Re: [PATCH]: Fix MSR_K7_EVNTSEL{0,3} for SVM

Joerg Roedel
2008-04-28T12:46:09Z

On Fri, Apr 25, 2008 at 02:43:19PM -0400, Chris Lalancette wrote:
> Unfortunately, we can't just "fake emulate" MSR_K7_PERFCTR[0-3] like we are
> doing for MSR_K7_EVNTSEL[0-3]; if they are there, linux expects to be able to
> put values into them. I think the correct solution here is to emulate
> MSR_K7_PERFCTR[0-3] and MSR_K7_EVNTSEL[0-3] for real. I'm working on a patch to
> do this now.

We already discussed the emulation of the performance counter registers
in the past. The conclusion is, that we loose live migration with that
emulation because performance monitoring is implemented differently
between AMD and Intel systems. Maybe discarding _any_ writes to
the performance counter MSRs will fix the guest crash. What we should
not do is injecting GPF on zero writes to the MSRs because that will
break Windows XP 64bit installation.

Joerg

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