Re: [PATCH v2 17/23] KVM: arm64: Account for partitioning in PMCR_EL0 access

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

Hi Colton,

kernel test robot noticed the following build errors:

[auto build test ERROR on 79150772457f4d45e38b842d786240c36bb1f97f]

url:    https://github.com/intel-lab-lkp/linux/commits/Colton-Lewis/arm64-cpufeature-Add-cpucap-for-HPMN0/20250621-102220
base:   79150772457f4d45e38b842d786240c36bb1f97f
patch link:    https://lore.kernel.org/r/20250620221326.1261128-19-coltonlewis%40google.com
patch subject: [PATCH v2 17/23] KVM: arm64: Account for partitioning in PMCR_EL0 access
config: arm64-randconfig-r073-20250622 (https://download.01.org/0day-ci/archive/20250622/202506221711.tFNGpzj4-lkp@intel.com/config)
compiler: aarch64-linux-gcc (GCC) 8.5.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250622/202506221711.tFNGpzj4-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/202506221711.tFNGpzj4-lkp@intel.com/

All errors (new ones prefixed by >>):

   In file included from arch/arm64/include/asm/kvm_host.h:32,
                    from include/linux/kvm_host.h:45,
                    from arch/arm64/kvm/sys_regs.c:16:
   arch/arm64/include/asm/kvm_pmu.h:236:50: warning: 'struct arm_pmu' declared inside parameter list will not be visible outside of this definition or declaration
    static inline bool kvm_pmu_is_partitioned(struct arm_pmu *pmu)
                                                     ^~~~~~~
   arch/arm64/include/asm/kvm_pmu.h:241:52: warning: 'struct arm_pmu' declared inside parameter list will not be visible outside of this definition or declaration
    static inline u64 kvm_pmu_host_counter_mask(struct arm_pmu *pmu)
                                                       ^~~~~~~
   arch/arm64/include/asm/kvm_pmu.h:246:53: warning: 'struct arm_pmu' declared inside parameter list will not be visible outside of this definition or declaration
    static inline u64 kvm_pmu_guest_counter_mask(struct arm_pmu *pmu)
                                                        ^~~~~~~
   arch/arm64/kvm/sys_regs.c:856:6: warning: no previous prototype for 'pmu_access_el0_disabled' [-Wmissing-prototypes]
    bool pmu_access_el0_disabled(struct kvm_vcpu *vcpu)
         ^~~~~~~~~~~~~~~~~~~~~~~
   arch/arm64/kvm/sys_regs.c: In function 'access_pmu_evtyper':
   arch/arm64/kvm/sys_regs.c:1076:7: error: implicit declaration of function 'kvm_vcpu_pmu_is_partitioned'; did you mean 'kvm_pmu_is_partitioned'? [-Werror=implicit-function-declaration]
      if (kvm_vcpu_pmu_is_partitioned(vcpu))
          ^~~~~~~~~~~~~~~~~~~~~~~~~~~
          kvm_pmu_is_partitioned
   arch/arm64/kvm/sys_regs.c: In function 'set_pmcr':
>> arch/arm64/kvm/sys_regs.c:1271:33: error: dereferencing pointer to incomplete type 'struct arm_pmu'
          new_n <= kvm->arch.arm_pmu->hpmn_max))
                                    ^~
   cc1: some warnings being treated as errors


vim +1271 arch/arm64/kvm/sys_regs.c

  1253	
  1254	static int set_pmcr(struct kvm_vcpu *vcpu, const struct sys_reg_desc *r,
  1255			    u64 val)
  1256	{
  1257		u8 new_n = FIELD_GET(ARMV8_PMU_PMCR_N, val);
  1258		struct kvm *kvm = vcpu->kvm;
  1259	
  1260		mutex_lock(&kvm->arch.config_lock);
  1261	
  1262		/*
  1263		 * The vCPU can't have more counters than the PMU hardware
  1264		 * implements. Ignore this error to maintain compatibility
  1265		 * with the existing KVM behavior.
  1266		 */
  1267		if (!kvm_vm_has_ran_once(kvm) &&
  1268		    !vcpu_has_nv(vcpu)	      &&
  1269		    new_n <= kvm_arm_pmu_get_max_counters(kvm) &&
  1270		    (!kvm_vcpu_pmu_is_partitioned(vcpu) ||
> 1271		     new_n <= kvm->arch.arm_pmu->hpmn_max))
  1272			kvm->arch.nr_pmu_counters = new_n;
  1273	
  1274		mutex_unlock(&kvm->arch.config_lock);
  1275	
  1276		/*
  1277		 * Ignore writes to RES0 bits, read only bits that are cleared on
  1278		 * vCPU reset, and writable bits that KVM doesn't support yet.
  1279		 * (i.e. only PMCR.N and bits [7:0] are mutable from userspace)
  1280		 * The LP bit is RES0 when FEAT_PMUv3p5 is not supported on the vCPU.
  1281		 * But, we leave the bit as it is here, as the vCPU's PMUver might
  1282		 * be changed later (NOTE: the bit will be cleared on first vCPU run
  1283		 * if necessary).
  1284		 */
  1285		val &= ARMV8_PMU_PMCR_MASK;
  1286	
  1287		/* The LC bit is RES1 when AArch32 is not supported */
  1288		if (!kvm_supports_32bit_el0())
  1289			val |= ARMV8_PMU_PMCR_LC;
  1290	
  1291		__vcpu_assign_sys_reg(vcpu, r->reg, val);
  1292		kvm_make_request(KVM_REQ_RELOAD_PMU, vcpu);
  1293	
  1294		return 0;
  1295	}
  1296	

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