diff --git a/tools/libxc/include/xc_dom.h b/tools/libxc/include/xc_dom.h
index 07d7224b76..6b8ddf41a1 100644
--- a/tools/libxc/include/xc_dom.h
+++ b/tools/libxc/include/xc_dom.h
@@ -129,6 +129,7 @@ struct xc_dom_image {
      */
     xen_pfn_t rambase_pfn;
     xen_pfn_t total_pages;
+    xen_pfn_t p2m_size;         /* number of pfns covered by p2m */
     struct xc_dom_phys *phys_pages;
     int realmodearea_log;
 #if defined (__arm__) || defined(__aarch64__)
diff --git a/tools/libxc/xc_dom_arm.c b/tools/libxc/xc_dom_arm.c
index c7feca73e1..b9fa66daa0 100644
--- a/tools/libxc/xc_dom_arm.c
+++ b/tools/libxc/xc_dom_arm.c
@@ -449,6 +449,7 @@ int arch_setup_meminit(struct xc_dom_image *dom)
     assert(dom->rambank_size[0] != 0);
     assert(ramsize == 0); /* Too much RAM is rejected above */
 
+    dom->p2m_size = p2m_size;
     dom->p2m_host = xc_dom_malloc(dom, sizeof(xen_pfn_t) * p2m_size);
     if ( dom->p2m_host == NULL )
         return -EINVAL;
diff --git a/tools/libxc/xc_dom_core.c b/tools/libxc/xc_dom_core.c
index ecbf981988..b100ce1970 100644
--- a/tools/libxc/xc_dom_core.c
+++ b/tools/libxc/xc_dom_core.c
@@ -931,9 +931,9 @@ int xc_dom_update_guest_p2m(struct xc_dom_image *dom)
     {
     case 4:
         DOMPRINTF("%s: dst 32bit, pages 0x%" PRIpfn "",
-                  __FUNCTION__, dom->total_pages);
+                  __FUNCTION__, dom->p2m_size);
         p2m_32 = dom->p2m_guest;
-        for ( i = 0; i < dom->total_pages; i++ )
+        for ( i = 0; i < dom->p2m_size; i++ )
             if ( dom->p2m_host[i] != INVALID_P2M_ENTRY )
                 p2m_32[i] = dom->p2m_host[i];
             else
@@ -941,9 +941,9 @@ int xc_dom_update_guest_p2m(struct xc_dom_image *dom)
         break;
     case 8:
         DOMPRINTF("%s: dst 64bit, pages 0x%" PRIpfn "",
-                  __FUNCTION__, dom->total_pages);
+                  __FUNCTION__, dom->p2m_size);
         p2m_64 = dom->p2m_guest;
-        for ( i = 0; i < dom->total_pages; i++ )
+        for ( i = 0; i < dom->p2m_size; i++ )
             if ( dom->p2m_host[i] != INVALID_P2M_ENTRY )
                 p2m_64[i] = dom->p2m_host[i];
             else
diff --git a/tools/libxc/xc_dom_x86.c b/tools/libxc/xc_dom_x86.c
index 9dbaedb51a..bea54f2bd2 100644
--- a/tools/libxc/xc_dom_x86.c
+++ b/tools/libxc/xc_dom_x86.c
@@ -122,11 +122,11 @@ static int count_pgtables(struct xc_dom_image *dom, int pae,
 
         try_pfn_end = (try_virt_end - dom->parms.virt_base) >> PAGE_SHIFT_X86;
 
-        if ( try_pfn_end > dom->total_pages )
+        if ( try_pfn_end > dom->p2m_size )
         {
             xc_dom_panic(dom->xch, XC_OUT_OF_MEMORY,
                          "%s: not enough memory for initial mapping (%#"PRIpfn" > %#"PRIpfn")",
-                         __FUNCTION__, try_pfn_end, dom->total_pages);
+                         __FUNCTION__, try_pfn_end, dom->p2m_size);
             return -ENOMEM;
         }
 
@@ -440,10 +440,11 @@ pfn_error:
 
 static int alloc_magic_pages(struct xc_dom_image *dom)
 {
-    size_t p2m_size = dom->total_pages * dom->arch_hooks->sizeof_pfn;
+    size_t p2m_alloc_size = dom->p2m_size * dom->arch_hooks->sizeof_pfn;
 
     /* allocate phys2mach table */
-    if ( xc_dom_alloc_segment(dom, &dom->p2m_seg, "phys2mach", 0, p2m_size) )
+    if ( xc_dom_alloc_segment(dom, &dom->p2m_seg, "phys2mach",
+                              0, p2m_alloc_size) )
         return -1;
     dom->p2m_guest = xc_dom_seg_to_ptr(dom, &dom->p2m_seg);
     if ( dom->p2m_guest == NULL )
@@ -777,8 +778,9 @@ int arch_setup_meminit(struct xc_dom_image *dom)
         int count = dom->total_pages >> SUPERPAGE_PFN_SHIFT;
         xen_pfn_t extents[count];
 
+        dom->p2m_size = dom->total_pages;
         dom->p2m_host = xc_dom_malloc(dom, sizeof(xen_pfn_t) *
-                                      dom->total_pages);
+                                      dom->p2m_size);
         if ( dom->p2m_host == NULL )
             return -EINVAL;
 
@@ -810,8 +812,9 @@ int arch_setup_meminit(struct xc_dom_image *dom)
                 return rc;
         }
         /* setup initial p2m */
+        dom->p2m_size = dom->total_pages;
         dom->p2m_host = xc_dom_malloc(dom, sizeof(xen_pfn_t) *
-                                      dom->total_pages);
+                                      dom->p2m_size);
         if ( dom->p2m_host == NULL )
             return -EINVAL;
         for ( pfn = 0; pfn < dom->total_pages; pfn++ )
@@ -860,7 +863,7 @@ static int map_grant_table_frames(struct xc_dom_image *dom)
     {
         rc = xc_domain_add_to_physmap(dom->xch, dom->guest_domid,
                                       XENMAPSPACE_grant_table,
-                                      i, dom->total_pages + i);
+                                      i, dom->p2m_size + i);
         if ( rc != 0 )
         {
             if ( (i > 0) && (errno == EINVAL) )
@@ -870,7 +873,7 @@ static int map_grant_table_frames(struct xc_dom_image *dom)
             }
             xc_dom_panic(dom->xch, XC_INTERNAL_ERROR,
                          "%s: mapping grant tables failed " "(pfn=0x%" PRIpfn
-                         ", rc=%d)", __FUNCTION__, dom->total_pages + i, rc);
+                         ", rc=%d)", __FUNCTION__, dom->p2m_size + i, rc);
             return rc;
         }
     }