gpu/drm, x86, PAT: routine to keep identity map in sync

Add a function to check and keep identity maps in sync, when changing
any memory type. One of the follow on patches will also use this
routine.
Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Cc: Dave Airlie <airlied@redhat.com>
Cc: Jesse Barnes <jbarnes@virtuousgeek.org>
Cc: Eric Anholt <eric@anholt.net>
Cc: Keith Packard <keithp@keithp.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

arch/x86/include/asm/pat.h

@@ -19,4 +19,7 @@ extern int free_memtype(u64 start, u64 end);
 
 extern void pat_disable(char *reason);
 
+extern int kernel_map_sync_memtype(u64 base, unsigned long size,
+		unsigned long flag);
+
 #endif /* _ASM_X86_PAT_H */

arch/x86/mm/pat.c

@@ -624,6 +624,33 @@ void unmap_devmem(unsigned long pfn, unsigned long size, pgprot_t vma_prot)
 	free_memtype(addr, addr + size);
 }
 
+/*
+ * Change the memory type for the physial address range in kernel identity
+ * mapping space if that range is a part of identity map.
+ */
+int kernel_map_sync_memtype(u64 base, unsigned long size, unsigned long flags)
+{
+	unsigned long id_sz;
+
+	if (!pat_enabled || base >= __pa(high_memory))
+		return 0;
+
+	id_sz = (__pa(high_memory) < base + size) ?
+				__pa(high_memory) - base :
+				size;
+
+	if (ioremap_change_attr((unsigned long)__va(base), id_sz, flags) < 0) {
+		printk(KERN_INFO
+			"%s:%d ioremap_change_attr failed %s "
+			"for %Lx-%Lx\n",
+			current->comm, current->pid,
+			cattr_name(flags),
+			base, (unsigned long long)(base + size));
+		return -EINVAL;
+	}
+	return 0;
+}
+
 /*
  * Internal interface to reserve a range of physical memory with prot.
  * Reserved non RAM regions only and after successful reserve_memtype,
@@ -633,7 +660,7 @@ static int reserve_pfn_range(u64 paddr, unsigned long size, pgprot_t *vma_prot,
 				int strict_prot)
 {
 	int is_ram = 0;
-	int id_sz, ret;
+	int ret;
 	unsigned long flags;
 	unsigned long want_flags = (pgprot_val(*vma_prot) & _PAGE_CACHE_MASK);
 
@@ -670,23 +697,8 @@ static int reserve_pfn_range(u64 paddr, unsigned long size, pgprot_t *vma_prot,
 				     flags);
 	}
 
-	/* Need to keep identity mapping in sync */
-	if (paddr >= __pa(high_memory))
-		return 0;
-
-	id_sz = (__pa(high_memory) < paddr + size) ?
-				__pa(high_memory) - paddr :
-				size;
-
-	if (ioremap_change_attr((unsigned long)__va(paddr), id_sz, flags) < 0) {
+	if (kernel_map_sync_memtype(paddr, size, flags) < 0) {
 		free_memtype(paddr, paddr + size);
-		printk(KERN_ERR
-			"%s:%d reserve_pfn_range ioremap_change_attr failed %s "
-			"for %Lx-%Lx\n",
-			current->comm, current->pid,
-			cattr_name(flags),
-			(unsigned long long)paddr,
-			(unsigned long long)(paddr + size));
 		return -EINVAL;
 	}
 	return 0;