x86, pat: Add PAT reserve free to io_mapping* APIs

io_mapping_* interfaces were added, mainly for graphics drivers.
Make this interface go through the PAT reserve/free, instead of
hardcoding WC mapping. This makes sure that there are no
aliases due to unconditional WC setting.

Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>

1 files changed, 12 insertions, 5 deletions

diff --git a/include/linux/io-mapping.h b/include/linux/io-mapping.h
index 0adb0f9..97eb928 100644
--- a/include/linux/io-mapping.h
+++ b/include/linux/io-mapping.h
@@ -49,23 +49,30 @@ static inline struct io_mapping *
 io_mapping_create_wc(resource_size_t base, unsigned long size)
 {
 	struct io_mapping *iomap;
-
-	if (!is_io_mapping_possible(base, size))
-		return NULL;
+	pgprot_t prot;
 
 	iomap = kmalloc(sizeof(*iomap), GFP_KERNEL);
 	if (!iomap)
-		return NULL;
+		goto out_err;
+
+	if (iomap_create_wc(base, size, &prot))
+		goto out_free;
 
 	iomap->base = base;
 	iomap->size = size;
-	iomap->prot = pgprot_writecombine(__pgprot(__PAGE_KERNEL));
+	iomap->prot = prot;
 	return iomap;
+
+out_free:
+	kfree(iomap);
+out_err:
+	return NULL;
 }
 
 static inline void
 io_mapping_free(struct io_mapping *mapping)
 {
+	iomap_free(mapping->base, mapping->size);
 	kfree(mapping);
 }