diff --git a/arch/arm/include/asm/xen/page.h b/arch/arm/include/asm/xen/page.h
index 359a7b5..8edc674 100644
--- a/arch/arm/include/asm/xen/page.h
+++ b/arch/arm/include/asm/xen/page.h
@@ -9,9 +9,7 @@
 
 #include <xen/interface/grant_table.h>
 
-#define pfn_to_mfn(pfn)			(pfn)
 #define phys_to_machine_mapping_valid(pfn) (1)
-#define mfn_to_pfn(mfn)			(mfn)
 #define mfn_to_virt(m)			(__va(mfn_to_pfn(m) << PAGE_SHIFT))
 
 #define pte_mfn	    pte_pfn
@@ -32,6 +30,10 @@ typedef struct xpaddr {
 
 #define INVALID_P2M_ENTRY      (~0UL)
 
+unsigned long pfn_to_mfn(unsigned long pfn);
+unsigned long mfn_to_pfn(unsigned long mfn);
+unsigned long mfn_to_local_pfn(unsigned long mfn);
+
 static inline xmaddr_t phys_to_machine(xpaddr_t phys)
 {
 	unsigned offset = phys.paddr & ~PAGE_MASK;
@@ -76,11 +78,9 @@ static inline int m2p_remove_override(struct page *page, bool clear_pte)
 	return 0;
 }
 
-static inline bool __set_phys_to_machine(unsigned long pfn, unsigned long mfn)
-{
-	BUG_ON(pfn != mfn && mfn != INVALID_P2M_ENTRY);
-	return true;
-}
+bool __set_phys_to_machine(unsigned long pfn, unsigned long mfn);
+bool __set_phys_to_machine_multi(unsigned long pfn, unsigned long mfn,
+		unsigned long nr_pages);
 
 static inline bool set_phys_to_machine(unsigned long pfn, unsigned long mfn)
 {
diff --git a/arch/arm/xen/Makefile b/arch/arm/xen/Makefile
index 4384103..21e6ff5 100644
--- a/arch/arm/xen/Makefile
+++ b/arch/arm/xen/Makefile
@@ -1 +1 @@
-obj-y		:= enlighten.o hypercall.o grant-table.o
+obj-y		:= enlighten.o hypercall.o grant-table.o p2m.o
diff --git a/arch/arm/xen/p2m.c b/arch/arm/xen/p2m.c
new file mode 100644
index 0000000..49c2b57
--- /dev/null
+++ b/arch/arm/xen/p2m.c
@@ -0,0 +1,237 @@
+#include <linux/bootmem.h>
+#include <linux/gfp.h>
+#include <linux/export.h>
+#include <linux/slab.h>
+#include <linux/types.h>
+#include <linux/dma-mapping.h>
+#include <linux/vmalloc.h>
+#include <linux/swiotlb.h>
+
+#include <xen/xen.h>
+#include <xen/interface/memory.h>
+#include <xen/swiotlb-xen.h>
+
+#include <asm/cacheflush.h>
+#include <asm/xen/page.h>
+#include <asm/xen/hypercall.h>
+#include <asm/xen/interface.h>
+
+struct xen_p2m_entry {
+	unsigned long pfn;
+	unsigned long mfn;
+	unsigned long nr_pages;
+	struct rb_node rbnode_mach;
+	struct rb_node rbnode_phys;
+};
+
+spinlock_t p2m_lock;
+static struct rb_root phys_to_mach = RB_ROOT;
+static struct rb_root mach_to_phys = RB_ROOT;
+
+static int xen_add_phys_to_mach_entry(struct xen_p2m_entry *new)
+{
+	struct rb_node **link = &phys_to_mach.rb_node;
+	struct rb_node *parent = NULL;
+	struct xen_p2m_entry *entry;
+	int rc = 0;
+
+	while (*link) {
+		parent = *link;
+		entry = rb_entry(parent, struct xen_p2m_entry, rbnode_phys);
+
+		if (new->mfn == entry->mfn)
+			goto err_out;
+		if (new->pfn == entry->pfn)
+			goto err_out;
+
+		if (new->pfn < entry->pfn)
+			link = &(*link)->rb_left;
+		else
+			link = &(*link)->rb_right;
+	}
+	rb_link_node(&new->rbnode_phys, parent, link);
+	rb_insert_color(&new->rbnode_phys, &phys_to_mach);
+	goto out;
+
+err_out:
+	rc = -EINVAL;
+	pr_warn("%s: cannot add pfn=%pa -> mfn=%pa: pfn=%pa -> mfn=%pa already exists\n",
+			__func__, &new->pfn, &new->mfn, &entry->pfn, &entry->mfn);
+out:
+	return rc;
+}
+
+static struct xen_p2m_entry *xen_get_p2m_entry_from_phys(unsigned long phys)
+{
+	struct rb_node *n = phys_to_mach.rb_node;
+	struct xen_p2m_entry *entry;
+	unsigned long irqflags;
+
+	spin_lock_irqsave(&p2m_lock, irqflags);
+	while (n) {
+		entry = rb_entry(n, struct xen_p2m_entry, rbnode_phys);
+		if (entry->pfn <= phys &&
+				entry->pfn + entry->nr_pages > phys) {
+			spin_unlock_irqrestore(&p2m_lock, irqflags);
+			return entry;
+		}
+		if (phys < entry->pfn)
+			n = n->rb_left;
+		else
+			n = n->rb_right;
+	}
+	spin_unlock_irqrestore(&p2m_lock, irqflags);
+
+	return NULL;
+}
+
+static int xen_add_mach_to_phys_entry(struct xen_p2m_entry *new)
+{
+	struct rb_node **link = &mach_to_phys.rb_node;
+	struct rb_node *parent = NULL;
+	struct xen_p2m_entry *entry;
+	int rc = 0;
+
+	while (*link) {
+		parent = *link;
+		entry = rb_entry(parent, struct xen_p2m_entry, rbnode_mach);
+
+		if (new->mfn == entry->mfn)
+			goto err_out;
+		if (new->pfn == entry->pfn)
+			goto err_out;
+
+		if (new->mfn < entry->mfn)
+			link = &(*link)->rb_left;
+		else
+			link = &(*link)->rb_right;
+	}
+	rb_link_node(&new->rbnode_mach, parent, link);
+	rb_insert_color(&new->rbnode_mach, &mach_to_phys);
+	goto out;
+
+err_out:
+	rc = -EINVAL;
+	pr_warn("%s: cannot add pfn=%pa -> mfn=%pa: pfn=%pa -> mfn=%pa already exists\n",
+			__func__, &new->pfn, &new->mfn, &entry->pfn, &entry->mfn);
+out:
+	return rc;
+}
+
+static struct xen_p2m_entry *xen_get_p2m_entry_from_mach(unsigned long mfn)
+{
+	struct rb_node *n = mach_to_phys.rb_node;
+	struct xen_p2m_entry *entry;
+	unsigned long irqflags;
+
+	spin_lock_irqsave(&p2m_lock, irqflags);
+	while (n) {
+		entry = rb_entry(n, struct xen_p2m_entry, rbnode_mach);
+		if (entry->mfn <= mfn &&
+				entry->mfn + entry->nr_pages > mfn) {
+			spin_unlock_irqrestore(&p2m_lock, irqflags);
+			return entry;
+		}
+		if (mfn < entry->mfn)
+			n = n->rb_left;
+		else
+			n = n->rb_right;
+	}
+	spin_unlock_irqrestore(&p2m_lock, irqflags);
+
+	return NULL;
+}
+
+unsigned long pfn_to_mfn(unsigned long pfn)
+{
+	struct xen_p2m_entry *p2m_entry;
+
+	p2m_entry = xen_get_p2m_entry_from_phys(pfn);
+	if (p2m_entry != NULL)
+		return p2m_entry->mfn;
+
+	if (xen_initial_domain())
+		return pfn;
+	else
+		return INVALID_P2M_ENTRY;
+}
+
+unsigned long mfn_to_pfn(unsigned long mfn)
+{
+	struct xen_p2m_entry *p2m_entry;
+
+	p2m_entry = xen_get_p2m_entry_from_mach(mfn);
+	if (p2m_entry != NULL)
+		return p2m_entry->pfn;
+
+	if (xen_initial_domain())
+		return mfn;
+	else
+		return INVALID_P2M_ENTRY;
+}
+
+unsigned long mfn_to_local_pfn(unsigned long mfn)
+{
+	struct xen_p2m_entry *p2m_entry;
+
+	if (!xen_initial_domain())
+		return INVALID_P2M_ENTRY;
+
+	p2m_entry = xen_get_p2m_entry_from_mach(mfn);
+	if (p2m_entry != NULL)
+		return INVALID_P2M_ENTRY;
+
+	return mfn;
+}
+
+bool __set_phys_to_machine_multi(unsigned long pfn,
+		unsigned long mfn, unsigned long nr_pages)
+{
+	int rc;
+	unsigned long irqflags;
+	struct xen_p2m_entry *p2m_entry;
+
+	p2m_entry = xen_get_p2m_entry_from_phys(pfn);
+	if (p2m_entry != NULL) {
+		BUG_ON(pfn != mfn && mfn != INVALID_P2M_ENTRY);
+		spin_lock_irqsave(&p2m_lock, irqflags);
+		rb_erase(&p2m_entry->rbnode_mach, &mach_to_phys);
+		rb_erase(&p2m_entry->rbnode_phys, &phys_to_mach);
+		spin_unlock_irqrestore(&p2m_lock, irqflags);
+		kfree(p2m_entry);	
+		return true;
+	} else if (mfn == INVALID_P2M_ENTRY)
+		return true;
+
+	p2m_entry = kzalloc(sizeof(struct xen_p2m_entry), GFP_NOWAIT);
+	if (!p2m_entry) {
+		pr_warn("cannot allocate xen_p2m_entry\n");
+		return false;
+	}
+	p2m_entry->pfn = pfn;
+	p2m_entry->nr_pages = nr_pages;
+	p2m_entry->mfn = mfn;
+
+	spin_lock_irqsave(&p2m_lock, irqflags);
+	if ((rc = xen_add_phys_to_mach_entry(p2m_entry) < 0) ||
+		(rc = xen_add_mach_to_phys_entry(p2m_entry) < 0)) {
+		spin_unlock_irqrestore(&p2m_lock, irqflags);
+		return false;
+	}
+	spin_unlock_irqrestore(&p2m_lock, irqflags);
+	return true;
+}
+EXPORT_SYMBOL_GPL(__set_phys_to_machine_multi);
+
+bool __set_phys_to_machine(unsigned long pfn, unsigned long mfn)
+{
+	return __set_phys_to_machine_multi(pfn, mfn, 1);
+}
+EXPORT_SYMBOL_GPL(__set_phys_to_machine);
+
+int p2m_init(void)
+{
+	spin_lock_init(&p2m_lock);
+	return 0;
+}
+arch_initcall(p2m_init);
diff --git a/arch/arm64/xen/Makefile b/arch/arm64/xen/Makefile
index be24040..cd866b0 100644
--- a/arch/arm64/xen/Makefile
+++ b/arch/arm64/xen/Makefile
@@ -1,2 +1,2 @@
-xen-arm-y	+= $(addprefix ../../arm/xen/, enlighten.o grant-table.o)
+xen-arm-y	+= $(addprefix ../../arm/xen/, enlighten.o grant-table.o p2m.o)
 obj-y		:= xen-arm.o hypercall.o
