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) - Issue migrate_client_info - Issue migrate_set_speed - Issue migrate - Loop - Issue query-migrate - Break if finished/failed 4. Finish(dst) - If success - start CPUs Else - Kill QEMU 5. Confirm(src) - If success - Kill QEMU Else - Restart CPUs 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. Regards, Daniel -- |: http://berrange.com -o- http://www.flickr.com/photos/dberrange/ :| |: http://libvirt.org -o- http://virt-manager.org :| |: http://autobuild.org -o- http://search.cpan.org/~danberr/ :| |: http://entangle-photo.org -o- http://live.gnome.org/gtk-vnc :|