From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760759Ab2CNKqT (ORCPT ); Wed, 14 Mar 2012 06:46:19 -0400 Received: from mx1.redhat.com ([209.132.183.28]:1025 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751612Ab2CNKqR (ORCPT ); Wed, 14 Mar 2012 06:46:17 -0400 Date: Wed, 14 Mar 2012 12:46:08 +0200 From: Gleb Natapov To: Avi Kivity Cc: Wen Congyang , "Daniel P. Berrange" , kvm list , qemu-devel , "linux-kernel@vger.kernel.org" , KAMEZAWA Hiroyuki , Jan Kiszka , Amit Shah Subject: Re: [PATCH 0/2 v3] kvm: notify host when guest panicked Message-ID: <20120314104608.GU2304@redhat.com> References: <4F5DBC26.7060204@cn.fujitsu.com> <4F5DD0FD.9070904@redhat.com> <20120313091843.GB3800@redhat.com> <4F5F25BF.7060100@redhat.com> <4F6056FE.3020202@cn.fujitsu.com> <4F6063C8.8010005@redhat.com> <4F606A7C.9090900@cn.fujitsu.com> <4F606DCC.3020908@redhat.com> <4F60726E.3090807@cn.fujitsu.com> <4F607325.6050607@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4F607325.6050607@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Mar 14, 2012 at 12:29:57PM +0200, Avi Kivity wrote: > On 03/14/2012 12:26 PM, Wen Congyang wrote: > > >> If so, is this channel visible to guest userspace? If the channle is visible to guest > > >> userspace, the program running in userspace may write the same message to the channel. > > >> > > > > > > Surely there's some kind of access control on channels. > > > > The virtio-serial depends on more things than touching the hypervisor. So I think touching > > the hypervisor is more reliable than using virtio-serial device, and it is very simple and > > easy to use. > > > > If we pass something from guest userspace to host, we can use virtio-serial. But If we pass > > something from guest kernelspace to host, I still prefer to touch the hypervisor. > > There's no argument that it's easier. My concern is different, we're > adding more and more stuff to the hypervisor because it's easier, which > bloats it. Every time we do it we add to compatibility and security > problems. > > The panic notification is *really* simple, so I don't expect it to cause > a lot of problems. But still, if it's possible not to change the > hypervisor, we must make an effort in that direction. > One more point against using virtio-serial is that it will be likely compiled as a module which means panic during early boot will not be reported. -- Gleb.