reproduce (this is a W=1 build):
        git remote add shuah-kselftest https://git.kernel.org/pub/scm/linux/kernel/git/shuah/linux-kselftest.git
        git fetch shuah-kselftest next
        git checkout shuah-kselftest/next
        b4 shazam https://lore.kernel.org/r/6c36de14b00a3f06df3a602f18baf6b51fde429f.1760487869.git.nicolinc@nvidia.com
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        make W=1 O=build_dir ARCH=i386 olddefconfig
        make W=1 O=build_dir ARCH=i386 SHELL=/bin/bash drivers/iommu/iommufd/