Re: [RFC][PATCH] perf, intel: Don't touch MSR_IA32_DEBUGCTLMSR fromNMI context

From: Peter Zijlstra
Date: Wed Sep 12 2012 - 13:45:09 EST

On Wed, 2012-09-12 at 19:37 +0200, Peter Zijlstra wrote:
> Ah, so I do think EIO will re-enable LBR,

OK, it does not, but the:

> also the handler is wrapped in
> x86_pmu::{dis,en}able_all() which does end up calling
> intel_pmu_lbr_{dis,en}able_all().

Thing does the re-enable for us,

> However that leaves the MSR in the
> exact same state on exit as it was on enter, so that's not a problem for
> the: read-modify-write change.

in a safe way.
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