tunneling: Add datapath GRE support.

Add a new vport type that implements GRE support inside of the
datapath instead of relying on Linux devices.  This provides
greater scalability, performance, and control.

The new GRE implementation supports nearly all features of the
Linux implementation.  It does not currently support multicast,
NBMA tunnels, or non-Ethernet devices.

This implementation of GRE has several important benefits over the
existing Linux implementation.  The first is simply that is not a
Linux device.  Linux devices are fairly heavy weight both in terms
of memory consumption and interactions with the rest of the system
(notifications, processes polling, etc.).  There are many pieces of
code that make assumptions about the maximum reasonable number of
ports.  Simply maintaining the state of several thousand devices is
enough to full occupy the CPU.

A tighter coupling between the GRE implementation and datapath
also allows more flexibility.  The key can be set and retrieved
from the flow table, which allows even greater scalability.
There will probably be additional use cases in the future.

1 files changed, 28 insertions, 0 deletions

diff --git a/include/openvswitch/gre.h b/include/openvswitch/gre.h
index 2b24cf6e..27417bb3 100644
--- a/include/openvswitch/gre.h
+++ b/include/openvswitch/gre.h
@@ -43,6 +43,34 @@
 #include <linux/if_tunnel.h>
 #include <linux/version.h>
 
+#ifdef __KERNEL__
+#include <linux/types.h>
+#else
+#include <sys/types.h>
+#endif
+
+/* New GRE config. */
+
+#define GRE_F_IN_CSUM		(1 << 0) /* Require incoming packets to have checksums. */
+#define GRE_F_OUT_CSUM		(1 << 1) /* Checksum outgoing packets. */
+#define GRE_F_IN_KEY_MATCH	(1 << 2) /* Store the key in tun_id to match in flow table. */
+#define GRE_F_OUT_KEY_ACTION	(1 << 3) /* Get the key from a SET_TUNNEL action. */
+#define GRE_F_TOS_INHERIT	(1 << 4) /* Inherit the ToS from the inner packet. */
+#define GRE_F_TTL_INHERIT	(1 << 5) /* Inherit the TTL from the inner packet. */
+#define GRE_F_PMTUD		(1 << 6) /* Enable path MTU discovery. */
+
+struct gre_port_config {
+	__u32	flags;
+	__be32	saddr;
+	__be32	daddr;
+	__be32	in_key;
+	__be32	out_key;
+	__u8	tos;
+	__u8	ttl;
+};
+
+/* Old GRE config. */
+
 #if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,23)
 #define GRE_IOCTL_ONLY
 #elif LINUX_VERSION_CODE < KERNEL_VERSION(2,6,28)