piix: use 64 bit window programmed by guest

Detect the 64 bit window programmed by firmware
and configure properties accordingly.
Signed-off-by: NMichael S. Tsirkin <mst@redhat.com>

hw/pci-host/piix.c

@@ -235,18 +235,24 @@ static void i440fx_pcihost_get_pci_hole64_start(Object *obj, Visitor *v,
                                                 void *opaque, const char *name,
                                                 Error **errp)
 {
-    I440FXState *s = I440FX_PCI_HOST_BRIDGE(obj);
+    PCIHostState *h = PCI_HOST_BRIDGE(obj);
+    Range w64;
+
+    pci_bus_get_w64_range(h->bus, &w64);
 
-    visit_type_uint64(v, &s->pci_info.w64.begin, name, errp);
+    visit_type_uint64(v, &w64.begin, name, errp);
 }
 
 static void i440fx_pcihost_get_pci_hole64_end(Object *obj, Visitor *v,
                                               void *opaque, const char *name,
                                               Error **errp)
 {
-    I440FXState *s = I440FX_PCI_HOST_BRIDGE(obj);
+    PCIHostState *h = PCI_HOST_BRIDGE(obj);
+    Range w64;
+
+    pci_bus_get_w64_range(h->bus, &w64);
 
-    visit_type_uint64(v, &s->pci_info.w64.end, name, errp);
+    visit_type_uint64(v, &w64.end, name, errp);
 }
 
 static void i440fx_pcihost_initfn(Object *obj)