Re: [PATCH 0/3] x86/paravirt: Fix baremetal paravirt MSR ops

From: Peter Zijlstra
Date: Thu Sep 17 2015 - 08:33:20 EST


On Thu, Sep 17, 2015 at 01:40:30PM +0200, Paolo Bonzini wrote:
>
>
> On 17/09/2015 10:58, Peter Zijlstra wrote:
> > But the far greater problem I have with the whole virt thing is that
> > you cannot use rdmsr_safe() to probe if an MSR exists at all because, as
> > you told me, these virt thingies return 0 for all 'unknown' MSRs instead
> > of faulting.
>
> At least for KVM, that behavior is opt-in (the ignore_msrs parameter)
> and no distro that I know enables it by default.

Ah, that would be good news. Andy earlier argued I could not rely on
rdmsr_safe() faulting on unknown MSRs. If practically we can there's
some code I can simplify :-)
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