Messages in this thread | | | From | Namhyung Kim <> | Subject | Re: [PATCH 2/3] perf: require exclude_guest to use PEBS - kernel side enforcement | Date | Thu, 13 Sep 2012 11:38:08 +0900 |
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Hi David,
On Wed, 12 Sep 2012 09:16:29 -0600, David Ahern wrote: > From: Peter Zijlstra <peterz@infradead.org> > > 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. :)
Thanks, Namhyung
> + > /* Support for constant skid */ > if (x86_pmu.pebs_active && !x86_pmu.pebs_broken) { > precise++;
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