netdev - [PATCH net-next 5/6] sfc: introduce pedit add actions on the ipv4 ttl field

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Message-ID: <20230823111725.28090-6-pieter.jansen-van-vuuren@amd.com>
Date: Wed, 23 Aug 2023 12:17:24 +0100
From: Pieter Jansen van Vuuren <pieter.jansen-van-vuuren@....com>
To: <netdev@...r.kernel.org>, <linux-net-drivers@....com>
CC: <davem@...emloft.net>, <kuba@...nel.org>, <pabeni@...hat.com>,
	<edumazet@...gle.com>, <ecree.xilinx@...il.com>, <habetsm.xilinx@...il.com>,
	Pieter Jansen van Vuuren <pieter.jansen-van-vuuren@....com>
Subject: [PATCH net-next 5/6] sfc: introduce pedit add actions on the ipv4 ttl field

Introduce pedit add actions and use it to achieve decrement ttl offload.
Decrement ttl can be achieved by adding 0xff to the ttl field.

Co-developed-by: Edward Cree <ecree.xilinx@...il.com>
Signed-off-by: Edward Cree <ecree.xilinx@...il.com>
Signed-off-by: Pieter Jansen van Vuuren <pieter.jansen-van-vuuren@....com>
---
 drivers/net/ethernet/sfc/tc.c | 45 +++++++++++++++++++++++++++++++++++
 1 file changed, 45 insertions(+)

diff --git a/drivers/net/ethernet/sfc/tc.c b/drivers/net/ethernet/sfc/tc.c
index dc6275dee94a..8ba5816b51f2 100644
--- a/drivers/net/ethernet/sfc/tc.c
+++ b/drivers/net/ethernet/sfc/tc.c
@@ -1067,6 +1067,46 @@ static int efx_tc_complete_mac_mangle(struct efx_nic *efx,
  * earlier partial mangle, consume and apply to @act by calling
  * efx_tc_complete_mac_mangle().
  */
+static int efx_tc_pedit_add(struct efx_nic *efx, struct efx_tc_action_set *act,
+			    const struct flow_action_entry *fa,
+			    struct netlink_ext_ack *extack)
+{
+	switch (fa->mangle.htype) {
+	case FLOW_ACT_MANGLE_HDR_TYPE_IP4:
+		switch (fa->mangle.offset) {
+		case offsetof(struct iphdr, ttl):
+			/* check that pedit applies to ttl only */
+			if (fa->mangle.mask != ~EFX_TC_HDR_TYPE_TTL_MASK)
+				break;
+
+			/* Adding 0xff is equivalent to decrementing the ttl.
+			 * Other added values are not supported.
+			 */
+			if ((fa->mangle.val & EFX_TC_HDR_TYPE_TTL_MASK) != U8_MAX)
+				break;
+
+			/* check that we do not decrement ttl twice */
+			if (!efx_tc_flower_action_order_ok(act,
+							   EFX_TC_AO_DEC_TTL)) {
+				NL_SET_ERR_MSG_MOD(extack, "Unsupported: multiple dec ttl");
+				return -EOPNOTSUPP;
+			}
+			act->do_ttl_dec = 1;
+			return 0;
+		default:
+			break;
+		}
+		break;
+	default:
+		break;
+	}
+
+	NL_SET_ERR_MSG_FMT_MOD(extack,
+			       "Unsupported: ttl add action type %x %x %x/%x",
+			       fa->mangle.htype, fa->mangle.offset,
+			       fa->mangle.val, fa->mangle.mask);
+	return -EOPNOTSUPP;
+}
 
 static int efx_tc_mangle(struct efx_nic *efx, struct efx_tc_action_set *act,
 			 const struct flow_action_entry *fa,
@@ -2013,6 +2053,11 @@ static int efx_tc_flower_replace(struct efx_nic *efx,
 			act->vlan_proto[act->vlan_push] = fa->vlan.proto;
 			act->vlan_push++;
 			break;
+		case FLOW_ACTION_ADD:
+			rc = efx_tc_pedit_add(efx, act, fa, extack);
+			if (rc < 0)
+				goto release;
+			break;
 		case FLOW_ACTION_MANGLE:
 			rc = efx_tc_mangle(efx, act, fa, &mung, extack, &match);
 			if (rc < 0)
-- 
2.17.1