mlxsw: spectrum_acl: Allocate default actions for internal TCAM regions

In Spectrum-2 and later ASICs, each TCAM region has a default action
that is executed in case a packet did not match any rule in the region.
The location of the action in the database (KVDL) is computed by adding
the region's index to a base value.

Some TCAM regions are not exposed to the host and used internally by the
device. Allocate KVDL entries for the default actions of these regions
to avoid the host from overwriting them.

With mlxsw, lookups in the internal regions are not currently performed,
but it is a good practice not to overwrite their default actions.
Signed-off-by: Ido Schimmel <idosch@nvidia.com>
Reviewed-by: Petr Machata <petrm@nvidia.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

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

@@ -33,6 +33,7 @@ enum mlxsw_res_id {
 	MLXSW_RES_ID_ACL_MAX_REGIONS,
 	MLXSW_RES_ID_ACL_MAX_GROUPS,
 	MLXSW_RES_ID_ACL_MAX_GROUP_SIZE,
+	MLXSW_RES_ID_ACL_MAX_DEFAULT_ACTIONS,
 	MLXSW_RES_ID_ACL_FLEX_KEYS,
 	MLXSW_RES_ID_ACL_MAX_ACTION_PER_RULE,
 	MLXSW_RES_ID_ACL_ACTIONS_PER_SET,
@@ -90,6 +91,7 @@ static u16 mlxsw_res_ids[] = {
 	[MLXSW_RES_ID_ACL_MAX_REGIONS] = 0x2903,
 	[MLXSW_RES_ID_ACL_MAX_GROUPS] = 0x2904,
 	[MLXSW_RES_ID_ACL_MAX_GROUP_SIZE] = 0x2905,
+	[MLXSW_RES_ID_ACL_MAX_DEFAULT_ACTIONS] = 0x2908,
 	[MLXSW_RES_ID_ACL_FLEX_KEYS] = 0x2910,
 	[MLXSW_RES_ID_ACL_MAX_ACTION_PER_RULE] = 0x2911,
 	[MLXSW_RES_ID_ACL_ACTIONS_PER_SET] = 0x2912,

drivers/net/ethernet/mellanox/mlxsw/spectrum2_acl_tcam.c

@@ -77,7 +77,14 @@ static int mlxsw_sp2_acl_tcam_init(struct mlxsw_sp *mlxsw_sp, void *priv,
 	int i;
 	int err;
 
+	/* Some TCAM regions are not exposed to the host and used internally
+	 * by the device. Allocate KVDL entries for the default actions of
+	 * these regions to avoid the host from overwriting them.
+	 */
 	tcam->kvdl_count = _tcam->max_regions;
+	if (MLXSW_CORE_RES_VALID(mlxsw_sp->core, ACL_MAX_DEFAULT_ACTIONS))
+		tcam->kvdl_count = MLXSW_CORE_RES_GET(mlxsw_sp->core,
+						      ACL_MAX_DEFAULT_ACTIONS);
 	err = mlxsw_sp_kvdl_alloc(mlxsw_sp, MLXSW_SP_KVDL_ENTRY_TYPE_ACTSET,
 				  tcam->kvdl_count, &tcam->kvdl_index);
 	if (err)
@@ -97,7 +104,10 @@ static int mlxsw_sp2_acl_tcam_init(struct mlxsw_sp *mlxsw_sp, void *priv,
 		goto err_afa_block_continue;
 	enc_actions = mlxsw_afa_block_cur_set(afa_block);
 
-	for (i = 0; i < tcam->kvdl_count; i++) {
+	/* Only write to KVDL entries used by TCAM regions exposed to the
+	 * host.
+	 */
+	for (i = 0; i < _tcam->max_regions; i++) {
 		mlxsw_reg_pefa_pack(pefa_pl, tcam->kvdl_index + i,
 				    true, enc_actions);
 		err = mlxsw_reg_write(mlxsw_sp->core, MLXSW_REG(pefa), pefa_pl);