Hi Marc,

On 2020-02-14 6:36 pm, Marc Zyngier wrote:
@@ -585,6 +585,14 @@ static void kvm_pmu_create_perf_event(struct kvm_vcpu 
*vcpu, u64 select_idx)
            pmc->idx != ARMV8_PMU_CYCLE_IDX)
+ /*
+        * If we have a filter in place and that the event isn't allowed, do
+        * not install a perf event either.
+        */
+       if (vcpu->kvm->arch.pmu_filter &&
+           !test_bit(eventsel, vcpu->kvm->arch.pmu_filter))
+               return;

If I'm reading the derivation of eventsel right, this will end up treating cycle counter events (aliased to SW_INCR) differently from CPU_CYCLES, which doesn't seem desirable.

Also, if the user did try to blacklist SW_INCR for ridiculous reasons, we'd need to special-case kvm_pmu_software_increment() to make it (not) work as expected, right?


        memset(&attr, 0, sizeof(struct perf_event_attr));
        attr.type = PERF_TYPE_RAW;
        attr.size = sizeof(attr);
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