commit 4ffb15ba091326a5a6572481b950a98eaae631b0
Author: Alex Williamson <alex.williamson@redhat.com>
Date:   Tue Dec 18 14:58:27 2012 -0700

    pci-assign: Enable MSIX on device to match guest
    
    When a Linux guest enables MSIX on a device we evaluate the MSIX
    vector table, find no unmasked vectors and don't switch the device to
    MSIX mode.  Typically this works fine and the device will be switched
    once the guest enables and therefore unmaskes a vector.  Unfortunately
    some drivers enable MSIX, then use interfaces to send commands between
    VF & PF or PF & firmware that act based on the host state of the
    device.  These therefore break when we lazily enable MSIX.  This
    change re-enables the previous test used to enable MSIX, which
    basically guesses whether a vector will be used based on the data
    field of the vector table.  We'll still tear down and start over if
    new vectors are added, so freebsd still works, and we update vectors
    as they change, so SMP affinity still works.
    
    Signed-off-by: Alex Williamson <alex.williamson@redhat.com>

diff --git a/hw/kvm/pci-assign.c b/hw/kvm/pci-assign.c
index e80dad0..5d17ef2 100644
--- a/hw/kvm/pci-assign.c
+++ b/hw/kvm/pci-assign.c
@@ -1025,6 +1025,11 @@ static bool assigned_dev_msix_masked(MSIXTableEntry *entry)
     return (entry->ctrl & cpu_to_le32(0x1)) != 0;
 }
 
+static bool assigned_dev_msix_skipped(MSIXTableEntry *entry)
+{
+    return !entry->data;
+}
+
 static int assigned_dev_update_msix_mmio(PCIDevice *pci_dev)
 {
     AssignedDevice *adev = DO_UPCAST(AssignedDevice, dev, pci_dev);
@@ -1035,7 +1040,7 @@ static int assigned_dev_update_msix_mmio(PCIDevice *pci_dev)
 
     /* Get the usable entry number for allocating */
     for (i = 0; i < adev->msix_max; i++, entry++) {
-        if (assigned_dev_msix_masked(entry)) {
+        if (assigned_dev_msix_skipped(entry)) {
             continue;
         }
         entries_nr++;
@@ -1064,7 +1069,7 @@ static int assigned_dev_update_msix_mmio(PCIDevice *pci_dev)
     for (i = 0; i < adev->msix_max; i++, entry++) {
         adev->msi_virq[i] = -1;
 
-        if (assigned_dev_msix_masked(entry)) {
+        if (assigned_dev_msix_skipped(entry)) {
             continue;
         }