On Fri, Sep 22, 2023 at 11:22 AM Sean Christopherson <seanjc@xxxxxxxxxx> wrote: >The SDM doesn't explicitly state that mask bit is left > unset in these cases, but my reading of > > When the local APIC handles a performance-monitoring counters interrupt, it > automatically sets the mask flag in the LVT performance counter register. > > is that there has to be an actual interrupt. I assume you mean an actual interrupt from the APIC, not an actual PMI to the APIC. I would argue that one way of "handling" a performance-monitoring counters interrupt is to do nothing with it, but apparently I'm wrong. At least, if I set the delivery mode in LVTPC to the illegal value of 6, I never see the LVTPC.MASK bit get set.
