From mboxrd@z Thu Jan 1 00:00:00 1970 From: Keir Fraser Subject: Re: machine check support in HVM guests Date: Mon, 27 Nov 2006 14:36:12 +0000 Message-ID: References: <456B0090.76E4.0078.0@novell.com> Mime-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <456B0090.76E4.0078.0@novell.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: Jan Beulich , Keir Fraser Cc: xen-devel@lists.xensource.com List-Id: xen-devel@lists.xenproject.org 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. -- Keir On 27/11/06 14:13, "Jan Beulich" 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 27.11.06 14:27 >>> > On 27/11/06 12:29, "Jan Beulich" 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@lists.xensource.com > http://lists.xensource.com/xen-devel