copy to a directory not file
diff --git a/tools/build_kvm.sh b/tools/build_kvm.sh
index 4ca1f1a..3f32598 100755
--- a/tools/build_kvm.sh
+++ b/tools/build_kvm.sh
@@ -290,6 +290,7 @@
     if [ ! -f $IMAGES_DIR/$IMAGE_FNAME ]; then
         wget -c $image_url -O $IMAGES_DIR/$IMAGE_FNAME
     fi
+    mkdir -p $ROOTFS/$DEST/devstack/files/images
     cp $IMAGES_DIR/$IMAGE_FNAME $ROOTFS/$DEST/devstack/files/images
 done