---
 arch/x86_64/mm/pageattr.c |    3 -
 arch/x86_64/mm/pat.c      |  137 ++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 139 insertions(+), 1 deletion(-)

Index: linux/arch/x86_64/mm/pageattr.c
===================================================================
--- linux.orig/arch/x86_64/mm/pageattr.c
+++ linux/arch/x86_64/mm/pageattr.c
@@ -13,7 +13,7 @@
 #include <asm/tlbflush.h>
 #include <asm/io.h>
 
-static inline pte_t *lookup_address(unsigned long address) 
+pte_t *lookup_address(unsigned long address)
 { 
 	pgd_t *pgd = pgd_offset_k(address);
 	pud_t *pud;
@@ -120,6 +120,7 @@ __change_page_attr(unsigned long address
 	pte_t *kpte; 
 	struct page *kpte_page;
 	pgprot_t ref_prot2;
+	printk("cpa address %lx prot %lx\n", address, pgprot_val(prot));
 	kpte = lookup_address(address);
 	if (!kpte) return 0;
 	kpte_page = virt_to_page(((unsigned long)kpte) & PAGE_MASK);
Index: linux/arch/x86_64/mm/pat.c
===================================================================
--- linux.orig/arch/x86_64/mm/pat.c
+++ linux/arch/x86_64/mm/pat.c
@@ -177,8 +177,10 @@ static int revert_hole(unsigned long *ho
 	unsigned long i = -1;
 	int err = 0;
 	u64 len = end - start;
+	printk("revert hole len %lu end %lx\n", len, end);
 	while ((i = find_next_zero_bit(holemap, len, i + 1)) < len) {
 		*flush = 1;
+		printk("revert hole %lx\n", (start >> PAGE_SHIFT) + i);
 		err = __change_page_attr_pfn((start >> PAGE_SHIFT) + i, 1,
 					     PAGE_KERNEL);
 		if (err)
@@ -310,6 +312,7 @@ void *get_pages_mattr(gfp_t mask, unsign
 		return NULL;
 	err = reserve_mattr(__pa(p), __pa(p) + (order<<PAGE_SHIFT), attr, NULL);
 	if (err) {
+		printk("get_pages_mattr failed %d\n", err);
 		free_pages((unsigned long)p, order);
 		p = NULL;
 	}
@@ -323,3 +326,137 @@ void free_pages_mattr(void *p, unsigned 
 	free_pages((unsigned long)p, order);
 }
 EXPORT_SYMBOL(free_pages_mattr);
+
+extern pte_t *lookup_address(unsigned long);
+
+enum {
+	N = 5,
+};
+
+void *pages[N];
+
+#include <asm/msr.h>
+
+void *page2;
+
+void bench(char *name, void *p)
+{
+	u64 start, end, rd, wr;
+	int i, k;
+	rd = wr = 0;
+	for (k = 0; k < 10; k++) {
+	for (i = 0; i < PAGE_SIZE; i += 64)
+		asm volatile("clflush (%0)" :: "r" (p + i));
+	rdtscll(start);
+	memset(p, 0, PAGE_SIZE);
+	rdtscll(end);
+	rd += end-start;
+
+	for (i = 0; i < PAGE_SIZE; i += 64)
+		asm volatile("clflush (%0)" :: "r" (p + i));
+	rdtscll(start);
+	memcpy(page2, p, PAGE_SIZE);
+	rdtscll(end);
+
+	wr += end-start;
+	}
+	printk("%s: write %lu\n", name, wr/10);
+	printk("%s: read %lu\n", name, rd/10);
+}
+
+#define C(x) if ((err=(x)) < 0) printk("%d:%s failed with %d\n", __LINE__,#x,err)
+#define CT(x) if ((err=(x)) != !0) printk("%d:%s failed with %d\n", __LINE__,#x,err)
+#define CE(x) if ((err=(x)) != 0) printk("%d:%s failed with %d\n", __LINE__,#x,err)
+int test(void)
+{
+	int i, err;
+	printk("testing PAT\n");
+
+	page2 = (void *)__get_free_page(GFP_KERNEL);
+	void *np = (void *)get_pages_mattr(GFP_KERNEL, 0, _PAGE_WC);
+	bench("cached", page2);
+	bench("wc", np);
+
+	free_page((unsigned long) page2);
+	free_pages_mattr(np, 0, _PAGE_WC);
+
+	C(reserve_mattr(__pa(np), __pa(np)+PAGE_SIZE, _PAGE_WC, NULL));
+
+	for (i = 0; i < N; i++) {
+		unsigned long attr2;
+		pages[i] = get_pages_mattr(GFP_KERNEL, 0, _PAGE_WC);
+		CT(pages[i] != NULL);
+		C(reserve_mattr(__pa(pages[i]), __pa(pages[i])+PAGE_SIZE,
+				  _PAGE_PCD, NULL));
+		C(reserve_mattr(__pa(pages[i]), __pa(pages[i])+PAGE_SIZE,
+				  -1, &attr2));
+		if (attr2 != _PAGE_WC)
+			printk("unexpected attr2 %lx\n", attr2);
+		C(free_mattr(__pa(pages[i]), __pa(pages[i])+PAGE_SIZE,
+				  attr2));
+
+		pte_t *pte = lookup_address((unsigned long)pages[i]) ;
+		if (!pte) {
+			printk("pte of %p not found\n", pages[i]);
+			continue;
+		}
+		if (pgprot_nonstd(pte_pgprot(*pte)) != _PAGE_WC)
+			printk("direct %p unexpected pte %lx attr %lx\n", pages[i],
+				pte_val(*pte), pgprot_nonstd(pte_pgprot(*pte)));
+	}
+
+	printk("freeing\n");
+	for (i = 0; i < N; i++) {
+		free_pages_mattr(pages[i], 0, _PAGE_WC);
+	}
+
+
+	printk("large test\n");
+	void *large;
+	unsigned long attr;
+	large = __get_free_pages(GFP_KERNEL, 8);
+	if (large) {
+		C(reserve_mattr(__pa(large),
+				__pa(large) +   (7<<PAGE_SHIFT), _PAGE_WC,NULL));
+		C(reserve_mattr(__pa(large) +   (7<<PAGE_SHIFT),
+				__pa(large) + 2*(7<<PAGE_SHIFT), _PAGE_WC,NULL));
+		C(reserve_mattr(__pa(large) +   (7<<PAGE_SHIFT) - PAGE_SIZE,
+				__pa(large) +   (7<<PAGE_SHIFT) + PAGE_SIZE,
+				_PAGE_WC, NULL));
+
+		for (i = 0; i < 8<<PAGE_SHIFT; i += PAGE_SIZE) {
+			pte_t *pte = lookup_address((unsigned long)large + i);
+			CT(pte && pgprot_nonstd(pte_pgprot(*pte)) == _PAGE_WC);
+			CE(reserve_mattr(large + i, large + i + PAGE_SIZE,
+					 0, NULL));
+			C(reserve_mattr(large + i, large + i + PAGE_SIZE,
+					 -1, &attr));
+			CT(attr == _PAGE_WC);
+			C(free_mattr(large + i, large + i + PAGE_SIZE, attr));
+		}
+
+		C(free_mattr(__pa(large),
+				__pa(large) +   (7<<PAGE_SHIFT), _PAGE_WC));
+		C(free_mattr(__pa(large) +   (7<<PAGE_SHIFT),
+				__pa(large) + 2*(7<<PAGE_SHIFT), _PAGE_WC));
+		C(free_mattr(__pa(large) +   (7<<PAGE_SHIFT) - PAGE_SIZE,
+				__pa(large) +   (7<<PAGE_SHIFT) + PAGE_SIZE,
+				_PAGE_WC));
+
+		for (i = 0; i < 8<<PAGE_SHIFT; i += PAGE_SIZE) {
+			pte_t *pte = lookup_address(large + i);
+			CT(pte && pgprot_nonstd(pte_pgprot(*pte)) == 0);
+			CE(reserve_mattr(large + i, large + i + PAGE_SIZE,
+					 0, NULL));
+			C(reserve_mattr(large + i, large + i + PAGE_SIZE,
+					 -1, &attr));
+			CT(attr == 0);
+			C(free_mattr(large + i, large + i + PAGE_SIZE, attr));
+		}
+
+	} else
+		printk("Cannot get 1MB\n");
+	return 0;
+}
+__initcall(test);
+