drivers/vfio/pci: Fix wrong MSI interrupt count
authorGavin Shan <gwshan@linux.vnet.ibm.com>
Fri, 30 May 2014 17:35:54 +0000 (11:35 -0600)
committerAlex Williamson <alex.williamson@redhat.com>
Fri, 30 May 2014 17:35:54 +0000 (11:35 -0600)
According PCI local bus specification, the register of Message
Control for MSI (offset: 2, length: 2) has bit#0 to enable or
disable MSI logic and it shouldn't be part contributing to the
calculation of MSI interrupt count. The patch fixes the issue.

Signed-off-by: Gavin Shan <gwshan@linux.vnet.ibm.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
drivers/vfio/pci/vfio_pci.c

index 85063f1c12d7f2c7e35d622b6da746042ac48a06..010e0f8b8e4fe0099dff900742ce4564391742a2 100644 (file)
@@ -197,8 +197,7 @@ static int vfio_pci_get_irq_count(struct vfio_pci_device *vdev, int irq_type)
                if (pos) {
                        pci_read_config_word(vdev->pdev,
                                             pos + PCI_MSI_FLAGS, &flags);
-
-                       return 1 << (flags & PCI_MSI_FLAGS_QMASK);
+                       return 1 << ((flags & PCI_MSI_FLAGS_QMASK) >> 1);
                }
        } else if (irq_type == VFIO_PCI_MSIX_IRQ_INDEX) {
                u8 pos;