1 files changed, 4 insertions, 3 deletions

diff --git a/arch/x86/xen/mmu.c b/arch/x86/xen/mmu.c
index 1e56ff583459..63146c378f1e 100644
--- a/arch/x86/xen/mmu.c
+++ b/arch/x86/xen/mmu.c
@@ -2038,7 +2038,8 @@ static unsigned long __init xen_read_phys_ulong(phys_addr_t addr)
 
 /*
  * Translate a virtual address to a physical one without relying on mapped
- * page tables.
+ * page tables. Don't rely on big pages being aligned in (guest) physical
+ * space!
  */
 static phys_addr_t __init xen_early_virt_to_phys(unsigned long vaddr)
 {
@@ -2059,7 +2060,7 @@ static phys_addr_t __init xen_early_virt_to_phys(unsigned long vaddr)
                                                        sizeof(pud)));
         if (!pud_present(pud))
                 return 0;
-        pa = pud_pfn(pud) << PAGE_SHIFT;
+        pa = pud_val(pud) & PTE_PFN_MASK;
         if (pud_large(pud))
                 return pa + (vaddr & ~PUD_MASK);
 
@@ -2067,7 +2068,7 @@ static phys_addr_t __init xen_early_virt_to_phys(unsigned long vaddr)
                                                        sizeof(pmd)));
         if (!pmd_present(pmd))
                 return 0;
-        pa = pmd_pfn(pmd) << PAGE_SHIFT;
+        pa = pmd_val(pmd) & PTE_PFN_MASK;
         if (pmd_large(pmd))
                 return pa + (vaddr & ~PMD_MASK);