x86 PAT: consolidate old memtype new memtype check into a function

Impact: cleanup

Move the new memtype old memtype allowed check to header so that is can be
shared by other users. Subsequent patch uses this in pat.c in remap_pfn_range()
code path. No functionality change in this patch.

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>

diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h
index 83e69f4..06bbcbd 100644 (file)
--- a/arch/x86/include/asm/pgtable.h
+++ b/arch/x86/include/asm/pgtable.h
@@ -341,6 +341,25 @@ static inline pgprot_t pgprot_modify(pgprot_t oldprot, pgprot_t newprot)
 
 #define canon_pgprot(p) __pgprot(pgprot_val(p) & __supported_pte_mask)
 
+static inline int is_new_memtype_allowed(unsigned long flags,
+                                               unsigned long new_flags)
+{
+       /*
+        * Certain new memtypes are not allowed with certain
+        * requested memtype:
+        * - request is uncached, return cannot be write-back
+        * - request is write-combine, return cannot be write-back
+        */
+       if ((flags == _PAGE_CACHE_UC_MINUS &&
+            new_flags == _PAGE_CACHE_WB) ||
+           (flags == _PAGE_CACHE_WC &&
+            new_flags == _PAGE_CACHE_WB)) {
+               return 0;
+       }
+
+       return 1;
+}
+
 #ifndef __ASSEMBLY__
 /* Indicate that x86 has its own track and untrack pfn vma functions */
 #define __HAVE_PFNMAP_TRACKING

diff --git a/arch/x86/pci/i386.c b/arch/x86/pci/i386.c
index f884740..5ead808 100644 (file)
--- a/arch/x86/pci/i386.c
+++ b/arch/x86/pci/i386.c
@@ -314,17 +314,7 @@ int pci_mmap_page_range(struct pci_dev *dev, struct vm_area_struct *vma,
                return retval;
 
        if (flags != new_flags) {
-               /*
-                * Do not fallback to certain memory types with certain
-                * requested type:
-                * - request is uncached, return cannot be write-back
-                * - request is uncached, return cannot be write-combine
-                * - request is write-combine, return cannot be write-back
-                */
-               if ((flags == _PAGE_CACHE_UC_MINUS &&
-                    (new_flags == _PAGE_CACHE_WB)) ||
-                   (flags == _PAGE_CACHE_WC &&
-                    new_flags == _PAGE_CACHE_WB)) {
+               if (!is_new_memtype_allowed(flags, new_flags)) {
                        free_memtype(addr, addr+len);
                        return -EINVAL;
                }