On Wed, Oct 30, 2019 at 06:49:42AM +0000, Kang, Luwei wrote:
> > >> > static void pmc_reprogram_counter(struct kvm_pmc *pmc, u32 type,
> > >> > unsigned config, bool exclude_user,
> > >> > bool exclude_kernel, bool intr,
> > >> > - bool in_tx, bool in_tx_cp)
> > >> > + bool in_tx, bool in_tx_cp, bool pebs)
> > >> > {
> > >> > struct perf_event *event;
> > >> > struct perf_event_attr attr = {
> > >> > @@ -111,9 +111,12 @@ static void pmc_reprogram_counter(struct kvm_pmc *pmc, u32 type,
> > >> > .exclude_user = exclude_user,
> > >> > .exclude_kernel = exclude_kernel,
> > >> > .config = config,
> > >> > + .precise_ip = pebs ? 1 : 0,
> > >> > + .aux_output = pebs ? 1 : 0,
> > >>
> > >> srsly?
> > >
> > > Hi Peter,
> > > Thanks for review. For aux_output, I think it should be set 1 when the guest wants to enabled PEBS by Intel PT.
> >
> > attr.aux_output==1 means your group leader should be an intel_pt event for this to succeed. Luckily for this instance,
> > perf_event_create_kernel_counter() doesn't actually check the attr.aux_output.
> >
> > Also, does 'bool pebs' mean PEBS-via-PT or just a PEBS counter? Or does it mean that in kvm it's the same thing?
>
> It is the same thing. Allocate a counter for PEBS event and use PEBS-via-PT.
It is not the same thing, obviously. It strictly means pebs-over-pt
here.
