1 files changed, 8 insertions, 4 deletions

diff --git a/arch/x86/xen/mmu.c b/arch/x86/xen/mmu.c
index 8cce339db5e7..20a614275064 100644
--- a/arch/x86/xen/mmu.c
+++ b/arch/x86/xen/mmu.c
@@ -1713,15 +1713,19 @@ static void __init xen_map_identity_early(pmd_t *pmd, unsigned long max_pfn)
 void __init xen_setup_machphys_mapping(void)
 {
         struct xen_machphys_mapping mapping;
-        unsigned long machine_to_phys_nr_ents;
 
         if (HYPERVISOR_memory_op(XENMEM_machphys_mapping, &mapping) == 0) {
                 machine_to_phys_mapping = (unsigned long *)mapping.v_start;
-                machine_to_phys_nr_ents = mapping.max_mfn + 1;
+                machine_to_phys_nr = mapping.max_mfn + 1;
         } else {
-                machine_to_phys_nr_ents = MACH2PHYS_NR_ENTRIES;
+                machine_to_phys_nr = MACH2PHYS_NR_ENTRIES;
         }
-        machine_to_phys_order = fls(machine_to_phys_nr_ents - 1);
+#ifdef CONFIG_X86_32
+        if ((machine_to_phys_mapping + machine_to_phys_nr)
+            < machine_to_phys_mapping)
+                machine_to_phys_nr = (unsigned long *)NULL
+                                     - machine_to_phys_mapping;
+#endif
 }
 
 #ifdef CONFIG_X86_64