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xen-devel
RE: [Xen-devel] machine check support in HVM guests
> -----Original Message-----
> From: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx
> [mailto:xen-devel-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of
> Keir Fraser
> Sent: 27 November 2006 14:36
> To: Jan Beulich; Keir Fraser
> Cc: xen-devel@xxxxxxxxxxxxxxxxxxx
> Subject: Re: [Xen-devel] machine check support in HVM guests
>
>
> No, I'm not saying that. I was simply expecting that it would
> be easy to
> fake out a very minimal machine-check emulation where nothing
> ever goes
> wrong. :-) If that involves GPFing on some MSR accesses,
> those are easy to
> inject into an HVM guest I believe.
Yupp, just one call to svm_inject_exception() - for some reason Intel's
side is a bit more confusing, as there seems to be about 4 different
types of exception injection code - not sure which is the right one.
--
Mats
>
> -- Keir
>
> On 27/11/06 14:13, "Jan Beulich" <jbeulich@xxxxxxxxxx> wrote:
>
> > Oh, btw., are you implicitly telling me that forcing a GP
> fault on reads
> > (and ideally also writes) of invalid MSRs then is also
> impossible? That
> > is what I'm in the process of adding, at least for the case
> where Xen
> > itself also receives a GP fault when reading the respective physical
> > MSR.
> >
> > Jan
> >
> >>>> Keir Fraser <keir@xxxxxxxxxxxxx> 27.11.06 14:27 >>>
> > On 27/11/06 12:29, "Jan Beulich" <jbeulich@xxxxxxxxxx> wrote:
> >
> >> Neither SVM nor VMX suppress CPUID[1].EDX.MC{E,A}, but
> there also is no
> >> virtualization of the respective MSRs. Since the latter
> seems to have at best
> >> marginal usefulness, shouldn't CPUID be respectively updated?
> >
> > Virtualisation of CPUID is currently back-to-front imo. We should be
> > supplying an entirely fake CPUID space, filled in with
> native info only in
> > places where that makes sense. Instead we supply native
> info, replaced with
> > virtualised alternatives where that turns out to be needed.
> This, for
> > example, means we cannot guarantee to support HVM guests
> with current Xen on
> > future processors. They may extend the CPUID space in a way
> that current Xen
> > does not understand and cause guests to try to use features
> that Xen does
> > not virtualise or emulate.
> >
> > For your specific question, MCE/MCA used to be removed but
> 64-bit Windows
> > requires this feature to be available (not sure if it's
> just for WHQL
> > though). So we should emulate some basic MC support; enough
> to accept and
> > discard MSR programming at least.
> >
> > -- Keir
> >
> >
> > _______________________________________________
> > Xen-devel mailing list
> > Xen-devel@xxxxxxxxxxxxxxxxxxx
> > http://lists.xensource.com/xen-devel
>
>
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@xxxxxxxxxxxxxxxxxxx
> http://lists.xensource.com/xen-devel
>
>
>
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