1 files changed, 73 insertions, 0 deletions

diff --git a/drivers/xen/grant-table.c b/drivers/xen/grant-table.c
index 6c4531816496..fd725cde6ad1 100644
--- a/drivers/xen/grant-table.c
+++ b/drivers/xen/grant-table.c
@@ -447,6 +447,79 @@ unsigned int gnttab_max_grant_frames(void)
 }
 EXPORT_SYMBOL_GPL(gnttab_max_grant_frames);
 
+int gnttab_map_refs(struct gnttab_map_grant_ref *map_ops,
+                    struct page **pages, unsigned int count)
+{
+        int i, ret;
+        pte_t *pte;
+        unsigned long mfn;
+
+        ret = HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref, map_ops, count);
+        if (ret)
+                return ret;
+
+        if (xen_feature(XENFEAT_auto_translated_physmap))
+                return ret;
+
+        for (i = 0; i < count; i++) {
+                /* Do not add to override if the map failed. */
+                if (map_ops[i].status)
+                        continue;
+
+                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);
+                } 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;
+        }
+
+        return ret;
+}
+EXPORT_SYMBOL_GPL(gnttab_map_refs);
+
+int gnttab_unmap_refs(struct gnttab_unmap_grant_ref *unmap_ops,
+                struct page **pages, unsigned int count)
+{
+        int i, ret;
+
+        ret = HYPERVISOR_grant_table_op(GNTTABOP_unmap_grant_ref, unmap_ops, count);
+        if (ret)
+                return ret;
+
+        if (xen_feature(XENFEAT_auto_translated_physmap))
+                return ret;
+
+        for (i = 0; i < count; i++) {
+                ret = m2p_remove_override(pages[i], true /* clear the PTE */);
+                if (ret)
+                        return ret;
+        }
+
+        return ret;
+}
+EXPORT_SYMBOL_GPL(gnttab_unmap_refs);
+
 static int gnttab_map(unsigned int start_idx, unsigned int end_idx)
 {
         struct gnttab_setup_table setup;