On Wed, Sep 11, 2024, Colton Lewis wrote: > Previously any PMU overflow interrupt that fired while a VCPU was > loaded was recorded as a guest event whether it truly was or not. This > resulted in nonsense perf recordings that did not honor > perf_event_attr.exclude_guest and recorded guest IPs where it should > have recorded host IPs. > > Rework the sampling logic to only record guest samples for events with > exclude_guest clear. This way any host-only events with exclude_guest > set will never see unexpected guest samples. The behaviour of events > with exclude_guest clear is unchanged. Nit, "with exclude_guest clear" is easy to misread as simply "with exclude_guest" (I did so at least three times). Maybe The behavior of exclude_guest=0 events is unchanged. or The behavior of events without exclude_guest is unchanged. I think it's also worth explicitly calling out that events that are configured to sample both host and guest may still be prone to misattributing a PMI that arrived in the host as a guest event, depending on the KVM arch and/or vendor behavior.
