On Tue, May 01, 2012 at 01:27:05PM +0100, Ian Campbell wrote: > On Mon, 2012-04-30 at 17:38 +0300, Michael S. Tsirkin wrote: > > The following makes 'x86info -r' dump hypervisor leaf cpu ids > > (for kvm this is 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 > > > > Hypervisor flag is checked to avoid output changes when not > > running on a VM. > > > > Signed-off-by: Michael S. Tsirkin <m...@redhat.com> > > > > Changes from v1: > > Make work on non KVM hypervisors (only KVM was tested). > > Avi Kivity said kvm will in the future report > > max HV leaf in eax. For now it reports eax = 0 > > so add a work around for that. > > > > --- > > > > diff --git a/identify.c b/identify.c > > index 33f35de..a4a3763 100644 > > --- a/identify.c > > +++ b/identify.c > > @@ -9,8 +9,8 @@ > > > > void get_cpu_info_basics(struct cpudata *cpu) > > { > > - unsigned int maxi, maxei, vendor, address_bits; > > - unsigned int eax; > > + unsigned int maxi, maxei, maxhv, vendor, address_bits; > > + unsigned int eax, ebx, ecx; > > > > cpuid(cpu->number, 0, &maxi, &vendor, NULL, NULL); > > maxi &= 0xffff; /* The high-order word is non-zero on some > > Cyrix CPUs */ > > @@ -19,7 +19,7 @@ void get_cpu_info_basics(struct cpudata *cpu) > > return; > > > > /* Everything that supports cpuid supports these. */ > > - cpuid(cpu->number, 1, &eax, NULL, NULL, NULL); > > + cpuid(cpu->number, 1, &eax, &ebx, &ecx, NULL); > > You probably want to check ebx, ecx, edx for the signatures of the > hypervisor's you are willing to support and which you know do something > sane with eax?
Everyone puts the max leaf in eax - this is what hardware CPUs do. So I think we can just interpret eax as such. If someone wants to put broken info in cpuid, send a patch to blacklist it. > Also it would be something worth reporting in its own > right? > > BTW, according to arch/x86/include/asm/kvm_para.h unsurprisingly KVM has > a signature too 'KVMKVMKVM'. > > > cpu->stepping = eax & 0xf; > > cpu->model = (eax >> 4) & 0xf; > > cpu->family = (eax >> 8) & 0xf; > > @@ -29,6 +29,19 @@ void get_cpu_info_basics(struct cpudata *cpu) > > > > cpuid(cpu->number, 0xC0000000, &maxei, NULL, NULL, NULL); > > cpu->maxei2 = maxei; > > + if (ecx & 0x80000000) { > > + cpuid(cpu->number, 0x40000000, &maxhv, NULL, NULL, NULL); > > + /* > > + * KVM up to linux 3.4 reports 0 as the max hypervisor leaf, > > + * where it really means 0x40000001. > > This is something where I definitely think you want to check the > signature first. > > Ian. kvm lets users change the signature. But worst case we print one useless line. Better than not printing something potentially useful. -- MST -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html