reproduce (this is a W=1 build):
        # https://git.kernel.org/pub/scm/linux/kernel/git/kvms390/linux.git/commit/?id=4095afb932d1a98a6fcb3f4f490964949d0de338
        git remote add kvms390 https://git.kernel.org/pub/scm/linux/kernel/git/kvms390/linux.git
        git fetch --no-tags kvms390 sae
        git checkout 4095afb932d1a98a6fcb3f4f490964949d0de338

        git clone https://github.com/intel/lkp-tests.git ~/lkp-tests

        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-15.2.0 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=s390 olddefconfig
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-15.2.0 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=s390 SHELL=/bin/bash arch/s390/kvm/arm64/