Re: [PATCH hyperv-next v4 04/16] arch/x86: mshyperv: Trap on access for some synthetic MSRs

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

Hi Roman,

kernel test robot noticed the following build errors:

[auto build test ERROR on d9016a249be5316ec2476f9947356711e70a16ec]

url:    https://github.com/intel-lab-lkp/linux/commits/Roman-Kisel/Documentation-hyperv-Confidential-VMBus/20250715-062125
base:   d9016a249be5316ec2476f9947356711e70a16ec
patch link:    https://lore.kernel.org/r/20250714221545.5615-5-romank%40linux.microsoft.com
patch subject: [PATCH hyperv-next v4 04/16] arch/x86: mshyperv: Trap on access for some synthetic MSRs
config: x86_64-buildonly-randconfig-002-20250715 (https://download.01.org/0day-ci/archive/20250716/202507160105.yQ34bnKl-lkp@intel.com/config)
compiler: gcc-12 (Debian 12.2.0-14+deb12u1) 12.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250716/202507160105.yQ34bnKl-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202507160105.yQ34bnKl-lkp@intel.com/

All errors (new ones prefixed by >>):

   ld: vmlinux.o: in function `hv_set_non_nested_msr':
>> arch/x86/kernel/cpu/mshyperv.c:91: undefined reference to `vmbus_is_confidential'


vim +91 arch/x86/kernel/cpu/mshyperv.c

    79	
    80	void hv_set_non_nested_msr(unsigned int reg, u64 value)
    81	{
    82		if (hv_is_synic_msr(reg) && ms_hyperv.paravisor_present) {
    83			/* The hypervisor will get the intercept. */
    84			hv_ivm_msr_write(reg, value);
    85	
    86			if (hv_is_sint_msr(reg)) {
    87				/*
    88				 * Write proxy bit in the case of non-confidential VMBus.
    89				 * Using wrmsrq instruction so the following goes to the paravisor.
    90				 */
  > 91				u32 proxy = vmbus_is_confidential() ? 0 : 1;
    92	
    93				value |= (proxy << 20);
    94				native_wrmsrq(reg, value);
    95			}
    96		} else {
    97			native_wrmsrq(reg, value);
    98		}
    99	}
   100	EXPORT_SYMBOL_GPL(hv_set_non_nested_msr);
   101	

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