Hi Roman,

Thank you for the patch! Yet something to improve:

[auto build test ERROR on tip/x86/core]
[cannot apply to v5.4-rc1 next-20190930]
[if your patch is applied to the wrong git tree, please drop us a note to help
improve the system. BTW, we also suggest to use '--base' option to specify the
base tree in git format-patch, please see https://stackoverflow.com/a/37406982]

url:    https://github.com/0day-ci/linux/commits/Roman-Kagan/x86-hyperv-make-vapic-support-x2apic-mode/20191001-044238
config: x86_64-randconfig-s0-201939 (attached as .config)
compiler: gcc-5 (Ubuntu 5.5.0-12ubuntu1) 5.5.0 20171010
reproduce:
        # save the attached .config to linux build tree
        make ARCH=x86_64 

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

All errors (new ones prefixed by >>):

   arch/x86//hyperv/hv_apic.c: In function 'hv_x2apic_read':
>> arch/x86//hyperv/hv_apic.c:91:10: error: implicit declaration of function 'native_apic_msr_read' [-Werror=implicit-function-declaration]
      return native_apic_msr_read(reg);
             ^
   arch/x86//hyperv/hv_apic.c: In function 'hv_x2apic_write':
>> arch/x86//hyperv/hv_apic.c:119:3: error: implicit declaration of function 'native_apic_msr_write' [-Werror=implicit-function-declaration]
      native_apic_msr_write(reg, val);
      ^
   cc1: some warnings being treated as errors

vim +/native_apic_msr_read +91 arch/x86//hyperv/hv_apic.c

    77	
    78	static u32 hv_x2apic_read(u32 reg)
    79	{
    80		u32 reg_val, hi;
    81	
    82		switch (reg) {
    83		case APIC_EOI:
    84			rdmsr(HV_X64_MSR_EOI, reg_val, hi);
    85			return reg_val;
    86		case APIC_TASKPRI:
    87			rdmsr(HV_X64_MSR_TPR, reg_val, hi);
    88			return reg_val;
    89	
    90		default:
  > 91			return native_apic_msr_read(reg);
    92		}
    93	}
    94	
    95	static void hv_apic_write(u32 reg, u32 val)
    96	{
    97		switch (reg) {
    98		case APIC_EOI:
    99			wrmsr(HV_X64_MSR_EOI, val, 0);
   100			break;
   101		case APIC_TASKPRI:
   102			wrmsr(HV_X64_MSR_TPR, val, 0);
   103			break;
   104		default:
   105			native_apic_mem_write(reg, val);
   106		}
   107	}
   108	
   109	static void hv_x2apic_write(u32 reg, u32 val)
   110	{
   111		switch (reg) {
   112		case APIC_EOI:
   113			wrmsr(HV_X64_MSR_EOI, val, 0);
   114			break;
   115		case APIC_TASKPRI:
   116			wrmsr(HV_X64_MSR_TPR, val, 0);
   117			break;
   118		default:
 > 119			native_apic_msr_write(reg, val);
   120		}
   121	}
   122	

---
0-DAY kernel test infrastructure                Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all                   Intel Corporation