[net 03/15] net/mlx5e: Allow IPv4 ttl & IPv6 hop_limit rewrite for all L4 protocols

[Saeed Mahameed]

From: Dmytro Linkin <dmitro...@mellanox.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 <dmitro...@mellanox.com>
Signed-off-by: Saeed Mahameed <sae...@mellanox.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