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

[Vadim Rozenfeld <vrozenfe@redhat.com>]

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.