diff --git a/xen/arch/x86/domain_build.c b/xen/arch/x86/domain_build.c
index d02dc4bfbf..cb287f0698 100644
--- a/xen/arch/x86/domain_build.c
+++ b/xen/arch/x86/domain_build.c
@@ -1533,7 +1533,7 @@ int __init construct_dom0(
 
     /* The hardware domain is initially permitted full I/O capabilities. */
     rc |= ioports_permit_access(d, 0, 0xFFFF);
-    rc |= iomem_permit_access(d, 0UL, ~0UL);
+    rc |= iomem_permit_access(d, 0UL, (1UL << (paddr_bits - PAGE_SHIFT)) - 1);
     rc |= irqs_permit_access(d, 1, nr_irqs_gsi - 1);
 
     /*
diff --git a/xen/arch/x86/mm.c b/xen/arch/x86/mm.c
index fcf6577dbb..83f82b87be 100644
--- a/xen/arch/x86/mm.c
+++ b/xen/arch/x86/mm.c
@@ -4604,7 +4604,7 @@ struct memory_map_context
 static int _handle_iomem_range(unsigned long s, unsigned long e,
                                struct memory_map_context *ctxt)
 {
-    if ( s > ctxt->s )
+    if ( s > ctxt->s && !(s >> (paddr_bits - PAGE_SHIFT)) )
     {
         e820entry_t ent;
         XEN_GUEST_HANDLE_PARAM(e820entry_t) buffer_param;