[PATCH v3 03/14] KVM: arm64: PMU: Always advertise the CHAIN event

Marc Zyngier
2022-11-07T08:55:08Z

Even when the underlying HW doesn't offer the CHAIN event
(which happens with QEMU), we can always support it as we're
in control of the counter overflow.

Always advertise the event via PMCEID0_EL0.

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

diff --git a/arch/arm64/kvm/pmu-emul.c b/arch/arm64/kvm/pmu-emul.c
index a38b3127f649..e63ed0c71a37 100644
--- a/arch/arm64/kvm/pmu-emul.c
+++ b/arch/arm64/kvm/pmu-emul.c
@@ -703,6 +703,8 @@ u64 kvm_pmu_get_pmceid(struct kvm_vcpu *vcpu, bool pmceid1)

if (!pmceid1) {
val = read_sysreg(pmceid0_el0);
+ /* always support CHAIN */
+ val |= BIT(ARMV8_PMUV3_PERFCTR_CHAIN);
base = 0;
} else {
val = read_sysreg(pmceid1_el0);
--
2.34.1