From mboxrd@z Thu Jan  1 00:00:00 1970
From: "Michael S. Tsirkin" <mst@redhat.com>
Subject: Re: [virtio-dev] Re: [Qemu-devel] [PATCH] qemu: Introduce
	VIRTIO_NET_F_STANDBY feature bit to virtio_net
Date: Tue, 26 Jun 2018 04:50:25 +0300
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Cc: Alexander Duyck <alexander.h.duyck@intel.com>,
	virtio-dev@lists.oasis-open.org, Jiri Pirko <jiri@resnulli.us>,
	konrad.wilk@oracle.com, Jakub Kicinski <kubakici@wp.pl>,
	Netdev <netdev@vger.kernel.org>,
	Cornelia Huck <cohuck@redhat.com>, qemu-devel@nongnu.org,
	virtualization@lists.linux-foundation.org, Siwei Liu <loseweigh@gmail.com>,
	Venu Busireddy <venu.busireddy@oracle.com>,
	boris.ostrovsky@oracle.com, aaron.f.brown@intel.com,
	Joao Martins <joao.m.martins@oracle.com>
To: "Samudrala, Sridhar" <sridhar.samudrala@intel.com>
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On Mon, Jun 25, 2018 at 10:54:09AM -0700, Samudrala, Sridhar wrote:
> > > > > Might not neccessarily be something wrong, but it's very limited =
to
> > > > > prohibit the MAC of VF from changing when enslaved by failover.
> > > > You mean guest changing MAC? I'm not sure why we prohibit that.
> > > I think Sridhar and Jiri might be better person to answer it. My
> > > impression was that sync'ing the MAC address change between all 3
> > > devices is challenging, as the failover driver uses MAC address to
> > > match net_device internally.
> =

> Yes. The MAC address is assigned by the hypervisor and it needs to manage=
 the movement
> of the MAC between the PF and VF.=A0 Allowing the guest to change the MAC=
 will require
> synchronization between the hypervisor and the PF/VF drivers. Most of the=
 VF drivers
> don't allow changing guest MAC unless it is a trusted VF.

OK but it's a policy thing. Maybe it's a trusted VF. Who knows?
For example I can see host just
failing VIRTIO_NET_CTRL_MAC_ADDR_SET if it wants to block it.
I'm not sure why VIRTIO_NET_F_STANDBY has to block it in the guest.

-- =

MST