Wed, May 02, 2018 at 05:34:44PM CEST, sridhar.samudr...@intel.com wrote: >On 5/2/2018 12:50 AM, Jiri Pirko wrote: >> Wed, May 02, 2018 at 02:20:26AM CEST, sridhar.samudr...@intel.com wrote: >> > 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 that is easy. You allow the change of the mac and in the "failover" >> mac change implementation you propagate the change down to slaves. If >> one slave does not support the change, you bail out. And since VF does >> not allow it as you say, once it will be enslaved, the mac change could >> not be done. Seems like a correct behavior to me and is in-sync with how >> bond/team behaves. > >If we allow the mac to be changed when the VF is not yet plugged in >and the guest changes the mac, then VF cannot join the failover when >it is hot plugged with the original mac assigned by the hypervisor. >Specifically there could be timing window during the live migration where >VF would be unplugged at the source and if we allow the guest to change the >failover mac, then VF would not be able to register with the failover after >the VM is migrated to the destination.
Okay. So as suggested by mst, just forbid the mac changes all together. > >> >> > So for the initial implementation, do you see any issues with having this >> > restriction >> > in STANDBY mode. >> > >> > >
