linux-cp: Add VPP->Linux synchronization

Part 1 -- notes in https://ipng.ch/s/articles/2021/08/13/vpp-2.html
Add the ability for VPP to copy out (sync) its state from the dataplane
to Linux Interface Pairs, when they exist. Gated by a configuration
flag (linux-cp { lcp-sync }), and by a CLI option to toggle on/off,
synchronize the following events:

- Interface state changes
- Interface MTU changes
- Interface IPv4/IPv6 address add/deletion

In VPP, subints can have any link state and MTU, orthogonal to their
phy. In Linux, setting admin-down on a phy forces its children to be
down as well. Also, in Linux, MTU of children must not exceed that of
the phy. Add a state synchronizer which walks over phy+subints to
ensure Linux and VPP end up in the same consistent state.

Part 2 -- notes in https://ipng.ch/s/articles/2021/08/15/vpp-3.html
Add the ability for VPP to autocreate sub-interfaces of existing Linux
Interface pairs. Gated by a configuration flag
(linux-cp { lcp-auto-subint }), and by a CLI option to toggle on/off,
synchronize the following event:

- Sub-interface creation (dot1q, dot1ad, QinQ and QinAD)

A few other changes:
- Add two functions into netlink.[ch] to delete ip4 and ip6 addresses.
- Remove a spurious logline (printing MTU) in netlink.c.
- Resolve a TODO around vnet_sw_interface_supports_addressing()

Type: improvement
Signed-off-by: Pim van Pelt <pim@ipng.nl>
Change-Id: I34fc070e80af4013be58d7a8cbf64296cc760e4e
Signed-off-by: Pim van Pelt <pim@ipng.nl>

1 files changed, 37 insertions, 0 deletions

diff --git a/src/plugins/linux-cp/lcp.c b/src/plugins/linux-cp/lcp.c
index a4d3faf081a..69a7a6e42ba 100644
--- a/src/plugins/linux-cp/lcp.c
+++ b/src/plugins/linux-cp/lcp.c
@@ -20,6 +20,7 @@
 #include <net/if.h>
 
 #include <plugins/linux-cp/lcp.h>
+#include <plugins/linux-cp/lcp_interface.h>
 
 lcp_main_t lcp_main;
 
@@ -76,6 +77,42 @@ lcp_set_default_ns (u8 *ns)
   return 0;
 }
 
+void
+lcp_set_sync (u8 is_auto)
+{
+  lcp_main_t *lcpm = &lcp_main;
+
+  lcpm->lcp_sync = (is_auto != 0);
+
+  // If we set to 'on', do a one-off sync of LCP interfaces
+  if (is_auto)
+    lcp_itf_pair_sync_state_all ();
+}
+
+int
+lcp_sync (void)
+{
+  lcp_main_t *lcpm = &lcp_main;
+
+  return lcpm->lcp_sync;
+}
+
+void
+lcp_set_auto_subint (u8 is_auto)
+{
+  lcp_main_t *lcpm = &lcp_main;
+
+  lcpm->lcp_auto_subint = (is_auto != 0);
+}
+
+int
+lcp_auto_subint (void)
+{
+  lcp_main_t *lcpm = &lcp_main;
+
+  return lcpm->lcp_auto_subint;
+}
+
 /*
  * fd.io coding-style-patch-verification: ON
  *