From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756622Ab3LaWlH (ORCPT ); Tue, 31 Dec 2013 17:41:07 -0500 Received: from terminus.zytor.com ([198.137.202.10]:45487 "EHLO mail.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756481Ab3LaWlF (ORCPT ); Tue, 31 Dec 2013 17:41:05 -0500 Message-ID: <52C347F0.8070902@zytor.com> Date: Tue, 31 Dec 2013 14:40:48 -0800 From: "H. Peter Anvin" User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.2.0 MIME-Version: 1.0 To: Konrad Rzeszutek Wilk CC: halfdog , Thomas Gleixner , Ingo Molnar , x86@kernel.org, linux-kernel@vger.kernel.org Subject: Re: Sanitize CPU-state when switching from virtual-8086 mode to other task References: <52BF4A80.3010503@halfdog.net> <52BF8AEE.6020904@zytor.com> <52C089AC.4000401@halfdog.net> <52C0C9F4.50101@zytor.com> <52C196C3.1040300@halfdog.net> <52C31027.2030101@zytor.com> <20131231192106.GA22535@phenom.dumpdata.com> In-Reply-To: <20131231192106.GA22535@phenom.dumpdata.com> X-Enigmail-Version: 1.6 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12/31/2013 11:21 AM, Konrad Rzeszutek Wilk wrote: > > So, I am wondering if this is related to " x86/fpu: CR0.TS should be set before trap > into PV guest's #NM exception handle" which does have a similar pattern - you > do enough of the task switches and the FPU is screwed. > > See http://mid.gmane.org/1383720072-6242-1-git-send-email-gaoyang.zyh@taobao.com > > (I thought there was a thread about this on LKML too but I can't > find it). That would be a bug in Xen, so I guess you're surmising a similar bug in VirtualBox? -hpa