Re: [Qemu-devel] [PATCH v5] net: add support of mac-programming over macvtap in QEMU side

[Daniel P. Berrange]

On Wed, Jun 05, 2013 at 06:42:13PM +0800, Amos Kong wrote:
> Currently macvtap based macvlan device is working in promiscuous
> mode, we want to implement mac-programming over macvtap through
> Libvirt for better performance.
> 
> Design:
> QEMU notifies Libvirt when rx-filter config is changed in guest,
> then Libvirt query the rx-filter information by a monitor command,
> and sync the change to macvtap device. Related rx-filter config
> of the nic contains main mac, rx-mode items and vlan table.
> 
> This patch adds a QMP event to notify management of rx-filter change,
> and adds a monitor command for management to query rx-filter
> information.
> 
> For reducing length of output, we just return the entries of vlan
> filter table that have active vlan.
> 
> Event_throttle API can avoid the events to flood QMP client, but it
> could cause an unexpected delay. So a flag for each nic is used to
> avoid events flooding, if management doesn't query rx-filter after
> it receives one event, new events won't be emitted to QMP monitor.
> 
> There maybe exist an uncontrollable delay if we let Libvirt do the
> real change, guests normally expect rx-filter updates immediately.
> But it's another separate issue, we can investigate it when the
> work in Libvirt side is done.

What work is libvirt expected to do in response to these events ?
It this just about updating the ebtables rules to allow packets
with the newly configured MAC addr to be sent/received on the
tap backend ?

Daniel
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