[PATCH v4 07/23] iommufd/selftest: Support user_data in mock_viommu_alloc

[Tian, Kevin]

> From: Nicolin Chen <nicolinc at nvidia.com>
> Sent: Friday, May 9, 2025 11:02 AM
> 
> Add a simple user_data for an input-to-output loopback test.
> 
> Reviewed-by: Pranjal Shrivastava <praan at google.com>
> Signed-off-by: Nicolin Chen <nicolinc at nvidia.com>

Reviewed-by: Kevin Tian <kevin.tian at intel.com>