mlxsw: spectrum_span: Add SPAN session identifier support

When packets are mirrored to the CPU, the trap identifier with which the
packets are trapped is determined according to the session identifier of
the SPAN agent performing the mirroring. Packets that are trapped for
the same logical reason (e.g., buffer drops) should use the same session
identifier.

Currently, a single session is implicitly supported (identifier 0) and
is used for packets that are mirrored to the CPU due to buffer drops
(e.g., early drop).

Subsequent patches are going to mirror packets to the CPU due to
sampling, which will require a different session identifier.

Prepare for that by making the session identifier an attribute of the
SPAN agent.
Signed-off-by: Ido Schimmel <idosch@nvidia.com>
Reviewed-by: Jiri Pirko <jiri@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/mellanox/mlxsw/spectrum_qdisc.c

@@ -1404,7 +1404,9 @@ static int mlxsw_sp_qevent_trap_configure(struct mlxsw_sp *mlxsw_sp,
 					  struct mlxsw_sp_mall_entry *mall_entry,
 					  struct mlxsw_sp_qevent_binding *qevent_binding)
 {
-	struct mlxsw_sp_span_agent_parms agent_parms = {};
+	struct mlxsw_sp_span_agent_parms agent_parms = {
+		.session_id = MLXSW_SP_SPAN_SESSION_ID_BUFFER,
+	};
 	int err;
 
 	err = mlxsw_sp_trap_group_policer_hw_id_get(mlxsw_sp,

drivers/net/ethernet/mellanox/mlxsw/spectrum_span.c

@@ -186,6 +186,7 @@ mlxsw_sp_span_entry_phys_configure(struct mlxsw_sp_span_entry *span_entry,
 	/* Create a new port analayzer entry for local_port. */
 	mlxsw_reg_mpat_pack(mpat_pl, pa_id, local_port, true,
 			    MLXSW_REG_MPAT_SPAN_TYPE_LOCAL_ETH);
+	mlxsw_reg_mpat_session_id_set(mpat_pl, sparms.session_id);
 	mlxsw_reg_mpat_pide_set(mpat_pl, sparms.policer_enable);
 	mlxsw_reg_mpat_pid_set(mpat_pl, sparms.policer_id);
 
@@ -203,6 +204,7 @@ mlxsw_sp_span_entry_deconfigure_common(struct mlxsw_sp_span_entry *span_entry,
 	int pa_id = span_entry->id;
 
 	mlxsw_reg_mpat_pack(mpat_pl, pa_id, local_port, false, span_type);
+	mlxsw_reg_mpat_session_id_set(mpat_pl, span_entry->parms.session_id);
 	mlxsw_reg_write(mlxsw_sp->core, MLXSW_REG(mpat), mpat_pl);
 }
 
@@ -938,7 +940,8 @@ mlxsw_sp_span_entry_find_by_parms(struct mlxsw_sp *mlxsw_sp,
 
 		if (refcount_read(&curr->ref_count) && curr->to_dev == to_dev &&
 		    curr->parms.policer_enable == sparms->policer_enable &&
-		    curr->parms.policer_id == sparms->policer_id)
+		    curr->parms.policer_id == sparms->policer_id &&
+		    curr->parms.session_id == sparms->session_id)
 			return curr;
 	}
 	return NULL;
@@ -1085,6 +1088,7 @@ int mlxsw_sp_span_agent_get(struct mlxsw_sp *mlxsw_sp, int *p_span_id,
 
 	sparms.policer_id = parms->policer_id;
 	sparms.policer_enable = parms->policer_enable;
+	sparms.session_id = parms->session_id;
 	span_entry = mlxsw_sp_span_entry_get(mlxsw_sp, to_dev, ops, sparms);
 	if (!span_entry)
 		return -ENOBUFS;

drivers/net/ethernet/mellanox/mlxsw/spectrum_span.h

@@ -13,6 +13,18 @@
 struct mlxsw_sp;
 struct mlxsw_sp_port;
 
+/* SPAN session identifiers that correspond to MLXSW_TRAP_ID_MIRROR_SESSION<i>
+ * trap identifiers. The session identifier is an attribute of the SPAN agent,
+ * which determines the trap identifier of packets that are mirrored to the
+ * CPU. Packets that are trapped to the CPU for the same logical reason (e.g.,
+ * buffer drops) should use the same session identifier.
+ */
+enum mlxsw_sp_span_session_id {
+	MLXSW_SP_SPAN_SESSION_ID_BUFFER,
+
+	__MLXSW_SP_SPAN_SESSION_ID_MAX = 8,
+};
+
 struct mlxsw_sp_span_parms {
 	struct mlxsw_sp_port *dest_port; /* NULL for unoffloaded SPAN. */
 	unsigned int ttl;
@@ -23,6 +35,7 @@ struct mlxsw_sp_span_parms {
 	u16 vid;
 	u16 policer_id;
 	bool policer_enable;
+	enum mlxsw_sp_span_session_id session_id;
 };
 
 enum mlxsw_sp_span_trigger {
@@ -41,6 +54,7 @@ struct mlxsw_sp_span_agent_parms {
 	const struct net_device *to_dev;
 	u16 policer_id;
 	bool policer_enable;
+	enum mlxsw_sp_span_session_id session_id;
 };
 
 struct mlxsw_sp_span_entry_ops;