mlxsw: spectrum_qdisc: Offload mirroring on RED qevent early_drop

The RED qevents early_drop and mark can be offloaded under the following
fairly strict conditions:

- At most one filter is configured at the qevent block
- The protocol is "any"
- The classifier is matchall
- The action is trap, sample, or mirror with the same conditions as
  with other SPAN offloads
- The hw_counters type is none

In this patchset, implement offload of mirror for early_drop qevent.
The ECN trigger is currently not implemented in the FW and therefore
the mark qevent is not supported.

The qevent notifications look exactly like regular block binding
notifications with a binder type that identifies them as qevents.
Therefore the details of processing this binding are fairly similar
to the matchall offload.

struct flow_block_offload.sch points at the qdisc in question. Use it to
figure out if the qdisc is offloaded at all and what TC it configures.
Bounce bindings on not-offloaded qdiscs.

Individual bindings are kept in a list so that several qevents can share
the same block and all binding points get configured as the configured
filters change.
Signed-off-by: Petr Machata <petrm@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

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

@@ -1337,6 +1337,8 @@ static int mlxsw_sp_setup_tc_block(struct mlxsw_sp_port *mlxsw_sp_port,
 		return mlxsw_sp_setup_tc_block_clsact(mlxsw_sp_port, f, true);
 	case FLOW_BLOCK_BINDER_TYPE_CLSACT_EGRESS:
 		return mlxsw_sp_setup_tc_block_clsact(mlxsw_sp_port, f, false);
+	case FLOW_BLOCK_BINDER_TYPE_RED_EARLY_DROP:
+		return mlxsw_sp_setup_tc_block_qevent_early_drop(mlxsw_sp_port, f);
 	default:
 		return -EOPNOTSUPP;
 	}

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

@@ -1031,6 +1031,8 @@ int mlxsw_sp_setup_tc_tbf(struct mlxsw_sp_port *mlxsw_sp_port,
 			  struct tc_tbf_qopt_offload *p);
 int mlxsw_sp_setup_tc_fifo(struct mlxsw_sp_port *mlxsw_sp_port,
 			   struct tc_fifo_qopt_offload *p);
+int mlxsw_sp_setup_tc_block_qevent_early_drop(struct mlxsw_sp_port *mlxsw_sp_port,
+					      struct flow_block_offload *f);
 
 /* spectrum_fid.c */
 bool mlxsw_sp_fid_is_dummy(struct mlxsw_sp *mlxsw_sp, u16 fid_index);