diff --git a/tools/libxc/include/xenctrl.h b/tools/libxc/include/xenctrl.h
index df182921fa..7853fdbb4c 100644
--- a/tools/libxc/include/xenctrl.h
+++ b/tools/libxc/include/xenctrl.h
@@ -1315,7 +1315,7 @@ int xc_domain_get_tsc_info(xc_interface *xch,
 
 int xc_domain_disable_migrate(xc_interface *xch, uint32_t domid);
 
-int xc_domain_maximum_gpfn(xc_interface *xch, domid_t domid);
+int xc_domain_maximum_gpfn(xc_interface *xch, domid_t domid, xen_pfn_t *gpfns);
 
 int xc_domain_increase_reservation(xc_interface *xch,
                                    uint32_t domid,
diff --git a/tools/libxc/xc_core_arm.c b/tools/libxc/xc_core_arm.c
index 16508e77af..c3f5868044 100644
--- a/tools/libxc/xc_core_arm.c
+++ b/tools/libxc/xc_core_arm.c
@@ -30,12 +30,6 @@ xc_core_arch_gpfn_may_present(struct xc_core_arch_context *arch_ctxt,
     return 0;
 }
 
-
-static int nr_gpfns(xc_interface *xch, domid_t domid)
-{
-    return xc_domain_maximum_gpfn(xch, domid) + 1;
-}
-
 int
 xc_core_arch_auto_translated_physmap(const xc_dominfo_t *info)
 {
@@ -48,9 +42,12 @@ xc_core_arch_memory_map_get(xc_interface *xch, struct xc_core_arch_context *unus
                             xc_core_memory_map_t **mapp,
                             unsigned int *nr_entries)
 {
-    unsigned long p2m_size = nr_gpfns(xch, info->domid);
+    xen_pfn_t p2m_size = 0;
     xc_core_memory_map_t *map;
 
+    if ( xc_domain_maximum_gpfn(xch, info->domid, &p2m_size) < 0 )
+        return -1;
+
     map = malloc(sizeof(*map));
     if ( map == NULL )
     {
diff --git a/tools/libxc/xc_core_x86.c b/tools/libxc/xc_core_x86.c
index d8846f1fc5..4552e432b3 100644
--- a/tools/libxc/xc_core_x86.c
+++ b/tools/libxc/xc_core_x86.c
@@ -35,12 +35,6 @@ xc_core_arch_gpfn_may_present(struct xc_core_arch_context *arch_ctxt,
     return 1;
 }
 
-
-static int nr_gpfns(xc_interface *xch, domid_t domid)
-{
-    return xc_domain_maximum_gpfn(xch, domid) + 1;
-}
-
 int
 xc_core_arch_auto_translated_physmap(const xc_dominfo_t *info)
 {
@@ -53,9 +47,12 @@ xc_core_arch_memory_map_get(xc_interface *xch, struct xc_core_arch_context *unus
                             xc_core_memory_map_t **mapp,
                             unsigned int *nr_entries)
 {
-    unsigned long p2m_size = nr_gpfns(xch, info->domid);
+    xen_pfn_t p2m_size = 0;
     xc_core_memory_map_t *map;
 
+    if ( xc_domain_maximum_gpfn(xch, info->domid, &p2m_size) < 0 )
+        return -1;
+
     map = malloc(sizeof(*map));
     if ( map == NULL )
     {
@@ -88,7 +85,12 @@ xc_core_arch_map_p2m_rw(xc_interface *xch, struct domain_info_context *dinfo, xc
     int err;
     int i;
 
-    dinfo->p2m_size = nr_gpfns(xch, info->domid);
+    if ( xc_domain_maximum_gpfn(xch, info->domid, &dinfo->p2m_size) < 0 )
+    {
+        ERROR("Could not get maximum GPFN!");
+        goto out;
+    }
+
     if ( dinfo->p2m_size < info->nr_pages  )
     {
         ERROR("p2m_size < nr_pages -1 (%lx < %lx", dinfo->p2m_size, info->nr_pages - 1);
@@ -210,16 +212,7 @@ int
 xc_core_arch_get_scratch_gpfn(xc_interface *xch, domid_t domid,
                               xen_pfn_t *gpfn)
 {
-    int rc;
-
-    rc = xc_domain_maximum_gpfn(xch, domid);
-
-    if ( rc < 0 )
-        return rc;
-
-    *gpfn = (xen_pfn_t)rc + 1;
-
-    return 0;
+    return xc_domain_maximum_gpfn(xch, domid, gpfn);
 }
 
 /*
diff --git a/tools/libxc/xc_domain.c b/tools/libxc/xc_domain.c
index 2fed727aac..da88e08fd2 100644
--- a/tools/libxc/xc_domain.c
+++ b/tools/libxc/xc_domain.c
@@ -789,9 +789,16 @@ int xc_domain_get_tsc_info(xc_interface *xch,
 }
 
 
-int xc_domain_maximum_gpfn(xc_interface *xch, domid_t domid)
+int xc_domain_maximum_gpfn(xc_interface *xch, domid_t domid, xen_pfn_t *gpfns)
 {
-    return do_memory_op(xch, XENMEM_maximum_gpfn, &domid, sizeof(domid));
+    int rc = do_memory_op(xch, XENMEM_maximum_gpfn, &domid, sizeof(domid));
+
+    if ( rc >= 0 )
+    {
+        *gpfns = rc + 1;
+        rc = 0;
+    }
+    return rc;
 }
 
 int xc_domain_increase_reservation(xc_interface *xch,
diff --git a/tools/libxc/xc_domain_save.c b/tools/libxc/xc_domain_save.c
index 254fdb344d..b611c07524 100644
--- a/tools/libxc/xc_domain_save.c
+++ b/tools/libxc/xc_domain_save.c
@@ -939,7 +939,11 @@ int xc_domain_save(xc_interface *xch, int io_fd, uint32_t dom, uint32_t max_iter
     }
 
     /* Get the size of the P2M table */
-    dinfo->p2m_size = xc_domain_maximum_gpfn(xch, dom) + 1;
+    if ( xc_domain_maximum_gpfn(xch, dom, &dinfo->p2m_size) < 0 )
+    {
+        ERROR("Could not get maximum GPFN!");
+        goto out;
+    }
 
     if ( dinfo->p2m_size > ~XEN_DOMCTL_PFINFO_LTAB_MASK )
     {