Expose incremental RX resize through ethtool channel control.

get_channels() reports rx_count from adapter->num_rx_queues and max_rx
as IBMVETH_MAX_RX_QUEUES when MQ firmware is enabled, else 1.

set_channels() validates rx_count is within 1..IBMVETH_MAX_RX_QUEUES.
When rx_count changes and the interface is up, call
ibmveth_resize_rx_queues_incremental(). When the interface is down,
store the requested rx_count in adapter->num_rx_queues so the next open
registers that many queues. Non-MQ firmware returns -EOPNOTSUPP for
rx > 1.

TX queue changes keep existing stop/wake behavior when tx_count changes.

Signed-off-by: Mingming Cao <mmc@linux.ibm.com>
Reviewed-by: Dave Marquardt <davemarq@linux.ibm.com>
---
 drivers/net/ethernet/ibm/ibmveth.c | 58 +++++++++++++++++++++++++++---
 1 file changed, 54 insertions(+), 4 deletions(-)

diff --git a/drivers/net/ethernet/ibm/ibmveth.c b/drivers/net/ethernet/ibm/ibmveth.c
index ac4d89a66a8d..50a332ab83fd 100644
--- a/drivers/net/ethernet/ibm/ibmveth.c
+++ b/drivers/net/ethernet/ibm/ibmveth.c
@@ -2534,19 +2534,69 @@ static int ibmveth_set_channels(struct net_device *netdev,
 				struct ethtool_channels *channels)
 {
 	struct ibmveth_adapter *adapter = netdev_priv(netdev);
-	unsigned int old = netdev->real_num_tx_queues,
-		     goal = channels->tx_count;
+	unsigned int old_rx = adapter->num_rx_queues;
+	unsigned int goal_rx = channels->rx_count;
+	unsigned int old = netdev->real_num_tx_queues;
+	unsigned int goal = channels->tx_count;
+	int rxq_entries = adapter->rx_queue[0].num_slots;
 	int rc, i;
 
 	/* If ndo_open has not been called yet then don't allocate, just set
 	 * desired netdev_queue's and return
 	 */
-	if (!(netdev->flags & IFF_UP))
+	if (!(netdev->flags & IFF_UP)) {
+		if (goal_rx > 1 && !adapter->multi_queue) {
+			netdev_err(netdev,
+				   "Cannot resize to %u RX queues: multi-queue mode not supported by firmware\n",
+				   goal_rx);
+			return -EOPNOTSUPP;
+		}
+
+		if (goal_rx < 1 || goal_rx > IBMVETH_MAX_RX_QUEUES) {
+			netdev_err(netdev,
+				   "Invalid RX queue count %u (must be 1-%d)\n",
+				   goal_rx, IBMVETH_MAX_RX_QUEUES);
+			return -EINVAL;
+		}
+
+		/* Stash desired RX count; open() publishes it via
+		 * netif_set_real_num_rx_queues() after queue registration.
+		 */
+		if (goal_rx != adapter->num_rx_queues)
+			adapter->num_rx_queues = goal_rx;
+
 		return netif_set_real_num_tx_queues(netdev, goal);
+	}
+
+	if (goal_rx > 1 && !adapter->multi_queue) {
+		netdev_err(netdev,
+			   "Cannot resize to %u RX queues: multi-queue mode not supported by firmware\n",
+			   goal_rx);
+		return -EOPNOTSUPP;
+	}
+
+	if (goal_rx < 1 || goal_rx > IBMVETH_MAX_RX_QUEUES) {
+		netdev_err(netdev,
+			   "Invalid RX queue count %u (must be 1-%d)\n",
+			   goal_rx, IBMVETH_MAX_RX_QUEUES);
+		return -EINVAL;
+	}
+
+	if (goal_rx != old_rx) {
+		rc = ibmveth_resize_rx_queues_incremental(adapter, goal_rx,
+							  rxq_entries);
+		if (rc) {
+			netdev_err(netdev, "Failed to resize RX queues: %d\n", rc);
+			return rc;
+		}
+	}
 
 	/* We have IBMVETH_MAX_QUEUES netdev_queue's allocated
 	 * but we may need to alloc/free the ltb's.
 	 */
+	if (goal == old)
+		return 0;
+
 	netif_tx_stop_all_queues(netdev);
 
 	/* Allocate any queue that we need */
@@ -2580,7 +2630,7 @@ static int ibmveth_set_channels(struct net_device *netdev,
 
 	netif_tx_wake_all_queues(netdev);
 
-	return rc;
+	return 0;
 }
 
 static const struct ethtool_ops netdev_ethtool_ops = {
-- 
2.39.3 (Apple Git-146)