virtio-net: make VirtIOFeature usable for other virtio devices

In order to use VirtIOFeature also in other virtio devices, we move
its declaration and the endof() macro (renamed in virtio_endof())
in virtio.h.
We add virtio_feature_get_config_size() function to iterate the array
of VirtIOFeature and to return the config size depending on the
features enabled. (as virtio_net_set_config_size() did)

Suggested-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
Message-id: 20190221103314.58500-5-sgarzare@redhat.com
Message-Id: <20190221103314.58500-5-sgarzare@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
index a1ff647..2626a89 100644
--- a/hw/virtio/virtio.c
+++ b/hw/virtio/virtio.c
@@ -2036,6 +2036,21 @@
     return ret;
 }
 
+size_t virtio_feature_get_config_size(VirtIOFeature *feature_sizes,
+                                      uint64_t host_features)
+{
+    size_t config_size = 0;
+    int i;
+
+    for (i = 0; feature_sizes[i].flags != 0; i++) {
+        if (host_features & feature_sizes[i].flags) {
+            config_size = MAX(feature_sizes[i].end, config_size);
+        }
+    }
+
+    return config_size;
+}
+
 int virtio_load(VirtIODevice *vdev, QEMUFile *f, int version_id)
 {
     int i, ret;