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

[Gonglei (Arei)]

> 
> 
> 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