virtio: Allow .get_vhost() without vhost_started

Historically, .get_vhost() was probably only called when
vdev->vhost_started is true.  However, we now decidedly want to call it
also when vhost_started is false, specifically so we can issue a reset
to the vhost back-end while device operation is stopped.

Some .get_vhost() implementations dereference some pointers (or return
offsets from them) that are probably guaranteed to be non-NULL when
vhost_started is true, but not necessarily otherwise.  This patch makes
all such implementations check all such pointers, returning NULL if any
is NULL.

Signed-off-by: Hanna Czenczek <hreitz@redhat.com>
Message-Id: <20240723163941.48775-2-hreitz@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/include/hw/virtio/virtio.h b/include/hw/virtio/virtio.h
index 0fcbc5c0c6..f526ecc8fc 100644
--- a/include/hw/virtio/virtio.h
+++ b/include/hw/virtio/virtio.h
@@ -223,6 +223,7 @@ struct VirtioDeviceClass {
     int (*post_load)(VirtIODevice *vdev);
     const VMStateDescription *vmsd;
     bool (*primary_unplug_pending)(void *opaque);
+    /* May be called even when vdev->vhost_started is false */
     struct vhost_dev *(*get_vhost)(VirtIODevice *vdev);
     void (*toggle_device_iotlb)(VirtIODevice *vdev);
 };