libqos: add missing virtio-9p feature negotiation

VIRTIO Device Initialization requires feature negotiation.  The libqos
virtio-9p driver lacks feature negotiation and is therefore
non-compliant.

libqos tests acknowledge all feature bits advertised by the device,
except VIRTIO_F_BAD_FEATURE (which devices use to detect broken
drivers!) and VIRTIO_RING_F_EVENT_IDX (which is not implemented in
libqos and accepting it would break notifications).

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-Id: <20191023100425.12168-7-stefanha@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Thomas Huth" <thuth@redhat.com>

diff --git a/tests/libqos/virtio-9p.c b/tests/libqos/virtio-9p.c
index 8c9efce3e19415bfdd2847949ce479ae3cb13ebc..77dbfb62ad6acc3860f09c9d3c6094735cf89caf 100644 (file)
--- a/tests/libqos/virtio-9p.c
+++ b/tests/libqos/virtio-9p.c
@@ -32,6 +32,12 @@ static void virtio_9p_cleanup(QVirtio9P *interface)
 
 static void virtio_9p_setup(QVirtio9P *interface)
 {
+    uint64_t features;
+
+    features = qvirtio_get_features(interface->vdev);
+    features &= ~(QVIRTIO_F_BAD_FEATURE | (1ull << VIRTIO_RING_F_EVENT_IDX));
+    qvirtio_set_features(interface->vdev, features);
+
     interface->vq = qvirtqueue_setup(interface->vdev, alloc, 0);
     qvirtio_set_driver_ok(interface->vdev);
 }