From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
	id S1752962AbcFTHNg (ORCPT <rfc822;w@1wt.eu>);
	Mon, 20 Jun 2016 03:13:36 -0400
Received: from mx1.redhat.com ([209.132.183.28]:56772 "EHLO mx1.redhat.com"
	rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP
	id S1752918AbcFTHN1 (ORCPT <rfc822;linux-kernel@vger.kernel.org>);
	Mon, 20 Jun 2016 03:13:27 -0400
Subject: Re: [PATCH v2 3/3] KVM: VMX: enable guest access to LMCE related MSRs
To: Eduardo Habkost <ehabkost@redhat.com>, kvm@vger.kernel.org,
        rkrcmar@redhat.com, Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, "H . Peter Anvin" <hpa@zytor.com>,
        x86@kernel.org, linux-kernel@vger.kernel.org,
        Gleb Natapov <gleb@kernel.org>, Boris Petkov <bp@suse.de>,
        Tony Luck <tony.luck@intel.com>, Andi Kleen <andi.kleen@intel.com>,
        Ashok Raj <ashok.raj@intel.com>, libvir-list@redhat.com,
        Jiri Denemark <jdenemar@redhat.com>
References: <20160616060531.30028-1-haozhong.zhang@intel.com>
 <20160616060531.30028-4-haozhong.zhang@intel.com>
 <1785f481-033b-2780-37b8-d27f80276d33@redhat.com>
 <20160616145546.GJ18662@thinpad.lan.raisama.net>
 <20160617011116.7k7e2zmkwhfvajla@hz-desktop>
 <20160617171515.GJ18662@thinpad.lan.raisama.net>
 <20160620014951.3kk45qtar7tohj6c@hz-desktop>
From: Paolo Bonzini <pbonzini@redhat.com>
Message-ID: <da441ea3-1adf-13f7-0254-82814d5055aa@redhat.com>
Date: Mon, 20 Jun 2016 08:55:40 +0200
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101
 Thunderbird/45.1.0
MIME-Version: 1.0
In-Reply-To: <20160620014951.3kk45qtar7tohj6c@hz-desktop>
Content-Type: text/plain; charset=windows-1252
Content-Transfer-Encoding: 7bit
X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.25]); Mon, 20 Jun 2016 06:55:47 +0000 (UTC)
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org



On 20/06/2016 03:49, Haozhong Zhang wrote:
> Thanks for the explanation!
> 
> If we disable LMCE in QEMU by default (even for -cpu host), will it
> still be a problem? That is,
> 
> - pc-2.7 can continue to run on old kernels unless users explicitly
>   require LMCE
> 
> - existing libvirt VM configurations can continue to work on pc-2.7
>   because LMCE is not specified in those configurations and are
>   disabled by default (i.e. no requirement for new kernels)
> 
> - existing QEMU configurations/scripts using pc alias can continue to
>   work on pc-27 for the same reason above.

Yes, that would be fine.  "-cpu host" can leave LMCE enabled if
supported by the kernel.

Paolo