From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: [PATCH] kvm: notify host when guest paniced Date: Wed, 29 Feb 2012 12:46:55 +0200 Message-ID: <4F4E021F.80206@redhat.com> References: <4F4AF1FB.6000903@cn.fujitsu.com> <4F4CB926.6050600@redhat.com> <4F4D7F5E.5040202@cn.fujitsu.com> <4F4DF4C6.90609@redhat.com> <20120229095842.GF5050@redhat.com> <4F4DF86C.5010407@redhat.com> <4F4DFE7C.3030501@cn.fujitsu.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Cc: qemu-devel , KAMEZAWA Hiroyuki , kvm list , linux-kernel@vger.kernel.org To: Wen Congyang Return-path: In-Reply-To: <4F4DFE7C.3030501@cn.fujitsu.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 On 02/29/2012 12:31 PM, Wen Congyang wrote: > At 02/29/2012 06:05 PM, Avi Kivity Wrote: > > On 02/29/2012 11:58 AM, Daniel P. Berrange wrote: > >>> > >>> How about using a virtio-serial channel for this? You can transfer any > >>> amount of information (including the dump itself). > >> > >> When the guest OS has crashed, any dumps will be done from the host > >> OS using libvirt's core dump mechanism. The guest OS isn't involved > >> and is likely too dead to be of any use anyway. Likewise it is > >> quite probably too dead to work a virtio-serial channel or any > >> similarly complex device. We're really just after the simplest > >> possible notification that the guest kernel has paniced. > > > > If it's alive enough to panic, it's alive enough to kexec its kdump > > kernel. After that it can do anything. > > > > Guest-internal dumps are more useful IMO that host-initiated dumps. In > > Yes, guest-internal dump is better than host dump. But the user may not > start guest-internal dump or guest-internal dump failed. So we need the > following feature: > 1. If the guest-internal dump does not work, the guest's status is 'crashed'. > And then the user does the host dump. > 2. If the guest-internal dump is working, the guest's status should be > 'dumping'. The user see this status and know the guest has paniced, and > the guest-internal dump is working. I agree. There is room for host dump, and we do want notification about what the guest is doing. The question is whether we should reuse virtio-serial for guest-host communication in this case. It's more complicated, but allows us to avoid touching the hypervisor. -- error compiling committee.c: too many arguments to function From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757669Ab2B2KrI (ORCPT ); Wed, 29 Feb 2012 05:47:08 -0500 Received: from mx1.redhat.com ([209.132.183.28]:15620 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757022Ab2B2KrG (ORCPT ); Wed, 29 Feb 2012 05:47:06 -0500 Message-ID: <4F4E021F.80206@redhat.com> Date: Wed, 29 Feb 2012 12:46:55 +0200 From: Avi Kivity User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:9.0) Gecko/20111222 Thunderbird/9.0 MIME-Version: 1.0 To: Wen Congyang CC: "Daniel P. Berrange" , kvm list , KAMEZAWA Hiroyuki , 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> <20120229095842.GF5050@redhat.com> <4F4DF86C.5010407@redhat.com> <4F4DFE7C.3030501@cn.fujitsu.com> In-Reply-To: <4F4DFE7C.3030501@cn.fujitsu.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 02/29/2012 12:31 PM, Wen Congyang wrote: > At 02/29/2012 06:05 PM, Avi Kivity Wrote: > > On 02/29/2012 11:58 AM, Daniel P. Berrange wrote: > >>> > >>> How about using a virtio-serial channel for this? You can transfer any > >>> amount of information (including the dump itself). > >> > >> When the guest OS has crashed, any dumps will be done from the host > >> OS using libvirt's core dump mechanism. The guest OS isn't involved > >> and is likely too dead to be of any use anyway. Likewise it is > >> quite probably too dead to work a virtio-serial channel or any > >> similarly complex device. We're really just after the simplest > >> possible notification that the guest kernel has paniced. > > > > If it's alive enough to panic, it's alive enough to kexec its kdump > > kernel. After that it can do anything. > > > > Guest-internal dumps are more useful IMO that host-initiated dumps. In > > Yes, guest-internal dump is better than host dump. But the user may not > start guest-internal dump or guest-internal dump failed. So we need the > following feature: > 1. If the guest-internal dump does not work, the guest's status is 'crashed'. > And then the user does the host dump. > 2. If the guest-internal dump is working, the guest's status should be > 'dumping'. The user see this status and know the guest has paniced, and > the guest-internal dump is working. I agree. There is room for host dump, and we do want notification about what the guest is doing. The question is whether we should reuse virtio-serial for guest-host communication in this case. It's more complicated, but allows us to avoid touching the hypervisor. -- error compiling committee.c: too many arguments to function From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:38621) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1S2h3w-00042t-Gj for qemu-devel@nongnu.org; Wed, 29 Feb 2012 05:47:18 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1S2h3q-0007ie-4f for qemu-devel@nongnu.org; Wed, 29 Feb 2012 05:47:12 -0500 Received: from mx1.redhat.com ([209.132.183.28]:65213) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1S2h3p-0007iP-T3 for qemu-devel@nongnu.org; Wed, 29 Feb 2012 05:47:06 -0500 Message-ID: <4F4E021F.80206@redhat.com> Date: Wed, 29 Feb 2012 12:46:55 +0200 From: Avi Kivity MIME-Version: 1.0 References: <4F4AF1FB.6000903@cn.fujitsu.com> <4F4CB926.6050600@redhat.com> <4F4D7F5E.5040202@cn.fujitsu.com> <4F4DF4C6.90609@redhat.com> <20120229095842.GF5050@redhat.com> <4F4DF86C.5010407@redhat.com> <4F4DFE7C.3030501@cn.fujitsu.com> In-Reply-To: <4F4DFE7C.3030501@cn.fujitsu.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH] kvm: notify host when guest paniced List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Wen Congyang Cc: qemu-devel , KAMEZAWA Hiroyuki , kvm list , linux-kernel@vger.kernel.org On 02/29/2012 12:31 PM, Wen Congyang wrote: > At 02/29/2012 06:05 PM, Avi Kivity Wrote: > > On 02/29/2012 11:58 AM, Daniel P. Berrange wrote: > >>> > >>> How about using a virtio-serial channel for this? You can transfer any > >>> amount of information (including the dump itself). > >> > >> When the guest OS has crashed, any dumps will be done from the host > >> OS using libvirt's core dump mechanism. The guest OS isn't involved > >> and is likely too dead to be of any use anyway. Likewise it is > >> quite probably too dead to work a virtio-serial channel or any > >> similarly complex device. We're really just after the simplest > >> possible notification that the guest kernel has paniced. > > > > If it's alive enough to panic, it's alive enough to kexec its kdump > > kernel. After that it can do anything. > > > > Guest-internal dumps are more useful IMO that host-initiated dumps. In > > Yes, guest-internal dump is better than host dump. But the user may not > start guest-internal dump or guest-internal dump failed. So we need the > following feature: > 1. If the guest-internal dump does not work, the guest's status is 'crashed'. > And then the user does the host dump. > 2. If the guest-internal dump is working, the guest's status should be > 'dumping'. The user see this status and know the guest has paniced, and > the guest-internal dump is working. I agree. There is room for host dump, and we do want notification about what the guest is doing. The question is whether we should reuse virtio-serial for guest-host communication in this case. It's more complicated, but allows us to avoid touching the hypervisor. -- error compiling committee.c: too many arguments to function