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[XENVKBD PATCH] Reduce the strength of Xen barriers on x86


  • To: win-pv-devel@xxxxxxxxxxxxxxxxxxxx
  • From: Tu Dinh <ngoc-tu.dinh@xxxxxxxxxx>
  • Date: Mon, 18 May 2026 12:25:30 +0200
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  • Cc: Tu Dinh <ngoc-tu.dinh@xxxxxxxxxx>
  • Delivery-date: Mon, 18 May 2026 10:25:43 +0000
  • Feedback-id: default:8631fc262581453bbf619ec5b2062170:Sweego
  • List-id: Developer list for the Windows PV Drivers subproject <win-pv-devel.lists.xenproject.org>

x86 is TSO and only needs a compiler barrier as read/write barriers.

Signed-off-by: Tu Dinh <ngoc-tu.dinh@xxxxxxxxxx>
---
 include/xen-types.h | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/include/xen-types.h b/include/xen-types.h
index 2480526..3446ac7 100644
--- a/include/xen-types.h
+++ b/include/xen-types.h
@@ -48,7 +48,12 @@ typedef ULONG   uint32_t;
 typedef ULONG64 uint64_t;
 
 #define xen_mb()    KeMemoryBarrier()
+#if defined(_M_IX86) || defined(_M_X64)
+#define xen_wmb()   KeMemoryBarrierWithoutFence()
+#define xen_rmb()   KeMemoryBarrierWithoutFence()
+#else
 #define xen_wmb()   KeMemoryBarrier()
-#define xen_rmb()   KememoryBarrier()
+#define xen_rmb()   KeMemoryBarrier()
+#endif
 
 #endif  // _XEN_TYPES_H
-- 
2.54.0.windows.1



--
Ngoc Tu Dinh | Vates XCP-ng Developer

XCP-ng & Xen Orchestra - Vates solutions

web: https://vates.tech

 


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