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Re: [Xen-devel] [PATCH] MSR related clean up

To: "Dong, Eddie" <eddie.dong@xxxxxxxxx>, Sheng Yang <sheng@xxxxxxxxxxxxxxx>
Subject: Re: [Xen-devel] [PATCH] MSR related clean up
From: Keir Fraser <keir.fraser@xxxxxxxxxxxxx>
Date: Wed, 24 Jun 2009 11:48:27 +0100
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On 24/06/2009 10:45, "Dong, Eddie" <eddie.dong@xxxxxxxxx> wrote:

> Returning 0 solves the security concern. But the argument is still that if the
> guest should see same MSR sets with native. The CPUID virtualization provides
> close features with native, but still not identical.
> An ideal solution for those MSR read should consult guest CPUID and then
> decide to either inject #GP if guest CPUID doesn't indicate this MSR, or
> return a virtual MSR. In this case MSR write side should provide the virtual
> MSR too.

Nice plan, but apart from my doubts about anyone actually bothering to a
comprehensive job of this for current processors, there's also the problem
that future processors may have MSRs detected via means such as
model/family-id which we currently pass through.

 -- Keir

> BTW, user can identify certain filtering policy or force some bits of guest
> CPUID, so current approach can't satisfy both cases.



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