From: "Michael S. Tsirkin" <mst@redhat•com>
To: "Samudrala, Sridhar" <sridhar.samudrala@intel•com>
Cc: Siwei Liu <loseweigh@gmail•com>,
Stephen Hemminger <stephen@networkplumber•org>,
David Miller <davem@davemloft•net>,
Netdev <netdev@vger•kernel.org>, Jiri Pirko <jiri@resnulli•us>,
virtio-dev@lists•oasis-open.org, "Brandeburg,
Jesse" <jesse.brandeburg@intel•com>,
Alexander Duyck <alexander.h.duyck@intel•com>,
Jakub Kicinski <kubakici@wp•pl>
Subject: Re: [PATCH v4 2/2] virtio_net: Extend virtio to use VF datapath when available
Date: Wed, 14 Mar 2018 02:44:23 +0200 [thread overview]
Message-ID: <20180314024228-mutt-send-email-mst@kernel.org> (raw)
In-Reply-To: <eac018bf-58fe-188d-0dad-f454c9affebb@intel.com>
On Tue, Mar 13, 2018 at 05:28:07PM -0700, Samudrala, Sridhar wrote:
> > I am not sure if it's a good idea to leave the
> > virtio_bypass around if running into failure: the guest is not
> > migratable as the VF doesn't have a backup path,
>
> Are you talking about a failure when registering backup netdev? This should not
> happen, but i guess we can improve error handling in such scenario.
A nice way to do this would be to clear the backup feature bit.
>
> > And perhaps the worse
> > part is that, it now has two interfaces with identical MAC address but
> > one of them is invalid (user cannot use the virtio interface as it has
> > a dampened datapath). IMHO the virtio_bypass and its lower netdev
> > should be destroyed at all when it fails to bind the VF, and
> > technically, there should be some way to propogate the failure status
> > to the hypervisor/backend, indicating that the VM is not migratable
> > because of guest software errors (maybe by clearing out the backup
> > feature from the guest virtio driver so host can see/learn it).
>
> In BACKUP mode, user can only use the upper virtio_bypass netdev and that will
> always be there. Any failure to enslave VF netdev is not fatal, but i will see
> if we can improve the error handling of failure to enslave backup netdev.
> Also, i don't think the BACKUP feature bit is negotiable with the host.
>
> Thanks
> Sridhar
All bits are negotiable. It's up to the host whether to support
a device with this bit clear, or to fail negotiation.
--
MST
next prev parent reply other threads:[~2018-03-14 0:44 UTC|newest]
Thread overview: 59+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-03-01 20:08 [PATCH v4 0/2] Enable virtio_net to act as a backup for a passthru device Sridhar Samudrala
2018-03-01 20:08 ` [PATCH v4 1/2] virtio_net: Introduce VIRTIO_NET_F_BACKUP feature bit Sridhar Samudrala
2018-03-01 20:08 ` [PATCH v4 2/2] virtio_net: Extend virtio to use VF datapath when available Sridhar Samudrala
2018-03-02 8:36 ` Jiri Pirko
2018-03-02 15:26 ` Alexander Duyck
2018-03-02 16:20 ` Jiri Pirko
2018-03-02 16:37 ` Samudrala, Sridhar
2018-03-02 17:06 ` Alexander Duyck
2018-03-02 19:42 ` Michael S. Tsirkin
2018-03-02 20:49 ` Siwei Liu
2018-03-03 11:31 ` Jiri Pirko
2018-03-03 18:04 ` Alexander Duyck
2018-03-03 21:25 ` Jiri Pirko
2018-03-04 0:26 ` Alexander Duyck
2018-03-04 7:13 ` Jiri Pirko
2018-03-04 18:24 ` Alexander Duyck
2018-03-04 18:50 ` Jiri Pirko
2018-03-04 21:54 ` Samudrala, Sridhar
2018-03-04 21:58 ` Alexander Duyck
2018-03-05 9:21 ` Jiri Pirko
2018-03-05 16:11 ` Stephen Hemminger
2018-03-05 22:30 ` Jiri Pirko
2018-03-05 22:47 ` Alexander Duyck
2018-03-06 3:15 ` Stephen Hemminger
2018-03-06 19:08 ` Alexander Duyck
2018-03-06 22:59 ` Jiri Pirko
2018-03-06 23:27 ` Alexander Duyck
2018-03-07 2:38 ` Michael S. Tsirkin
2018-03-07 17:50 ` Alexander Duyck
2018-03-07 18:06 ` Stephen Hemminger
2018-03-07 18:55 ` Alexander Duyck
2018-03-07 20:11 ` Michael S. Tsirkin
2018-03-12 18:47 ` Samudrala, Sridhar
2018-03-02 19:41 ` Michael S. Tsirkin
2018-03-02 19:52 ` Samudrala, Sridhar
2018-03-02 20:10 ` Michael S. Tsirkin
2018-03-02 20:44 ` Siwei Liu
2018-03-02 20:56 ` Samudrala, Sridhar
2018-03-02 21:33 ` Michael S. Tsirkin
2018-03-02 21:31 ` Michael S. Tsirkin
2018-03-02 22:26 ` Siwei Liu
2018-03-04 4:00 ` Michael S. Tsirkin
2018-03-02 21:11 ` Siwei Liu
2018-03-02 21:36 ` Michael S. Tsirkin
2018-03-02 23:56 ` Siwei Liu
2018-03-04 4:04 ` Michael S. Tsirkin
2018-03-12 21:53 ` Siwei Liu
2018-03-02 23:12 ` Samudrala, Sridhar
2018-03-03 0:09 ` Siwei Liu
2018-03-12 20:12 ` Jiri Pirko
2018-03-12 20:58 ` Samudrala, Sridhar
2018-03-12 21:08 ` Jiri Pirko
2018-03-14 0:36 ` Samudrala, Sridhar
2018-03-14 0:54 ` Stephen Hemminger
2018-03-14 15:45 ` Jiri Pirko
2018-03-12 22:44 ` Siwei Liu
2018-03-14 0:28 ` Samudrala, Sridhar
2018-03-14 0:44 ` Michael S. Tsirkin [this message]
2018-03-14 4:50 ` Siwei Liu
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