diff --git a/hw/pass-through.c b/hw/pass-through.c
index 919937f..976d28f 100644
--- a/hw/pass-through.c
+++ b/hw/pass-through.c
@@ -1455,8 +1455,7 @@ out:
     return index;
 }
 
-static void pt_pci_write_config(PCIDevice *d, uint32_t address, uint32_t val,
-                                int len)
+void pt_pci_write_config(PCIDevice *d, uint32_t address, uint32_t val, int len)
 {
     struct pt_dev *assigned_device = (struct pt_dev *)d;
     struct pci_dev *pci_dev = assigned_device->pci_dev;
@@ -1637,7 +1636,7 @@ exit:
     return;
 }
 
-static uint32_t pt_pci_read_config(PCIDevice *d, uint32_t address, int len)
+uint32_t pt_pci_read_config(PCIDevice *d, uint32_t address, int len)
 {
     struct pt_dev *assigned_device = (struct pt_dev *)d;
     struct pci_dev *pci_dev = assigned_device->pci_dev;
@@ -4191,7 +4190,8 @@ static struct pt_dev * register_real_device(PCIBus *e_bus,
     /* Register device */
     assigned_device = (struct pt_dev *) pci_register_device(e_bus, e_dev_name,
                                 sizeof(struct pt_dev), e_devfn,
-                                pt_pci_read_config, pt_pci_write_config);
+                                gfx_passthru ? vgapt_pci_read_config : pt_pci_read_config,
+                                gfx_passthru ? vgapt_pci_write_config : pt_pci_write_config);
     if ( assigned_device == NULL )
     {
         PT_LOG("Error: couldn't register real device\n");
diff --git a/hw/pass-through.h b/hw/pass-through.h
index 884139c..c898c7c 100644
--- a/hw/pass-through.h
+++ b/hw/pass-through.h
@@ -422,6 +422,10 @@ PCIBus *intel_pci_bridge_init(PCIBus *bus, int devfn, uint16_t vid,
            uint16_t did, const char *name, uint16_t revision);
 void igd_pci_write(PCIDevice *pci_dev, uint32_t config_addr, uint32_t val, int len);
 uint32_t igd_pci_read(PCIDevice *pci_dev, uint32_t config_addr, int len);
+void vgapt_pci_write_config(PCIDevice *pci_dev, uint32_t config_addr, uint32_t val, int len);
+uint32_t vgapt_pci_read_config(PCIDevice *pci_dev, uint32_t config_addr, int len);
+uint32_t pt_pci_read_config(PCIDevice *d, uint32_t address, int len);
+void pt_pci_write_config(PCIDevice *d, uint32_t address, uint32_t val, int len);
 
 #endif /* __PASSTHROUGH_H__ */
 
diff --git a/hw/pt-graphics.c b/hw/pt-graphics.c
index fec7390..33cbff5 100644
--- a/hw/pt-graphics.c
+++ b/hw/pt-graphics.c
@@ -13,6 +13,8 @@
 extern int gfx_passthru;
 extern int igd_passthru;
 
+static uint32_t igd_guest_opregion = 0;
+
 static int pch_map_irq(PCIDevice *pci_dev, int irq_num)
 {
     PT_LOG("pch_map_irq called\n");
@@ -37,6 +39,77 @@ void intel_pch_init(PCIBus *bus)
                         pch_map_irq, "intel_bridge_1f");
 }
 
+static void igd_write_opregion(PCIDevice *pci_dev, uint32_t val, int len)
+{
+    struct pt_dev *real_dev = (struct pt_dev *)pci_dev;
+    uint32_t host_opregion = 0;
+    int ret;
+
+    if ( igd_guest_opregion || len != 4 )
+        return;
+
+    host_opregion = pt_pci_host_read(real_dev->pci_dev,
+            PCI_INTEL_OPREGION, len);
+    igd_guest_opregion = (val & ~0xfff) | (host_opregion & 0xfff);
+    PT_LOG("Map OpRegion: %x -> %x\n", host_opregion, igd_guest_opregion);
+
+    ret = xc_domain_memory_mapping(xc_handle, domid,
+            igd_guest_opregion >> XC_PAGE_SHIFT,
+            host_opregion >> XC_PAGE_SHIFT,
+            2,
+            DPCI_ADD_MAPPING);
+
+    if ( ret != 0 )
+    {
+        PT_LOG("Error: Can't map opregion\n");
+        igd_guest_opregion = 0;
+    }
+}
+
+void vgapt_pci_write_config(PCIDevice *pci_dev, uint32_t config_addr, uint32_t val, int len)
+{
+#ifdef PT_DEBUG_PCI_CONFIG_ACCESS
+    PT_LOG("vgapt_pci_write_config: %x:%x.%x: addr=%x len=%x val=%x\n",
+            pci_bus_num(pci_dev->bus), PCI_SLOT(pci_dev->devfn),
+            PCI_FUNC(pci_dev->devfn), config_addr, len, val);
+#endif
+
+    if ( igd_passthru )
+    {
+        switch ( config_addr )
+        {
+            case 0xfc : /* Opregion */
+                igd_write_opregion(pci_dev, val, len);
+                return;
+        }
+    }
+
+    pt_pci_write_config(pci_dev, config_addr, val, len);
+}
+
+uint32_t vgapt_pci_read_config(PCIDevice *pci_dev, uint32_t config_addr, int len)
+{
+    uint32_t val;
+
+    val = pt_pci_read_config(pci_dev, config_addr, len);
+
+    if ( igd_passthru )
+    {
+        switch ( config_addr )
+        {
+            case 0xfc: /* OpRegion */
+                if ( igd_guest_opregion )
+                    val = igd_guest_opregion;
+                break;
+        }
+    }
+#ifdef PT_DEBUG_PCI_CONFIG_ACCESS
+    PT_LOG_DEV(pci_dev, "vgapt_pci_read_config: %x:%x.%x: addr=%x len=%x val=%x\n",
+            config_addr, len, val);
+#endif
+    return val;
+}
+
 void igd_pci_write(PCIDevice *pci_dev, uint32_t config_addr, uint32_t val, int len)
 {
     struct pci_dev *pci_dev_host_bridge = pt_pci_get_dev(0, 0, 0);
@@ -99,7 +172,6 @@ uint32_t igd_pci_read(PCIDevice *pci_dev, uint32_t config_addr, int len)
 int register_vga_regions(struct pt_dev *real_device)
 {
     u16 vendor_id;
-    int igd_opregion;
     int ret = 0;
 
     if ( !gfx_passthru || real_device->pci_dev->device_class != 0x0300 )
@@ -117,19 +189,6 @@ int register_vga_regions(struct pt_dev *real_device)
             0x20,
             DPCI_ADD_MAPPING);
 
-    /* 1:1 map ASL Storage register value */
-    vendor_id = pt_pci_host_read(real_device->pci_dev, 0, 2);
-    igd_opregion = pt_pci_host_read(real_device->pci_dev, PCI_INTEL_OPREGION, 4);
-    if ( (vendor_id == PCI_VENDOR_ID_INTEL ) && igd_opregion )
-    {
-        ret |= xc_domain_memory_mapping(xc_handle, domid,
-                igd_opregion >> XC_PAGE_SHIFT,
-                igd_opregion >> XC_PAGE_SHIFT,
-                2,
-                DPCI_ADD_MAPPING);
-        PT_LOG("register_vga: igd_opregion = %x\n", igd_opregion);
-    }
-
     if ( ret != 0 )
         PT_LOG("VGA region mapping failed\n");
 
@@ -141,7 +200,7 @@ int register_vga_regions(struct pt_dev *real_device)
  */
 int unregister_vga_regions(struct pt_dev *real_device)
 {
-    u32 vendor_id, igd_opregion;
+    u32 vendor_id;
     int ret = 0;
 
     if ( !gfx_passthru || real_device->pci_dev->device_class != 0x0300 )
@@ -160,12 +219,11 @@ int unregister_vga_regions(struct pt_dev *real_device)
             DPCI_REMOVE_MAPPING);
 
     vendor_id = pt_pci_host_read(real_device->pci_dev, PCI_VENDOR_ID, 2);
-    igd_opregion = pt_pci_host_read(real_device->pci_dev, PCI_INTEL_OPREGION, 4);
-    if ( (vendor_id == PCI_VENDOR_ID_INTEL) && igd_opregion )
+    if ( (vendor_id == PCI_VENDOR_ID_INTEL) && igd_guest_opregion )
     {
         ret |= xc_domain_memory_mapping(xc_handle, domid,
-                igd_opregion >> XC_PAGE_SHIFT,
-                igd_opregion >> XC_PAGE_SHIFT,
+                igd_guest_opregion >> XC_PAGE_SHIFT,
+                igd_guest_opregion >> XC_PAGE_SHIFT,
                 2,
                 DPCI_REMOVE_MAPPING);
     }