Merge branch 'core-iommu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel...

[pandora-kernel.git] / drivers / xen / grant-table.c

diff --git a/drivers/xen/grant-table.c b/drivers/xen/grant-table.c
index 3745a31..fd725cd 100644 (file)
--- a/drivers/xen/grant-table.c
+++ b/drivers/xen/grant-table.c
@@ -466,13 +466,30 @@ int gnttab_map_refs(struct gnttab_map_grant_ref *map_ops,
                if (map_ops[i].status)
                        continue;
 
-               /* m2p override only supported for GNTMAP_contains_pte mappings */
-               if (!(map_ops[i].flags & GNTMAP_contains_pte))
-                       continue;
-               pte = (pte_t *) (mfn_to_virt(PFN_DOWN(map_ops[i].host_addr)) +
+               if (map_ops[i].flags & GNTMAP_contains_pte) {
+                       pte = (pte_t *) (mfn_to_virt(PFN_DOWN(map_ops[i].host_addr)) +
                                (map_ops[i].host_addr & ~PAGE_MASK));
-               mfn = pte_mfn(*pte);
-               ret = m2p_add_override(mfn, pages[i]);
+                       mfn = pte_mfn(*pte);
+               } else {
+                       /* If you really wanted to do this:
+                        * mfn = PFN_DOWN(map_ops[i].dev_bus_addr);
+                        *
+                        * The reason we do not implement it is b/c on the
+                        * unmap path (gnttab_unmap_refs) we have no means of
+                        * checking whether the page is !GNTMAP_contains_pte.
+                        *
+                        * That is without some extra data-structure to carry
+                        * the struct page, bool clear_pte, and list_head next
+                        * tuples and deal with allocation/delallocation, etc.
+                        *
+                        * The users of this API set the GNTMAP_contains_pte
+                        * flag so lets just return not supported until it
+                        * becomes neccessary to implement.
+                        */
+                       return -EOPNOTSUPP;
+               }
+               ret = m2p_add_override(mfn, pages[i],
+                                      map_ops[i].flags & GNTMAP_contains_pte);
                if (ret)
                        return ret;
        }
@@ -494,7 +511,7 @@ int gnttab_unmap_refs(struct gnttab_unmap_grant_ref *unmap_ops,
                return ret;
 
        for (i = 0; i < count; i++) {
-               ret = m2p_remove_override(pages[i]);
+               ret = m2p_remove_override(pages[i], true /* clear the PTE */);
                if (ret)
                        return ret;
        }