x86/p2m: also tear down altp2m

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
Release-acked-by: Wei Liu <wei.liu2@citrix.com>
Acked-by: George Dunlap <george.dunlap@citrix.com>

xen/arch/x86/mm/p2m.c

@@ -618,9 +618,11 @@ void p2m_teardown(struct p2m_domain *p2m)
 
 void p2m_final_teardown(struct domain *d)
 {
-    /* We must teardown unconditionally because
+    /*
+     * We must teardown both of them unconditionally because
      * we initialise them unconditionally.
      */
+    p2m_teardown_altp2m(d);
     p2m_teardown_nestedp2m(d);
 
     /* Iterate over all p2m tables per domain */