drm/cache: Use wbinvd helpers

When the original drm code was written there were no centralized functions for
doing a coordinated wbinvd across all CPUs. Now (since 2010) there are, so use
them instead of rolling a new one.

v2: On x86 UP systems the wbinvd_on_all_cpus() is defined as a static inline in
smp.h. We must therefore include this file so we don't get compiler errors.
This error was found by 0-DAY kernel test infrastructure. We only need this for
x86.

Cc: Intel GFX <intel-gfx@lists.freedesktop.org>
Signed-off-by: Ben Widawsky <ben@bwidawsk.net>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk> (v1)
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/drm_cache.c

@@ -32,6 +32,7 @@
 #include <drm/drmP.h>
 
 #if defined(CONFIG_X86)
+#include <asm/smp.h>
 
 /*
  * clflushopt is an unordered instruction which needs fencing with mfence or
@@ -64,12 +65,6 @@ static void drm_cache_flush_clflush(struct page *pages[],
 		drm_clflush_page(*pages++);
 	mb();
 }
-
-static void
-drm_clflush_ipi_handler(void *null)
-{
-	wbinvd();
-}
 #endif
 
 void
@@ -82,7 +77,7 @@ drm_clflush_pages(struct page *pages[], unsigned long num_pages)
 		return;
 	}
 
-	if (on_each_cpu(drm_clflush_ipi_handler, NULL, 1) != 0)
+	if (wbinvd_on_all_cpus())
 		printk(KERN_ERR "Timed out waiting for cache flush.\n");
 
 #elif defined(__powerpc__)
@@ -121,7 +116,7 @@ drm_clflush_sg(struct sg_table *st)
 		return;
 	}
 
-	if (on_each_cpu(drm_clflush_ipi_handler, NULL, 1) != 0)
+	if (wbinvd_on_all_cpus())
 		printk(KERN_ERR "Timed out waiting for cache flush.\n");
 #else
 	printk(KERN_ERR "Architecture has no drm_cache.c support\n");
@@ -144,7 +139,7 @@ drm_clflush_virt_range(void *addr, unsigned long length)
 		return;
 	}
 
-	if (on_each_cpu(drm_clflush_ipi_handler, NULL, 1) != 0)
+	if (wbinvd_on_all_cpus())
 		printk(KERN_ERR "Timed out waiting for cache flush.\n");
 #else
 	printk(KERN_ERR "Architecture has no drm_cache.c support\n");