s390x: fix virtio feature bitmap

The feature bitmap in the s390 virtio machine is little endian. To
address for that, we need to bswap the values after reading them out.
Signed-off-by: NAlexander Graf <agraf@suse.de>
Signed-off-by: NAurelien Jarno <aurelien@aurel32.net>

hw/s390-virtio-bus.c

@@ -223,7 +223,7 @@ void s390_virtio_device_sync(VirtIOS390Device *dev)
     cur_offs += num_vq * VIRTIO_VQCONFIG_LEN;
 
     /* Sync feature bitmap */
-    stl_phys(cur_offs, dev->host_features);
+    stl_phys(cur_offs, bswap32(dev->host_features));
 
     dev->feat_offs = cur_offs + dev->feat_len;
     cur_offs += dev->feat_len * 2;
@@ -246,7 +246,7 @@ void s390_virtio_device_update_status(VirtIOS390Device *dev)
 
     /* Update guest supported feature bitmap */
 
-    features = ldl_phys(dev->feat_offs);
+    features = bswap32(ldl_phys(dev->feat_offs));
     if (vdev->set_features) {
         vdev->set_features(vdev, features);
     }