gve: add support to change ring size via ethtool

Allow the user to change ring size via ethtool if
supported by the device. The driver relies on the
ring size ranges queried from device to validate
ring sizes requested by the user.

Reviewed-by: Praveen Kaligineedi <pkaligineedi@google.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: Harshitha Ramamurthy <hramamurthy@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 79 insertions, 6 deletions

diff --git a/drivers/net/ethernet/google/gve/gve_ethtool.c b/drivers/net/ethernet/google/gve/gve_ethtool.c
index dbe05402d40b..815dead31673 100644
--- a/drivers/net/ethernet/google/gve/gve_ethtool.c
+++ b/drivers/net/ethernet/google/gve/gve_ethtool.c
@@ -490,8 +490,8 @@ static void gve_get_ringparam(struct net_device *netdev,
 {
 	struct gve_priv *priv = netdev_priv(netdev);
 
-	cmd->rx_max_pending = priv->rx_desc_cnt;
-	cmd->tx_max_pending = priv->tx_desc_cnt;
+	cmd->rx_max_pending = priv->max_rx_desc_cnt;
+	cmd->tx_max_pending = priv->max_tx_desc_cnt;
 	cmd->rx_pending = priv->rx_desc_cnt;
 	cmd->tx_pending = priv->tx_desc_cnt;
 
@@ -503,20 +503,93 @@ static void gve_get_ringparam(struct net_device *netdev,
 		kernel_cmd->tcp_data_split = ETHTOOL_TCP_DATA_SPLIT_DISABLED;
 }
 
+static int gve_adjust_ring_sizes(struct gve_priv *priv,
+				 u16 new_tx_desc_cnt,
+				 u16 new_rx_desc_cnt)
+{
+	struct gve_tx_alloc_rings_cfg tx_alloc_cfg = {0};
+	struct gve_rx_alloc_rings_cfg rx_alloc_cfg = {0};
+	struct gve_qpls_alloc_cfg qpls_alloc_cfg = {0};
+	struct gve_qpl_config new_qpl_cfg;
+	int err;
+
+	/* get current queue configuration */
+	gve_get_curr_alloc_cfgs(priv, &qpls_alloc_cfg,
+				&tx_alloc_cfg, &rx_alloc_cfg);
+
+	/* copy over the new ring_size from ethtool */
+	tx_alloc_cfg.ring_size = new_tx_desc_cnt;
+	rx_alloc_cfg.ring_size = new_rx_desc_cnt;
+
+	/* qpl_cfg is not read-only, it contains a map that gets updated as
+	 * rings are allocated, which is why we cannot use the yet unreleased
+	 * one in priv.
+	 */
+	qpls_alloc_cfg.qpl_cfg = &new_qpl_cfg;
+	tx_alloc_cfg.qpl_cfg = &new_qpl_cfg;
+	rx_alloc_cfg.qpl_cfg = &new_qpl_cfg;
+
+	if (netif_running(priv->dev)) {
+		err = gve_adjust_config(priv, &qpls_alloc_cfg,
+					&tx_alloc_cfg, &rx_alloc_cfg);
+		if (err)
+			return err;
+	}
+
+	/* Set new ring_size for the next up */
+	priv->tx_desc_cnt = new_tx_desc_cnt;
+	priv->rx_desc_cnt = new_rx_desc_cnt;
+
+	return 0;
+}
+
+static int gve_validate_req_ring_size(struct gve_priv *priv, u16 new_tx_desc_cnt,
+				      u16 new_rx_desc_cnt)
+{
+	/* check for valid range */
+	if (new_tx_desc_cnt < priv->min_tx_desc_cnt ||
+	    new_tx_desc_cnt > priv->max_tx_desc_cnt ||
+	    new_rx_desc_cnt < priv->min_rx_desc_cnt ||
+	    new_rx_desc_cnt > priv->max_rx_desc_cnt) {
+		dev_err(&priv->pdev->dev, "Requested descriptor count out of range\n");
+		return -EINVAL;
+	}
+
+	if (!is_power_of_2(new_tx_desc_cnt) || !is_power_of_2(new_rx_desc_cnt)) {
+		dev_err(&priv->pdev->dev, "Requested descriptor count has to be a power of 2\n");
+		return -EINVAL;
+	}
+	return 0;
+}
+
 static int gve_set_ringparam(struct net_device *netdev,
 			     struct ethtool_ringparam *cmd,
 			     struct kernel_ethtool_ringparam *kernel_cmd,
 			     struct netlink_ext_ack *extack)
 {
 	struct gve_priv *priv = netdev_priv(netdev);
+	u16 new_tx_cnt, new_rx_cnt;
+	int err;
+
+	err = gve_set_hsplit_config(priv, kernel_cmd->tcp_data_split);
+	if (err)
+		return err;
 
-	if (priv->tx_desc_cnt != cmd->tx_pending ||
-	    priv->rx_desc_cnt != cmd->rx_pending) {
-		dev_info(&priv->pdev->dev, "Modify ring size is not supported.\n");
+	if (cmd->tx_pending == priv->tx_desc_cnt && cmd->rx_pending == priv->rx_desc_cnt)
+		return 0;
+
+	if (!priv->modify_ring_size_enabled) {
+		dev_err(&priv->pdev->dev, "Modify ring size is not supported.\n");
 		return -EOPNOTSUPP;
 	}
 
-	return gve_set_hsplit_config(priv, kernel_cmd->tcp_data_split);
+	new_tx_cnt = cmd->tx_pending;
+	new_rx_cnt = cmd->rx_pending;
+
+	if (gve_validate_req_ring_size(priv, new_tx_cnt, new_rx_cnt))
+		return -EINVAL;
+
+	return gve_adjust_ring_sizes(priv, new_tx_cnt, new_rx_cnt);
 }
 
 static int gve_user_reset(struct net_device *netdev, u32 *flags)