From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([140.186.70.92]:43891) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Qwtuh-00080o-VT for qemu-devel@nongnu.org; Fri, 26 Aug 2011 06:45:28 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Qwtug-0000fl-CR for qemu-devel@nongnu.org; Fri, 26 Aug 2011 06:45:27 -0400 Received: from mx1.redhat.com ([209.132.183.28]:58243) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Qwtuf-0000fe-UK for qemu-devel@nongnu.org; Fri, 26 Aug 2011 06:45:26 -0400 Received: from int-mx01.intmail.prod.int.phx2.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id p7QAjOG3001667 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK) for ; Fri, 26 Aug 2011 06:45:24 -0400 Date: Fri, 26 Aug 2011 13:43:42 +0300 From: Alon Levy Message-ID: <20110826104342.GY6393@bow.redhat.com> References: <1313773728-6104-1-git-send-email-alevy@redhat.com> <4E576D69.8020103@redhat.com> <20110826100338.GH3944@redhat.com> <4E5772D6.1090304@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4E5772D6.1090304@redhat.com> 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: Gerd Hoffmann Cc: qemu-devel@nongnu.org On Fri, Aug 26, 2011 at 12:17:58PM +0200, Gerd Hoffmann wrote: > 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. Is that different then what I suggested in my reply to Daniel's 5 stage outline? > > cheers, > Gerd > >