netdev - [net 03/15] net/mlx5e: Allow IPv4 ttl & IPv6 hop

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Date:   Fri, 29 Mar 2019 13:42:11 -0700
From:   Saeed Mahameed <saeedm@...lanox.com>
To:     "David S. Miller" <davem@...emloft.net>
Cc:     netdev@...r.kernel.org, Dmytro Linkin <dmitrolin@...lanox.com>,
        Saeed Mahameed <saeedm@...lanox.com>
Subject: [net 03/15] net/mlx5e: Allow IPv4 ttl & IPv6 hop_limit rewrite for all L4 protocols

From: Dmytro Linkin <dmitrolin@...lanox.com>

For some protocols we are not allowing IP header rewrite offload, since
the HW is not capable to properly adjust the l4 checksum. However, TTL
& HOPLIMIT modification can be done for all IP protocols, because they
are not part of the pseudo header taken into account for checksum.

Fixes: 738678817573 ("drivers: net: use flow action infrastructure")
Signed-off-by: Dmytro Linkin <dmitrolin@...lanox.com>
Signed-off-by: Saeed Mahameed <saeedm@...lanox.com>
---
 .../net/ethernet/mellanox/mlx5/core/en_tc.c   | 52 +++++++++++++++++--
 1 file changed, 48 insertions(+), 4 deletions(-)

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_tc.c b/drivers/net/ethernet/mellanox/mlx5/core/en_tc.c
index b4967a0ff8c7..2b85f93a1c52 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/en_tc.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en_tc.c
@@ -2158,6 +2158,52 @@ static bool csum_offload_supported(struct mlx5e_priv *priv,
 	return true;
 }
 
+struct ip_ttl_word {
+	__u8	ttl;
+	__u8	protocol;
+	__sum16	check;
+};
+
+struct ipv6_hoplimit_word {
+	__be16	payload_len;
+	__u8	nexthdr;
+	__u8	hop_limit;
+};
+
+static bool is_action_keys_supported(const struct flow_action_entry *act)
+{
+	u32 mask, offset;
+	u8 htype;
+
+	htype = act->mangle.htype;
+	offset = act->mangle.offset;
+	mask = ~act->mangle.mask;
+	/* For IPv4 & IPv6 header check 4 byte word,
+	 * to determine that modified fields
+	 * are NOT ttl & hop_limit only.
+	 */
+	if (htype == FLOW_ACT_MANGLE_HDR_TYPE_IP4) {
+		struct ip_ttl_word *ttl_word =
+			(struct ip_ttl_word *)&mask;
+
+		if (offset != offsetof(struct iphdr, ttl) ||
+		    ttl_word->protocol ||
+		    ttl_word->check) {
+			return true;
+		}
+	} else if (htype == FLOW_ACT_MANGLE_HDR_TYPE_IP6) {
+		struct ipv6_hoplimit_word *hoplimit_word =
+			(struct ipv6_hoplimit_word *)&mask;
+
+		if (offset != offsetof(struct ipv6hdr, payload_len) ||
+		    hoplimit_word->payload_len ||
+		    hoplimit_word->nexthdr) {
+			return true;
+		}
+	}
+	return false;
+}
+
 static bool modify_header_match_supported(struct mlx5_flow_spec *spec,
 					  struct flow_action *flow_action,
 					  u32 actions,
@@ -2165,9 +2211,9 @@ static bool modify_header_match_supported(struct mlx5_flow_spec *spec,
 {
 	const struct flow_action_entry *act;
 	bool modify_ip_header;
-	u8 htype, ip_proto;
 	void *headers_v;
 	u16 ethertype;
+	u8 ip_proto;
 	int i;
 
 	if (actions & MLX5_FLOW_CONTEXT_ACTION_DECAP)
@@ -2187,9 +2233,7 @@ static bool modify_header_match_supported(struct mlx5_flow_spec *spec,
 		    act->id != FLOW_ACTION_ADD)
 			continue;
 
-		htype = act->mangle.htype;
-		if (htype == FLOW_ACT_MANGLE_HDR_TYPE_IP4 ||
-		    htype == FLOW_ACT_MANGLE_HDR_TYPE_IP6) {
+		if (is_action_keys_supported(act)) {
 			modify_ip_header = true;
 			break;
 		}
-- 
2.20.1