reproduce (this is a W=1 build):
        # https://github.com/intel/tdx/commit/1fc7ddf713cc79be07e23bb18e52ba6ddb9a7f3a
        git remote add intel-tdx https://github.com/intel/tdx.git
        git fetch --no-tags intel-tdx guest-tdx-setup
        git checkout 1fc7ddf713cc79be07e23bb18e52ba6ddb9a7f3a
        # 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/