Re: [PATCH net-next v9 3/4] virtio_net: Extend virtio to use VF datapath when available

["Samudrala, Sridhar" <sridhar.samudrala@intel.com>]

On 4/30/2018 12:20 AM, Jiri Pirko wrote:
> > > Now I try to change mac of the failover master:
> > > [root@test1 ~]# ip link set ens3 addr 52:54:00:b2:a7:f3
> > > RTNETLINK answers: Operation not supported
> > >
> > > That I did expect to work. I would expect this would change the mac of
> > > the master and both standby and primary slaves.
> > If a VF is untrusted, a VM will not able to change its MAC and moreover
> Note that at this point, I have no VF. So I'm not sure why you mention
> that.
>
>
> > in this mode we are assuming that the hypervisor has assigned the MAC and
> > guest is not expected to change the MAC.
> Wait, for ordinary old-fashioned virtio_net, as a VM user, I can change
> mac and all works fine. How is this different? Change mac on "failover
> instance" should work and should propagate the mac down to its slaves.
>
>
> > For the initial implementation, i would propose not allowing the guest to
> > change the MAC of failover or standby dev.
> I see no reason for such restriction.

It is true that a VM user can change mac address of a normal virtio-net interface,
however when it is in STANDBY mode i think we should not allow this change specifically
because we are creating a failover instance based on a MAC that is assigned by the
hypervisor.

Moreover,  in a cloud environment i would think that PF/hypervisor assigns a MAC to
the VF and it cannot be changed by the guest.

So for the initial implementation, do you see any issues with having this restriction
in STANDBY mode.