linux-kernel - Re: [PATCH v2 0/5] Enlightened VMCS support for KVM on Hyper-V

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Date:   Wed, 28 Feb 2018 18:19:21 +0100 (CET)
From:   Thomas Gleixner <tglx@...utronix.de>
To:     Vitaly Kuznetsov <vkuznets@...hat.com>
cc:     kvm@...r.kernel.org, x86@...nel.org,
        Paolo Bonzini <pbonzini@...hat.com>,
        Radim Krčmář <rkrcmar@...hat.com>,
        "K. Y. Srinivasan" <kys@...rosoft.com>,
        Haiyang Zhang <haiyangz@...rosoft.com>,
        Stephen Hemminger <sthemmin@...rosoft.com>,
        "Michael Kelley (EOSG)" <Michael.H.Kelley@...rosoft.com>,
        Mohammed Gamal <mmorsy@...hat.com>,
        Cathy Avery <cavery@...hat.com>, Bandan Das <bsd@...hat.com>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 0/5] Enlightened VMCS support for KVM on Hyper-V

On Mon, 26 Feb 2018, Vitaly Kuznetsov wrote:

For the non KVM pats of this series:

Acked-by: Thomas Gleixner <tglx@...utronix.de>


> Changes since v1:
> - The only comment I got for v1 was from kbuild test robot. The issue
>   was addressed by moving HV_X64_ENLIGHTENED_VMCS_RECOMMENDED definition
>   to PATCH2.
> - Rebased to current kvm/queue.
> 
> 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. In addition, clean field mask
> provides a huge room for optimization on L0's side.
> 
> Tight CPUID loop test shows significant speedup (current kvm/queue on
> E5-2667 v4 @ 3.20GHz):
>  Before: 20766 cycles
>  After: 8912 cycles
> 
> The series is based on current kvm/queue tree.
> 
> Ladi Prosek (1):
>   x86/kvm: rename HV_X64_MSR_APIC_ASSIST_PAGE to
>     HV_X64_MSR_VP_ASSIST_PAGE
> 
> Vitaly Kuznetsov (4):
>   x86/hyper-v: allocate and use Virtual Processor Assist Pages
>   x86/hyper-v: define struct hv_enlightened_vmcs and clean field bits
>   x86/hyper-v: detect nested features
>   x86/kvm: use Enlightened VMCS when running on Hyper-V
> 
>  arch/x86/hyperv/hv_init.c          |  33 +++
>  arch/x86/include/asm/mshyperv.h    |  12 +
>  arch/x86/include/uapi/asm/hyperv.h | 223 ++++++++++++++-
>  arch/x86/kernel/cpu/mshyperv.c     |   3 +
>  arch/x86/kvm/hyperv.c              |   8 +-
>  arch/x86/kvm/lapic.h               |   2 +-
>  arch/x86/kvm/vmx.c                 | 561 ++++++++++++++++++++++++++++++++++++-
>  arch/x86/kvm/x86.c                 |   2 +-
>  8 files changed, 825 insertions(+), 19 deletions(-)
> 
> -- 
> 2.14.3
> 
>