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>

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>
Daniel De Graaf · Konrad Rzeszutek Wilk
1 parent 2946a52ac7
Showing 3 changed files with 8 additions and 21 deletions Side-by-side Diff
drivers/xen/gntdev.c
drivers/xen/grant-table.c
include/xen/grant_table.h
@@ -314,7 +314,8 @@
 		}
 	}
  
-	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;
  
@@ -761,24 +761,10 @@
 				(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 @@
 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 @@
 		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;
 	}
@@ -185,7 +185,7 @@
 		    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__ */
...	...	@@ -314,7 +314,8 @@
314	314	}
315	315	}
316	316
317		- err = gnttab_unmap_refs(map->unmap_ops + offset, map->pages + offset, pages);
	317	+ err = gnttab_unmap_refs(map->unmap_ops + offset, map->pages + offset,
	318	+ pages, true);
318	319	if (err)
319	320	return err;
320	321
...	...	@@ -761,24 +761,10 @@
761	761	(map_ops[i].host_addr & ~PAGE_MASK));
762	762	mfn = pte_mfn(*pte);
763	763	} else {
764		- /* If you really wanted to do this:
765		- * mfn = PFN_DOWN(map_ops[i].dev_bus_addr);
766		- *
767		- * The reason we do not implement it is b/c on the
768		- * unmap path (gnttab_unmap_refs) we have no means of
769		- * checking whether the page is !GNTMAP_contains_pte.
770		- *
771		- * That is without some extra data-structure to carry
772		- * the struct page, bool clear_pte, and list_head next
773		- * tuples and deal with allocation/delallocation, etc.
774		- *
775		- * The users of this API set the GNTMAP_contains_pte
776		- * flag so lets just return not supported until it
777		- * becomes neccessary to implement.
778		- */
779		- return -EOPNOTSUPP;
	764	+ mfn = PFN_DOWN(map_ops[i].dev_bus_addr);
780	765	}
781		- ret = m2p_add_override(mfn, pages[i], &kmap_ops[i]);
	766	+ ret = m2p_add_override(mfn, pages[i], kmap_ops ?
	767	+ &kmap_ops[i] : NULL);
782	768	if (ret)
783	769	return ret;
784	770	}
...	...	@@ -788,7 +774,7 @@
788	774	EXPORT_SYMBOL_GPL(gnttab_map_refs);
789	775
790	776	int gnttab_unmap_refs(struct gnttab_unmap_grant_ref *unmap_ops,
791		- struct page **pages, unsigned int count)
	777	+ struct page **pages, unsigned int count, bool clear_pte)
792	778	{
793	779	int i, ret;
794	780
...	...	@@ -800,7 +786,7 @@
800	786	return ret;
801	787
802	788	for (i = 0; i < count; i++) {
803		- ret = m2p_remove_override(pages[i], true /* clear the PTE */);
	789	+ ret = m2p_remove_override(pages[i], clear_pte);
804	790	if (ret)
805	791	return ret;
806	792	}
...	...	@@ -185,7 +185,7 @@
185	185	struct gnttab_map_grant_ref *kmap_ops,
186	186	struct page **pages, unsigned int count);
187	187	int gnttab_unmap_refs(struct gnttab_unmap_grant_ref *unmap_ops,
188		- struct page **pages, unsigned int count);
	188	+ struct page **pages, unsigned int count, bool clear_pte);
189	189
190	190	#endif /* __ASM_GNTTAB_H__ */