[Xen-devel] [PATCH for-4.5 v2 7/8] xen: arm: weaken SMP barriers to inner shareable.

[Ian Campbell <ian.campbell@xxxxxxxxxx>]

Since all processors are in the inner-shareable domain and we map everything
that way this is sufficient.

The non-SMP barriers remain full system. Although in principle they could
become outer shareable barriers for some hardware this would require us to
know which class a given device is. Given the small number of device drivers
in Xen itself its probably not worth worrying over, although maybe someone
will benchmark at some point.

Signed-off-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
Acked-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
Acked-by: Tim Deegan <tim@xxxxxxx>
---
 xen/include/asm-arm/system.h |    6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/xen/include/asm-arm/system.h b/xen/include/asm-arm/system.h
index e1f126a..32ed277 100644
--- a/xen/include/asm-arm/system.h
+++ b/xen/include/asm-arm/system.h
@@ -20,9 +20,9 @@
 #define rmb()           dsb(sy)
 #define wmb()           dsb(sy)
 
-#define smp_mb()        dmb(sy)
-#define smp_rmb()       dmb(sy)
-#define smp_wmb()       dmb(sy)
+#define smp_mb()        dmb(ish)
+#define smp_rmb()       dmb(ish)
+#define smp_wmb()       dmb(ish)
 
 #define xchg(ptr,x) \
         ((__typeof__(*(ptr)))__xchg((unsigned long)(x),(ptr),sizeof(*(ptr))))
-- 
1.7.10.4


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