xen/grant-table: Support mappings required by blkback

Add support for mappings without GNTMAP_contains_pte. This was not
supported because the unmap operation assumed that this flag was being
used; adding a parameter to the unmap operation to allow the PTE
clearing to be disabled is sufficient to make unmap capable of
supporting either mapping type.

Signed-off-by: Daniel De Graaf <dgdegra@tycho.nsa.gov>
[v1: Fix cleanpatch warnings]
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

diff --git a/drivers/xen/gntdev.c b/drivers/xen/gntdev.c
index f52f661f8f82c731b678891bf1d27149b6f63421..99d8151c824adbff0611a16f493dde6e6927de4c 100644 (file)
--- a/drivers/xen/gntdev.c
+++ b/drivers/xen/gntdev.c
@@ -314,7 +314,8 @@ static int __unmap_grant_pages(struct grant_map *map, int offset, int pages)
                }
        }
 
-       err = gnttab_unmap_refs(map->unmap_ops + offset, map->pages + offset, pages);
+       err = gnttab_unmap_refs(map->unmap_ops + offset, map->pages + offset,
+                               pages, true);
        if (err)
                return err;
 

diff --git a/drivers/xen/grant-table.c b/drivers/xen/grant-table.c
index a3d0e1e278c1e12c31a353d360a47acda025552c..1cd94daa71db8379443115dd052bc5705fc74432 100644 (file)
--- a/drivers/xen/grant-table.c
+++ b/drivers/xen/grant-table.c
@@ -761,24 +761,10 @@ int gnttab_map_refs(struct gnttab_map_grant_ref *map_ops,
                                (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;
+                       mfn = PFN_DOWN(map_ops[i].dev_bus_addr);
                }
-               ret = m2p_add_override(mfn, pages[i], &kmap_ops[i]);
+               ret = m2p_add_override(mfn, pages[i], kmap_ops ?
+                                      &kmap_ops[i] : NULL);
                if (ret)
                        return ret;
        }
@@ -788,7 +774,7 @@ int gnttab_map_refs(struct gnttab_map_grant_ref *map_ops,
 EXPORT_SYMBOL_GPL(gnttab_map_refs);
 
 int gnttab_unmap_refs(struct gnttab_unmap_grant_ref *unmap_ops,
-                     struct page **pages, unsigned int count)
+                     struct page **pages, unsigned int count, bool clear_pte)
 {
        int i, ret;
 
@@ -800,7 +786,7 @@ 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], true /* clear the PTE */);
+               ret = m2p_remove_override(pages[i], clear_pte);
                if (ret)
                        return ret;
        }

diff --git a/include/xen/grant_table.h b/include/xen/grant_table.h
index f1e17b70588bb4f5dc4e8584edd9e6db02c86dee..15f8a00ff003953639a4caba0e97109b8db06b36 100644 (file)
--- a/include/xen/grant_table.h
+++ b/include/xen/grant_table.h
@@ -185,6 +185,6 @@ int gnttab_map_refs(struct gnttab_map_grant_ref *map_ops,
                    struct gnttab_map_grant_ref *kmap_ops,
                    struct page **pages, unsigned int count);
 int gnttab_unmap_refs(struct gnttab_unmap_grant_ref *unmap_ops,
-                     struct page **pages, unsigned int count);
+                     struct page **pages, unsigned int count, bool clear_pte);
 
 #endif /* __ASM_GNTTAB_H__ */