[Xen-changelog] [qemu-upstream-unstable] pci-assign: Enable MSIX on device to match guest

[patchbot@xxxxxxx]

commit 006c747440b1b22aa5bbef89442ef037741adabc
Author:     Alex Williamson <alex.williamson@xxxxxxxxxx>
AuthorDate: Sun Jan 6 21:30:31 2013 -0700
Commit:     Michael Roth <mdroth@xxxxxxxxxxxxxxxxxx>
CommitDate: Tue Jan 15 23:05:44 2013 -0600

    pci-assign: Enable MSIX on device to match guest
    
    When a guest enables MSIX on a device we evaluate the MSIX vector
    table, typically find no unmasked vectors and don't switch the device
    to MSIX mode.  This generally works fine and the device will be
    switched once the guest enables and therefore unmasks 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 may break when MSIX is managed
    lazily.  This change re-enables the previous test used to enable MSIX
    (see qemu-kvm a6b402c9), which basically guesses whether a vector
    will be used based on the data field of the vector table.
    
    Cc: qemu-stable@xxxxxxxxxx
    Signed-off-by: Alex Williamson <alex.williamson@xxxxxxxxxx>
    Acked-by: Michael S. Tsirkin <mst@xxxxxxxxxx>
    Signed-off-by: Michael S. Tsirkin <mst@xxxxxxxxxx>
    (cherry picked from commit feb9a2ab4b0260d8d680a7ffd25063dafc7ec628)
    
    Signed-off-by: Michael Roth <mdroth@xxxxxxxxxxxxxxxxxx>
---
 hw/kvm/pci-assign.c |   17 +++++++++++++++--
 1 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/hw/kvm/pci-assign.c b/hw/kvm/pci-assign.c
index e80dad0..12a219b 100644
--- a/hw/kvm/pci-assign.c
+++ b/hw/kvm/pci-assign.c
@@ -1025,6 +1025,19 @@ static bool assigned_dev_msix_masked(MSIXTableEntry 
*entry)
     return (entry->ctrl & cpu_to_le32(0x1)) != 0;
 }
 
+/*
+ * When MSI-X is first enabled the vector table typically has all the
+ * vectors masked, so we can't use that as the obvious test to figure out
+ * how many vectors to initially enable.  Instead we look at the data field
+ * because this is what worked for pci-assign for a long time.  This makes
+ * sure the physical MSI-X state tracks the guest's view, which is important
+ * for some VF/PF and PF/fw communication channels.
+ */
+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 +1048,7 @@ 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 +1077,7 @@ 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;
         }
 
--
generated by git-patchbot for /home/xen/git/qemu-upstream-unstable.git

_______________________________________________
Xen-changelog mailing list
Xen-changelog@xxxxxxxxxxxxx
http://lists.xensource.com/xen-changelog