reproduce:
        git clone https://github.com/intel/lkp-tests.git ~/lkp-tests
        # apt-get install sparse
        # sparse version: v0.6.4-66-g0196afe1
        # https://github.com/jgunthorpe/linux/commit/b263d240f7a6cb7d4e44ebf6e80b55003ef8c1e7
        git remote add jgunthorpe https://github.com/jgunthorpe/linux
        git fetch --no-tags jgunthorpe smmuv3_nesting
        git checkout b263d240f7a6cb7d4e44ebf6e80b55003ef8c1e7
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        ~/lkp-tests/kbuild/make.cross C=1 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__ -fmax-errors=unlimited -fmax-warnings=unlimited' O=build_dir ARCH=arm64 olddefconfig
        ~/lkp-tests/kbuild/make.cross C=1 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__ -fmax-errors=unlimited -fmax-warnings=unlimited' O=build_dir ARCH=arm64 SHELL=/bin/bash drivers/iommu/arm/arm-smmu-v3/