kvm: x86/pmu: Correct the mask used in a pmu event filter lookup

When checking if a pmu event the guest is attempting to program should
be filtered, only consider the event select + unit mask in that
decision. Use an architecture specific mask to mask out all other bits,
including bits 35:32 on Intel.  Those bits are not part of the event
select and should not be considered in that decision.

Fixes: 66bb8a0 ("KVM: x86: PMU Event Filter")
Signed-off-by: Aaron Lewis <aaronlewis@google.com>
Link: https://lore.kernel.org/r/20221220161236.555143-2-aaronlewis@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>

Author: suomilewis

arch/x86/kvm/pmu.c

@@ -279,7 +279,8 @@ static bool check_pmu_event_filter(struct kvm_pmc *pmc)
 		goto out;
 
 	if (pmc_is_gp(pmc)) {
-		key = pmc->eventsel & AMD64_RAW_EVENT_MASK_NB;
+		key = pmc->eventsel & (kvm_pmu_ops.EVENTSEL_EVENT |
+				       ARCH_PERFMON_EVENTSEL_UMASK);
 		if (bsearch(&key, filter->events, filter->nevents,
 			    sizeof(__u64), cmp_u64))
 			allow_event = filter->action == KVM_PMU_EVENT_ALLOW;

arch/x86/kvm/pmu.h

@@ -40,6 +40,8 @@ struct kvm_pmu_ops {
 	void (*reset)(struct kvm_vcpu *vcpu);
 	void (*deliver_pmi)(struct kvm_vcpu *vcpu);
 	void (*cleanup)(struct kvm_vcpu *vcpu);
+
+	const u64 EVENTSEL_EVENT;
 };
 
 void kvm_pmu_ops_update(const struct kvm_pmu_ops *pmu_ops);

arch/x86/kvm/svm/pmu.c

@@ -231,4 +231,5 @@ struct kvm_pmu_ops amd_pmu_ops __initdata = {
 	.refresh = amd_pmu_refresh,
 	.init = amd_pmu_init,
 	.reset = amd_pmu_reset,
+	.EVENTSEL_EVENT = AMD64_EVENTSEL_EVENT,
 };

arch/x86/kvm/vmx/pmu_intel.c

@@ -811,4 +811,5 @@ struct kvm_pmu_ops intel_pmu_ops __initdata = {
 	.reset = intel_pmu_reset,
 	.deliver_pmi = intel_pmu_deliver_pmi,
 	.cleanup = intel_pmu_cleanup,
+	.EVENTSEL_EVENT = ARCH_PERFMON_EVENTSEL_EVENT,
 };