[PATCH v2 54/54] KVM: x86/pmu/svm: Wire up PMU filtering functionality for passthrough PMU

Mingwei Zhang
2024-05-06T05:32:08Z

From: Manali Shukla <manali.shukla@amd.com>

With the Passthrough PMU enabled, the PERF_CTLx MSRs (event selectors) are
always intercepted and the event filter checking can be directly done
inside amd_pmu_set_msr().

Add a check to allow writing to event selector for GP counters if and only
if the event is allowed in filter.

Signed-off-by: Manali Shukla <manali.shukla@amd.com>
---
arch/x86/kvm/svm/pmu.c | 9 +++++++++
1 file changed, 9 insertions(+)

diff --git a/arch/x86/kvm/svm/pmu.c b/arch/x86/kvm/svm/pmu.c
index 9629a172aa1b..cb6d3bfdd588 100644
--- a/arch/x86/kvm/svm/pmu.c
+++ b/arch/x86/kvm/svm/pmu.c
@@ -166,6 +166,15 @@ static int amd_pmu_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
if (data != pmc->eventsel) {
pmc->eventsel = data;
if (is_passthrough_pmu_enabled(vcpu)) {
+ if (!check_pmu_event_filter(pmc)) {
+ /*
+ * When guest request an invalid event,
+ * stop the counter by clearing the
+ * event selector MSR.
+ */
+ pmc->eventsel_hw = 0;
+ return 0;
+ }
data &= ~AMD64_EVENTSEL_HOSTONLY;
pmc->eventsel_hw = data | AMD64_EVENTSEL_GUESTONLY;
} else {
--
2.45.0.rc1.225.g2a3ae87e7f-goog