xen-netback: enable IPv6 TCP GSO to the guest

This patch adds code to handle SKB_GSO_TCPV6 skbs and construct appropriate
extra or prefix segments to pass the large packet to the frontend. New
xenstore flags, feature-gso-tcpv6 and feature-gso-tcpv6-prefix, are sampled
to determine if the frontend is capable of handling such packets.

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, 27 insertions, 2 deletions

diff --git a/drivers/net/xen-netback/xenbus.c b/drivers/net/xen-netback/xenbus.c
index 02cb00bebdc9..f0358992b04f 100644
--- a/drivers/net/xen-netback/xenbus.c
+++ b/drivers/net/xen-netback/xenbus.c
@@ -577,15 +577,40 @@ static int connect_rings(struct backend_info *be)
                 val = 0;
         vif->can_sg = !!val;
 
+        vif->gso_mask = 0;
+        vif->gso_prefix_mask = 0;
+
         if (xenbus_scanf(XBT_NIL, dev->otherend, "feature-gso-tcpv4",
                          "%d", &val) < 0)
                 val = 0;
-        vif->gso = !!val;
+        if (val)
+                vif->gso_mask |= GSO_BIT(TCPV4);
 
         if (xenbus_scanf(XBT_NIL, dev->otherend, "feature-gso-tcpv4-prefix",
                          "%d", &val) < 0)
                 val = 0;
-        vif->gso_prefix = !!val;
+        if (val)
+                vif->gso_prefix_mask |= GSO_BIT(TCPV4);
+
+        if (xenbus_scanf(XBT_NIL, dev->otherend, "feature-gso-tcpv6",
+                         "%d", &val) < 0)
+                val = 0;
+        if (val)
+                vif->gso_mask |= GSO_BIT(TCPV6);
+
+        if (xenbus_scanf(XBT_NIL, dev->otherend, "feature-gso-tcpv6-prefix",
+                         "%d", &val) < 0)
+                val = 0;
+        if (val)
+                vif->gso_prefix_mask |= GSO_BIT(TCPV6);
+
+        if (vif->gso_mask & vif->gso_prefix_mask) {
+                xenbus_dev_fatal(dev, err,
+                                 "%s: gso and gso prefix flags are not "
+                                 "mutually exclusive",
+                                 dev->otherend);
+                return -EOPNOTSUPP;
+        }
 
         if (xenbus_scanf(XBT_NIL, dev->otherend, "feature-no-csum-offload",
                          "%d", &val) < 0)