Using query_post to Retrieve All Pages

Hey everyone, I recently found a thread on how to retrieve multiple pages with query_post, similar to this:

$args = array(
‘post_type’ => ‘page’,
‘post__in’ => array(5,7,17)
);
query_posts($args);

This works fine, but I would really just like to retrieve all posts that are of type page, even sub pages.

Does anyone know how to do this? Thanks.