qemu/virtio: mark msi vectors used on load

Usage of msi vectors is controlled by the guest and so needs to be
restored on load. Do this for msi vectors used by the virtio device.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>

hw/virtio-pci.c

diff --git a/hw/virtio-pci.c b/hw/virtio-pci.c
index 39e290d..3b9bfd1 100644
--- a/hw/virtio-pci.c
+++ b/hw/virtio-pci.c
@@ -126,11 +126,18 @@
     VirtIOPCIProxy *proxy = opaque;
     int ret;
     ret = pci_device_load(&proxy->pci_dev, f);
-    if (ret)
+    if (ret) {
         return ret;
+    }
     msix_load(&proxy->pci_dev, f);
-    if (msix_present(&proxy->pci_dev))
+    if (msix_present(&proxy->pci_dev)) {
         qemu_get_be16s(f, &proxy->vdev->config_vector);
+    } else {
+        proxy->vdev->config_vector = VIRTIO_NO_VECTOR;
+    }
+    if (proxy->vdev->config_vector != VIRTIO_NO_VECTOR) {
+        return msix_vector_use(&proxy->pci_dev, proxy->vdev->config_vector);
+    }
     return 0;
 }
 
@@ -138,10 +145,15 @@
 {
     VirtIOPCIProxy *proxy = opaque;
     uint16_t vector;
-    if (!msix_present(&proxy->pci_dev))
-        return 0;
-    qemu_get_be16s(f, &vector);
+    if (msix_present(&proxy->pci_dev)) {
+        qemu_get_be16s(f, &vector);
+    } else {
+        vector = VIRTIO_NO_VECTOR;
+    }
     virtio_queue_set_vector(proxy->vdev, n, vector);
+    if (vector != VIRTIO_NO_VECTOR) {
+        return msix_vector_use(&proxy->pci_dev, vector);
+    }
     return 0;
 }