reproduce (this is a W=1 build):
        # https://git.kernel.org/pub/scm/linux/kernel/git/kvms390/linux.git/commit/?id=134336e0cba8dd18185738333bc26c1b0b020b6d
        git remote add kvms390 https://git.kernel.org/pub/scm/linux/kernel/git/kvms390/linux.git
        git fetch --no-tags kvms390 sae
        git checkout 134336e0cba8dd18185738333bc26c1b0b020b6d

        # 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 arch/x86/kvm/