net/mlx5e: Don't attempt to dereference the ppriv struct if not being eswitch manager

[ Upstream commit 8ffd569a ]

The check for cpu hit statistics was not returning immediate false for
any non vport rep netdev and hence we crashed (say on mlx5 probed VFs) if
user-space tool was calling into any possible netdev in the system.

Fix that by doing a proper check before dereferencing.

Fixes: 1d447a39 ('net/mlx5e: Extendable vport representor netdev private data')
Signed-off-by: Or Gerlitz <ogerlitz@mellanox.com>
Reported-by: Eli Cohen <eli@melloanox.com>
Reviewed-by: Eli Cohen <eli@melloanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/net/ethernet/mellanox/mlx5/core/en_rep.c

@@ -724,8 +724,12 @@ bool mlx5e_is_uplink_rep(struct mlx5e_priv *priv)
 static bool mlx5e_is_vf_vport_rep(struct mlx5e_priv *priv)
 {
 	struct mlx5e_rep_priv *rpriv = priv->ppriv;
-	struct mlx5_eswitch_rep *rep = rpriv->rep;
+	struct mlx5_eswitch_rep *rep;
 
+	if (!MLX5_CAP_GEN(priv->mdev, eswitch_flow_table))
+		return false;
+
+	rep = rpriv->rep;
 	if (rep && rep->vport != FDB_UPLINK_VPORT)
 		return true;