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

[Andy Lutomirski <luto@xxxxxxxxxxxxxx>]

On Sep 17, 2015 5:33 AM, "Peter Zijlstra" <peterz@xxxxxxxxxxxxx> wrote:
>
> 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 :-)

I was taking about QEMU TCG, not KVM.


--Andy

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