reproduce (this is a W=1 build):
        # https://github.com/intel/tdx/commit/f42730edbdb812e13ddfbebed4c49a6f30795433
        git remote add intel-tdx https://github.com/intel/tdx.git
        git fetch --no-tags intel-tdx kvm-upstream
        git checkout f42730edbdb812e13ddfbebed4c49a6f30795433
        # 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