Hi Zengruan,

Thank you for the patch! Yet something to improve:

[auto build test ERROR on kvmarm/next]
[also build test ERROR on kvm/linux-next linus/master v5.5-rc3 next-20191220]
[cannot apply to arm64/for-next/core]
[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/Zengruan-Ye/KVM-arm64-VCPU-preempted-check-support/20191227-000637
base:   https://git.kernel.org/pub/scm/linux/kernel/git/kvmarm/kvmarm.git next
config: arm64-alldefconfig (attached as .config)
compiler: aarch64-linux-gcc (GCC) 7.5.0
reproduce:
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # save the attached .config to linux build tree
        GCC_VERSION=7.5.0 make.cross ARCH=arm64 

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

All errors (new ones prefixed by >>):

   In file included from include/linux/spinlock.h:89:0,
                    from include/linux/radix-tree.h:16,
                    from include/linux/idr.h:15,
                    from include/linux/kernfs.h:13,
                    from include/linux/sysfs.h:16,
                    from include/linux/kobject.h:20,
                    from include/linux/of.h:17,
                    from include/linux/irqdomain.h:35,
                    from include/linux/acpi.h:13,
                    from include/acpi/apei.h:9,
                    from include/acpi/ghes.h:5,
                    from include/linux/arm_sdei.h:8,
                    from arch/arm64/kernel/asm-offsets.c:10:
   arch/arm64/include/asm/spinlock.h: In function 'vcpu_is_preempted':
>> arch/arm64/include/asm/spinlock.h:18:9: error: implicit declaration of function 'pv_vcpu_is_preempted'; did you mean 'vcpu_is_preempted'? [-Werror=implicit-function-declaration]
     return pv_vcpu_is_preempted(cpu);
            ^~~~~~~~~~~~~~~~~~~~
            vcpu_is_preempted
   cc1: some warnings being treated as errors
   make[2]: *** [arch/arm64/kernel/asm-offsets.s] Error 1
   make[2]: Target '__build' not remade because of errors.
   make[1]: *** [prepare0] Error 2
   make[1]: Target 'prepare' not remade because of errors.
   make: *** [sub-make] Error 2
   27 real  5 user  7 sys  48.63% cpu 	make prepare

vim +18 arch/arm64/include/asm/spinlock.h

    14	
    15	#define vcpu_is_preempted vcpu_is_preempted
    16	static inline bool vcpu_is_preempted(long cpu)
    17	{
  > 18		return pv_vcpu_is_preempted(cpu);
    19	}
    20	

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0-DAY kernel test infrastructure                 Open Source Technology Center
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