[XEN] Fix page-fault handler to fall back to shadow-mode fault path if

writable pagetable logic fails to fix up a fault.
Signed-off-by: Keir Fraser <keir@xensource.com>

diff --git a/xen/arch/x86/traps.c b/xen/arch/x86/traps.c
index 2d398712fed785471f7f8ae59234f6040fa227d2..7a5d2f868af76b876b791f90ae044db094bba8df 100644 (file)
--- a/xen/arch/x86/traps.c
+++ b/xen/arch/x86/traps.c
@@ -888,11 +888,12 @@ static int fixup_page_fault(unsigned long addr, struct cpu_user_regs *regs)
         return (spurious_page_fault(addr, regs) ? EXCRET_not_a_fault : 0);
     }
 
-    if ( likely(VM_ASSIST(d, VMASST_TYPE_writable_pagetables)) &&
+    if ( VM_ASSIST(d, VMASST_TYPE_writable_pagetables) &&
          guest_kernel_mode(v, regs) &&
          ((regs->error_code & (PGERR_write_access|PGERR_page_present)) ==
-          (PGERR_write_access|PGERR_page_present)) )
-        return ptwr_do_page_fault(d, addr, regs) ? EXCRET_fault_fixed : 0;
+          (PGERR_write_access|PGERR_page_present)) &&
+         ptwr_do_page_fault(d, addr, regs) )
+        return EXCRET_fault_fixed;
 
     if ( shadow2_mode_enabled(d) )
         return shadow2_fault(addr, regs);