drm/amdgpu: use CPU for page table update if SDMA is unavailable

avoid using SDMA if it is unavailable.
Signed-off-by: Yifan Zhang <yifan1.zhang@amd.com>
Reviewed-by: Tim Huang <tim.huang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

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

@@ -2397,6 +2397,7 @@ void amdgpu_vm_set_task_info(struct amdgpu_vm *vm)
 int amdgpu_vm_init(struct amdgpu_device *adev, struct amdgpu_vm *vm,
 		   int32_t xcp_id)
 {
+	struct amdgpu_ip_block *ip_block;
 	struct amdgpu_bo *root_bo;
 	struct amdgpu_bo_vm *root;
 	int r, i;
@@ -2426,6 +2427,11 @@ int amdgpu_vm_init(struct amdgpu_device *adev, struct amdgpu_vm *vm,
 	vm->use_cpu_for_update = !!(adev->vm_manager.vm_update_mode &
 				    AMDGPU_VM_USE_CPU_FOR_GFX);
 
+	/* use CPU for page table update if SDMA is unavailable */
+	ip_block = amdgpu_device_ip_get_ip_block(adev, AMD_IP_BLOCK_TYPE_SDMA);
+	if (!ip_block || ip_block->status.valid == false)
+		vm->use_cpu_for_update = true;
+
 	DRM_DEBUG_DRIVER("VM update mode is %s\n",
 			 vm->use_cpu_for_update ? "CPU" : "SDMA");
 	WARN_ONCE((vm->use_cpu_for_update &&