On Thu, Dec 25, 2014 at 03:10:01AM +0008, Jason Wang wrote:

On Thu, Dec 25, 2014 at 2:59 AM, Michael S. Tsirkin [off-list ref] wrote:

quoted

On Wed, Dec 24, 2014 at 07:11:20PM +0100, Ben Hutchings wrote:

quoted

On Thu, 2014-12-18 at 00:28 -0500, Jason Wang wrote:

quoted

 > ----- Original Message -----

quoted

UFO support in the kernel applies to both IPv4 and IPv6 protocols
with the same device feature.  However some devices may not be able
to support one of the offloads.  For this we split the UFO offload
feature into 2 pieces.  NETIF_F_UFO now controlls the IPv4 part and
this series introduces NETIF_F_UFO6.
 > > As a result of this work, we can now re-enable NETIF_F_UFO on
virtio_net devices and restore UDP over IPv4 performance for

guests.

quoted

quoted

We also continue to support legacy guests that assume that UFO6
support included into UFO(4).
 > > Without this work, migrating a guest to a 3.18 kernel fails.
 >  > This series eliminate the ambiguous NETIF_F_UFO.

 > But VIRTIO_NET_F_{HOST|GUEST}_UFO and VIRTIO_NET_F_HDR_GSO_UDP is

still

quoted

ambigious. I know it was used to keep compatibility for legacy guest.

But

quoted

what's the future plan? Differentiate UFOv4 and UFOv6 in virtio

features and

quoted

gso type in vnet header looks sufficient?

[...]
  The IPv6 fragmentation ID needs to be added to the vnet header, to do
UFOv6 properly.  If it wasn't for that lack, we wouldn't have to split
the feature flag.
Ben.

Right.

I think a good plan is as follows:

1. add code generating IDs on rx path for virtio,
  and re-enable UFO (4+6).

2. Ben's patch doing similar things for tun/macvtap

I wonder whether or not we can do this lazily.

E.g during UFO6 software segment for dodgy packets?

And this can eliminate the effort of duplicating it in all untrusted
sources?

But then we'll need to then change it again in step 5,
probably by setting some flag?
Might as well do it directly.

quoted

3. similarly for packet sockets


above seem appropriate for stable

4. 4+6 split, to make it easier for drivers
  to identify when fragment ID is needed

5. extend vnet header, and add ways to enable it,
  when enabled, use that to pass
  fragment ID for tun/virtio/vhost/macvtap/packet socket

4 is what this patchset does.

quoted

--  Ben Hutchings
If more than one person is responsible for a bug, no one is at fault.

--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html