ibmvnic: Clear pending interrupt after device reset

Due to a firmware bug, the hypervisor can send an interrupt to a
transmit or receive queue just prior to a partition migration, not
allowing the device enough time to handle it and send an EOI. When
the partition migrates, the interrupt is lost but an "EOI-pending"
flag for the interrupt line is still set in firmware. No further
interrupts will be sent until that flag is cleared, effectively
freezing that queue. To workaround this, the driver will disable the
hardware interrupt and send an H_EOI signal prior to re-enabling it.
This will flush the pending EOI and allow the driver to continue
operation.
Signed-off-by: Thomas Falcon <tlfalcon@linux.vnet.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/ibm/ibmvnic.c

@@ -1049,7 +1049,6 @@ static int __ibmvnic_open(struct net_device *netdev)
 		netdev_dbg(netdev, "Enabling rx_scrq[%d] irq\n", i);
 		if (prev_state == VNIC_CLOSED)
 			enable_irq(adapter->rx_scrq[i]->irq);
-		else
 		enable_scrq_irq(adapter, adapter->rx_scrq[i]);
 	}
 
@@ -1057,7 +1056,6 @@ static int __ibmvnic_open(struct net_device *netdev)
 		netdev_dbg(netdev, "Enabling tx_scrq[%d] irq\n", i);
 		if (prev_state == VNIC_CLOSED)
 			enable_irq(adapter->tx_scrq[i]->irq);
-		else
 		enable_scrq_irq(adapter, adapter->tx_scrq[i]);
 	}
 
@@ -1199,6 +1197,7 @@ static void ibmvnic_disable_irqs(struct ibmvnic_adapter *adapter)
 			if (adapter->tx_scrq[i]->irq) {
 				netdev_dbg(netdev,
 					   "Disabling tx_scrq[%d] irq\n", i);
+				disable_scrq_irq(adapter, adapter->tx_scrq[i]);
 				disable_irq(adapter->tx_scrq[i]->irq);
 			}
 	}
@@ -1208,6 +1207,7 @@ static void ibmvnic_disable_irqs(struct ibmvnic_adapter *adapter)
 			if (adapter->rx_scrq[i]->irq) {
 				netdev_dbg(netdev,
 					   "Disabling rx_scrq[%d] irq\n", i);
+				disable_scrq_irq(adapter, adapter->rx_scrq[i]);
 				disable_irq(adapter->rx_scrq[i]->irq);
 			}
 		}
@@ -2617,12 +2617,19 @@ static int enable_scrq_irq(struct ibmvnic_adapter *adapter,
 {
 	struct device *dev = &adapter->vdev->dev;
 	unsigned long rc;
+	u64 val;
 
 	if (scrq->hw_irq > 0x100000000ULL) {
 		dev_err(dev, "bad hw_irq = %lx\n", scrq->hw_irq);
 		return 1;
 	}
 
+	val = (0xff000000) | scrq->hw_irq;
+	rc = plpar_hcall_norets(H_EOI, val);
+	if (rc)
+		dev_err(dev, "H_EOI FAILED irq 0x%llx. rc=%ld\n",
+			val, rc);
+
 	rc = plpar_hcall_norets(H_VIOCTL, adapter->vdev->unit_address,
 				H_ENABLE_VIO_INTERRUPT, scrq->hw_irq, 0, 0);
 	if (rc)