Re: [Qemu-devel] [Help] Windows2012 as Guest 64+cores on KVM Halts

[Vadim Rozenfeld]

On 21/02/17 00:18, Gonglei (Arei) wrote:
> > On 20/02/2017 12:54, Gonglei (Arei) wrote:
> > > > On 20/02/2017 10:19, Gonglei (Arei) wrote:
> > > > > Hi Paolo,
> > > > >
> > > > > > On 16/02/2017 02:31, Gonglei (Arei) wrote:
> > > > > > > And the below patch works for me, I can support max 255 vcpus for
> > > > WS2012
> > > > > > > with hyper-v enlightenments.
> > > > > > >
> > > > > > > diff --git a/target/i386/kvm.c b/target/i386/kvm.c
> > > > > > > index 27fd050..efe3cbc 100644
> > > > > > > --- a/target/i386/kvm.c
> > > > > > > +++ b/target/i386/kvm.c
> > > > > > > @@ -772,7 +772,7 @@ int kvm_arch_init_vcpu(CPUState *cs)
> > > > > > >
> > > > > > >           c = &cpuid_data.entries[cpuid_i++];
> > > > > > >           c->function = HYPERV_CPUID_IMPLEMENT_LIMITS;
> > > > > > > -        c->eax = 0x40;
> > > > > > > +        c->eax = -1;
> > > > > > >           c->ebx = 0x40;
> > > > > > >
> > > > > > >           kvm_base = KVM_CPUID_SIGNATURE_NEXT;
> > > > > > This needs to depend on the machine type, but apart from that I think
> > > > > I don't know why. Because the negative effects for this change don't exist
> > > > > on current QEMU IIUC, and we don't have compatible problems for live
> > > > migration.
> > > >
> > > > CPUID should never change with the same machine type and command line.
> > > OK, then how do we add compat code for the CPUID change? It's not a visible
> > property.
> >
> > You can add a new property, something like hv-cpuid-limits-eax.
> Sounds good. Let me try.  :)
>
> Thanks,
> -Gonglei
Hi Gonglei,
Any update on this issue?

We've found that SVVP on WS2016  is passing successfully with the above 
change
and more than 64 vCPUs defined.

Vadim.