commit 2d620f593d9395abd9aa453f8ae0861a51d674d8
author Michael S. Tsirkin <mst@redhat.com> Thu Dec 20 14:28:58 2012 +0200
committer Michael S. Tsirkin <mst@redhat.com> Mon Jan 07 19:42:22 2013 +0200
tree d3cab64b07a957ce4334b1a3ad5f1ba1a08c95d4
parent 8e4a424b305e29dc0e454f52df3b35577f342975

virtio: don't waste irqfds on control vqs

Pass nvqs to set_guest_notifiers. This makes it possible to
save on irqfds by not allocating one for the control vq
for virtio-net.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

hw/virtio-pci.c

diff --git a/hw/virtio-pci.c b/hw/virtio-pci.c
index c7f0c4d..65a563b 100644
--- a/hw/virtio-pci.c
+++ b/hw/virtio-pci.c
@@ -535,7 +535,7 @@
     VirtIODevice *vdev = proxy->vdev;
     int ret, queue_no;
 
-    for (queue_no = 0; queue_no < VIRTIO_PCI_QUEUE_MAX; queue_no++) {
+    for (queue_no = 0; queue_no < proxy->nvqs_with_notifiers; queue_no++) {
         if (!virtio_queue_get_num(vdev, queue_no)) {
             break;
         }
@@ -565,7 +565,7 @@
     VirtIODevice *vdev = proxy->vdev;
     int queue_no;
 
-    for (queue_no = 0; queue_no < VIRTIO_PCI_QUEUE_MAX; queue_no++) {
+    for (queue_no = 0; queue_no < proxy->nvqs_with_notifiers; queue_no++) {
         if (!virtio_queue_get_num(vdev, queue_no)) {
             break;
         }
@@ -587,7 +587,7 @@
     EventNotifier *notifier;
     VirtQueue *vq;
 
-    for (queue_no = 0; queue_no < VIRTIO_PCI_QUEUE_MAX; queue_no++) {
+    for (queue_no = 0; queue_no < proxy->nvqs_with_notifiers; queue_no++) {
         if (!virtio_queue_get_num(vdev, queue_no)) {
             break;
         }
@@ -631,7 +631,7 @@
     return msix_enabled(&proxy->pci_dev);
 }
 
-static int virtio_pci_set_guest_notifiers(DeviceState *d, bool assign)
+static int virtio_pci_set_guest_notifiers(DeviceState *d, int nvqs, bool assign)
 {
     VirtIOPCIProxy *proxy = to_virtio_pci_proxy(d);
     VirtIODevice *vdev = proxy->vdev;
@@ -639,6 +639,15 @@
     bool with_irqfd = msix_enabled(&proxy->pci_dev) &&
         kvm_msi_via_irqfd_enabled();
 
+    nvqs = MIN(nvqs, VIRTIO_PCI_QUEUE_MAX);
+
+    /* When deassigning, pass a consistent nvqs value
+     * to avoid leaking notifiers.
+     */
+    assert(assign || nvqs == proxy->nvqs_with_notifiers);
+
+    proxy->nvqs_with_notifiers = nvqs;
+
     /* Must unset vector notifier while guest notifier is still assigned */
     if (proxy->vector_irqfd && !assign) {
         msix_unset_vector_notifiers(&proxy->pci_dev);
@@ -646,7 +655,7 @@
         proxy->vector_irqfd = NULL;
     }
 
-    for (n = 0; n < VIRTIO_PCI_QUEUE_MAX; n++) {
+    for (n = 0; n < nvqs; n++) {
         if (!virtio_queue_get_num(vdev, n)) {
             break;
         }