linux-kernel - Re: [PATCH v4 7/7] x86/kvm: use Enlightened VMCS when running on Hyper-V

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20180316160609.GD5180@flask>
Date:   Fri, 16 Mar 2018 17:06:09 +0100
From:   Radim Krčmář <rkrcmar@...hat.com>
To:     Vitaly Kuznetsov <vkuznets@...hat.com>
Cc:     kvm@...r.kernel.org, x86@...nel.org,
        Paolo Bonzini <pbonzini@...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>,
        Thomas Gleixner <tglx@...utronix.de>,
        Christoph Hellwig <hch@...radead.org>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 7/7] x86/kvm: use Enlightened VMCS when running on
 Hyper-V

2018-03-16 15:22+0100, Vitaly Kuznetsov:
> Enlightened VMCS is just a structure in memory, the main benefit
> besides avoiding somewhat slower VMREAD/VMWRITE is using clean field
> mask: we tell the underlying hypervisor which fields were modified
> since VMEXIT so there's no need to inspect them all.
> 
> Tight CPUID loop test shows significant speedup:
> Before: 18890 cycles
> After: 8304 cycles
> 
> Static key is being used to avoid performance penalty for non-Hyper-V
> deployments.
> 
> Signed-off-by: Vitaly Kuznetsov <vkuznets@...hat.com>
> ---

Looks good, thanks.

Reviewed-by: Radim Krčmář <rkrcmar@...hat.com>