[PATCH 3/9] KVM: arm64: PMU: Only narrow counters that are not 64bit wide

[Marc Zyngier]

The current PMU emulation sometimes narrows counters to 32bit
if the counter isn't the cycle counter. As this is going to
change with PMUv3p5 where the counters are all 64bit, only
perform the narrowing on 32bit counters.

Signed-off-by: Marc Zyngier <maz at kernel.org>
---
 arch/arm64/kvm/pmu-emul.c | 17 +++++++++--------
 1 file changed, 9 insertions(+), 8 deletions(-)

diff --git a/arch/arm64/kvm/pmu-emul.c b/arch/arm64/kvm/pmu-emul.c
index 9040d3c80096..0ab6f59f433c 100644
--- a/arch/arm64/kvm/pmu-emul.c
+++ b/arch/arm64/kvm/pmu-emul.c
@@ -149,22 +149,22 @@ static void kvm_pmu_release_perf_event(struct kvm_pmc *pmc)
  */
 static void kvm_pmu_stop_counter(struct kvm_vcpu *vcpu, struct kvm_pmc *pmc)
 {
-	u64 counter, reg, val;
+	u64 counter, reg;
 
 	if (!pmc->perf_event)
 		return;
 
 	counter = kvm_pmu_get_counter_value(vcpu, pmc->idx);
 
-	if (pmc->idx == ARMV8_PMU_CYCLE_IDX) {
+	if (pmc->idx == ARMV8_PMU_CYCLE_IDX)
 		reg = PMCCNTR_EL0;
-		val = counter;
-	} else {
+	else
 		reg = PMEVCNTR0_EL0 + pmc->idx;
-		val = lower_32_bits(counter);
-	}
 
-	__vcpu_sys_reg(vcpu, reg) = val;
+	if (!kvm_pmu_idx_is_64bit(vcpu, pmc->idx))
+		counter = lower_32_bits(counter);
+
+	__vcpu_sys_reg(vcpu, reg) = counter;
 
 	kvm_pmu_release_perf_event(pmc);
 }
@@ -417,7 +417,8 @@ static void kvm_pmu_counter_increment(struct kvm_vcpu *vcpu,
 
 		/* Increment this counter */
 		reg = __vcpu_sys_reg(vcpu, PMEVCNTR0_EL0 + i) + 1;
-		reg = lower_32_bits(reg);
+		if (!kvm_pmu_idx_is_64bit(vcpu, i))
+			reg = lower_32_bits(reg);
 		__vcpu_sys_reg(vcpu, PMEVCNTR0_EL0 + i) = reg;
 
 		if (reg) /* No overflow? move on */
-- 
2.34.1