tree:   https://github.com/atishp04/linux kvm_perf_rfc_buildtest
head:   ff2f56ec4ff4f67ae3da3936939b1dcf53099a6e
commit: 0775c1675beacd92eb1e9bf80363e0678aacb4d4 [21/24] RISC-V: KVM: Add SBI PMU extension support
config: riscv-defconfig
compiler: riscv64-linux-gcc (GCC) 12.1.0
reproduce (this is a W=1 build):
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # https://github.com/atishp04/linux/commit/0775c1675beacd92eb1e9bf80363e0678aacb4d4
        git remote add atishp04 https://github.com/atishp04/linux
        git fetch --no-tags atishp04 kvm_perf_rfc_buildtest
        git checkout 0775c1675beacd92eb1e9bf80363e0678aacb4d4
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.1.0 make.cross W=1 O=build_dir ARCH=riscv SHELL=/bin/bash arch/riscv/kvm/

If you fix the issue, kindly add following tag where applicable
Reported-by: kernel test robot <lkp@intel.com>

All warnings (new ones prefixed by >>):

>> arch/riscv/kvm/vcpu_sbi_pmu.c:66:15: warning: no previous prototype for 'kvm_sbi_ext_pmu_probe' [-Wmissing-prototypes]
      66 | unsigned long kvm_sbi_ext_pmu_probe(unsigned long extid)
         |               ^~~~~~~~~~~~~~~~~~~~~


vim +/kvm_sbi_ext_pmu_probe +66 arch/riscv/kvm/vcpu_sbi_pmu.c

    65	
  > 66	unsigned long kvm_sbi_ext_pmu_probe(unsigned long extid)
    67	{
    68		/*
    69		 * PMU Extension is only available to guests if privilege mode filtering
    70		 * is available. Otherwise, guest will always count events while the
    71		 * execution is in hypervisor mode.
    72		 */
    73		return riscv_isa_extension_available(NULL, SSCOFPMF);
    74	}
    75	

-- 
0-DAY CI Kernel Test Service
https://01.org/lkp