vdpa/mlx5: make MTU/STATUS presence conditional on feature bits

The spec says:
    mtu only exists if VIRTIO_NET_F_MTU is set
    status only exists if VIRTIO_NET_F_STATUS is set

We should only present MTU and STATUS conditionally depending on
the feature bits.
Signed-off-by: Si-Wei Liu <si-wei.liu@oracle.com>
Reviewed-by: Eli Cohen <elic@nvidia.com>
Message-Id: <1675725124-7375-6-git-send-email-si-wei.liu@oracle.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

drivers/vdpa/mlx5/net/mlx5_vnet.c

@@ -3046,6 +3046,8 @@ static int event_handler(struct notifier_block *nb, unsigned long event, void *p
 	struct mlx5_vdpa_wq_ent *wqent;
 
 	if (event == MLX5_EVENT_TYPE_PORT_CHANGE) {
+		if (!(ndev->mvdev.actual_features & BIT_ULL(VIRTIO_NET_F_STATUS)))
+			return NOTIFY_DONE;
 		switch (eqe->sub_type) {
 		case MLX5_PORT_CHANGE_SUBTYPE_DOWN:
 		case MLX5_PORT_CHANGE_SUBTYPE_ACTIVE:
@@ -3155,16 +3157,20 @@ static int mlx5_vdpa_dev_add(struct vdpa_mgmt_dev *v_mdev, const char *name,
 			goto err_alloc;
 	}
 
-	err = query_mtu(mdev, &mtu);
-	if (err)
-		goto err_alloc;
+	if (ndev->mvdev.mlx_features & BIT_ULL(VIRTIO_NET_F_MTU)) {
+		err = query_mtu(mdev, &mtu);
+		if (err)
+			goto err_alloc;
 
-	ndev->config.mtu = cpu_to_mlx5vdpa16(mvdev, mtu);
+		ndev->config.mtu = cpu_to_mlx5vdpa16(mvdev, mtu);
+	}
 
-	if (get_link_state(mvdev))
-		ndev->config.status |= cpu_to_mlx5vdpa16(mvdev, VIRTIO_NET_S_LINK_UP);
-	else
-		ndev->config.status &= cpu_to_mlx5vdpa16(mvdev, ~VIRTIO_NET_S_LINK_UP);
+	if (ndev->mvdev.mlx_features & BIT_ULL(VIRTIO_NET_F_STATUS)) {
+		if (get_link_state(mvdev))
+			ndev->config.status |= cpu_to_mlx5vdpa16(mvdev, VIRTIO_NET_S_LINK_UP);
+		else
+			ndev->config.status &= cpu_to_mlx5vdpa16(mvdev, ~VIRTIO_NET_S_LINK_UP);
+	}
 
 	if (add_config->mask & (1 << VDPA_ATTR_DEV_NET_CFG_MACADDR)) {
 		memcpy(ndev->config.mac, add_config->net.mac, ETH_ALEN);