[PATCH v2 6/6] KVM: arm64: Let kvm_vcpu_read_pmcr() return an EL-dependent value for PMCR_EL0.N

[Marc Zyngier]

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.

Signed-off-by: Marc Zyngier <maz at kernel.org>
---
 arch/arm64/kvm/pmu-emul.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/kvm/pmu-emul.c b/arch/arm64/kvm/pmu-emul.c
index 01fda19b0c825..f9edd0a2427c2 100644
--- a/arch/arm64/kvm/pmu-emul.c
+++ b/arch/arm64/kvm/pmu-emul.c
@@ -1295,8 +1295,12 @@ 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.pmcr_n;
 
-	return u64_replace_bits(pmcr, vcpu->kvm->arch.pmcr_n, 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)
-- 
2.39.2