On 03/07/2013 06:52 PM, Michael S. Tsirkin wrote: > On Thu, Mar 07, 2013 at 06:33:30PM +0800, Jason Wang wrote: >> On 03/07/2013 06:25 PM, Michael S. Tsirkin wrote: >>> On Thu, Mar 07, 2013 at 06:13:41PM +0800, Jason Wang wrote: >>>> On 03/07/2013 06:04 PM, Michael S. Tsirkin wrote: >>>>> On Thu, Mar 07, 2013 at 04:23:46PM +0800, Jason Wang wrote: >>>>>> This series tries to let guest instead of qemu to send the gratuitous >>>>>> packets >>>>>> after migration when guest is capable of doing this. This is needed >>>>>> since it's >>>>>> impossible for qemu to keep track of all configurations (e.g 802.1Q) and >>>>>> mac >>>>>> addresses (more than one mac address may be used by guest). So qemu >>>>>> can't build >>>>>> gratuitous packets for all those configurations properly. The only >>>>>> solution is >>>>>> let guest driver who knew all needed information to do this. >>>>>> >>>>>> The series first introduces a new runstate which just tracks the state >>>>>> when the >>>>>> migration is finished and guest is about to start. And then we can just >>>>>> trying >>>>>> to notify the guest to send the GARP after changing from this state to >>>>>> running. A model specific announcing method were also also introduced to >>>>>> let >>>>>> each kinds of nic do its own notification. When there's no such method >>>>>> register >>>>>> for the nic, the old style of sending RARP were kept. And the last two >>>>>> patches >>>>>> implemented the virtio-net method of notification. >>>>> Do we want to retry SELF_ANNOUNCE_ROUNDS? >>>> Yes, we do the announcement several times like in the past. >>>>>> Changes from V6: >>>>>> - introduce a new runstate instead of using a global variable check the >>>>>> state >>>>>> >>>>>> Changes from V5: >>>>>> - use a global variable to decide whether an announcement is needed >>>>>> after migration >>>>>> - align with virtio spec and let guest ack the announcement notification >>>>>> through >>>>>> control vq instead of config status writing >>>>>> >>>>>> Changes from V4: >>>>>> - keep the old behavior that send the gratuitous packets only after >>>>>> migration >>>>> I wonder why it's a sane thing to do. How about simply sending the event >>>>> after load? >>>> The aim is to limit the change of the behaviour to focus on migration. >>>> We may also need this after cont, >>> Hmm why after cont? >> If we stop the vm for a long period, the mac will be missed in the >> forward table of the bridge also. > Hmm okay, needs some thought. > >>>> and then maybe we can just do this >>>> unconditionally in vm_start(). >>> OK but then the new infrastructure we are adding will be dead code, >>> won't it? >> If we do this, there's no need to introduce a new state then. >>> Can we do this simply using a post load hook for now? >> Maybe not, this means we may want to inject an interrupt to guest when >> vm is not running. > What I'm suggesting is basically: > - set some per device flag on load > - announce based on vmstart if flag is set
The only difference is how to figure out the correct time to do the announcement. My proposal is using a global runstate but yours is using both device specific method and global changes (and may also lead the garp to be sent after loadvm). > We can drop the flag later if we want it on every vmstart. If we want it on every vmstart, we can just register per-deivce vmstate change handler to do this. > >>>>>> - decide whether to send gratuitous packets by previous runstate instead >>>>>> of a dedicated parameter >>>>>> - check virtio_net_started() instead of VIRTIO_NET_S_LINK_UP before >>>>>> issue the config update interrupt >>>>>> - move VIRTIO_NET_S_ANNOUNCE to 0x100 and supress guest config write to >>>>>> RO bits >>>>>> - cleanups suggested by Michael >>>>>> >>>>>> Tested with migration within 802.1Q. >>>>>> >>>>>> Jason Wang (5): >>>>>> runstate: introduce prelaunch-migrate state >>>>>> net: announce self after vm is started >>>>>> net: model specific announcing support >>>>>> virtio-net: notify guest to annouce itself >>>>>> virtio-net: compat guest announce >>>>>> >>>>>> hw/pc.h | 6 +++++- >>>>>> hw/virtio-net.c | 30 ++++++++++++++++++++++++++++++ >>>>>> hw/virtio-net.h | 15 ++++++++++++++- >>>>>> include/net/net.h | 2 ++ >>>>>> migration.c | 4 +--- >>>>>> qapi-schema.json | 5 ++++- >>>>>> savevm.c | 8 ++++++-- >>>>>> vl.c | 8 +++++++- >>>>>> 8 files changed, 69 insertions(+), 9 deletions(-)
