Hi Lan,

Thank you for the patch! Yet something to improve:

[auto build test ERROR on iommu/next]
[also build test ERROR on v5.0-rc4 next-20190201]
[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/lantianyu1986-gmail-com/x86-Hyper-V-IOMMU-Add-Hyper-V-IOMMU-driver-to-support-x2apic-mode/20190204-132009
base:   https://git.kernel.org/pub/scm/linux/kernel/git/joro/iommu.git next
config: x86_64-randconfig-x005-201905 (attached as .config)
compiler: gcc-8 (Debian 8.2.0-14) 8.2.0
reproduce:
        # save the attached .config to linux build tree
        make ARCH=x86_64 

All errors (new ones prefixed by >>):

   arch/x86//kernel/cpu/mshyperv.c: In function 'ms_hyperv_init_platform':
>> arch/x86//kernel/cpu/mshyperv.c:339:3: error: 'x2apic_phys' undeclared (first use in this function); did you mean 'x2apic_mode'?
      x2apic_phys = 1;
      ^~~~~~~~~~~
      x2apic_mode
   arch/x86//kernel/cpu/mshyperv.c:339:3: note: each undeclared identifier is reported only once for each function it appears in

vim +339 arch/x86//kernel/cpu/mshyperv.c

   331	
   332	/*
   333	 * Hyper-V doesn't provide irq remapping for IO-APIC. To enable x2apic,
   334	 * set x2apic destination mode to physcial mode when x2apic is available
   335	 * and Hyper-V IOMMU driver makes sure cpus assigned with IO-APIC irqs
   336	 * have 8-bit APIC id.
   337	 */
   338		if (IS_ENABLED(CONFIG_HYPERV_IOMMU) && x2apic_supported())
 > 339			x2apic_phys = 1;
   340	

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