net/mlx5: SD, Do not query MPIR register if no sd_group

Unconditionally calling the MPIR query on BF separate mode yields the FW
syndrome below [1]. Do not call it unless admin clearly specified the SD
group, i.e. expressing the intention of using the multi-PF netdev
feature.

This fix covers cases not covered in
commit fca3b479 ("net/mlx5: Do not query MPIR on embedded CPU function").

[1]
mlx5_cmd_out_err:808:(pid 8267): ACCESS_REG(0x805) op_mod(0x1) failed,
status bad system state(0x4), syndrome (0x685f19), err(-5)

Fixes: 678eb448 ("net/mlx5: SD, Implement basic query and instantiation")
Signed-off-by: Tariq Toukan <tariqt@nvidia.com>
Reviewed-by: Gal Pressman <gal@nvidia.com>
Link: https://patch.msgid.link/20240808144107.2095424-2-tariqt@nvidia.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/ethernet/mellanox/mlx5/core/lib/sd.c

@@ -126,7 +126,7 @@ static bool mlx5_sd_is_supported(struct mlx5_core_dev *dev, u8 host_buses)
 }
 
 static int mlx5_query_sd(struct mlx5_core_dev *dev, bool *sdm,
-			 u8 *host_buses, u8 *sd_group)
+			 u8 *host_buses)
 {
 	u32 out[MLX5_ST_SZ_DW(mpir_reg)];
 	int err;
@@ -135,10 +135,6 @@ static int mlx5_query_sd(struct mlx5_core_dev *dev, bool *sdm,
 	if (err)
 		return err;
 
-	err = mlx5_query_nic_vport_sd_group(dev, sd_group);
-	if (err)
-		return err;
-
 	*sdm = MLX5_GET(mpir_reg, out, sdm);
 	*host_buses = MLX5_GET(mpir_reg, out, host_buses);
 
@@ -166,19 +162,23 @@ static int sd_init(struct mlx5_core_dev *dev)
 	if (mlx5_core_is_ecpf(dev))
 		return 0;
 
+	err = mlx5_query_nic_vport_sd_group(dev, &sd_group);
+	if (err)
+		return err;
+
+	if (!sd_group)
+		return 0;
+
 	if (!MLX5_CAP_MCAM_REG(dev, mpir))
 		return 0;
 
-	err = mlx5_query_sd(dev, &sdm, &host_buses, &sd_group);
+	err = mlx5_query_sd(dev, &sdm, &host_buses);
 	if (err)
 		return err;
 
 	if (!sdm)
 		return 0;
 
-	if (!sd_group)
-		return 0;
-
 	group_id = mlx5_sd_group_id(dev, sd_group);
 
 	if (!mlx5_sd_is_supported(dev, host_buses)) {