x86: Use clflushopt in drm_clflush_virt_range

If clflushopt is available on the system, use it instead of clflush in
drm_clflush_virt_range.

Signed-off-by: Ross Zwisler <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: H. Peter Anvin <[email protected]>

drivers/gpu/drm/drm_cache.c

@@ -139,7 +139,7 @@ drm_clflush_virt_range(char *addr, unsigned long length)
 		mb();
 		for (; addr < end; addr += boot_cpu_data.x86_clflush_size)
 			clflush(addr);
-		clflush(end - 1);
+		clflushopt(end - 1);
 		mb();
 		return;
 	}