5 files changed, 31 insertions, 20 deletions
diff --git a/hw/block/dataplane/virtio-blk.c b/hw/block/dataplane/virtio-blk.c
index 90ef557..d1f9f63 100644
--- a/hw/block/dataplane/virtio-blk.c
+++ b/hw/block/dataplane/virtio-blk.c
@@ -68,9 +68,7 @@ static void notify_guest_bh(void *opaque)
             unsigned i = j + ctzl(bits);
             VirtQueue *vq = virtio_get_queue(s->vdev, i);
 
-            if (virtio_should_notify(s->vdev, vq)) {
-                event_notifier_set(virtio_queue_get_guest_notifier(vq));
-            }
+            virtio_notify_irqfd(s->vdev, vq);
 
             bits &= bits - 1; /* clear right-most bit */
         }
diff --git a/hw/scsi/virtio-scsi-dataplane.c b/hw/scsi/virtio-scsi-dataplane.c
index f2ea29d..6b8d0f0 100644
--- a/hw/scsi/virtio-scsi-dataplane.c
+++ b/hw/scsi/virtio-scsi-dataplane.c
@@ -95,13 +95,6 @@ static int virtio_scsi_vring_init(VirtIOSCSI *s, VirtQueue *vq, int n,
     return 0;
 }
 
-void virtio_scsi_dataplane_notify(VirtIODevice *vdev, VirtIOSCSIReq *req)
-{
-    if (virtio_should_notify(vdev, req->vq)) {
-        event_notifier_set(virtio_queue_get_guest_notifier(req->vq));
-    }
-}
-
 /* assumes s->ctx held */
 static void virtio_scsi_clear_aio(VirtIOSCSI *s)
 {
diff --git a/hw/scsi/virtio-scsi.c b/hw/scsi/virtio-scsi.c
index 3e5ae6a..10fd687 100644
--- a/hw/scsi/virtio-scsi.c
+++ b/hw/scsi/virtio-scsi.c
@@ -69,7 +69,7 @@ static void virtio_scsi_complete_req(VirtIOSCSIReq *req)
     qemu_iovec_from_buf(&req->resp_iov, 0, &req->resp, req->resp_size);
     virtqueue_push(vq, &req->elem, req->qsgl.size + req->resp_iov.size);
     if (s->dataplane_started && !s->dataplane_fenced) {
-        virtio_scsi_dataplane_notify(vdev, req);
+        virtio_notify_irqfd(vdev, vq);
     } else {
         virtio_notify(vdev, vq);
     }
diff --git a/hw/virtio/trace-events b/hw/virtio/trace-events
index 8756cef..7b6f55e 100644
--- a/hw/virtio/trace-events
+++ b/hw/virtio/trace-events
@@ -5,7 +5,7 @@ virtqueue_fill(void *vq, const void *elem, unsigned int len, unsigned int idx) "
 virtqueue_flush(void *vq, unsigned int count) "vq %p count %u"
 virtqueue_pop(void *vq, void *elem, unsigned int in_num, unsigned int out_num) "vq %p elem %p in_num %u out_num %u"
 virtio_queue_notify(void *vdev, int n, void *vq) "vdev %p n %d vq %p"
-virtio_irq(void *vq) "vq %p"
+virtio_notify_irqfd(void *vdev, void *vq) "vdev %p vq %p"
 virtio_notify(void *vdev, void *vq) "vdev %p vq %p"
 virtio_set_status(void *vdev, uint8_t val) "vdev %p val %u"
 
diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
index 138a414..1af2de2 100644
--- a/hw/virtio/virtio.c
+++ b/hw/virtio/virtio.c
@@ -1330,13 +1330,6 @@ static void virtio_set_isr(VirtIODevice *vdev, int value)
     }
 }
 
-void virtio_irq(VirtQueue *vq)
-{
-    trace_virtio_irq(vq);
-    virtio_set_isr(vq->vdev, 0x1);
-    virtio_notify_vector(vq->vdev, vq->vector);
-}
-
 bool virtio_should_notify(VirtIODevice *vdev, VirtQueue *vq)
 {
     uint16_t old, new;
@@ -1360,6 +1353,33 @@ bool virtio_should_notify(VirtIODevice *vdev, VirtQueue *vq)
     return !v || vring_need_event(vring_get_used_event(vq), new, old);
 }
 
+void virtio_notify_irqfd(VirtIODevice *vdev, VirtQueue *vq)
+{
+    if (!virtio_should_notify(vdev, vq)) {
+        return;
+    }
+
+    trace_virtio_notify_irqfd(vdev, vq);
+
+    /*
+     * virtio spec 1.0 says ISR bit 0 should be ignored with MSI, but
+     * windows drivers included in virtio-win 1.8.0 (circa 2015) are
+     * incorrectly polling this bit during crashdump and hibernation
+     * in MSI mode, causing a hang if this bit is never updated.
+     * Recent releases of Windows do not really shut down, but rather
+     * log out and hibernate to make the next startup faster.  Hence,
+     * this manifested as a more serious hang during shutdown with
+     *
+     * Next driver release from 2016 fixed this problem, so working around it
+     * is not a must, but it's easy to do so let's do it here.
+     *
+     * Note: it's safe to update ISR from any thread as it was switched
+     * to an atomic operation.
+     */
+    virtio_set_isr(vq->vdev, 0x1);
+    event_notifier_set(&vq->guest_notifier);
+}
+
 void virtio_notify(VirtIODevice *vdev, VirtQueue *vq)
 {
     if (!virtio_should_notify(vdev, vq)) {
@@ -1994,7 +2014,7 @@ static void virtio_queue_guest_notifier_read(EventNotifier *n)
 {
     VirtQueue *vq = container_of(n, VirtQueue, guest_notifier);
     if (event_notifier_test_and_clear(n)) {
-        virtio_irq(vq);
+        virtio_notify_vector(vq->vdev, vq->vector);
     }
 }