diff --git a/xen/arch/arm/mm.c b/xen/arch/arm/mm.c
index 018f44a6d1..d3674e732e 100644
--- a/xen/arch/arm/mm.c
+++ b/xen/arch/arm/mm.c
@@ -138,8 +138,8 @@ uint64_t init_ttbr;
 static paddr_t phys_offset;
 
 /* Limits of the Xen heap */
-unsigned long xenheap_mfn_start __read_mostly = ~0UL;
-unsigned long xenheap_mfn_end __read_mostly;
+mfn_t xenheap_mfn_start __read_mostly = INVALID_MFN_INITIALIZER;
+mfn_t xenheap_mfn_end __read_mostly;
 vaddr_t xenheap_virt_end __read_mostly;
 #ifdef CONFIG_ARM_64
 vaddr_t xenheap_virt_start __read_mostly;
@@ -801,8 +801,8 @@ void __init setup_xenheap_mappings(unsigned long base_mfn,
 
     /* Record where the xenheap is, for translation routines. */
     xenheap_virt_end = XENHEAP_VIRT_START + nr_mfns * PAGE_SIZE;
-    xenheap_mfn_start = base_mfn;
-    xenheap_mfn_end = base_mfn + nr_mfns;
+    xenheap_mfn_start = _mfn(base_mfn);
+    xenheap_mfn_end = _mfn(base_mfn + nr_mfns);
 }
 #else /* CONFIG_ARM_64 */
 void __init setup_xenheap_mappings(unsigned long base_mfn,
@@ -816,16 +816,16 @@ void __init setup_xenheap_mappings(unsigned long base_mfn,
     mfn = base_mfn & ~((FIRST_SIZE>>PAGE_SHIFT)-1);
 
     /* First call sets the xenheap physical and virtual offset. */
-    if ( xenheap_mfn_start == ~0UL )
+    if ( mfn_eq(xenheap_mfn_start, INVALID_MFN) )
     {
-        xenheap_mfn_start = base_mfn;
+        xenheap_mfn_start = _mfn(base_mfn);
         xenheap_virt_start = DIRECTMAP_VIRT_START +
             (base_mfn - mfn) * PAGE_SIZE;
     }
 
-    if ( base_mfn < xenheap_mfn_start )
+    if ( base_mfn < mfn_x(xenheap_mfn_start) )
         panic("cannot add xenheap mapping at %lx below heap start %lx",
-              base_mfn, xenheap_mfn_start);
+              base_mfn, mfn_x(xenheap_mfn_start));
 
     end_mfn = base_mfn + nr_mfns;
 
diff --git a/xen/arch/arm/setup.c b/xen/arch/arm/setup.c
index ab4d8e4218..3b34855668 100644
--- a/xen/arch/arm/setup.c
+++ b/xen/arch/arm/setup.c
@@ -555,8 +555,8 @@ static void __init setup_mm(unsigned long dtb_paddr, size_t dtb_size)
      * and enough mapped pages for copying the DTB.
      */
     dtb_pages = (dtb_size + PAGE_SIZE-1) >> PAGE_SHIFT;
-    boot_mfn_start = xenheap_mfn_end - dtb_pages - 1;
-    boot_mfn_end = xenheap_mfn_end;
+    boot_mfn_start = mfn_x(xenheap_mfn_end) - dtb_pages - 1;
+    boot_mfn_end = mfn_x(xenheap_mfn_end);
 
     init_boot_pages(pfn_to_paddr(boot_mfn_start), pfn_to_paddr(boot_mfn_end));
 
@@ -591,11 +591,11 @@ static void __init setup_mm(unsigned long dtb_paddr, size_t dtb_size)
                 e = bank_end;
 
             /* Avoid the xenheap */
-            if ( s < pfn_to_paddr(xenheap_mfn_start+xenheap_pages)
-                 && pfn_to_paddr(xenheap_mfn_start) < e )
+            if ( s < mfn_to_maddr(mfn_add(xenheap_mfn_start, xenheap_pages))
+                 && mfn_to_maddr(xenheap_mfn_start) < e )
             {
-                e = pfn_to_paddr(xenheap_mfn_start);
-                n = pfn_to_paddr(xenheap_mfn_start+xenheap_pages);
+                e = mfn_to_maddr(xenheap_mfn_start);
+                n = mfn_to_maddr(mfn_add(xenheap_mfn_start, xenheap_pages));
             }
 
             dt_unreserved_regions(s, e, init_boot_pages, 0);
@@ -610,7 +610,7 @@ static void __init setup_mm(unsigned long dtb_paddr, size_t dtb_size)
 
     /* Add xenheap memory that was not already added to the boot
        allocator. */
-    init_xenheap_pages(pfn_to_paddr(xenheap_mfn_start),
+    init_xenheap_pages(mfn_to_maddr(xenheap_mfn_start),
                        pfn_to_paddr(boot_mfn_start));
 }
 #else /* CONFIG_ARM_64 */
@@ -662,8 +662,8 @@ static void __init setup_mm(unsigned long dtb_paddr, size_t dtb_size)
     total_pages += ram_size >> PAGE_SHIFT;
 
     xenheap_virt_end = XENHEAP_VIRT_START + ram_end - ram_start;
-    xenheap_mfn_start = ram_start >> PAGE_SHIFT;
-    xenheap_mfn_end = ram_end >> PAGE_SHIFT;
+    xenheap_mfn_start = maddr_to_mfn(ram_start);
+    xenheap_mfn_end = maddr_to_mfn(ram_end);
 
     /*
      * Need enough mapped pages for copying the DTB.
diff --git a/xen/include/asm-arm/mm.h b/xen/include/asm-arm/mm.h
index ddb3f35ed1..7a35063546 100644
--- a/xen/include/asm-arm/mm.h
+++ b/xen/include/asm-arm/mm.h
@@ -107,7 +107,7 @@ struct page_info
 #define PGC_count_width   PG_shift(9)
 #define PGC_count_mask    ((1UL<<PGC_count_width)-1)
 
-extern unsigned long xenheap_mfn_start, xenheap_mfn_end;
+extern mfn_t xenheap_mfn_start, xenheap_mfn_end;
 extern vaddr_t xenheap_virt_end;
 #ifdef CONFIG_ARM_64
 extern vaddr_t xenheap_virt_start;
@@ -117,7 +117,8 @@ extern vaddr_t xenheap_virt_start;
 #define is_xen_heap_page(page) is_xen_heap_mfn(page_to_mfn(page))
 #define is_xen_heap_mfn(mfn) ({                                 \
     unsigned long _mfn = (mfn);                                 \
-    (_mfn >= xenheap_mfn_start && _mfn < xenheap_mfn_end);      \
+    (_mfn >= mfn_x(xenheap_mfn_start) &&                        \
+     _mfn < mfn_x(xenheap_mfn_end));                            \
 })
 #else
 #define is_xen_heap_page(page) ((page)->count_info & PGC_xen_heap)
@@ -227,7 +228,7 @@ static inline paddr_t __virt_to_maddr(vaddr_t va)
 static inline void *maddr_to_virt(paddr_t ma)
 {
     ASSERT(is_xen_heap_mfn(ma >> PAGE_SHIFT));
-    ma -= pfn_to_paddr(xenheap_mfn_start);
+    ma -= mfn_to_maddr(xenheap_mfn_start);
     return (void *)(unsigned long) ma + XENHEAP_VIRT_START;
 }
 #else
@@ -235,7 +236,7 @@ static inline void *maddr_to_virt(paddr_t ma)
 {
     ASSERT(pfn_to_pdx(ma >> PAGE_SHIFT) < (DIRECTMAP_SIZE >> PAGE_SHIFT));
     return (void *)(XENHEAP_VIRT_START -
-                    pfn_to_paddr(xenheap_mfn_start) +
+                    mfn_to_maddr(xenheap_mfn_start) +
                     ((ma & ma_va_bottom_mask) |
                      ((ma & ma_top_mask) >> pfn_pdx_hole_shift)));
 }
@@ -276,7 +277,7 @@ static inline struct page_info *virt_to_page(const void *v)
     ASSERT(va < xenheap_virt_end);
 
     pdx = (va - XENHEAP_VIRT_START) >> PAGE_SHIFT;
-    pdx += pfn_to_pdx(xenheap_mfn_start);
+    pdx += pfn_to_pdx(mfn_x(xenheap_mfn_start));
     return frame_table + pdx - frametable_base_pdx;
 }
 
