Index: target-i386/helper.c
--- target-i386/helper.c	18 Nov 2007 01:44:38 -0000	1.95
+++ target-i386/helper.c	6 Dec 2007 19:22:55 -0000
@@ -4250,8 +4331,8 @@
             uint64_t addr = ldq_phys(env->vm_vmcb + offsetof(struct vmcb, control.iopm_base_pa));
             uint16_t port = (uint16_t) (param >> 16);
 
-            if(ldub_phys(addr + port / 8) & (1 << (port % 8)))
-                vmexit(type, param);
+	    if(ldub_phys(addr + port / 8) & (((1 << ((param >> 4) & 0x7)) - 1) << (port % 8)))
+	      vmexit(type, param);
         }
         break;