[PATCH] drm/amdgpu: fix VM faults with per VM BOs

[Christian König]

There was a small window where the freshly allocated BO could have been
evicted without the VM noticing it.

Signed-off-by: Christian König <christian.koenig at amd.com>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c | 22 ++++++++++++++++++++--
 1 file changed, 20 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
index af7dceb7131e..e623109be202 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
@@ -1745,8 +1745,26 @@ struct amdgpu_bo_va *amdgpu_vm_bo_add(struct amdgpu_device *adev,
 	INIT_LIST_HEAD(&bo_va->valids);
 	INIT_LIST_HEAD(&bo_va->invalids);
 
-	if (bo)
-		list_add_tail(&bo_va->base.bo_list, &bo->va);
+	if (!bo)
+		return bo_va;
+
+	list_add_tail(&bo_va->base.bo_list, &bo->va);
+
+	if (bo->tbo.resv != vm->root.base.bo->tbo.resv)
+		return bo_va;
+
+	if (bo->preferred_domains &
+	    amdgpu_mem_type_to_domain(bo->tbo.mem.mem_type))
+		return bo_va;
+
+	/*
+	 * We checked all the prerequisites, but it looks like this per VM BO
+	 * is currently evicted. add the BO to the evicted list to make sure it
+	 * is validated on next VM use to avoid fault.
+	 * */
+	spin_lock(&vm->status_lock);
+	list_move_tail(&bo_va->base.vm_status, &vm->evicted);
+	spin_unlock(&vm->status_lock);
 
 	return bo_va;
 }
-- 
2.11.0