[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [Xen-devel] machine check support in HVM guests


  • To: Jan Beulich <jbeulich@xxxxxxxxxx>, <xen-devel@xxxxxxxxxxxxxxxxxxx>
  • From: Keir Fraser <keir@xxxxxxxxxxxxx>
  • Date: Mon, 27 Nov 2006 13:27:22 +0000
  • Delivery-date: Mon, 27 Nov 2006 05:27:29 -0800
  • List-id: Xen developer discussion <xen-devel.lists.xensource.com>
  • Thread-index: AccSJ8TpA6h6Sn4bEduPjQAX8io7RQ==
  • Thread-topic: [Xen-devel] machine check support in HVM guests

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


 


Rackspace

Lists.xenproject.org is hosted with RackSpace, monitoring our
servers 24x7x365 and backed by RackSpace's Fanatical Support®.