drm/amdgpu: adapt vm size for multi vmpt

Signed-off-by: NChunming Zhou <David1.Zhou@amd.com>
Reviewed-by: NChristian König <christian.koenig@amd.com>
Reviewed-by: NJunwei Zhang <Jerry.Zhang@amd.com>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/amdgpu/gmc_v9_0.c

@@ -500,6 +500,12 @@ static int gmc_v9_0_vm_init(struct amdgpu_device *adev)
 	 * amdkfd will use VMIDs 8-15
 	 */
 	adev->vm_manager.num_ids = AMDGPU_NUM_OF_VMIDS;
+	/* Because of four level VMPTs, vm size at least is 256GB.
+	256TB is OK as well */
+	if (amdgpu_vm_size < 256) {
+		DRM_WARN("vm size at least is 256GB!\n");
+		amdgpu_vm_size = 256;
+	}
 	adev->vm_manager.num_level = 1;
 	amdgpu_vm_manager_init(adev);