MTU: Software interface / Per-protocol MTU support

This patch separates setting of hardware interfaec and software
interface MTU. Software MTU is L2 payload MTU (i.e. not including L2
header). Per-protocol MTU for IPv4, IPv6 and MPLS can also be set.
Currently only IP4, IP6 are enabled in adjacency / rewrite code.

Documentation in src/vnet/MTU.md

Change-Id: Iee2fd6f0bbc8210748dd8e073ab9fab87d323690
Signed-off-by: Ole Troan <ot@cisco.com>

1 files changed, 16 insertions, 9 deletions

diff --git a/src/vnet/interface_funcs.h b/src/vnet/interface_funcs.h
index e1568e33b5d..c4dd3b72e51 100644
--- a/src/vnet/interface_funcs.h
+++ b/src/vnet/interface_funcs.h
@@ -262,20 +262,22 @@ vnet_hw_interface_get_flags (vnet_main_t * vnm, u32 hw_if_index)
   return hw->flags;
 }
 
-always_inline uword
-vnet_hw_interface_get_mtu (vnet_main_t * vnm, u32 hw_if_index,
-			   vlib_rx_or_tx_t dir)
+always_inline u32
+vnet_hw_interface_get_mtu (vnet_main_t * vnm, u32 hw_if_index)
 {
   vnet_hw_interface_t *hw = vnet_get_hw_interface (vnm, hw_if_index);
-  return hw->max_l3_packet_bytes[dir];
+  return hw->max_packet_bytes;
 }
 
-always_inline uword
-vnet_sw_interface_get_mtu (vnet_main_t * vnm, u32 sw_if_index,
-			   vlib_rx_or_tx_t dir)
+always_inline u32
+vnet_sw_interface_get_mtu (vnet_main_t * vnm, u32 sw_if_index, vnet_mtu_t af)
 {
-  vnet_hw_interface_t *hw = vnet_get_sup_hw_interface (vnm, sw_if_index);
-  return (hw->max_l3_packet_bytes[dir]);
+  vnet_sw_interface_t *sw = vnet_get_sw_interface (vnm, sw_if_index);
+  u32 mtu;
+  mtu = sw->mtu[af] > 0 ? sw->mtu[af] : sw->mtu[VNET_MTU_L3];
+  if (mtu == 0)
+    return 9000;		/* $$$ Deal with interface-types not setting MTU */
+  return mtu;
 }
 
 always_inline uword
@@ -339,6 +341,11 @@ clib_error_t *set_hw_interface_change_rx_mode (vnet_main_t * vnm,
 /* Set the MTU on the HW interface */
 void vnet_hw_interface_set_mtu (vnet_main_t * vnm, u32 hw_if_index, u32 mtu);
 
+/* Set the MTU on the SW interface */
+void vnet_sw_interface_set_mtu (vnet_main_t * vnm, u32 sw_if_index, u32 mtu);
+void vnet_sw_interface_set_protocol_mtu (vnet_main_t * vnm, u32 sw_if_index,
+					 u32 mtu[]);
+
 /* update the unnumbered state of an interface */
 void vnet_sw_interface_update_unnumbered (u32 sw_if_index,
 					  u32 ip_sw_if_index, u8 enable);