kernel: DSA roaming fix for Marvell mv88e6xxx

Marvell mv88e6xxx switch series cannot perform MAC learning from
CPU-injected (FROM_CPU) DSA frames, which results in 2 issues.
- excessive flooding, due to the fact that DSA treats those addresses
as unknown
- the risk of stale routes, which can lead to temporary packet loss

Backport those patch series from netdev mailing list, which solve these
issues by adding and clearing static entries to the switch's FDB.

Add a hack patch to set default VID to 1 in port_fdb_{add,del}. Otherwise
the static entries will be added to the switch's private FDB if VLAN
filtering disabled, which will not work.

The switch may generate an "ATU violation" warning when a client moves
from the CPU port to a switch port because the static ATU entry added by
DSA core still points to the CPU port. DSA core will then clear the static
entry so it is not fatal. Disable the warning so it will not confuse users.

Link: https://lore.kernel.org/netdev/20210106095136.224739-1-olteanv@gmail.com/
Link: https://lore.kernel.org/netdev/20210116012515.3152-1-tobias@waldekranz.com/
Ref: https://gitlab.nic.cz/turris/turris-build/-/issues/165
Signed-off-by: DENG Qingfang <dqfext@gmail.com>

1 files changed, 36 insertions, 0 deletions

diff --git a/target/linux/generic/pending-5.10/765-net-dsa-Include-local-addresses-in-assisted-CPU-port.patch b/target/linux/generic/pending-5.10/765-net-dsa-Include-local-addresses-in-assisted-CPU-port.patch
new file mode 100644
index 0000000000..9246d1fa40
--- /dev/null
+++ b/target/linux/generic/pending-5.10/765-net-dsa-Include-local-addresses-in-assisted-CPU-port.patch
@@ -0,0 +1,36 @@
+From dd082716b43a3684b2f473ae5d1e76d1c076d86d Mon Sep 17 00:00:00 2001
+From: Tobias Waldekranz <tobias@waldekranz.com>
+Date: Sat, 16 Jan 2021 02:25:12 +0100
+Subject: [PATCH] net: dsa: Include local addresses in assisted CPU port
+ learning
+
+Add local addresses (i.e. the ports' MAC addresses) to the hardware
+FDB when assisted CPU port learning is enabled.
+
+NOTE: The bridge's own MAC address is also "local". If that address is
+not shared with any port, the bridge's MAC is not be added by this
+functionality - but the following commit takes care of that case.
+
+Signed-off-by: Tobias Waldekranz <tobias@waldekranz.com>
+---
+ net/dsa/slave.c | 8 +++++---
+ 1 file changed, 5 insertions(+), 3 deletions(-)
+
+--- a/net/dsa/slave.c
++++ b/net/dsa/slave.c
+@@ -2144,10 +2144,12 @@ static int dsa_slave_switchdev_event(str
+ 		fdb_info = ptr;
+ 
+ 		if (dsa_slave_dev_check(dev)) {
+-			if (!fdb_info->added_by_user)
+-				return NOTIFY_OK;
+-
+ 			dp = dsa_slave_to_port(dev);
++
++			if (fdb_info->local && dp->ds->assisted_learning_on_cpu_port)
++				dp = dp->cpu_dp;
++			else if (!fdb_info->added_by_user)
++				return NOTIFY_OK;
+ 		} else {
+ 			/* Snoop addresses learnt on foreign interfaces
+ 			 * bridged with us, for switches that don't