There was a disconnect here because vdev->host_features was set to
random rubbish. This caused a weird negotiation between the driver and
device that took no account of the features provided by the backend.
To fix this we must set vdev->host_features once we have initialised
the vhost backend.

[AJB: however this is confusing because AFAICT none of the other
vhost-user devices do this.]

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
---
 hw/virtio/vhost-user-gpio.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/hw/virtio/vhost-user-gpio.c b/hw/virtio/vhost-user-gpio.c
index 5851cb3bc9..b2496c824c 100644
--- a/hw/virtio/vhost-user-gpio.c
+++ b/hw/virtio/vhost-user-gpio.c
@@ -228,6 +228,12 @@ static int vu_gpio_connect(DeviceState *dev, Error **errp)
         return ret;
     }
 
+    /*
+     * Once we have initialised the vhost backend we can finally set
+     * the what host features are available for this device.
+     */
+    vdev->host_features = vhost_dev->features;
+
     /* restore vhost state */
     if (virtio_device_started(vdev, vdev->status)) {
         vu_gpio_start(vdev);
-- 
2.34.1