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>

4 files changed, 54 insertions, 3 deletions

diff --git a/drivers/staging/android/ion/Kconfig b/drivers/staging/android/ion/Kconfig
index a9a64ea2343..5f520b7da64 100644
--- a/drivers/staging/android/ion/Kconfig
+++ b/drivers/staging/android/ion/Kconfig
@@ -23,3 +23,10 @@ config ION_TEGRA
 	help
 	  Choose this option if you wish to use ion on an nVidia Tegra.
 
+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.
diff --git a/drivers/staging/android/ion/ion_page_pool.c b/drivers/staging/android/ion/ion_page_pool.c
index 0e20e62ec4b..f08c6dbec12 100644
--- a/drivers/staging/android/ion/ion_page_pool.c
+++ b/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;
diff --git a/drivers/staging/android/ion/ion_priv.h b/drivers/staging/android/ion/ion_priv.h
index 7c06e2e4fc0..13531d17fa4 100644
--- a/drivers/staging/android/ion/ion_priv.h
+++ b/drivers/staging/android/ion/ion_priv.h
@@ -26,6 +26,9 @@
 #include <linux/sched.h>
 #include <linux/shrinker.h>
 #include <linux/types.h>
+#ifdef CONFIG_ION_POOL_CACHE_POLICY
+#include <asm/cacheflush.h>
+#endif
 
 #include "ion.h"
 
@@ -380,6 +383,37 @@ 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
diff --git a/drivers/staging/android/ion/ion_system_heap.c b/drivers/staging/android/ion/ion_system_heap.c
index 5945445ee5f..69c216806a8 100644
--- a/drivers/staging/android/ion/ion_system_heap.c
+++ b/drivers/staging/android/ion/ion_system_heap.c
@@ -91,10 +91,12 @@ 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);
 	}