[dpdk-stable] [PATCH 1/3] net/virtio: fix wrong MSI-X for modern devices

[Jianfeng Tan <jianfeng.tan@intel.com>]

The field, use_msix, in struct virtio_hw is not updated for modern
device, and is always zero. And now we depend on the status feature
and MSI-X to report LSC support (which is also not a correct
behavior). As a result, LSC is always disabled for modern devices.

Te fix this, we just recognize MSI-X capability when going through
capability list, and update the info in virtio.

Fixes: 6ba1f63b5ab0 ("virtio: support specification 1.0")
Cc: stable@dpdk.org

Signed-off-by: Jianfeng Tan <jianfeng.tan@intel.com>
---
 drivers/net/virtio/virtio_pci.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/net/virtio/virtio_pci.c b/drivers/net/virtio/virtio_pci.c
index b767c03..ecad46e 100644
--- a/drivers/net/virtio/virtio_pci.c
+++ b/drivers/net/virtio/virtio_pci.c
@@ -50,6 +50,7 @@
  */
 #define PCI_CAPABILITY_LIST	0x34
 #define PCI_CAP_ID_VNDR		0x09
+#define PCI_CAP_ID_MSIX		0x11
 
 /*
  * The remaining space is defined by each driver as the per-driver
@@ -650,6 +651,9 @@ virtio_read_caps(struct rte_pci_device *dev, struct virtio_hw *hw)
 			break;
 		}
 
+		if (cap.cap_vndr == PCI_CAP_ID_MSIX)
+			hw->use_msix = 1;
+
 		if (cap.cap_vndr != PCI_CAP_ID_VNDR) {
 			PMD_INIT_LOG(DEBUG,
 				"[%2x] skipping non VNDR cap id: %02x",
-- 
2.7.4