reproduce (this is a W=1 build):
        # https://github.com/intel/tdx/commit/a47c5a9442130f45fc09c1d4ae0e4352054be636
        git remote add intel-tdx https://github.com/intel/tdx.git
        git fetch --no-tags intel-tdx kvm-upstream-next
        git checkout a47c5a9442130f45fc09c1d4ae0e4352054be636
        # 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/