Re: [RFC 0/6] Enlightened VMCS support for KVM on Hyper-V

[Vitaly Kuznetsov]

Wanpeng Li <kernellwp@xxxxxxxxx> writes:

> 2018-01-16 1:30 GMT+08:00 Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>:
>> Early RFC. I'll refer to this patchset in my DevConf/FOSDEM
>> presentations.
>>
>> When running nested KVM on Hyper-V it's possible to use so called
>> 'Enlightened VMCS' and do normal memory reads/writes instead of
>> doing VMWRITE/VMREAD instructions. Tests show that this speeds up
>> tight CPUID loop almost 3 times:
>>
>> Before:
>> ./cpuid_tight
>> 20459
>>
>> After:
>> ./cpuid_tight
>> 7698
>
> Maybe you can apply a similar idea to kvm nested on kvm.
>

Yes we can. Basically, that would mean directly accessing 'struct
vmcs12' from L1 hypervisor.

-- 
  Vitaly