Add support for 802.1ad (QinQ tunneling)

Flow key handling changes:
 - Add VLAN header array in struct flow, to record multiple 802.1q VLAN
   headers.
 - Add dpif multi-VLAN capability probing. If datapath supports
   multi-VLAN, increase the maximum depth of nested OVS_KEY_ATTR_ENCAP.

Refactor VLAN handling in dpif-xlate:
 - Introduce 'xvlan' to track VLAN stack during flow processing.
 - Input and output VLAN translation according to the xbundle type.

Push VLAN action support:
 - Allow ethertype 0x88a8 in VLAN headers and push_vlan action.
 - Support push_vlan on dot1q packets.

Use other_config:vlan-limit in table Open_vSwitch to limit maximum VLANs
that can be matched. This allows us to preserve backwards compatibility.

Add test cases for VLAN depth limit, Multi-VLAN actions and QinQ VLAN
handling

Co-authored-by: Thomas F Herbert <thomasfherbert@gmail.com>
Signed-off-by: Thomas F Herbert <thomasfherbert@gmail.com>
Co-authored-by: Xiao Liang <shaw.leon@gmail.com>
Signed-off-by: Xiao Liang <shaw.leon@gmail.com>
Signed-off-by: Eric Garver <e@erig.me>
Signed-off-by: Ben Pfaff <blp@ovn.org>

2 files changed, 25 insertions, 0 deletions

diff --git a/vswitchd/bridge.c b/vswitchd/bridge.c
index 2e1001350..f1483112b 100644
--- a/vswitchd/bridge.c
+++ b/vswitchd/bridge.c
@@ -598,6 +598,8 @@ bridge_reconfigure(const struct ovsrec_open_vswitch *ovs_cfg)
                                         OFPROTO_FLOW_LIMIT_DEFAULT));
     ofproto_set_max_idle(smap_get_int(&ovs_cfg->other_config, "max-idle",
                                       OFPROTO_MAX_IDLE_DEFAULT));
+    ofproto_set_vlan_limit(smap_get_int(&ovs_cfg->other_config, "vlan-limit",
+                                       LEGACY_MAX_VLAN_HEADERS));
 
     ofproto_set_threads(
         smap_get_int(&ovs_cfg->other_config, "n-handler-threads", 0),
diff --git a/vswitchd/vswitch.xml b/vswitchd/vswitch.xml
index a91be59b0..464a211ad 100644
--- a/vswitchd/vswitch.xml
+++ b/vswitchd/vswitch.xml
@@ -350,6 +350,29 @@
           Defaults to 100 ie. there is (1/100 =) 1% chance of EMC insertion.
         </p>
       </column>
+
+      <column name="other_config" key="vlan-limit"
+              type='{"type": "integer", "minInteger": 0}'>
+        <p>
+          Limits the number of VLAN headers that can be matched to the
+          specified number.  Further VLAN headers will be treated as payload,
+          e.g. a packet with more 802.1q headers will match Ethernet type
+          0x8100.
+        </p>
+        <p>
+          Value <code>0</code> means unlimited.  The actual number of supported
+          VLAN headers is the smallest of <code>vlan-limit</code>, the number
+          of VLANs supported by Open vSwitch userspace (currently 2), and the
+          number supported by the datapath.
+        </p>
+
+        <p>
+          If this value is absent, the default is currently 1.  This maintains
+          backward compatibility with controllers that were designed for use
+          with Open vSwitch versions earlier than 2.8, which only supported one
+          VLAN.
+        </p>
+      </column>
     </group>
 
     <group title="Status">