igc: Fix trigger of incorrect irq in igc_xsk_wakeup function

This patch addresses the issue where the igc_xsk_wakeup function
was triggering an incorrect IRQ for tx-0 when the i226 is configured
with only 2 combined queues or in an environment with 2 active CPU cores.
This prevented XDP Zero-copy send functionality in such split IRQ
configurations.

The fix implements the correct logic for extracting q_vectors saved
during rx and tx ring allocation and utilizes flags provided by the
ndo_xsk_wakeup API to trigger the appropriate IRQ.

Fixes: fc9df2a ("igc: Enable RX via AF_XDP zero-copy")
Fixes: 15fd021 ("igc: Add Tx hardware timestamp request for AF_XDP zero-copy packet")
Signed-off-by: Vivek Behera <vivek.behera@siemens.com>
Reviewed-by: Jacob Keller <jacob.keller@intel.com>
Reviewed-by: Aleksandr loktinov <aleksandr.loktionov@intel.com>
Reviewed-by: Piotr Kwapulinski <piotr.kwapulinski@intel.com>
Reviewed-by: Song Yoong Siang <yoong.siang.song@intel.com>
Tested-by: Avigail Dahan <avigailx.dahan@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>

Author: Vivek Behera

drivers/net/ethernet/intel/igc/igc_main.c

@@ -6906,28 +6906,29 @@ static int igc_xdp_xmit(struct net_device *dev, int num_frames,
 	return nxmit;
 }
 
-static void igc_trigger_rxtxq_interrupt(struct igc_adapter *adapter,
-					struct igc_q_vector *q_vector)
+static u32 igc_sw_irq_prep(struct igc_q_vector *q_vector)
 {
-	struct igc_hw *hw = &adapter->hw;
 	u32 eics = 0;
 
-	eics |= q_vector->eims_value;
-	wr32(IGC_EICS, eics);
+	if (!napi_if_scheduled_mark_missed(&q_vector->napi))
+		eics = q_vector->eims_value;
+
+	return eics;
 }
 
 int igc_xsk_wakeup(struct net_device *dev, u32 queue_id, u32 flags)
 {
 	struct igc_adapter *adapter = netdev_priv(dev);
-	struct igc_q_vector *q_vector;
+	struct igc_hw *hw = &adapter->hw;
 	struct igc_ring *ring;
+	u32 eics = 0;
 
 	if (test_bit(__IGC_DOWN, &adapter->state))
 		return -ENETDOWN;
 
 	if (!igc_xdp_is_enabled(adapter))
 		return -ENXIO;
-
+	/* Check if queue_id is valid. Tx and Rx queue numbers are always same */
 	if (queue_id >= adapter->num_rx_queues)
 		return -EINVAL;
 
@@ -6936,9 +6937,22 @@ int igc_xsk_wakeup(struct net_device *dev, u32 queue_id, u32 flags)
 	if (!ring->xsk_pool)
 		return -ENXIO;
 
-	q_vector = adapter->q_vector[queue_id];
-	if (!napi_if_scheduled_mark_missed(&q_vector->napi))
-		igc_trigger_rxtxq_interrupt(adapter, q_vector);
+	if (flags & XDP_WAKEUP_RX)
+		eics |= igc_sw_irq_prep(ring->q_vector);
+
+	if (flags & XDP_WAKEUP_TX) {
+		/* If IGC_FLAG_QUEUE_PAIRS is active, the q_vector
+		 * and NAPI is shared between RX and TX.
+		 * If NAPI is already running it would be marked as missed
+		 * from the RX path, making this TX call a NOP
+		 */
+		ring = adapter->tx_ring[queue_id];
+		eics |= igc_sw_irq_prep(ring->q_vector);
+	}
+
+	if (eics)
+		/* Cause software interrupt */
+		wr32(IGC_EICS, eics);
 
 	return 0;
 }

drivers/net/ethernet/intel/igc/igc_ptp.c

@@ -550,7 +550,8 @@ static void igc_ptp_free_tx_buffer(struct igc_adapter *adapter,
 		tstamp->buffer_type = 0;
 
 		/* Trigger txrx interrupt for transmit completion */
-		igc_xsk_wakeup(adapter->netdev, tstamp->xsk_queue_index, 0);
+		igc_xsk_wakeup(adapter->netdev, tstamp->xsk_queue_index,
+			       XDP_WAKEUP_TX);
 
 		return;
 	}