From 2a0c772f1967565d5b71a98012e74d5a7bddc1c4 Mon Sep 17 00:00:00 2001 From: Ross Zwisler Date: Wed, 26 Feb 2014 12:06:51 -0700 Subject: [PATCH] x86: Use clflushopt in drm_clflush_page If clflushopt is available on the system, use it instead of clflush in drm_clflush_page. Signed-off-by: Ross Zwisler Link: http://lkml.kernel.org/r/1393441612-19729-4-git-send-email-ross.zwisler@linux.intel.com Signed-off-by: H. Peter Anvin --- drivers/gpu/drm/drm_cache.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/drivers/gpu/drm/drm_cache.c b/drivers/gpu/drm/drm_cache.c index bb8f58012189..c518fb6cfb63 100644 --- a/drivers/gpu/drm/drm_cache.c +++ b/drivers/gpu/drm/drm_cache.c @@ -32,6 +32,12 @@ #include #if defined(CONFIG_X86) + +/* + * clflushopt is an unordered instruction which needs fencing with mfence or + * sfence to avoid ordering issues. For drm_clflush_page this fencing happens + * in the caller. + */ static void drm_clflush_page(struct page *page) { @@ -44,7 +50,7 @@ drm_clflush_page(struct page *page) page_virtual = kmap_atomic(page); for (i = 0; i < PAGE_SIZE; i += size) - clflush(page_virtual + i); + clflushopt(page_virtual + i); kunmap_atomic(page_virtual); }