x86: PAT use reserve free memtype in set_memory_uc

Use reserve_memtype and free_memtype interfaces in set_memory_uc/set_memory_wb
interfaces to avoid aliasing.
Usage model of set_memory_uc and set_memory_wb is for RAM memory and users
will first call set_memory_uc and call set_memory_wb after use to reset the
attribute.
Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

arch/x86/mm/ioremap.c

@@ -95,10 +95,10 @@ int ioremap_change_attr(unsigned long vaddr, unsigned long size,
 	switch (prot_val) {
 	case _PAGE_CACHE_UC:
 	default:
-		err = set_memory_uc(vaddr, nrpages);
+		err = _set_memory_uc(vaddr, nrpages);
 		break;
 	case _PAGE_CACHE_WB:
-		err = set_memory_wb(vaddr, nrpages);
+		err = _set_memory_wb(vaddr, nrpages);
 		break;
 	}
 

arch/x86/mm/pageattr.c

@@ -19,6 +19,7 @@
 #include <asm/uaccess.h>
 #include <asm/pgalloc.h>
 #include <asm/proto.h>
+#include <asm/pat.h>
 
 /*
  * The current flushing context - we pass it instead of 5 arguments:
@@ -770,18 +771,34 @@ static inline int change_page_attr_clear(unsigned long addr, int numpages,
 	return change_page_attr_set_clr(addr, numpages, __pgprot(0), mask);
 }
 
-int set_memory_uc(unsigned long addr, int numpages)
+int _set_memory_uc(unsigned long addr, int numpages)
 {
 	return change_page_attr_set(addr, numpages,
 				    __pgprot(_PAGE_CACHE_UC));
 }
+
+int set_memory_uc(unsigned long addr, int numpages)
+{
+	if (reserve_memtype(addr, addr + numpages * PAGE_SIZE,
+	                    _PAGE_CACHE_UC, NULL))
+		return -EINVAL;
+
+	return _set_memory_uc(addr, numpages);
+}
 EXPORT_SYMBOL(set_memory_uc);
 
-int set_memory_wb(unsigned long addr, int numpages)
+int _set_memory_wb(unsigned long addr, int numpages)
 {
 	return change_page_attr_clear(addr, numpages,
 				      __pgprot(_PAGE_CACHE_MASK));
 }
+
+int set_memory_wb(unsigned long addr, int numpages)
+{
+	free_memtype(addr, addr + numpages * PAGE_SIZE);
+
+	return _set_memory_wb(addr, numpages);
+}
 EXPORT_SYMBOL(set_memory_wb);
 
 int set_memory_x(unsigned long addr, int numpages)

include/asm-x86/cacheflush.h

@@ -34,6 +34,8 @@ int set_pages_nx(struct page *page, int numpages);
 int set_pages_ro(struct page *page, int numpages);
 int set_pages_rw(struct page *page, int numpages);
 
+int _set_memory_uc(unsigned long addr, int numpages);
+int _set_memory_wb(unsigned long addr, int numpages);
 int set_memory_uc(unsigned long addr, int numpages);
 int set_memory_wb(unsigned long addr, int numpages);
 int set_memory_x(unsigned long addr, int numpages);