netdev - Re: Correct interpretation of VF link-state=auto

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Message-ID: <20210618093506.245a4186@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com>
Date:   Fri, 18 Jun 2021 09:35:06 -0700
From:   Jakub Kicinski <kuba@...nel.org>
To:     Íñigo Huguet <ihuguet@...hat.com>
Cc:     netdev@...r.kernel.org, Ivan Vecera <ivecera@...hat.com>,
        Edward Harold Cree <ecree@...inx.com>,
        Dinan Gunawardena <dinang@...inx.com>,
        Pablo Cascon <pabloc@...inx.com>
Subject: Re: Correct interpretation of VF link-state=auto

On Tue, 15 Jun 2021 12:34:00 +0200 Íñigo Huguet wrote:
> Hi,
> 
> Regarding link-state attribute for a VF, 'man ip-link' says:
> state auto|enable|disable - set the virtual link state as seen by the
> specified VF. Setting to auto means a reflection of the PF link state,
> enable lets the VF to communicate with other VFs on this host even if
> the PF link state is down, disable causes the HW to drop any packets
> sent by the VF.
> 
> However, I've seen that different interpretations are made about that
> explanation, especially about "auto" configuration. It is not clear if
> it should follow PF "physical link status" or PF "administrative link
> status". With the latter, `ip set PF down` would put the VF down too,
> but with the former you'd have to disconnect the physical port.

Like all legacy SR-IOV networking the correct thing to do here is clear
as mud. I'd go for the link status of the PF netdev. If the netdev
cannot pass traffic (either for administrative or physical link reasons)
then VFs shouldn't talk either. But as I said, every vendor will have their
own interpretation, and different users may expect different things...