[PATCH net-next v7 15/15] ibmveth: Complete set_channels down-path and mq_fallback max_rx cap

@@ -3399,15 +3399,32 @@ static void ibmveth_get_channels(struct net_device *netdev,
 				 struct ethtool_channels *channels)
 {
 	struct ibmveth_adapter *adapter = netdev_priv(netdev);
+	unsigned int rx_count = ibmveth_get_num_rx_queues(adapter);
 
-	channels->max_tx = ibmveth_real_max_tx_queues();
 	channels->tx_count = netdev->real_num_tx_queues;
+	/*
+	 * Never advertise max_tx below the live count. After CPU
+	 * offline, real_max can drop below real_num_tx_queues;
+	 * ethtool -L is read-modify-write and the core rejects
+	 * tx_count > max_tx, which would also block an RX-only
+	 * request. set_channels uses this same ceiling.
+	 */
+	channels->max_tx = max_t(unsigned int, channels->tx_count,
+				 ibmveth_real_max_tx_queues());
 
-	if (adapter->multi_queue)
+	/*
+	 * Always report the live RX count. ethtool -L is read-modify-
+	 * write, so a TX-only request echoes rx_count back at us; an
+	 * understated value would be applied as a silent RX shrink.
+	 * mq_fallback instead caps max_rx at the live count, which
+	 * blocks growth in the core without misreporting what is
+	 * currently configured.
+	 */
+	channels->rx_count = rx_count;
+	if (adapter->multi_queue && !adapter->mq_fallback)
 		channels->max_rx = IBMVETH_MAX_RX_QUEUES;
 	else
-		channels->max_rx = 1;
-	channels->rx_count = ibmveth_get_num_rx_queues(adapter);
+		channels->max_rx = rx_count;
 }
 
 /**

@@ -3416,9 +3433,8 @@ static void ibmveth_get_channels(struct net_device *netdev,
  * @goal_rx: requested RX queue count
  *
  * Rejects rx > 1 without MQ firmware (-EOPNOTSUPP) and rx outside
- * 1..IBMVETH_MAX_RX_QUEUES (-EINVAL). An RX count change while the
- * device is down is rejected (-EOPNOTSUPP); publishing it without
- * allocating arrives in the next patch. When up, apply via
+ * 1..IBMVETH_MAX_RX_QUEUES (-EINVAL). When RX resources are not live
+ * (!opened), only validate; do not allocate. When up, apply via
  * ibmveth_resize_rx_queues_incremental().
  *
  * Return: 0 or negative errno

@@ -3461,14 +3477,9 @@ static int ibmveth_resize_rx_channels(struct ibmveth_adapter *adapter,
 		return -EOPNOTSUPP;
 	}
 
-	/*
-	 * Down / failed-open: there is nothing to resize, and publishing
-	 * the desired count without allocating arrives in the next
-	 * patch. Refuse rather than report success for a request that
-	 * would be discarded.
-	 */
+	/* Down / failed-open: do not allocate. */
 	if (!adapter->opened)
-		return -EOPNOTSUPP;
+		return 0;
 
 	rxq_entries = adapter->rx_queue[0].num_slots;
 	rc = ibmveth_resize_rx_queues_incremental(adapter, goal_rx,

@@ -3482,28 +3493,90 @@ 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 = ibmveth_get_num_rx_queues(adapter);
+	unsigned int goal_rx = channels->rx_count;
+	unsigned int old_tx = netdev->real_num_tx_queues;
+	unsigned int goal_tx = channels->tx_count;
+	unsigned int want_tx = goal_tx;
+	unsigned int max_tx;
+	bool rx_changed = false;
 	int rc, i;
 
-	/* Validate RX (and resize when opened) before the down-path
-	 * early return so MQ/range errors are reported here. Publishing
-	 * the desired RX count and CMO while down is the next patch.
+	/*
+	 * Same ceiling get_channels reports: live count or the
+	 * online-CPU cap, whichever is larger.
 	 */
-	rc = ibmveth_resize_rx_channels(adapter, channels->rx_count);
+	max_tx = max_t(unsigned int, old_tx,
+		       ibmveth_real_max_tx_queues());
+	if (goal_tx < 1 || goal_tx > max_tx) {
+		netdev_err(netdev,
+			   "Invalid TX queue count %u (must be 1-%u)\n",
+			   goal_tx, max_tx);
+		return -EINVAL;
+	}
+
+	/* RX range / MQ checks live in ibmveth_resize_rx_channels(). */
+	rc = ibmveth_resize_rx_channels(adapter, goal_rx);
 	if (rc)
 		return rc;
 
-	if (!adapter->opened)
-		return netif_set_real_num_tx_queues(netdev, goal);
+	/* If RX resources are not live (never opened, or close+open failed
+	 * while IFF_UP stayed set), publish desired queue counts without
+	 * allocating.
+	 */
+	if (!adapter->opened) {
+		/* Apply TX first so a failure leaves the published RX
+		 * count unchanged.
+		 */
+		rc = netif_set_real_num_tx_queues(netdev, goal_tx);
+		if (rc)
+			return rc;
+
+		/* Publish desired RX count for next open() and refresh CMO;
+		 * do not allocate while down.
+		 */
+		if (goal_rx != ibmveth_get_num_rx_queues(adapter)) {
+			ibmveth_publish_num_rx_queues(adapter, goal_rx);
+			rc = netif_set_real_num_rx_queues(netdev, goal_rx);
+			if (rc) {
+				int tx_rc;
+
+				ibmveth_publish_num_rx_queues(adapter, old_rx);
+				tx_rc = netif_set_real_num_tx_queues(netdev,
+								     old_tx);
+				if (tx_rc)
+					netdev_err(netdev,
+						   "Failed to restore TX queues to %u after RX failure: %d\n",
+						   old_tx, tx_rc);
+				return rc;
+			}
+			if (firmware_has_feature(FW_FEATURE_CMO)) {
+				unsigned long dma;
+
+				dma = ibmveth_get_desired_dma(adapter->vdev);
+				vio_cmo_set_dev_desired(adapter->vdev, dma);
+			}
+		}
+		return 0;
+	}
+
+	if (goal_rx != old_rx)
+		rx_changed = true;
 
 	/* We have IBMVETH_MAX_QUEUES netdev_queue's allocated
 	 * but we may need to alloc/free the ltb's.
 	 */
+	if (goal_tx == old_tx)
+		return 0;
+
 	netif_tx_stop_all_queues(netdev);
 
-	/* Allocate any queue that we need */
-	for (i = old; i < goal; i++) {
+	/* Allocate any new TX LTBs. i starts at old_tx for the free walk
+	 * below when this loop body never runs (goal_tx == old_tx already
+	 * returned; goal_tx < old_tx is scale-down).
+	 */
+	i = old_tx;
+	for (; i < goal_tx; i++) {
 		if (adapter->tx_ltb_ptr[i])
 			continue;
 

@@ -3512,28 +3585,48 @@ static int ibmveth_set_channels(struct net_device *netdev,
 			continue;
 
 		/* if something goes wrong, free everything we just allocated */
-		netdev_err(netdev, "Failed to allocate more tx queues, returning to %d queues\n",
-			   old);
-		goal = old;
-		old = i;
+		netdev_err(netdev, "Failed to allocate more tx queues, returning to %u queues\n",
+			   old_tx);
+		goal_tx = old_tx;
+		old_tx = i;
 		break;
 	}
-	rc = netif_set_real_num_tx_queues(netdev, goal);
+	rc = netif_set_real_num_tx_queues(netdev, goal_tx);
 	if (rc) {
-		netdev_err(netdev, "Failed to set real tx queues, returning to %d queues\n",
-			   old);
-		goal = old;
-		old = i;
+		netdev_err(netdev, "Failed to set real tx queues, returning to %u queues\n",
+			   old_tx);
+		goal_tx = old_tx;
+		old_tx = i;
 	}
 	/* Free any that are no longer needed */
-	for (i = old; i > goal; i--) {
+	for (i = old_tx; i > goal_tx; i--) {
 		if (adapter->tx_ltb_ptr[i - 1])
 			ibmveth_free_tx_ltb(adapter, i - 1);
 	}
 
 	netif_tx_wake_all_queues(netdev);
 
-	return rc;
+	if (netdev->real_num_tx_queues != want_tx) {
+		if (rx_changed) {
+			/*
+			 * Restore the RX count from before this -L.
+			 * num_slots is the live size after that resize.
+			 */
+			int rxq_entries = adapter->rx_queue[0].num_slots;
+			int rb;
+
+			rb = ibmveth_resize_rx_queues_incremental(adapter,
+								  old_rx,
+								  rxq_entries);
+			if (rb)
+				netdev_err(netdev,
+					   "Failed to roll back RX queues to %u after TX failure: %d\n",
+					   old_rx, rb);
+		}
+		return rc ? rc : -ENOMEM;
+	}
+
+	return 0;
 }
 
 static const struct ethtool_ops netdev_ethtool_ops = {

@@ -4203,9 +4296,14 @@ static int ibmveth_change_mtu(struct net_device *dev, int new_mtu)
 static void ibmveth_poll_controller(struct net_device *dev)
 {
 	struct ibmveth_adapter *adapter = netdev_priv(dev);
-	unsigned int num = ibmveth_get_num_rx_queues(adapter);
+	unsigned int num;
 	int i;
 
+	if (!adapter->opened)
+		return;
+
+	num = ibmveth_get_num_rx_queues(adapter);
+
 	for (i = 0; i < num; i++)
 		ibmveth_replenish_task(adapter, i);