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

[Gonglei (Arei)]

> -----Original Message-----
> From: Vadim Rozenfeld [mailto:address@hidden
> Sent: Tuesday, September 05, 2017 2:33 PM
> To: Gonglei (Arei); Paolo Bonzini
> Cc: Hangaohuai; Yan Vugenfirer; address@hidden;
> address@hidden; Radim Krcmar
> Subject: Re: [Qemu-devel] [Help] Windows2012 as Guest 64+cores on KVM
> Halts
> 
> 
> 
> 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.

Thanks for reminding me :)

I'll send this patch this evening, and welcome to test it then.


Regards,
-Gonglei