Re: [tip:perfcounters/core] perf_counter: x86: Fix call-chain supportto use NMI-safe methods

[Jeremy Fitzhardinge]

On 06/15/09 12:21, Avi Kivity wrote:
> You can read cr2 on nmi entry and nmi exit, and only write it if it 
> has changed (if it turns out that writing cr2 is expensive; ISTR that 
> it isn't).

Writing the real cr2 is expensive, but it may be cheap to write the 
virtual cr2 in a vmx context.  Or something.

    J
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