Program nexthop table as a ternary match. (#59)

The P4 program has been modified to move the NextHop table from
the SEM block (exact match) to the WCM block (ternary match). This
requires a corresponding change in the Kernel Monitor.

This is a breaking change. Newer versions of krnlmon are incompatible
with older versions of the P4 program.

Signed-off-by: Sandeep N <[email protected]>
Co-authored-by: Derek G Foster <[email protected]>

README.md

@@ -1,2 +1,8 @@
 # ipdk-io/krnlmon
 The Kernel Monitor receives RFC 3549 messages from the Linux Kernel over a Netlink socket when changes are made to the kernel networking data structures.
+
+## Breaking changes
+
+### 11 Oct 2023
+
+- https://github.com/ipdk-io/krnlmon/pull/59: The NextHop table in the P4 program has been moved from the SEM block (exact match) to the WCM block (ternary block). The Kernel Monitor must use a different API to write the entry to the WCM block. krnlmon is no longer compatible with older versions of the P4 program.

switchapi/es2k/switch_pd_routing.c

@@ -25,6 +25,9 @@
 
 #include "port_mgr/dpdk/bf_dpdk_port_if.h"
 
+// Table match type definitions.
+#define NEXTHOP_TABLE_TERNARY_MATCH 1
+
 switch_status_t switch_routing_table_entry (
         switch_device_t device,
         const switch_pd_routing_info_t *api_routing_info,
@@ -180,10 +183,20 @@ switch_status_t switch_pd_nexthop_table_entry(
         goto dealloc_resources;
     }
 
+#if NEXTHOP_TABLE_TERNARY_MATCH
+    // When Nexthop table is of type ternary Match
+    status = tdi_key_field_set_value_and_mask(key_hdl, field_id,
+                                     (api_nexthop_pd_info->nexthop_handle &
+                                     ~(SWITCH_HANDLE_TYPE_NHOP <<
+                                     SWITCH_HANDLE_TYPE_SHIFT)), 0xFFFF);
+#else
+    // When Nexthop table is of type exact Match
     status = tdi_key_field_set_value(key_hdl, field_id,
                                      (api_nexthop_pd_info->nexthop_handle &
                                      ~(SWITCH_HANDLE_TYPE_NHOP <<
                                      SWITCH_HANDLE_TYPE_SHIFT)));
+#endif
+
     if (status != TDI_SUCCESS) {
         krnlmon_log_error("Unable to set value for key ID: %d for nexthop_table,"
                           " error: %d", field_id, status);