reproduce (this is a W=1 build):
        # https://git.kernel.org/pub/scm/linux/kernel/git/kvms390/linux.git/commit/?id=412a531e0fe32aad575353cda4214518278508d1
        git remote add kvms390 https://git.kernel.org/pub/scm/linux/kernel/git/kvms390/linux.git
        git fetch --no-tags kvms390 sae
        git checkout 412a531e0fe32aad575353cda4214518278508d1

        # save the config file
        mkdir build_dir && cp config build_dir/.config
        make W=1 O=build_dir ARCH=x86_64 olddefconfig
        make W=1 O=build_dir ARCH=x86_64 SHELL=/bin/bash drivers/vfio/