diff --git a/hw/vmport.c b/hw/vmport.c
index 884af3f..7ba6e2e 100644
--- a/hw/vmport.c
+++ b/hw/vmport.c
@@ -25,6 +25,7 @@
 #include "isa.h"
 #include "pc.h"
 #include "sysemu.h"
+#include "kvm.h"
 
 //#define VMPORT_DEBUG
 
@@ -51,7 +52,7 @@ void vmport_register(unsigned char command, IOPortReadFunc *func, void *opaque)
     port_state.opaque[command] = opaque;
 }
 
-static uint32_t vmport_ioport_read(void *opaque, uint32_t addr)
+static uint32_t vmport_ioport_command(void *opaque, uint32_t addr)
 {
     VMPortState *s = opaque;
     CPUState *env = cpu_single_env;
@@ -76,11 +77,24 @@ static uint32_t vmport_ioport_read(void *opaque, uint32_t addr)
     return s->func[command](s->opaque[command], addr);
 }
 
+static uint32_t vmport_ioport_read(void *opaque, uint32_t addr)
+{
+    CPUState *env = cpu_single_env;
+    uint32_t result;
+
+    cpu_synchronize_state(env, 0);
+    result = vmport_ioport_command(opaque, addr);
+    cpu_synchronize_state(env, 1);
+    return result;
+}
+
 static void vmport_ioport_write(void *opaque, uint32_t addr, uint32_t val)
 {
     CPUState *env = cpu_single_env;
 
-    env->regs[R_EAX] = vmport_ioport_read(opaque, addr);
+    cpu_synchronize_state(env, 0);
+    env->regs[R_EAX] = vmport_ioport_command(opaque, addr);
+    cpu_synchronize_state(env, 1);
 }
 
 static uint32_t vmport_cmd_get_version(void *opaque, uint32_t addr)