> -----Original Message----- > From: H. Peter Anvin [mailto:hpa@xxxxxxxxx] > Sent: Tuesday, July 23, 2013 2:46 PM > To: KY Srinivasan > Cc: Jason Wang; tglx@xxxxxxxxxxxxx; mingo@xxxxxxxxxx; x86@xxxxxxxxxx; > gleb@xxxxxxxxxx; pbonzini@xxxxxxxxxx; kvm@xxxxxxxxxxxxxxx; linux- > kernel@xxxxxxxxxxxxxxx > Subject: Re: [PATCH 4/4] x86: properly handle kvm emulation of hyperv > > On 07/23/2013 10:45 AM, KY Srinivasan wrote: > >> > >> One strategy would be to pick the *last* one in the CPUID list, since > >> the ones before it are logically the one(s) being emulated... > > > > Is it always possible to guarantee this ordering. As a hypothetical, what if > hypervisor A > > emulates Hypervisor B and Hypervisor B emulates Hypervisor A. In this case we > cannot > > have any "order" based detection that can yield "correct" detection. I define > "correctness" > > as follows: > > > > If a guest can run on both the hypervisors, the guest should detect the true > native > > Hypervisor.at > > > > My point was that most hypervisors tend to put the native signature at > the end of the list starting at 0x40000000, just to deal with naïve > guests which only look at 0x40000000 and not beyond. So a natural > convention would be to "use the last entry in the list you know how to > handle." Ok; thanks for the clarification. Regards, K. Y -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
