From mboxrd@z Thu Jan 1 00:00:00 1970 From: Wen Congyang Subject: Re: [PATCH] kvm: notify host when guest paniced Date: Thu, 01 Mar 2012 11:34:45 +0800 Message-ID: <4F4EEE55.4040506@cn.fujitsu.com> References: <4F4AF1FB.6000903@cn.fujitsu.com> <4F4CB926.6050600@redhat.com> <4F4D7F5E.5040202@cn.fujitsu.com> <4F4DF4C6.90609@redhat.com> <20120229095557.GE24600@redhat.com> <4F4DF749.7060507@redhat.com> <20120229100550.GF24600@redhat.com> <4F4DF913.5030809@redhat.com> <4F4DFB37.8060208@cn.fujitsu.com> <4F4E0061.1050508@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: Gleb Natapov , kvm list , qemu-devel , linux-kernel@vger.kernel.org, KAMEZAWA Hiroyuki To: Avi Kivity Return-path: In-Reply-To: <4F4E0061.1050508@redhat.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+gceq-qemu-devel=gmane.org@nongnu.org Sender: qemu-devel-bounces+gceq-qemu-devel=gmane.org@nongnu.org List-Id: kvm.vger.kernel.org At 02/29/2012 06:39 PM, Avi Kivity Wrote: > On 02/29/2012 12:17 PM, Wen Congyang wrote: >>>>> >>>> Yes, crash can be so severe that it is not even detected by a kernel >>>> itself, so not OOPS message even printed. But in most cases if kernel is >>>> functional enough to print OOPS it is functional enough to call single >>>> hypercall instruction. >>> >>> Why not print the oops to virtio-serial? Or even just a regular serial >>> port? That's what bare metal does. >> >> If virtio-serial's driver has bug or the guest doesn't have such device... > > We have the same issue with the hypercall; and virtio-serial is > available on many deployed versions. How to know whether a guest has virtio-serial? Thanks Wen Congyang > >>> >>>>>> Having special kdump >>>>>> kernel that transfers dump to a host via virtio-serial channel though >>>>>> sounds interesting. May be that's what you mean. >>>>> >>>>> Yes. The "panic, starting dump" signal should be initiated by the >>>>> panicking kernel though, in case the dump fails. >>>>> >>>> Then panic hypercall sounds like a reasonable solution. >>> >>> It is, but I'm trying to see if we can get away with doing nothing. >>> >> >> If we have a reliable way with doing nothing, it is better. But I donot >> find such way. > > We won't have a 100% reliable way. But I think a variant of the driver > that doesn't use interrupts, or just using the ordinary serial driver, > should be reliable enough. > From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758065Ab2CADdd (ORCPT ); Wed, 29 Feb 2012 22:33:33 -0500 Received: from cn.fujitsu.com ([222.73.24.84]:59966 "EHLO song.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1753607Ab2CADdc (ORCPT ); Wed, 29 Feb 2012 22:33:32 -0500 Message-ID: <4F4EEE55.4040506@cn.fujitsu.com> Date: Thu, 01 Mar 2012 11:34:45 +0800 From: Wen Congyang User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.9) Gecko/20100413 Fedora/3.0.4-2.fc13 Thunderbird/3.0.4 MIME-Version: 1.0 To: Avi Kivity CC: Gleb Natapov , kvm list , KAMEZAWA Hiroyuki , "Daniel P. Berrange" , linux-kernel@vger.kernel.org, qemu-devel Subject: Re: [PATCH] kvm: notify host when guest paniced References: <4F4AF1FB.6000903@cn.fujitsu.com> <4F4CB926.6050600@redhat.com> <4F4D7F5E.5040202@cn.fujitsu.com> <4F4DF4C6.90609@redhat.com> <20120229095557.GE24600@redhat.com> <4F4DF749.7060507@redhat.com> <20120229100550.GF24600@redhat.com> <4F4DF913.5030809@redhat.com> <4F4DFB37.8060208@cn.fujitsu.com> <4F4E0061.1050508@redhat.com> In-Reply-To: <4F4E0061.1050508@redhat.com> X-MIMETrack: Itemize by SMTP Server on mailserver/fnst(Release 8.5.1FP4|July 25, 2010) at 2012-03-01 11:31:39, Serialize by Router on mailserver/fnst(Release 8.5.1FP4|July 25, 2010) at 2012-03-01 11:31:41, Serialize complete at 2012-03-01 11:31:41 Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org At 02/29/2012 06:39 PM, Avi Kivity Wrote: > On 02/29/2012 12:17 PM, Wen Congyang wrote: >>>>> >>>> Yes, crash can be so severe that it is not even detected by a kernel >>>> itself, so not OOPS message even printed. But in most cases if kernel is >>>> functional enough to print OOPS it is functional enough to call single >>>> hypercall instruction. >>> >>> Why not print the oops to virtio-serial? Or even just a regular serial >>> port? That's what bare metal does. >> >> If virtio-serial's driver has bug or the guest doesn't have such device... > > We have the same issue with the hypercall; and virtio-serial is > available on many deployed versions. How to know whether a guest has virtio-serial? Thanks Wen Congyang > >>> >>>>>> Having special kdump >>>>>> kernel that transfers dump to a host via virtio-serial channel though >>>>>> sounds interesting. May be that's what you mean. >>>>> >>>>> Yes. The "panic, starting dump" signal should be initiated by the >>>>> panicking kernel though, in case the dump fails. >>>>> >>>> Then panic hypercall sounds like a reasonable solution. >>> >>> It is, but I'm trying to see if we can get away with doing nothing. >>> >> >> If we have a reliable way with doing nothing, it is better. But I donot >> find such way. > > We won't have a 100% reliable way. But I think a variant of the driver > that doesn't use interrupts, or just using the ordinary serial driver, > should be reliable enough. > From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:35098) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1S2wlu-0002Gy-99 for qemu-devel@nongnu.org; Wed, 29 Feb 2012 22:33:39 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1S2wls-00083Z-EO for qemu-devel@nongnu.org; Wed, 29 Feb 2012 22:33:37 -0500 Received: from [222.73.24.84] (port=56676 helo=song.cn.fujitsu.com) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1S2wls-00082f-2N for qemu-devel@nongnu.org; Wed, 29 Feb 2012 22:33:36 -0500 Message-ID: <4F4EEE55.4040506@cn.fujitsu.com> Date: Thu, 01 Mar 2012 11:34:45 +0800 From: Wen Congyang MIME-Version: 1.0 References: <4F4AF1FB.6000903@cn.fujitsu.com> <4F4CB926.6050600@redhat.com> <4F4D7F5E.5040202@cn.fujitsu.com> <4F4DF4C6.90609@redhat.com> <20120229095557.GE24600@redhat.com> <4F4DF749.7060507@redhat.com> <20120229100550.GF24600@redhat.com> <4F4DF913.5030809@redhat.com> <4F4DFB37.8060208@cn.fujitsu.com> <4F4E0061.1050508@redhat.com> In-Reply-To: <4F4E0061.1050508@redhat.com> Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset=ISO-8859-1 Subject: Re: [Qemu-devel] [PATCH] kvm: notify host when guest paniced List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Avi Kivity Cc: Gleb Natapov , kvm list , qemu-devel , linux-kernel@vger.kernel.org, KAMEZAWA Hiroyuki At 02/29/2012 06:39 PM, Avi Kivity Wrote: > On 02/29/2012 12:17 PM, Wen Congyang wrote: >>>>> >>>> Yes, crash can be so severe that it is not even detected by a kernel >>>> itself, so not OOPS message even printed. But in most cases if kernel is >>>> functional enough to print OOPS it is functional enough to call single >>>> hypercall instruction. >>> >>> Why not print the oops to virtio-serial? Or even just a regular serial >>> port? That's what bare metal does. >> >> If virtio-serial's driver has bug or the guest doesn't have such device... > > We have the same issue with the hypercall; and virtio-serial is > available on many deployed versions. How to know whether a guest has virtio-serial? Thanks Wen Congyang > >>> >>>>>> Having special kdump >>>>>> kernel that transfers dump to a host via virtio-serial channel though >>>>>> sounds interesting. May be that's what you mean. >>>>> >>>>> Yes. The "panic, starting dump" signal should be initiated by the >>>>> panicking kernel though, in case the dump fails. >>>>> >>>> Then panic hypercall sounds like a reasonable solution. >>> >>> It is, but I'm trying to see if we can get away with doing nothing. >>> >> >> If we have a reliable way with doing nothing, it is better. But I donot >> find such way. > > We won't have a 100% reliable way. But I think a variant of the driver > that doesn't use interrupts, or just using the ordinary serial driver, > should be reliable enough. >