[dpdk-dev] [PATCH] net/virtio: disable LSC interrupt if MSIX not enabled

[Allain Legacy <allain.legacy@windriver.com>]

From: Matt Peters <matt.peters@windriver.com>

The link state change interrupt can only be configured if the virtio device
supports MSIX.  Prior to this change the writing of the vector to the PCI
config space was causing it to overwrite the initial part of the MAC
address since the MSIX vector is not in the config space and is occupied by
the MAC address.

This has been reproduced in Virtual Box (v5.0.30.r112061) in Windows 7

Signed-off-by: Matt Peters <matt.peters@windriver.com>
Signed-off-by: Allain Legacy <allain.legacy@windriver.com>
---
 drivers/net/virtio/virtio_ethdev.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/net/virtio/virtio_ethdev.c b/drivers/net/virtio/virtio_ethdev.c
index 4dc03b9..66770fc 100644
--- a/drivers/net/virtio/virtio_ethdev.c
+++ b/drivers/net/virtio/virtio_ethdev.c
@@ -1338,11 +1338,11 @@ static int virtio_dev_xstats_get_names(struct rte_eth_dev *dev,
 		rte_eth_copy_pci_info(eth_dev, pci_dev);
 	}
 
-	/* If host does not support status then disable LSC */
-	if (!vtpci_with_feature(hw, VIRTIO_NET_F_STATUS))
-		eth_dev->data->dev_flags &= ~RTE_ETH_DEV_INTR_LSC;
-	else
+	/* If host does not support both status and MSI-X then disable LSC */
+	if (vtpci_with_feature(hw, VIRTIO_NET_F_STATUS) && hw->use_msix)
 		eth_dev->data->dev_flags |= RTE_ETH_DEV_INTR_LSC;
+	else
+		eth_dev->data->dev_flags &= ~RTE_ETH_DEV_INTR_LSC;
 
 	rx_func_get(eth_dev);
 
-- 
1.8.3.1