I don't see how this solves the A emulates B, B emulates A problem? KY Srinivasan <kys@xxxxxxxxxxxxx> wrote: > > >> -----Original Message----- >> From: Paolo Bonzini [mailto:paolo.bonzini@xxxxxxxxx] On Behalf Of >Paolo >> Bonzini >> Sent: Wednesday, July 24, 2013 3:07 AM >> To: Jason Wang >> Cc: H. Peter Anvin; KY Srinivasan; tglx@xxxxxxxxxxxxx; >mingo@xxxxxxxxxx; >> x86@xxxxxxxxxx; gleb@xxxxxxxxxx; kvm@xxxxxxxxxxxxxxx; linux- >> kernel@xxxxxxxxxxxxxxx >> Subject: Re: [PATCH 4/4] x86: properly handle kvm emulation of hyperv >> >> Il 24/07/2013 08:54, Jason Wang ha scritto: >> > On 07/24/2013 12:48 PM, H. Peter Anvin wrote: >> >> On 07/23/2013 09:37 PM, Jason Wang wrote: >> >>> On 07/23/2013 10:48 PM, H. Peter Anvin wrote: >> >>>> On 07/23/2013 06:55 AM, KY Srinivasan wrote: >> >>>>> This strategy of hypervisor detection based on some detection >order >> IMHO is not >> >>>>> a robust detection strategy. The current scheme works since the >only >> hypervisor emulated >> >>>>> (by other hypervisors happens to be Hyper-V). What if this were >to >> change. >> >>>>> >> >>>> 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... >> >>>> >> >>>> -hpa >> >>>> >> >>> How about simply does a reverse loop from 0x40010000 to >0x40010000? >> >>> >> >> Not all systems like being poked too far into hyperspace. Just >remember >> >> the last match and walk the list. >> >> >> >> -hpa >> >> >> > >> > Ok, but it raises a question - how to know it was the 'last' match >> > without knowing all signatures of other hyper-visor? >> >> You can return a "priority" value from the .detect function. The >> priority value can simply be the CPUID leaf where the signature was >> found (or a low value such as 1 if detection was done with DMI). >> >> Then you can pick the hypervisor with the highest priority instead of >> hard-coding the order. > >I like this idea; this allows some guest level control that is what we >want >when we have hypervisors emulating each other. > > >Regards, > >K. Y >> >> Paolo >> >> -- Sent from my mobile phone. Please excuse brevity and lack of formatting. -- 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
