Re: [Qemu-devel] [RESEND PATCH] kvm: Allow the Hyper-V vendor ID to be specified

[Alex Williamson <alex.williamson@redhat.com>]

On Fri, 2015-10-16 at 09:30 +0200, Paolo Bonzini wrote:
> 
> On 16/10/2015 00:16, Alex Williamson wrote:
> > According to Microsoft documentation, the signature in the standard
> > hypervisor CPUID leaf at 0x40000000 identifies the Vendor ID and is
> > for reporting and diagnostic purposes only.  We can therefore allow
> > the user to change it to whatever they want, within the 12 character
> > limit.  Add a new hyperv-vendor-id option to the -cpu flag to allow
> > for this, ex:
> > 
> >  -cpu host,hv_time,hv_vendor_id=KeenlyKVM
> > 
> > Link: http://msdn.microsoft.com/library/windows/hardware/hh975392
> > Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
> > ---
> > 
> > Cc'ing get_maintainers this time.  Any takers?  Thanks,
> > Alex
> > 
> >  target-i386/cpu-qom.h |    1 +
> >  target-i386/cpu.c     |    1 +
> >  target-i386/kvm.c     |   14 +++++++++++++-
> >  3 files changed, 15 insertions(+), 1 deletion(-)
> > 
> > diff --git a/target-i386/cpu-qom.h b/target-i386/cpu-qom.h
> > index c35b624..6c1eaaa 100644
> > --- a/target-i386/cpu-qom.h
> > +++ b/target-i386/cpu-qom.h
> > @@ -88,6 +88,7 @@ typedef struct X86CPU {
> >      bool hyperv_vapic;
> >      bool hyperv_relaxed_timing;
> >      int hyperv_spinlock_attempts;
> > +    char *hyperv_vendor_id;
> >      bool hyperv_time;
> >      bool hyperv_crash;
> >      bool check_cpuid;
> > diff --git a/target-i386/cpu.c b/target-i386/cpu.c
> > index 05d7f26..71df546 100644
> > --- a/target-i386/cpu.c
> > +++ b/target-i386/cpu.c
> > @@ -3146,6 +3146,7 @@ static Property x86_cpu_properties[] = {
> >      DEFINE_PROP_UINT32("level", X86CPU, env.cpuid_level, 0),
> >      DEFINE_PROP_UINT32("xlevel", X86CPU, env.cpuid_xlevel, 0),
> >      DEFINE_PROP_UINT32("xlevel2", X86CPU, env.cpuid_xlevel2, 0),
> > +    DEFINE_PROP_STRING("hv-vendor-id", X86CPU, hyperv_vendor_id),
> >      DEFINE_PROP_END_OF_LIST()
> >  };
> >  
> > diff --git a/target-i386/kvm.c b/target-i386/kvm.c
> > index 80d1a7e..5e3ab22 100644
> > --- a/target-i386/kvm.c
> > +++ b/target-i386/kvm.c
> > @@ -490,7 +490,19 @@ int kvm_arch_init_vcpu(CPUState *cs)
> >      if (hyperv_enabled(cpu)) {
> >          c = &cpuid_data.entries[cpuid_i++];
> >          c->function = HYPERV_CPUID_VENDOR_AND_MAX_FUNCTIONS;
> > -        memcpy(signature, "Microsoft Hv", 12);
> > +        if (!cpu->hyperv_vendor_id) {
> > +            memcpy(signature, "Microsoft Hv", 12);
> > +        } else {
> > +            size_t len = strlen(cpu->hyperv_vendor_id);
> > +
> > +            if (len > 12) {
> > +                fprintf(stderr,
> > +                        "hyperv-vendor-id too long, limited to 12 charaters");
> > +                abort();
> 
> I'm removing this abort and queueing the patch.  I'll send a pull
> request today.

If we don't abort then we should really set len = 12 here.  Thanks,

Alex

> > +            }
> > +            memset(signature, 0, 12);
> > +            memcpy(signature, cpu->hyperv_vendor_id, len);
> > +        }
> >          c->eax = HYPERV_CPUID_MIN;
> >          c->ebx = signature[0];
> >          c->ecx = signature[1];
> > 
> > --
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