From mboxrd@z Thu Jan  1 00:00:00 1970
From: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
Subject: Re: race between kvm-kmod-3.0 and kvm-kmod-3.3 // was: race condition
 in qemu-kvm-1.0.1
Date: Thu, 05 Jul 2012 14:48:45 +0800
Message-ID: <4FF538CD.9020505@linux.vnet.ibm.com>
References: <4FEB2945.1030607@dlhnet.de> <4FEB3AC6.6010206@web.de> <4FEC1FC9.7050103@dlhnet.de> <4FEC2210.1030005@siemens.com> <4FEC2475.4030202@dlhnet.de> <4FEC2626.90402@dlhnet.de> <4FF1B8A6.2020101@redhat.com> <4FF2ED2A.7080300@dlhnet.de> <4FF2EFE0.2090400@redhat.com> <4FF4CDD2.1090101@dlhnet.de>
Mime-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 7bit
Cc: Avi Kivity <avi@redhat.com>, Jan Kiszka <jan.kiszka@siemens.com>,
	qemu-devel@nongnu.org, kvm@vger.kernel.org,
	Gleb Natapov <gleb@redhat.com>, xiaoguangrong@cn.fujitsu.com
To: Peter Lieven <pl@dlhnet.de>
Return-path: <kvm-owner@vger.kernel.org>
Received: from e28smtp05.in.ibm.com ([122.248.162.5]:48600 "EHLO
	e28smtp05.in.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
	with ESMTP id S1751885Ab2GEGtC (ORCPT <rfc822;kvm@vger.kernel.org>);
	Thu, 5 Jul 2012 02:49:02 -0400
Received: from /spool/local
	by e28smtp05.in.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted
	for <kvm@vger.kernel.org> from <xiaoguangrong@linux.vnet.ibm.com>;
	Thu, 5 Jul 2012 12:18:57 +0530
Received: from d28av05.in.ibm.com (d28av05.in.ibm.com [9.184.220.67])
	by d28relay02.in.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id q656mopi47972488
	for <kvm@vger.kernel.org>; Thu, 5 Jul 2012 12:18:50 +0530
Received: from d28av05.in.ibm.com (loopback [127.0.0.1])
	by d28av05.in.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP id q65CJNMd003544
	for <kvm@vger.kernel.org>; Thu, 5 Jul 2012 22:19:24 +1000
In-Reply-To: <4FF4CDD2.1090101@dlhnet.de>
Sender: kvm-owner@vger.kernel.org
List-ID: <kvm.vger.kernel.org>

On 07/05/2012 07:12 AM, Peter Lieven wrote:
> On 07/03/12 15:13, Avi Kivity wrote:
>> On 07/03/2012 04:01 PM, Peter Lieven wrote:
>>> Further output from my testing.
>>>
>>> Working:
>>> Linux 2.6.38 with included kvm module
>>> Linux 3.0.0 with included kvm module
>>>
>>> Not-Working:
>>> Linux 3.2.0 with included kvm module
>>> Linux 2.6.28 with kvm-kmod 3.4
>>> Linux 3.0.0 with kvm-kmod 3.4
>>> Linux 3.2.0 with kvm-kmod 3.4
>>>
>>> I can trigger the race with any of qemu-kvm 0.12.5, 1.0 or 1.0.1.
>>> It might be that the code was introduced somewhere between 3.0.0
>>> and 3.2.0 in the kvm kernel module and that the flaw is not
>>> in qemu-kvm.
>>>
>>> Any hints?
>>>
>> A bisect could tell us where the problem is.
>>
>> To avoid bisecting all of linux, try
>>
>>     git bisect v3.2 v3.0 virt/kvm arch/x86/kvm
> here we go:
> 
> commit ca7d58f375c650cf36900cb1da1ca2cc99b13393
> Author: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
> Date:   Wed Jul 13 14:31:08 2011 +0800
> 
>     KVM: x86: fix broken read emulation spans a page boundary

Ah, i will try to reproduce it and fix it.

Thanks for your work.