datapath: Describe policy for extending flow key, implement needed changes.

When the datapath was converted to use Netlink attributes for describing
flow keys, I had a vague idea of how it could be smoothly extensible, but
I didn't actually implement extensibility or carefully think it through.
This commit adds a document that describes how flow keys can be extended
in a compatible fashion and adapts the existing interface to match what
it says.

This commit doesn't actually implement extensibility.  I already have a
separate patch series out for that.  This patch series borrows from that
one heavily, but the extensibility series will need to be reworked
somewhat once this one is in.

This commit is only lightly tested because I don't have a good test setup
for VLANs.

Signed-off-by: Ben Pfaff <blp@nicira.com>
Acked-by: Jesse Gross <jesse@nicira.com>

1 files changed, 29 insertions, 19 deletions

diff --git a/include/linux/openvswitch.h b/include/linux/openvswitch.h
index 966ef7a0a..2d141e0d6 100644
--- a/include/linux/openvswitch.h
+++ b/include/linux/openvswitch.h
@@ -264,10 +264,11 @@ struct ovs_flow_stats {
 
 enum ovs_key_attr {
 	OVS_KEY_ATTR_UNSPEC,
+	OVS_KEY_ATTR_ENCAP,	/* Nested set of encapsulated attributes. */
 	OVS_KEY_ATTR_PRIORITY,  /* u32 skb->priority */
 	OVS_KEY_ATTR_IN_PORT,   /* u32 OVS dp port number */
 	OVS_KEY_ATTR_ETHERNET,  /* struct ovs_key_ethernet */
-	OVS_KEY_ATTR_8021Q,     /* struct ovs_key_8021q */
+	OVS_KEY_ATTR_VLAN,	/* be16 VLAN TCI */
 	OVS_KEY_ATTR_ETHERTYPE,	/* be16 Ethernet type */
 	OVS_KEY_ATTR_IPV4,      /* struct ovs_key_ipv4 */
 	OVS_KEY_ATTR_IPV6,      /* struct ovs_key_ipv6 */
@@ -306,11 +307,6 @@ struct ovs_key_ethernet {
 	__u8	 eth_dst[6];
 };
 
-struct ovs_key_8021q {
-	__be16 q_tpid;
-	__be16 q_tci;
-};
-
 struct ovs_key_ipv4 {
 	__be32 ipv4_src;
 	__be32 ipv4_dst;
@@ -441,34 +437,48 @@ enum ovs_userspace_attr {
 #define OVS_USERSPACE_ATTR_MAX (__OVS_USERSPACE_ATTR_MAX - 1)
 
 /**
+ * struct ovs_action_push_vlan - %OVS_ACTION_ATTR_PUSH_VLAN action argument.
+ * @vlan_tpid: Tag protocol identifier (TPID) to push.
+ * @vlan_tci: Tag control identifier (TCI) to push.  The CFI bit must not be
+ * set.
+ *
+ * The @vlan_tpid value is typically %ETH_P_8021Q.  The only acceptable TPID
+ * values are those that the kernel module also parses as 802.1Q headers, to
+ * prevent %OVS_ACTION_ATTR_PUSH_VLAN followed by %OVS_ACTION_ATTR_POP_VLAN
+ * from having surprising results.
+ */
+struct ovs_action_push_vlan {
+	__be16 vlan_tpid;	/* 802.1Q TPID. */
+	__be16 vlan_tci;	/* 802.1Q TCI (VLAN ID and priority). */
+};
+
+/**
  * enum ovs_action_attr - Action types.
  *
  * @OVS_ACTION_ATTR_OUTPUT: Output packet to port.
  * @OVS_ACTION_ATTR_USERSPACE: Send packet to userspace according to nested
  * %OVS_USERSPACE_ATTR_* attributes.
- * @OVS_ACTION_ATTR_PUSH: Push header onto head of packet.  The single nested
- * %OVS_KEY_ATTR_* attribute specifies a header to push and its value, e.g.  a
- * nested attribute of type %OVS_KEY_ATTR_8021Q, with struct ovs_key_8021q as
- * argument, would push a VLAN header on the front of the packet.
- * @OVS_ACTION_ATTR_POP: Pop header according to %OVS_KEY_ATTR_ sent as
- * attribute data, e.g. %OVS_KEY_ATTR_8021Q as argument pops an outer VLAN
- * header.
- * @OVS_ACTION_ATTR_SET: Replaces the contents of an existing header.
- * The argument takes the same form as %OVS_ACTION_ATTR_PUSH.
+ * @OVS_ACTION_ATTR_SET: Replaces the contents of an existing header.  The
+ * single nested %OVS_KEY_ATTR_* attribute specifies a header to modify and its
+ * value.
+ * @OVS_ACTION_ATTR_PUSH_VLAN: Push a new outermost 802.1Q header onto the
+ * packet.
+ * @OVS_ACTION_ATTR_POP_VLAN: Pop the outermost 802.1Q header off the packet.
  * @OVS_ACTION_ATTR_SAMPLE: Probabilitically executes actions, as specified in
  * the nested %OVS_SAMPLE_ATTR_* attributes.
  *
- * Only a single field can be set with a single %OVS_ACTION_ATTR_{SET,PUSH}.
- * Not all fields are modifiable.
+ * Only a single header can be set with a single %OVS_ACTION_ATTR_SET.  Not all
+ * fields within a header are modifiable, e.g. the IPv4 protocol and fragment
+ * type may not be changed.
  */
 
 enum ovs_action_attr {
 	OVS_ACTION_ATTR_UNSPEC,
 	OVS_ACTION_ATTR_OUTPUT,	      /* u32 port number. */
 	OVS_ACTION_ATTR_USERSPACE,    /* Nested OVS_USERSPACE_ATTR_*. */
-	OVS_ACTION_ATTR_PUSH,         /* One nested OVS_KEY_ATTR_*. */
-	OVS_ACTION_ATTR_POP,          /* u16 OVS_KEY_ATTR_*. */
 	OVS_ACTION_ATTR_SET,          /* One nested OVS_KEY_ATTR_*. */
+	OVS_ACTION_ATTR_PUSH_VLAN,    /* struct ovs_action_push_vlan. */
+	OVS_ACTION_ATTR_POP_VLAN,     /* No argument. */
 	OVS_ACTION_ATTR_SAMPLE,       /* Nested OVS_SAMPLE_ATTR_*. */
 	__OVS_ACTION_ATTR_MAX
 };