On Tue, May 01, 2012 at 11:29:04AM +0100, Ian Campbell wrote: > On Mon, 2012-04-30 at 10:38 +0100, Michael S. Tsirkin wrote: > > On Mon, Apr 30, 2012 at 11:43:19AM +0300, Gleb Natapov wrote: > > > On Sun, Apr 29, 2012 at 01:10:21PM +0300, Michael S. Tsirkin wrote: > > > > The following makes 'x86info -r' dump kvm cpu ids > > > > (signature+features) when running in a vm. > > > > > > > > On the guest we see the signature and the features: > > > > eax in: 0x40000000, eax = 00000000 ebx = 4b4d564b ecx = 564b4d56 edx = 0000004d > > > > eax in: 0x40000001, eax = 0100007b ebx = 00000000 ecx = 00000000 edx = 00000000 > > > > > > > > On the host it just adds a couple of zero lines: > > > > eax in: 0x40000000, eax = 00000000 ebx = 00000000 ecx = 00000000 edx = 00000000 > > > > eax in: 0x40000001, eax = 00000000 ebx = 00000000 ecx = 00000000 edx = 00000000 > > > > > > > This is too KVM specific. > > > > That's what I have. I scratch my own itch. > > > > > Other hypervisors may use more cpuid leafs. > > > > But not less so no harm's done. > > > > > As far as I see Hyper-V uses 5 and use cpuid.0x40000000.eax as max cpuid > > > leaf available. Haven't checked Xen or VMWare. > > Xen does the same, documentation in the Xen public interfaces header: > http://xenbits.xen.org/docs/unstable/hypercall/include,public,arch-x86,cpuid.h.html. So ack to my patch? > If compat mode for another h/v is enabled then those leaves will appear > at 0x40000000 and Xen's will be bumped up, so a fully Xen aware set of > drivers (or detection routine, etc) should check at 0x100 intervals > until 0x40010000 for the appropriate signatures (I realise that the docs > are somewhat lacking in this regard, I should cook up a patch). > > Ian. How does guest know that the data at 0x40000100 makes sense? -- MST -- 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
