Re: [PATCH v4 1/5] perf/x86/core: Remove unnecessary stubs provided for KVM-only helpers

[kernel test robot <lkp@intel.com>]

Hi Sean,

I love your patch! Perhaps something to improve:

[auto build test WARNING on 372d07084593dc7a399bf9bee815711b1fb1bcf2]

url:    https://github.com/intel-lab-lkp/linux/commits/Sean-Christopherson/KVM-x86-Intel-LBR-related-perf-cleanups/20220902-013352
base:   372d07084593dc7a399bf9bee815711b1fb1bcf2
config: i386-randconfig-m021 (https://download.01.org/0day-ci/archive/20220902/202209021042.UcDPO3lL-lkp@intel.com/config)
compiler: gcc-11 (Debian 11.3.0-5) 11.3.0
reproduce (this is a W=1 build):
        # https://github.com/intel-lab-lkp/linux/commit/b1f1d2f5eb44253f5d059757c03e7fd413b2e306
        git remote add linux-review https://github.com/intel-lab-lkp/linux
        git fetch --no-tags linux-review Sean-Christopherson/KVM-x86-Intel-LBR-related-perf-cleanups/20220902-013352
        git checkout b1f1d2f5eb44253f5d059757c03e7fd413b2e306
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        make W=1 O=build_dir ARCH=i386 SHELL=/bin/bash arch/x86/events/

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/x86/events/core.c:696:31: warning: no previous prototype for 'perf_guest_get_msrs' [-Wmissing-prototypes]
     696 | struct perf_guest_switch_msr *perf_guest_get_msrs(int *nr, void *data)
         |                               ^~~~~~~~~~~~~~~~~~~


vim +/perf_guest_get_msrs +696 arch/x86/events/core.c

f87ad35d37fa54 arch/x86/kernel/cpu/perf_counter.c Jaswinder Singh Rajput 2009-02-27  695  
39a4d779546a99 arch/x86/events/core.c             Like Xu                2022-04-11 @696  struct perf_guest_switch_msr *perf_guest_get_msrs(int *nr, void *data)
abd562df94d19d arch/x86/events/core.c             Like Xu                2021-01-25  697  {
39a4d779546a99 arch/x86/events/core.c             Like Xu                2022-04-11  698  	return static_call(x86_pmu_guest_get_msrs)(nr, data);
abd562df94d19d arch/x86/events/core.c             Like Xu                2021-01-25  699  }
abd562df94d19d arch/x86/events/core.c             Like Xu                2021-01-25  700  EXPORT_SYMBOL_GPL(perf_guest_get_msrs);
abd562df94d19d arch/x86/events/core.c             Like Xu                2021-01-25  701  

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