ion: Handle the memory mapping correctly on x86

This patch modifies the ion page pool code to address
limitation in x86 PAT. When one physical page is mapped
to multiple virtual pages, the same cache policy
should be used. Add set_memory_wc/uc call to avoid aliases.
If not, all mappings will be cached(write back).

Change-Id: I98ee8902df0c80135dddfa998c4ca4c2bb44e40e
Signed-off-by: Zhebin Jin <zhebin.jin@intel.com>
Signed-off-by: Vinil Cheeramvelil <vinil.cheeramvelil@intel.com>
(cherry picked from commit 6db47cc7e2f1d8dd8fc84912202ed749d6781a76)

Conflicts:
	drivers/staging/android/ion/Kconfig
	drivers/staging/android/ion/ion_priv.h

drivers/staging/android/ion/Kconfig

@@ -64,3 +64,11 @@ config ION_SNAPSHOT_BUF_SHIFT
 	  Select ION snapshot buffer size as a power of 2
 
 endif
+
+config ION_POOL_CACHE_POLICY
+	bool "Ion set page pool cache policy"
+	depends on ION
+	default y if X86
+	help
+	  Choose this option if need to explicity set cache policy of the
+	  pages in the page pool.

drivers/staging/android/ion/ion_page_pool.c

@@ -34,6 +34,8 @@ static void *ion_page_pool_alloc_pages(struct ion_page_pool *pool)
 
 	if (!page)
 		return NULL;
+	ion_page_pool_alloc_set_cache_policy(pool, page);
+
 	ion_pages_sync_for_device(NULL, page, PAGE_SIZE << pool->order,
 						DMA_BIDIRECTIONAL);
 	return page;
@@ -42,6 +44,7 @@ static void *ion_page_pool_alloc_pages(struct ion_page_pool *pool)
 static void ion_page_pool_free_pages(struct ion_page_pool *pool,
 				     struct page *page)
 {
+	ion_page_pool_free_set_cache_policy(pool, page);
 	__free_pages(page, pool->order);
 }
 
@@ -117,6 +120,11 @@ void ion_page_pool_free(struct ion_page_pool *pool, struct page *page)
 		ion_page_pool_free_pages(pool, page);
 }
 
+void ion_page_pool_free_immediate(struct ion_page_pool *pool, struct page *page)
+{
+	ion_page_pool_free_pages(pool, page);
+}
+
 static int ion_page_pool_total(struct ion_page_pool *pool, bool high)
 {
 	int total = 0;

drivers/staging/android/ion/ion_priv.h

@@ -26,7 +26,9 @@
 #include <linux/sched.h>
 #include <linux/shrinker.h>
 #include <linux/types.h>
-#include <linux/device.h>
+#ifdef CONFIG_ION_POOL_CACHE_POLICY
+#include <asm/cacheflush.h>
+#endif
 
 #include "ion.h"
 
@@ -417,6 +419,37 @@ struct ion_page_pool *ion_page_pool_create(gfp_t gfp_mask, unsigned int order);
 void ion_page_pool_destroy(struct ion_page_pool *);
 void *ion_page_pool_alloc(struct ion_page_pool *);
 void ion_page_pool_free(struct ion_page_pool *, struct page *);
+void ion_page_pool_free_immediate(struct ion_page_pool *, struct page *);
+
+#ifdef CONFIG_ION_POOL_CACHE_POLICY
+static inline void ion_page_pool_alloc_set_cache_policy
+				(struct ion_page_pool *pool,
+				struct page *page){
+	void *va = page_address(page);
+
+	if (va)
+		set_memory_wc((unsigned long)va, 1 << pool->order);
+}
+
+static inline void ion_page_pool_free_set_cache_policy
+				(struct ion_page_pool *pool,
+				struct page *page){
+	void *va = page_address(page);
+
+	if (va)
+		set_memory_wb((unsigned long)va, 1 << pool->order);
+
+}
+#else
+static inline void ion_page_pool_alloc_set_cache_policy
+				(struct ion_page_pool *pool,
+				struct page *page){ }
+
+static inline void ion_page_pool_free_set_cache_policy
+				(struct ion_page_pool *pool,
+				struct page *page){ }
+#endif
+
 
 /** ion_page_pool_shrink - shrinks the size of the memory cached in the pool
  * @pool:		the pool

drivers/staging/android/ion/ion_system_heap.c

@@ -92,10 +92,12 @@ static void free_buffer_page(struct ion_system_heap *heap,
 {
 	bool cached = ion_buffer_cached(buffer);
 
-	if (!cached && !(buffer->private_flags & ION_PRIV_FLAG_SHRINKER_FREE)) {
+	if (!cached) {
 		struct ion_page_pool *pool = heap->pools[order_to_index(order)];
-
-		ion_page_pool_free(pool, page);
+		if (buffer->private_flags & ION_PRIV_FLAG_SHRINKER_FREE)
+			ion_page_pool_free_immediate(pool, page);
+		else
+			ion_page_pool_free(pool, page);
 	} else {
 		__free_pages(page, order);
 	}