Message-ID: <1415826239.3398.113.camel@decadent.org.uk>
Subject: Re: [PATCH 3.17 023/319] drivers/net: Disable UFO through virtio
From: Ben Hutchings <ben@decadent.org.uk>
To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: linux-kernel@vger.kernel.org, stable@vger.kernel.org,
        "David S. Miller" <davem@davemloft.net>
Date: Wed, 12 Nov 2014 21:03:59 +0000
In-Reply-To: <20141112010956.540146480@linuxfoundation.org>
References: <20141112010952.553519040@linuxfoundation.org>
	 <20141112010956.540146480@linuxfoundation.org>
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On Wed, 2014-11-12 at 10:12 +0900, Greg Kroah-Hartman wrote:
> 3.17-stable review patch.  If anyone has any objections, please let me kn=
ow.
>=20
> ------------------
>=20
> From: Ben Hutchings <ben@decadent.org.uk>
>=20
> [ Upstream commit 3d0ad09412ffe00c9afa201d01effdb6023d09b4 ]
>=20
> IPv6 does not allow fragmentation by routers, so there is no
> fragmentation ID in the fixed header.  UFO for IPv6 requires the ID to
> be passed separately, but there is no provision for this in the virtio
> net protocol.
>=20
> Until recently our software implementation of UFO/IPv6 generated a new
> ID, but this was a bug.  Now we will use ID=3D0 for any UFO/IPv6 packet
> passed through a tap, which is even worse.
>=20
> Unfortunately there is no distinction between UFO/IPv4 and v6
> features, so disable UFO on taps and virtio_net completely until we
> have a proper solution.
[...]

Please drop this patch for 3.14 and 3.17.  It causes problems for
migration of VMs and we're probably going to revert part of this.  The
following patch ("drivers/net, ipv6: Select IPv6 fragment idents for
virtio UFO packets") might no longer apply, in which case you can drop
that as well until we have this sorted out upstream.

Ben.

--=20
Ben Hutchings
Experience is directly proportional to the value of equipment destroyed.
                                                         - Carolyn Scheppne=
r

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