Re: [Qemu-devel] [PATCH V7 0/5] Send the gratuitous by guest

["Michael S. Tsirkin" <mst@redhat.com>]

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?

> 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?

> - 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(-)