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
index 252445f578f6..1425aab31233 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
@@ -166,48 +166,63 @@ int amdgpu_vm_grab_id(struct amdgpu_vm *vm, struct amdgpu_ring *ring,
 {
         uint64_t pd_addr = amdgpu_bo_gpu_offset(vm->page_directory);
         struct amdgpu_device *adev = ring->adev;
-        struct amdgpu_vm_id *id = vm->ids[ring->idx];
         struct fence *updates = sync->last_vm_update;
+        struct amdgpu_vm_id *id;
+        unsigned i = ring->idx;
         int r;
 
         mutex_lock(&adev->vm_manager.lock);
 
-        /* check if the id is still valid */
-        if (id) {
-                struct fence *flushed = id->flushed_updates;
-                long owner = atomic_long_read(&id->owner);
-                bool usable = pd_addr == id->pd_gpu_addr;
-
-                if (owner != (long)&vm->ids[ring->idx])
-                        usable = false;
-                else if (!flushed)
-                        usable = false;
-                else if (!updates)
-                        usable = true;
-                else
-                        usable = !fence_is_later(updates, flushed);
+        /* Check if we can use a VMID already assigned to this VM */
+        do {
+                struct fence *flushed;
 
-                if (usable) {
+                id = vm->ids[i++];
+                if (i == AMDGPU_MAX_RINGS)
+                        i = 0;
 
-                        r = amdgpu_sync_fence(ring->adev, sync, id->first);
-                        if (r)
-                                goto error;
+                /* Check all the prerequisites to using this VMID */
+                if (!id)
+                        continue;
+
+                if (atomic_long_read(&id->owner) != (long)vm)
+                        continue;
+
+                if (pd_addr != id->pd_gpu_addr)
+                        continue;
+
+                if (id != vm->ids[ring->idx] &&
+                    (!id->last_flush || !fence_is_signaled(id->last_flush)))
+                        continue;
+
+                flushed  = id->flushed_updates;
+                if (updates && (!flushed || fence_is_later(updates, flushed)))
+                        continue;
 
-                        r = amdgpu_sync_fence(ring->adev, &id->active, fence);
+                /* Good we can use this VMID */
+                if (id == vm->ids[ring->idx]) {
+                        r = amdgpu_sync_fence(ring->adev, sync,
+                                              id->first);
                         if (r)
                                 goto error;
+                }
+
+                /* And remember this submission as user of the VMID */
+                r = amdgpu_sync_fence(ring->adev, &id->active, fence);
+                if (r)
+                        goto error;
 
-                        list_move_tail(&id->list, &adev->vm_manager.ids_lru);
+                list_move_tail(&id->list, &adev->vm_manager.ids_lru);
+                vm->ids[ring->idx] = id;
 
-                        *vm_id = id - adev->vm_manager.ids;
-                        *vm_pd_addr = AMDGPU_VM_NO_FLUSH;
-                        trace_amdgpu_vm_grab_id(vm, ring->idx, *vm_id,
-                                                *vm_pd_addr);
+                *vm_id = id - adev->vm_manager.ids;
+                *vm_pd_addr = AMDGPU_VM_NO_FLUSH;
+                trace_amdgpu_vm_grab_id(vm, ring->idx, *vm_id, *vm_pd_addr);
 
-                        mutex_unlock(&adev->vm_manager.lock);
-                        return 0;
-                }
-        }
+                mutex_unlock(&adev->vm_manager.lock);
+                return 0;
+
+        } while (i != ring->idx);
 
         id = list_first_entry(&adev->vm_manager.ids_lru,
                               struct amdgpu_vm_id,
@@ -245,7 +260,7 @@ int amdgpu_vm_grab_id(struct amdgpu_vm *vm, struct amdgpu_ring *ring,
         id->pd_gpu_addr = pd_addr;
 
         list_move_tail(&id->list, &adev->vm_manager.ids_lru);
-        atomic_long_set(&id->owner, (long)id);
+        atomic_long_set(&id->owner, (long)vm);
         vm->ids[ring->idx] = id;
 
         *vm_id = id - adev->vm_manager.ids;
@@ -1464,7 +1479,7 @@ void amdgpu_vm_fini(struct amdgpu_device *adev, struct amdgpu_vm *vm)
                 if (!id)
                         continue;
 
-                atomic_long_cmpxchg(&id->owner, (long)&vm->ids[i], 0);
+                atomic_long_cmpxchg(&id->owner, (long)vm, 0);
         }
 }