virtio: clear signalled_used_valid when switching from dataplane

When the dataplane thread stops, its vring.c implementation synchronizes
vring state back to virtio.c so we can continue emulating the virtio
device.

This patch ensures that virtio.c's signalled_used_valid flag is reset so
that we do not suppress guest notifications due to stale signalled_used
values.

Suggested-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

diff --git a/hw/virtio/dataplane/vring.c b/hw/virtio/dataplane/vring.c
index 82cc151b172d7ea7044fd475f39c32a4a879a57d..351a343806516d66d6b0715d5002efe73a214b0f 100644 (file)
--- a/hw/virtio/dataplane/vring.c
+++ b/hw/virtio/dataplane/vring.c
@@ -52,6 +52,7 @@ bool vring_setup(Vring *vring, VirtIODevice *vdev, int n)
 void vring_teardown(Vring *vring, VirtIODevice *vdev, int n)
 {
     virtio_queue_set_last_avail_idx(vdev, n, vring->last_avail_idx);
+    virtio_queue_invalidate_signalled_used(vdev, n);
 
     hostmem_finalize(&vring->hostmem);
 }

diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
index 09f62c6c70e3341164181671a32cb310c7c61762..706bdf4c465726ffeef0951f5c4d143314ddb0f9 100644 (file)
--- a/hw/virtio/virtio.c
+++ b/hw/virtio/virtio.c
@@ -1059,6 +1059,11 @@ void virtio_queue_set_last_avail_idx(VirtIODevice *vdev, int n, uint16_t idx)
     vdev->vq[n].last_avail_idx = idx;
 }
 
+void virtio_queue_invalidate_signalled_used(VirtIODevice *vdev, int n)
+{
+    vdev->vq[n].signalled_used_valid = false;
+}
+
 VirtQueue *virtio_get_queue(VirtIODevice *vdev, int n)
 {
     return vdev->vq + n;

diff --git a/include/hw/virtio/virtio.h b/include/hw/virtio/virtio.h
index d7e9e0fc8a5506eceec3f2dd08b38b6d67a9d581..a90522d6d654ed28bff50e602dee7b609d49294f 100644 (file)
--- a/include/hw/virtio/virtio.h
+++ b/include/hw/virtio/virtio.h
@@ -237,6 +237,7 @@ hwaddr virtio_queue_get_used_size(VirtIODevice *vdev, int n);
 hwaddr virtio_queue_get_ring_size(VirtIODevice *vdev, int n);
 uint16_t virtio_queue_get_last_avail_idx(VirtIODevice *vdev, int n);
 void virtio_queue_set_last_avail_idx(VirtIODevice *vdev, int n, uint16_t idx);
+void virtio_queue_invalidate_signalled_used(VirtIODevice *vdev, int n);
 VirtQueue *virtio_get_queue(VirtIODevice *vdev, int n);
 uint16_t virtio_get_queue_index(VirtQueue *vq);
 int virtio_queue_get_id(VirtQueue *vq);