net/virtio: fix MAC address read

When virtio-net devices are bound to uio_pci_generic, we get
the wrong mac addr by virtio PMD. The wrong mac addr is a
addr that is 4-byte left shift of the correct addr.

It's a regression bug introduced by the cleanup patch below.
The condition of if we set use_msix should be if msix is
actually enabled. Only to check if there is a capability list
is not enough. For example, binding a transitional device
to uio_pci_device would trigger the wrong assignment of use_msix.

To correct that, we also check the flags of msix capability to
make sure it's enabled.

Fixes: ee1843bd8907 ("net/virtio: remove redundant MSI-X detection")
Cc: stable@dpdk.org
Reported-by: Vipin Varghese <vipin.varghese@intel.com>
Signed-off-by: Jianfeng Tan <jianfeng.tan@intel.com>
Acked-by: Yuanhan Liu <yliu@fridaylinux.org>

diff --git a/drivers/net/virtio/virtio_pci.c b/drivers/net/virtio/virtio_pci.c
index e6eda75..e6da680 100644 (file)
--- a/drivers/net/virtio/virtio_pci.c
+++ b/drivers/net/virtio/virtio_pci.c
@@ -580,6 +580,8 @@ get_cfg_addr(struct rte_pci_device *dev, struct virtio_pci_cap *cap)
        return base + offset;
 }
 
+#define PCI_MSIX_ENABLE 0x8000
+
 static int
 virtio_read_caps(struct rte_pci_device *dev, struct virtio_hw *hw)
 {
@@ -606,8 +608,17 @@ 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_MSIX) {
+                       /* Transitional devices would also have this capability,
+                        * that's why we also check if msix is enabled.
+                        * 1st byte is cap ID; 2nd byte is the position of next
+                        * cap; next two bytes are the flags.
+                        */
+                       uint16_t flags = ((uint16_t *)&cap)[1];
+
+                       if (flags & PCI_MSIX_ENABLE)
+                               hw->use_msix = 1;
+               }
 
                if (cap.cap_vndr != PCI_CAP_ID_VNDR) {
                        PMD_INIT_LOG(DEBUG,