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authorAlex Williamson <alex.williamson@redhat.com>2013-01-06 21:30:31 -0700
committerMichael S. Tsirkin <mst@redhat.com>2013-01-09 12:11:16 +0200
commitfeb9a2ab4b0260d8d680a7ffd25063dafc7ec628 (patch)
tree12fab7dbe07733955d3f851299c11015c1b65ca1
parent5c03a2542fbe1a275fe3dd7ebd48a6a283b249ed (diff)
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@nongnu.org Signed-off-by: Alex Williamson <alex.williamson@redhat.com> Acked-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
-rw-r--r--hw/kvm/pci-assign.c17
1 files changed, 15 insertions, 2 deletions
diff --git a/hw/kvm/pci-assign.c b/hw/kvm/pci-assign.c
index 8ee94287ff..896cfe8a59 100644
--- a/hw/kvm/pci-assign.c
+++ b/hw/kvm/pci-assign.c
@@ -1031,6 +1031,19 @@ 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);
@@ -1041,7 +1054,7 @@ 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++;
@@ -1070,7 +1083,7 @@ 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;
}