fix DOMID_IO mapping permission checks

When the permission checks for memory mapping were moved from
get_pg_owner to xsm_mmu_update in aaba7a677, the exception for DOMID_IO
was not taken into account. This will cause IO memory mappings by PV
domains (mini-os in particular) to fail when XSM/FLASK is not being
used. This patch reintroduces the exception for DOMID_IO; the actual
restrictions on IO memory mappings have always been checked separately
using iomem_access_permitted, so this change should not break existing
access control.

Reported-by: Eduardo Peixoto Macedo <epm@cin.ufpe.br>
Signed-off-by: Daniel De Graaf <dgdegra@tycho.nsa.gov>
master commit: 07344c0f33
master date: 2013-09-26 10:15:47 +0200

xen/include/xsm/dummy.h

@@ -567,9 +567,10 @@ static XSM_INLINE int xsm_domain_memory_map(XSM_DEFAULT_ARG struct domain *d)
 static XSM_INLINE int xsm_mmu_update(XSM_DEFAULT_ARG struct domain *d, struct domain *t,
                                      struct domain *f, uint32_t flags)
 {
-    int rc;
+    int rc = 0;
     XSM_ASSERT_ACTION(XSM_TARGET);
-    rc = xsm_default_action(action, d, f);
+    if ( f != dom_io )
+        rc = xsm_default_action(action, d, f);
     if ( t && !rc )
         rc = xsm_default_action(action, d, t);
     return rc;