Subject: [net-next 10/11] net/mlx5e: Implement queue mgmt ops and single channel swap

From: Saeed Mahameed <[email-masked]>
Date: Thu, 16 Jan 2025 13:55:28 -0800

From: Saeed Mahameed <[email-masked]>

The bulk of the work is done in mlx5e_queue_mem_alloc, where we allocate
and create the new channel resources, similar to
mlx5e_safe_switch_params, but here we do it for a single channel using
existing params, sort of a clone channel.
To swap the old channel with the new one, we deactivate and close the
old channel then replace it with the new one, since the swap procedure
doesn't fail in mlx5, we do it all in one place (mlx5e_queue_start).

Signed-off-by: Saeed Mahameed <[email-masked]>
Reviewed-by: Dragos Tatulea <[email-masked]>
Reviewed-by: Tariq Toukan <[email-masked]>
---
 .../net/ethernet/mellanox/mlx5/core/en_main.c | 96 +++++++++++++++++++
 1 file changed, 96 insertions(+)

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_main.c b/drivers/net/ethernet/mellanox/mlx5/core/en_main.c
index 340ed7d3feac..1e03f2afe625 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/en_main.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en_main.c
@@ -5489,6 +5489,101 @@ static const struct netdev_stat_ops mlx5e_stat_ops = {
 	.get_base_stats      = mlx5e_get_base_stats,
 };
 
+struct mlx5_qmgmt_data {
+	struct mlx5e_channel *c;
+	struct mlx5e_channel_param cparam;
+};
+
+static int mlx5e_queue_mem_alloc(struct net_device *dev, void *newq, int queue_index)
+{
+	struct mlx5_qmgmt_data *new = (struct mlx5_qmgmt_data *)newq;
+	struct mlx5e_priv *priv = netdev_priv(dev);
+	struct mlx5e_channels *chs = &priv->channels;
+	struct mlx5e_params params = chs->params;
+	struct mlx5_core_dev *mdev;
+	int err;
+
+	ASSERT_RTNL();
+	mutex_lock(&priv->state_lock);
+	if (!test_bit(MLX5E_STATE_OPENED, &priv->state)) {
+		err = -ENODEV;
+		goto unlock;
+	}
+
+	if (queue_index >= chs->num) {
+		err = -ERANGE;
+		goto unlock;
+	}
+
+	if (MLX5E_GET_PFLAG(&chs->params, MLX5E_PFLAG_TX_PORT_TS) ||
+	    chs->params.ptp_rx   ||
+	    chs->params.xdp_prog ||
+	    priv->htb) {
+		netdev_err(priv->netdev,
+			   "Cloning channels with Port/rx PTP, XDP or HTB is not supported\n");
+		err = -EOPNOTSUPP;
+		goto unlock;
+	}
+
+	mdev = mlx5_sd_ch_ix_get_dev(priv->mdev, queue_index);
+	err = mlx5e_build_channel_param(mdev, &params, &new->cparam);
+	if (err) {
+		return err;
+		goto unlock;
+	}
+
+	err = mlx5e_open_channel(priv, queue_index, &params, NULL, &new->c);
+unlock:
+	mutex_unlock(&priv->state_lock);
+	return err;
+}
+
+static void mlx5e_queue_mem_free(struct net_device *dev, void *mem)
+{
+	struct mlx5_qmgmt_data *data = (struct mlx5_qmgmt_data *)mem;
+
+	/* not supposed to happen since mlx5e_queue_start never fails
+	 * but this is how this should be implemented just in case
+	 */
+	if (data->c)
+		mlx5e_close_channel(data->c);
+}
+
+static int mlx5e_queue_stop(struct net_device *dev, void *oldq, int queue_index)
+{
+	/* mlx5e_queue_start does not fail, we stop the old queue there */
+	return 0;
+}
+
+static int mlx5e_queue_start(struct net_device *dev, void *newq, int queue_index)
+{
+	struct mlx5_qmgmt_data *new = (struct mlx5_qmgmt_data *)newq;
+	struct mlx5e_priv *priv = netdev_priv(dev);
+	struct mlx5e_channel *old;
+
+	mutex_lock(&priv->state_lock);
+
+	/* stop and close the old */
+	old = priv->channels.c[queue_index];
+	mlx5e_deactivate_priv_channels(priv);
+	/* close old before activating new, to avoid napi conflict */
+	mlx5e_close_channel(old);
+
+	/* start the new */
+	priv->channels.c[queue_index] = new->c;
+	mlx5e_activate_priv_channels(priv);
+	mutex_unlock(&priv->state_lock);
+	return 0;
+}
+
+static const struct netdev_queue_mgmt_ops mlx5e_queue_mgmt_ops = {
+	.ndo_queue_mem_size	=	sizeof(struct mlx5_qmgmt_data),
+	.ndo_queue_mem_alloc	=	mlx5e_queue_mem_alloc,
+	.ndo_queue_mem_free	=	mlx5e_queue_mem_free,
+	.ndo_queue_start	=	mlx5e_queue_start,
+	.ndo_queue_stop		=	mlx5e_queue_stop,
+};
+
 static void mlx5e_build_nic_netdev(struct net_device *netdev)
 {
 	struct mlx5e_priv *priv = netdev_priv(netdev);
@@ -5499,6 +5594,7 @@ static void mlx5e_build_nic_netdev(struct net_device *netdev)
 	SET_NETDEV_DEV(netdev, mdev->device);
 
 	netdev->netdev_ops = &mlx5e_netdev_ops;
+	netdev->queue_mgmt_ops = &mlx5e_queue_mgmt_ops;
 	netdev->xdp_metadata_ops = &mlx5e_xdp_metadata_ops;
 	netdev->xsk_tx_metadata_ops = &mlx5e_xsk_tx_metadata_ops;
 
-- 
2.48.0