x86: optimize clflush

clflush is sufficient to be issued on one CPU. The invalidation is
broadcast throughout the coherence domain.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 8 insertions, 14 deletions

diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c
index 90b658ac39c2..bbfc8e2466ab 100644
--- a/arch/x86/mm/pageattr.c
+++ b/arch/x86/mm/pageattr.c
@@ -64,35 +64,29 @@ static void cpa_flush_all(void)
         on_each_cpu(__cpa_flush_all, NULL, 1, 1);
 }
 
-struct clflush_data {
-        unsigned long addr;
-        int numpages;
-};
-
 static void __cpa_flush_range(void *arg)
 {
-        struct clflush_data *cld = arg;
-
         /*
          * We could optimize that further and do individual per page
          * tlb invalidates for a low number of pages. Caveat: we must
          * flush the high aliases on 64bit as well.
          */
         __flush_tlb_all();
-
-        clflush_cache_range((void *) cld->addr, cld->numpages * PAGE_SIZE);
 }
 
 static void cpa_flush_range(unsigned long addr, int numpages)
 {
-        struct clflush_data cld;
-
         BUG_ON(irqs_disabled());
 
-        cld.addr = addr;
-        cld.numpages = numpages;
+        on_each_cpu(__cpa_flush_range, NULL, 1, 1);
 
-        on_each_cpu(__cpa_flush_range, &cld, 1, 1);
+        /*
+         * We only need to flush on one CPU,
+         * clflush is a MESI-coherent instruction that
+         * will cause all other CPUs to flush the same
+         * cachelines:
+         */
+        clflush_cache_range((void *) addr, numpages * PAGE_SIZE);
 }
 
 /*