[PATCH v4 05/16] KVM: arm64: PMU: Narrow the overflow checking when required

[Marc Zyngier]

For 64bit counters that overflow on a 32bit boundary, make
sure we only check the bottom 32bit to generate a CHAIN event.

Signed-off-by: Marc Zyngier <maz at kernel.org>
---
 arch/arm64/kvm/pmu-emul.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/kvm/pmu-emul.c b/arch/arm64/kvm/pmu-emul.c
index d050143326b5..9e6bc7edc4de 100644
--- a/arch/arm64/kvm/pmu-emul.c
+++ b/arch/arm64/kvm/pmu-emul.c
@@ -417,7 +417,8 @@ static void kvm_pmu_counter_increment(struct kvm_vcpu *vcpu,
 		reg = lower_32_bits(reg);
 		__vcpu_sys_reg(vcpu, PMEVCNTR0_EL0 + i) = reg;
 
-		if (reg) /* No overflow? move on */
+		/* No overflow? move on */
+		if (kvm_pmu_idx_has_64bit_overflow(vcpu, i) ? reg : lower_32_bits(reg))
 			continue;
 
 		/* Mark overflow */
-- 
2.34.1