linux-kernel - Re: [PATCH] net/ixgbe: Allow resetting VF admin mac to zero

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Date:	Wed, 6 Jul 2016 20:57:21 -0700
From:	Stephen Hemminger <stephen@...workplumber.org>
To:	Juerg Haefliger <juerg.haefliger@....com>
Cc:	netdev@...r.kernel.org, jeffrey.t.kirsher@...el.com,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] net/ixgbe: Allow resetting VF admin mac to zero

On Fri,  1 Jul 2016 11:19:38 +0200
Juerg Haefliger <juerg.haefliger@....com> wrote:

> The VF administrative mac addresses (stored in the PF driver) are
> initialized to zero when the PF driver starts up.
> 
> These addresses may be modified in the PF driver through ndo calls
> initiated by iproute2 or libvirt.
> 
> While we allow the PF/host to change the VF admin mac address from zero
> to a valid unicast mac, we do not allow restoring the VF admin mac to
> zero. We currently only allow changing this mac to a different unicast mac.
> 
> This leads to problems when libvirt scripts are used to deal with
> VF mac addresses, and libvirt attempts to revoke the mac so this
> host will not use it anymore.
> 
> Fix this by allowing resetting a VF administrative MAC back to zero.
> 
> Implementation and commit message shamelessly stolen from:
> commit 6e5224224faa ("net/mlx4_core: Allow resetting VF admin mac to zero")
> 
> Signed-off-by: Juerg Haefliger <juerg.haefliger@....com>

Since set mac is allowed any time even when device is up, you must
prevent a a device that is in UP state from having all zero MAC address.