From: Vitaly Kuznetsov <vkuznets@redhat.com>
To: Wanpeng Li <kernellwp@gmail.com>
Cc: kvm <kvm@vger.kernel.org>,
"the arch/x86 maintainers" <x86@kernel.org>,
"Paolo Bonzini" <pbonzini@redhat.com>,
"Radim Krčmář" <rkrcmar@redhat.com>,
"K. Y. Srinivasan" <kys@microsoft.com>,
"Haiyang Zhang" <haiyangz@microsoft.com>,
"Stephen Hemminger" <sthemmin@microsoft.com>,
"Michael Kelley (EOSG)" <Michael.H.Kelley@microsoft.com>,
"Mohammed Gamal" <mmorsy@redhat.com>,
"Cathy Avery" <cavery@redhat.com>, "Bandan Das" <bsd@redhat.com>,
linux-kernel@vger.kernel.org
Subject: Re: [RFC 0/6] Enlightened VMCS support for KVM on Hyper-V
Date: Tue, 16 Jan 2018 13:05:26 +0100 [thread overview]
Message-ID: <87inc2huux.fsf@vitty.brq.redhat.com> (raw)
In-Reply-To: <CANRm+Cza82KuvEQQi=2Zio2u0EHm1kfPfr=aOhoLdra+fpB2Wg@mail.gmail.com> (Wanpeng Li's message of "Tue, 16 Jan 2018 09:21:04 +0800")
Wanpeng Li <kernellwp@gmail.com> writes:
> 2018-01-16 1:30 GMT+08:00 Vitaly Kuznetsov <vkuznets@redhat.com>:
>> 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
next prev parent reply other threads:[~2018-01-16 12:05 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-15 17:30 [RFC 0/6] Enlightened VMCS support for KVM on Hyper-V Vitaly Kuznetsov
2018-01-15 17:31 ` [RFC 1/6] x86/kvm: rename HV_X64_MSR_APIC_ASSIST_PAGE to HV_X64_MSR_VP_ASSIST_PAGE Vitaly Kuznetsov
2018-01-15 17:31 ` [RFC 2/6] x86/hyper-v: define virtual processor assist page structure Vitaly Kuznetsov
2018-01-15 17:31 ` [RFC 3/6] x86/hyper-v: allocate and use hv_vp_assist_pages Vitaly Kuznetsov
2018-01-15 17:31 ` [RFC 4/6] x86/hyper-v: define struct hv_enlightened_vmcs and clean field bits Vitaly Kuznetsov
2018-01-15 17:31 ` [RFC 5/6] x86/hyper-v: detect nested features Vitaly Kuznetsov
2018-01-15 17:31 ` [RFC 6/6] x86/kvm: use enlightened VMCS when running on Hyper-V Vitaly Kuznetsov
2018-01-16 1:21 ` [RFC 0/6] Enlightened VMCS support for KVM " Wanpeng Li
2018-01-16 12:05 ` Vitaly Kuznetsov [this message]
2018-01-16 13:39 ` David Hildenbrand
2018-01-16 13:47 ` Paolo Bonzini
2018-01-16 13:58 ` Vitaly Kuznetsov
2018-01-16 14:27 ` Paolo Bonzini
2018-01-16 14:43 ` Vitaly Kuznetsov
2018-01-16 14:56 ` David Hildenbrand
2018-01-16 15:03 ` Paolo Bonzini
2018-01-16 17:16 ` Radim Krčmář
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