From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([140.186.70.92]:36958) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1QwtUB-0005aV-8r for qemu-devel@nongnu.org; Fri, 26 Aug 2011 06:18:04 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1QwtUA-00044k-Bk for qemu-devel@nongnu.org; Fri, 26 Aug 2011 06:18:03 -0400 Received: from mx1.redhat.com ([209.132.183.28]:1032) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1QwtUA-00044e-2b for qemu-devel@nongnu.org; Fri, 26 Aug 2011 06:18:02 -0400 Received: from int-mx10.intmail.prod.int.phx2.redhat.com (int-mx10.intmail.prod.int.phx2.redhat.com [10.5.11.23]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id p7QAI1F2010012 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK) for ; Fri, 26 Aug 2011 06:18:01 -0400 Message-ID: <4E5772D6.1090304@redhat.com> Date: Fri, 26 Aug 2011 12:17:58 +0200 From: Gerd Hoffmann MIME-Version: 1.0 References: <1313773728-6104-1-git-send-email-alevy@redhat.com> <4E576D69.8020103@redhat.com> <20110826100338.GH3944@redhat.com> In-Reply-To: <20110826100338.GH3944@redhat.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH 0/3] client_migrate_switch and auto_switch (RHBZ 725009) List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "Daniel P. Berrange" Cc: Alon Levy , qemu-devel@nongnu.org On 08/26/11 12:03, Daniel P. Berrange wrote: > On Fri, Aug 26, 2011 at 11:54:49AM +0200, Gerd Hoffmann wrote: >> On 08/19/11 19:08, Alon Levy wrote: >>> Fix the ticket expiration on target vm for a spice connection without introducing >>> a race between the spice server switching the client to the new host itself and >>> the target libvirt setting the new expiration date, by adding an option to >>> client_migrate_info to not automatically switch the client on migration completion, >>> instead waiting for an explicit client_migrate_switch (new monitor command) from >>> libvirt. >> >> Hmm. Guess the fundamental issue is that libvirt wants to use the >> monitor to set the ticket instead of the command line for security >> reasons. The qemu monitor doesn't accept commands while the >> incoming migration is running. We also can't kick the incoming >> migration via monitor, so first setting the ticket then start >> migration doesn't work too. Correct? > > There is actually a reliable window where we can use the monitor > before incoming migration starts. Libvirt's migration is a 5 stage > handshake: > > 1. Begin(src) > - Gets current source VM XML config > 2. Prepare(dst) > - Launches QEMU -incoming > - Sets passwords, etc to monitor > 3. Perform(src) > Those stages are all serialized, so we can do anything we like > with the QEMU monitor at stage 2, before stage 3 will start > back on the src. Ok, so I think we should be able to fix the race outlined above without adding new monitor commands, just by letting libvirt set the spice ticket in stage 2. cheers, Gerd