[PATCH v3 05/14] KVM: arm64: PMU: Narrow the overflow checking when required

Marc Zyngier
2022-11-07T08:55:05Z

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@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 3724acefc07b..39a04ae424d1 100644
--- a/arch/arm64/kvm/pmu-emul.c
+++ b/arch/arm64/kvm/pmu-emul.c
@@ -419,7 +419,8 @@ 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