xen-netback: add support for IPv6 checksum offload from guest

For performance of VM to VM traffic on a single host it is better to avoid
calculation of TCP/UDP checksum in the sending frontend. To allow this this
patch adds the code necessary to set up partial checksum for IPv6 packets
and xenstore flag feature-ipv6-csum-offload to advertise that fact to
frontends.

Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
Cc: Wei Liu <wei.liu2@citrix.com>
Cc: David Vrabel <david.vrabel@citrix.com>
Cc: Ian Campbell <ian.campbell@citrix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 9 insertions, 0 deletions

diff --git a/drivers/net/xen-netback/xenbus.c b/drivers/net/xen-netback/xenbus.c
index ad27b15242cd..108e7523017a 100644
--- a/drivers/net/xen-netback/xenbus.c
+++ b/drivers/net/xen-netback/xenbus.c
@@ -105,6 +105,15 @@ static int netback_probe(struct xenbus_device *dev,
                         goto abort_transaction;
                 }
 
+                /* We support partial checksum setup for IPv6 packets */
+                err = xenbus_printf(xbt, dev->nodename,
+                                    "feature-ipv6-csum-offload",
+                                    "%d", 1);
+                if (err) {
+                        message = "writing feature-ipv6-csum-offload";
+                        goto abort_transaction;
+                }
+
                 /* We support rx-copy path. */
                 err = xenbus_printf(xbt, dev->nodename,
                                     "feature-rx-copy", "%d", 1);