linux-kernel - [PATCH 5.17 009/114] net: mscc: ocelot: restrict tc-trap actions to VCAP IS2 lookup 0

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Message-Id: <20220516193625.765249279@linuxfoundation.org>
Date:   Mon, 16 May 2022 21:35:43 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Vladimir Oltean <vladimir.oltean@....com>,
        Jakub Kicinski <kuba@...nel.org>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.17 009/114] net: mscc: ocelot: restrict tc-trap actions to VCAP IS2 lookup 0

From: Vladimir Oltean <vladimir.oltean@....com>

[ Upstream commit 477d2b91623e682e9a8126ea92acb8f684969cc7 ]

Once the CPU port was added to the destination port mask of a packet, it
can never be cleared, so even packets marked as dropped by the MASK_MODE
of a VCAP IS2 filter will still reach it. This is why we need the
OCELOT_POLICER_DISCARD to "kill dropped packets dead" and make software
stop seeing them.

We disallow policer rules from being put on any other chain than the one
for the first lookup, but we don't do this for "drop" rules, although we
should. This change is merely ascertaining that the rules dont't
(completely) work and letting the user know.

The blamed commit is the one that introduced the multi-chain architecture
in ocelot. Prior to that, we should have always offloaded the filters to
VCAP IS2 lookup 0, where they did work.

Fixes: 1397a2eb52e2 ("net: mscc: ocelot: create TCAM skeleton from tc filter chains")
Signed-off-by: Vladimir Oltean <vladimir.oltean@....com>
Signed-off-by: Jakub Kicinski <kuba@...nel.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/net/ethernet/mscc/ocelot_flower.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/mscc/ocelot_flower.c b/drivers/net/ethernet/mscc/ocelot_flower.c
index fdb4d7e7296c..cb602a226149 100644
--- a/drivers/net/ethernet/mscc/ocelot_flower.c
+++ b/drivers/net/ethernet/mscc/ocelot_flower.c
@@ -278,9 +278,10 @@ static int ocelot_flower_parse_action(struct ocelot *ocelot, int port,
 			filter->type = OCELOT_VCAP_FILTER_OFFLOAD;
 			break;
 		case FLOW_ACTION_TRAP:
-			if (filter->block_id != VCAP_IS2) {
+			if (filter->block_id != VCAP_IS2 ||
+			    filter->lookup != 0) {
 				NL_SET_ERR_MSG_MOD(extack,
-						   "Trap action can only be offloaded to VCAP IS2");
+						   "Trap action can only be offloaded to VCAP IS2 lookup 0");
 				return -EOPNOTSUPP;
 			}
 			if (filter->goto_target != -1) {
-- 
2.35.1