reproduce (this is a W=1 build):
        git clone https://github.com/intel/lkp-tests.git ~/lkp-tests
        # https://github.com/kvm-x86/linux/commit/00c8216399da1e7df22637dfb4d6d451adc5f24e
        git remote add kvm-x86 https://github.com/kvm-x86/linux
        git fetch --no-tags kvm-x86 mmio
        git checkout 00c8216399da1e7df22637dfb4d6d451adc5f24e
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang-20 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=x86_64 olddefconfig
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang-20 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=x86_64 SHELL=/bin/bash arch/x86/kvm/