Re: [PATCH 2/3] perf: require exclude_guest to use PEBS - kernelside enforcement

[David Ahern]

On 9/12/12 8:38 PM, Namhyung Kim wrote:
> Hi David,
>
> On Wed, 12 Sep 2012 09:16:29 -0600, David Ahern wrote:
> > From: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
> >
> > Per Peter:
> >    "Intel PEBS in VT-x context uses the DS address as a guest linear address,
> >    even though its programmed by the host as a host linear address. This
> >    either results in guest memory corruption and or the hardware faulting and
> >    'crashing' the virtual machine.  Therefore we have to disable PEBS on VT-x
> >    enter and re-enable on VT-x exit, enforcing a strict exclude_guest.
> >
> > This patch enforces exclude_guest kernel side.
> [snip]
> > @@ -380,6 +383,9 @@ int x86_pmu_hw_config(struct perf_event *event)
> >   	if (event->attr.precise_ip) {
> >   		int precise = 0;
> >
> > +		if (!event->attr.exclude_guest)
> > +				return -EOPNOTSUPP;
>
> I see a whitespace problem here. :)

grr.... an extra freaking tab.

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