vdpa/mlx5: update mlx_features with driver state check

Add logic in mlx5_vdpa_set_attr() to ensure the VIRTIO_NET_F_MAC
feature bit is properly set only when the device is not yet in
the DRIVER_OK (running) state.

This makes the MAC address visible in the output of:

 vdpa dev config show -jp

when the device is created without an initial MAC address.

Signed-off-by: Cindy Lu <lulu@redhat.com>
Reviewed-by: Dragos Tatulea <dtatulea@nvidia.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Message-Id: <20260126094848.9601-2-lulu@redhat.com>

Author: Cindy Lu

drivers/vdpa/mlx5/net/mlx5_vnet.c

@@ -4046,21 +4046,30 @@ static int mlx5_vdpa_set_attr(struct vdpa_mgmt_dev *v_mdev, struct vdpa_device *
 	struct mlx5_vdpa_dev *mvdev;
 	struct mlx5_vdpa_net *ndev;
 	struct mlx5_core_dev *mdev;
-	int err = -EOPNOTSUPP;
+	int err = 0;
 
 	mvdev = to_mvdev(dev);
 	ndev = to_mlx5_vdpa_ndev(mvdev);
 	mdev = mvdev->mdev;
 	config = &ndev->config;
 
 	down_write(&ndev->reslock);
-	if (add_config->mask & (1 << VDPA_ATTR_DEV_NET_CFG_MACADDR)) {
+
+	if (add_config->mask & BIT_ULL(VDPA_ATTR_DEV_NET_CFG_MACADDR)) {
+		if (!(ndev->mvdev.status & VIRTIO_CONFIG_S_DRIVER_OK)) {
+			ndev->mvdev.mlx_features |= BIT_ULL(VIRTIO_NET_F_MAC);
+		} else {
+			mlx5_vdpa_warn(mvdev, "device running, skip updating MAC\n");
+			err = -EBUSY;
+			goto out;
+		}
 		pfmdev = pci_get_drvdata(pci_physfn(mdev->pdev));
 		err = mlx5_mpfs_add_mac(pfmdev, config->mac);
 		if (!err)
 			ether_addr_copy(config->mac, add_config->net.mac);
 	}
 
+out:
 	up_write(&ndev->reslock);
 	return err;
 }