Hi Yi,

Thank you for the patch! Yet something to improve:

[auto build test ERROR on tip/x86/core]
[also build test ERROR on v4.19-rc4 next-20180921]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]

url:    https://github.com/0day-ci/linux/commits/Yi-Sun/Enable-PV-qspinlock-for-Hyper-V/20180921-234519
config: x86_64-randconfig-s1-09212334 (attached as .config)
compiler: gcc-6 (Debian 6.4.0-9) 6.4.0 20171026
reproduce:
        # save the attached .config to linux build tree
        make ARCH=x86_64 

All errors (new ones prefixed by >>):

   arch/x86/kernel/cpu/mshyperv.o: In function `hv_init_spinlocks':
>> arch/x86/include/asm/mshyperv.h:373: multiple definition of `hv_init_spinlocks'
   arch/x86/entry/vdso/vma.o:arch/x86/include/asm/mshyperv.h:373: first defined here

vim +373 arch/x86/include/asm/mshyperv.h

   359	
   360	#else /* CONFIG_HYPERV */
   361	static inline void hyperv_init(void) {}
   362	static inline bool hv_is_hyperv_initialized(void) { return false; }
   363	static inline void hyperv_cleanup(void) {}
   364	static inline void hyperv_setup_mmu_ops(void) {}
   365	static inline void set_hv_tscchange_cb(void (*cb)(void)) {}
   366	static inline void clear_hv_tscchange_cb(void) {}
   367	static inline void hyperv_stop_tsc_emulation(void) {};
   368	static inline struct hv_vp_assist_page *hv_get_vp_assist_page(unsigned int cpu)
   369	{
   370		return NULL;
   371	}
   372	static inline int hyperv_flush_guest_mapping(u64 as) { return -1; }
 > 373	void __init hv_init_spinlocks(void) {}
   374	#endif /* CONFIG_HYPERV */
   375	

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