reproduce (this is a W=1 build):
        git clone https://github.com/intel/lkp-tests.git ~/lkp-tests
        # https://github.com/kvm-riscv/linux/commit/9f585bd8f40b05487a17efae772ff0bd172060d7
        git remote add kvm-riscv https://github.com/kvm-riscv/linux.git
        git fetch --no-tags kvm-riscv riscv_kvm_queue
        git checkout 9f585bd8f40b05487a17efae772ff0bd172060d7
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-8.5.0 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=riscv olddefconfig
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-8.5.0 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=riscv SHELL=/bin/bash arch/riscv/kvm/