KVM: arm64: Let kvm_vcpu_read_pmcr() return an EL-dependent value for PMCR_EL0.N

When EL2 is present, PMCR_EL0.N is the effective value of MDCR_EL2.HPMN
when accessed from EL1 or EL0.

Make sure we honor this requirement.

Reviewed-by: Oliver Upton <oliver.upton@linux.dev>
Signed-off-by: Marc Zyngier <maz@kernel.org>

diff --git a/arch/arm64/kvm/pmu-emul.c b/arch/arm64/kvm/pmu-emul.c
index efc59f343acc84bfee6b03565016b3ffb0aa75d6..25c29107f13fda842e85d8accab77557fd7b1b48 100644 (file)
--- a/arch/arm64/kvm/pmu-emul.c
+++ b/arch/arm64/kvm/pmu-emul.c
@@ -1300,8 +1300,12 @@ u8 kvm_arm_pmu_get_pmuver_limit(void)
 u64 kvm_vcpu_read_pmcr(struct kvm_vcpu *vcpu)
 {
        u64 pmcr = __vcpu_sys_reg(vcpu, PMCR_EL0);
+       u64 n = vcpu->kvm->arch.nr_pmu_counters;
 
-       return u64_replace_bits(pmcr, vcpu->kvm->arch.nr_pmu_counters, ARMV8_PMU_PMCR_N);
+       if (vcpu_has_nv(vcpu) && !vcpu_is_el2(vcpu))
+               n = FIELD_GET(MDCR_EL2_HPMN, __vcpu_sys_reg(vcpu, MDCR_EL2));
+
+       return u64_replace_bits(pmcr, n, ARMV8_PMU_PMCR_N);
 }
 
 void kvm_pmu_nested_transition(struct kvm_vcpu *vcpu)