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

[Gonglei (Arei)]

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.

> you should submit the patch for 2.9.
> 

Thanks,
-Gonglei