drm/amdgpu: check flush fence context instead of same ring v2

Otherwise we can run into the following situation:

1. Process A grabs ID 1 for ring 0.
2. Process B grabs ID 1 for ring 0.
3. Process A grabs ID 1 for ring 1.
4. Process A tries to reuse ID1 for ring 0 but things he doesn't need to flush.

v2: check the context of the flush fence instead of messing with the owner field.

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

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

@@ -195,6 +195,7 @@ int amdgpu_vm_grab_id(struct amdgpu_vm *vm, struct amdgpu_ring *ring,
 		      struct amdgpu_job *job)
 {
 	struct amdgpu_device *adev = ring->adev;
+	uint64_t fence_context = adev->fence_context + ring->idx;
 	struct fence *updates = sync->last_vm_update;
 	struct amdgpu_vm_id *id, *idle;
 	struct fence **fences;
@@ -254,7 +255,6 @@ int amdgpu_vm_grab_id(struct amdgpu_vm *vm, struct amdgpu_ring *ring,
 	i = ring->idx;
 	do {
 		struct fence *flushed;
-		bool same_ring = ring->idx == i;
 
 		id = vm->ids[i++];
 		if (i == AMDGPU_MAX_RINGS)
@@ -272,8 +272,11 @@ int amdgpu_vm_grab_id(struct amdgpu_vm *vm, struct amdgpu_ring *ring,
 		if (job->vm_pd_addr != id->pd_gpu_addr)
 			continue;
 
-		if (!same_ring &&
-		    (!id->last_flush || !fence_is_signaled(id->last_flush)))
+		if (!id->last_flush)
+			continue;
+
+		if (id->last_flush->context != fence_context &&
+		    !fence_is_signaled(id->last_flush))
 			continue;
 
 		flushed  = id->flushed_updates;