From 7027bf625012c53bc0b9f619f0a04f8def6cd22f Mon Sep 17 00:00:00 2001
From: Pim van Pelt <pim@ipng.nl>
Date: Tue, 4 Oct 2022 13:16:30 +0000
Subject: [PATCH] Backport https://gerrit.fd.io/r/c/vpp/+/36814

---
 lcpng_if_node.c | 26 ++++++++++++++++++++++----
 1 file changed, 22 insertions(+), 4 deletions(-)

diff --git a/lcpng_if_node.c b/lcpng_if_node.c
index 69ba0d4..1095576 100644
--- a/lcpng_if_node.c
+++ b/lcpng_if_node.c
@@ -441,6 +441,7 @@ VNET_FEATURE_INIT(lcp_xc_ip6_mcast_node, static) = {
 typedef enum
 {
   LCP_XC_L3_NEXT_XC,
+  LCP_XC_L3_NEXT_LOOKUP,
   LCP_XC_L3_N_NEXT,
 } lcp_xc_l3_next_t;
 
@@ -455,6 +456,7 @@ lcp_xc_l3_inline (vlib_main_t *vm, vlib_node_runtime_t *node,
 {
   u32 n_left_from, *from, *to_next, n_left_to_next;
   lcp_xc_next_t next_index;
+  vnet_main_t *vnm = vnet_get_main ();
 
   next_index = 0;
   n_left_from = frame->n_vectors;
@@ -490,10 +492,24 @@ lcp_xc_l3_inline (vlib_main_t *vm, vlib_node_runtime_t *node,
 	    lcp_itf_pair_find_by_host (vnet_buffer (b0)->sw_if_index[VLIB_RX]);
 	  lip = lcp_itf_pair_get (lipi);
 
-	  vnet_buffer (b0)->sw_if_index[VLIB_TX] = lip->lip_phy_sw_if_index;
-	  next0 = LCP_XC_L3_NEXT_XC;
-	  vnet_buffer (b0)->ip.adj_index[VLIB_TX] =
-	    lip->lip_phy_adjs.adj_index[af];
+	  /* P2P tunnels can use generic adjacency */
+	  if (PREDICT_TRUE (
+		vnet_sw_interface_is_p2p (vnm, lip->lip_phy_sw_if_index)))
+	    {
+	      vnet_buffer (b0)->sw_if_index[VLIB_TX] =
+		lip->lip_phy_sw_if_index;
+	      vnet_buffer (b0)->ip.adj_index[VLIB_TX] =
+		lip->lip_phy_adjs.adj_index[af];
+	      next0 = LCP_XC_L3_NEXT_XC;
+	    }
+	  /* P2MP tunnels require a fib lookup to find the right adjacency */
+	  else
+	    {
+	      /* lookup should use FIB table associated with phy interface */
+	      vnet_buffer (b0)->sw_if_index[VLIB_RX] =
+		lip->lip_phy_sw_if_index;
+	      next0 = LCP_XC_L3_NEXT_LOOKUP;
+	    }
 
 	  if (PREDICT_FALSE ((b0->flags & VLIB_BUFFER_IS_TRACED)))
 	    {
@@ -537,6 +553,7 @@ VLIB_REGISTER_NODE(lcp_xc_l3_ip4_node) = {
     .next_nodes =
         {
             [LCP_XC_L3_NEXT_XC] = "ip4-midchain",
+            [LCP_XC_L3_NEXT_LOOKUP] = "ip4-lookup",
         },
 };
 
@@ -560,6 +577,7 @@ VLIB_REGISTER_NODE(lcp_xc_l3_ip6_node) = {
     .next_nodes =
         {
             [LCP_XC_L3_NEXT_XC] = "ip6-midchain",
+            [LCP_XC_L3_NEXT_LOOKUP] = "ip6-lookup",
         },
 };