[AGPGART] Fix TLB flushing issues with change_page_attr()

Calls to change_page_attr() need an explicit call to
global_flush_tlb() afterwards.  The AGP code didn't
do this in a number of cases.  This patch makes
map_page_into_agp/unmap_page_from_agp do the calls
themselves, which takes care of most of the problem.

The Intel AGP driver also has some slightly different calls to what
map_page_into_agp() does, as it changes 4 contiguous pages.
Introduce explicit flushes afterwards there too.

Thanks to Alan Cox for pointing this out.
Signed-off-by: Dave Jones <davej@redhat.com>

drivers/char/agp/ati-agp.c

@@ -61,9 +61,6 @@ static int ati_create_page_map(ati_page_map *page_map)
 
 	SetPageReserved(virt_to_page(page_map->real));
 	err = map_page_into_agp(virt_to_page(page_map->real));
-
-	/* CACHE_FLUSH(); */
-	global_cache_flush();
 	page_map->remapped = ioremap_nocache(virt_to_phys(page_map->real),
 					    PAGE_SIZE);
 	if (page_map->remapped == NULL || err) {

drivers/char/agp/generic.c

@@ -35,7 +35,10 @@
 #include <linux/pm.h>
 #include <linux/agp_backend.h>
 #include <linux/vmalloc.h>
+#include <linux/mm.h>
 #include <asm/io.h>
+#include <asm/cacheflush.h>
+#include <asm/pgtable.h>
 #include "agp.h"
 
 __u32 *agp_gatt_table;
@@ -47,6 +50,26 @@ int agp_memory_reserved;
  */
 EXPORT_SYMBOL_GPL(agp_memory_reserved);
 
+#if defined(CONFIG_X86)
+int map_page_into_agp(struct page *page)
+{
+	int i;
+	i = change_page_attr(page, 1, PAGE_KERNEL_NOCACHE);
+	global_flush_tlb();
+	return i;
+}
+EXPORT_SYMBOL_GPL(map_page_into_agp);
+
+int unmap_page_from_agp(struct page *page)
+{
+	int i;
+	i = change_page_attr(page, 1, PAGE_KERNEL);
+	global_flush_tlb();
+	return i;
+}
+EXPORT_SYMBOL_GPL(unmap_page_from_agp);
+#endif
+
 /*
  * Generic routines for handling agp_memory structures -
  * They use the basic page allocation routines to do the brunt of the work.

drivers/char/agp/intel-agp.c

@@ -161,13 +161,15 @@ static void *i8xx_alloc_pages(void)
 	struct page * page;
 
 	page = alloc_pages(GFP_KERNEL, 2);
-	if (page == NULL) {
+	if (page == NULL)
 		return NULL;
-	}
+
 	if (change_page_attr(page, 4, PAGE_KERNEL_NOCACHE) < 0) {
+		global_flush_tlb();
 		__free_page(page);
 		return NULL;
 	}
+	global_flush_tlb();
 	get_page(page);
 	SetPageLocked(page);
 	atomic_inc(&agp_bridge->current_memory_agp);
@@ -183,6 +185,7 @@ static void i8xx_destroy_pages(void *addr)
 
 	page = virt_to_page(addr);
 	change_page_attr(page, 4, PAGE_KERNEL);
+	global_flush_tlb();
 	put_page(page);
 	unlock_page(page);
 	free_pages((unsigned long)addr, 2);

include/asm-i386/agp.h

@@ -12,8 +12,8 @@
  * data corruption on some CPUs.
  */
 
-#define map_page_into_agp(page) change_page_attr(page, 1, PAGE_KERNEL_NOCACHE)
-#define unmap_page_from_agp(page) change_page_attr(page, 1, PAGE_KERNEL)
+int map_page_into_agp(struct page *page);
+int unmap_page_from_agp(struct page *page);
 #define flush_agp_mappings() global_flush_tlb()
 
 /* Could use CLFLUSH here if the cpu supports it. But then it would

include/asm-x86_64/agp.h

@@ -10,9 +10,8 @@
  * with different cachability attributes for the same page.
  */
 
-#define map_page_into_agp(page) \
-      change_page_attr(page, 1, PAGE_KERNEL_NOCACHE)
-#define unmap_page_from_agp(page) change_page_attr(page, 1, PAGE_KERNEL)
+int map_page_into_agp(struct page *page);
+int unmap_page_from_agp(struct page *page);
 #define flush_agp_mappings() global_flush_tlb()
 
 /* Could use CLFLUSH here if the cpu supports it. But then it would