From a4a4c5b9f0cd7e2a0395f7a53199f02ce2c683d1 Mon Sep 17 00:00:00 2001
From: Stefan Lankes <lankes@lfbs.rwth-aachen.de>
Date: Mon, 22 Aug 2011 13:16:54 -0700
Subject: [PATCH] use RCCE's method to flush the write combining buffers

---
 arch/x86/include/asm/svm.h | 12 +++++++++---
 arch/x86/mm/page.c         |  2 +-
 arch/x86/mm/svm.c          |  3 ++-
 3 files changed, 12 insertions(+), 5 deletions(-)

diff --git a/arch/x86/include/asm/svm.h b/arch/x86/include/asm/svm.h
index 1b0b3c1d..91e008ec 100644
--- a/arch/x86/include/asm/svm.h
+++ b/arch/x86/include/asm/svm.h
@@ -21,6 +21,10 @@
 #define __ARCH_SVM_H__
 
 #include <metalsvm/stddef.h>
+#include <asm/processor.h>
+#ifdef CONFIG_ROCKCREEK
+#include <asm/RCCE_lib.h>
+#endif
 
 #ifdef __cplusplus
 extern "C" {
@@ -72,11 +76,13 @@ static inline void svm_invalidate(void)
 
 static inline void svm_flush(void)
 {
-	mb();
-#ifndef SVM_WT
+#ifdef CONFIG_ROCKCREEK
+	// need to write to another line to make sure the write combine buffer gets flushed
+	*(int *)RCCE_fool_write_combine_buffer = 1;
+#endif
+#ifdef SVM_WB
 	flush_cache();
 #endif
-	//asm volatile ( ".byte 0x0f; .byte 0x0a;\n" ); // CL1FLUSHMB
 }
 
 #endif
diff --git a/arch/x86/mm/page.c b/arch/x86/mm/page.c
index 2bde433c..62dab193 100644
--- a/arch/x86/mm/page.c
+++ b/arch/x86/mm/page.c
@@ -356,7 +356,7 @@ size_t map_region(size_t viraddr, size_t phyaddr, uint32_t npages, uint32_t flag
 			pgt->entries[index] |= PG_MPE;
 #endif
 		if (flags & MAP_SVM)
-#ifdef SVM_WT
+#ifndef SVM_WB
 			pgt->entries[index] |= PG_SVM|PG_PWT;
 #else
 			pgt->entries[index] |= PG_SVM;
diff --git a/arch/x86/mm/svm.c b/arch/x86/mm/svm.c
index f3245071..2f09010a 100644
--- a/arch/x86/mm/svm.c
+++ b/arch/x86/mm/svm.c
@@ -228,7 +228,8 @@ int svm_emit_page(size_t phyaddr, int ue)
 		change_page_permissions(viraddr, viraddr+PAGE_SIZE, VMA_NOACCESS|VMA_READ|VMA_CACHEABLE);
 
 		page_owner[pageid] = ue;
-		mb();
+		// need to write to another line to make sure the write combine buffer gets flushed
+		*(int *)RCCE_fool_write_combine_buffer = 1;
 	}
 
 	return 0;