reproduce (this is a W=1 build):
        git checkout 6b36119b94d0b2bb8cea9d512017efafd461d6ac
        b4 shazam https://lore.kernel.org/r/20251015-b4-l1tf-percpu-v2-1-6d7a8d3d40e9@google.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 arch/x86/kvm/