[PATCH v2 1/2] x86/p2m: make p2m_get_page_from_gfn() handle grant case correctly

[Jan Beulich]

Grant P2M entries, which are covered by p2m_is_any_ram(), wouldn't pass
the get_page() unless the grant was a local one. These need to take the
same path as foreign entries. Just the assertion there is not valid for
local grants, and hence it triggering needs to be avoided.

Signed-off-by: Jan Beulich <jbeul...@suse.com>
---
Using | instead of || helps the compiler fold the two p2m_is_*().
---
v2: The shared case was fine; limit to grant adjustment.

--- a/xen/arch/x86/mm/p2m.c
+++ b/xen/arch/x86/mm/p2m.c
@@ -357,11 +357,11 @@ struct page_info *p2m_get_page_from_gfn(
              && !((q & P2M_UNSHARE) && p2m_is_shared(*t)) )
         {
             page = mfn_to_page(mfn);
-            if ( unlikely(p2m_is_foreign(*t)) )
+            if ( unlikely(p2m_is_foreign(*t) | p2m_is_grant(*t)) )
             {
                 struct domain *fdom = page_get_owner_and_reference(page);
 
-                ASSERT(fdom != p2m->domain);
+                ASSERT(!p2m_is_foreign(*t) || fdom != p2m->domain);
                 if ( fdom == NULL )
                     page = NULL;
             }