diff --git a/devicemodel/hw/pci/xhci.c b/devicemodel/hw/pci/xhci.c
index 4379c8014..dd9f5215e 100644
--- a/devicemodel/hw/pci/xhci.c
+++ b/devicemodel/hw/pci/xhci.c
@@ -95,7 +95,7 @@
 
 #undef LOG_TAG
 #define LOG_TAG			"xHCI: "
-#define	XHCI_MAX_DEVS		8	/* 4 USB3 + 4 USB2 devs */
+#define	XHCI_MAX_DEVS		20	/* 10 root hub + 10 external hub */
 #define	XHCI_MAX_SLOTS		64	/* min allowed by Windows drivers */
 
 /*
@@ -394,6 +394,7 @@ struct pci_xhci_vdev {
 #define VPORT_ASSIGNED (1)
 #define VPORT_CONNECTED (2)
 #define VPORT_EMULATED (3)
+#define VPORT_HUB_CONNECTED (4)
 
 /* helpers for get port mapping information */
 #define VPORT_NUM(state) (state & 0xFF)
@@ -479,6 +480,27 @@ static struct pci_xhci_option_elem xhci_option_table[] = {
 	{"cap", pci_xhci_parse_extcap}
 };
 
+static enum usb_native_dev_type
+pci_xhci_get_dev_type(struct pci_xhci_vdev *xdev, void *dev_data)
+{
+	uint16_t port, bus;
+	struct usb_native_devinfo *di;
+
+	assert(dev_data);
+
+	di = dev_data;
+	if (usb_get_parent_dev_type(di->priv_data, &bus, &port) == USB_HUB) {
+		if (VPORT_STATE(xdev->port_map_tbl[bus][port])  ==
+				VPORT_HUB_CONNECTED) {
+			di->port += PORT_HUB_BASE;
+			return USB_VALID_SUB_DEV;
+		} else
+			return USB_INVALID_SUB_DEV;
+	}
+
+	return USB_DEV;
+}
+
 static int
 pci_xhci_native_usb_dev_conn_cb(void *hci_data, void *dev_data)
 {
@@ -487,6 +509,9 @@ pci_xhci_native_usb_dev_conn_cb(void *hci_data, void *dev_data)
 	int vport_start, vport_end;
 	int port;
 	int need_intr = 1;
+	enum usb_native_dev_type type;
+	int state;
+	int rc;
 
 	xdev = hci_data;
 
@@ -501,12 +526,37 @@ pci_xhci_native_usb_dev_conn_cb(void *hci_data, void *dev_data)
 	UPRINTF(LDBG, "%04x:%04x %d-%d connecting.\r\n",
 			di->vid, di->pid, di->bus, di->port);
 
-	if (VPORT_STATE(xdev->port_map_tbl[di->bus][di->port]) ==
-			VPORT_FREE) {
-		UPRINTF(LDBG, "%04x:%04x %d-%d doesn't belong to this vm, bye."
-				"\r\n", di->vid, di->pid, di->bus, di->port);
+	type = pci_xhci_get_dev_type(xdev, di);
+	if (type == USB_DEV) {
+		if (VPORT_STATE(xdev->port_map_tbl[di->bus][di->port]) ==
+				VPORT_FREE) {
+			UPRINTF(LDBG, "%04x:%04x %d-%d doesn't belong to this"
+					" vm, bye.\r\n", di->vid, di->pid,
+					di->bus, di->port);
+			goto errout;
+		}
+	} else if (type == USB_INVALID_SUB_DEV)
+		return 0;
+
+	state = VPORT_STATE(xdev->port_map_tbl[di->bus][di->port]);
+	if (state == VPORT_CONNECTED || state == VPORT_EMULATED ||
+			state == VPORT_HUB_CONNECTED) {
+		UPRINTF(LFTL, "do not support multiple hubs currently, reject "
+				"device %d-%d\r\n", di->bus, di->port);
 		goto errout;
 	}
+
+	rc = usb_dev_is_hub(di->priv_data);
+	if (rc == USB_HUB) {
+		xdev->port_map_tbl[di->bus][di->port] =
+			VPORT_NUM_STATE(VPORT_HUB_CONNECTED, 0);
+		return 0;
+	} else if (rc == USB_TYPE_INVALID) {
+		UPRINTF(LWRN, "usb_dev_is_hub failed\r\n");
+		goto errout;
+	}
+
+
 	UPRINTF(LDBG, "%04x:%04x %d-%d belong to this vm.\r\n", di->vid,
 			di->pid, di->bus, di->port);
 
@@ -593,8 +643,6 @@ pci_xhci_native_usb_dev_disconn_cb(void *hci_data, void *dev_data)
 		if (xdev->slots[slot] == edev)
 			break;
 
-	assert(slot < XHCI_MAX_SLOTS);
-
 	status = VPORT_STATE(xdev->port_map_tbl[di.bus][di.port]);
 	assert(status == VPORT_EMULATED || status == VPORT_CONNECTED);
 	xdev->port_map_tbl[di.bus][di.port] = VPORT_NUM_STATE(VPORT_ASSIGNED,
diff --git a/devicemodel/hw/platform/usb_pmapper.c b/devicemodel/hw/platform/usb_pmapper.c
index 2aedf28f7..2ef05734a 100644
--- a/devicemodel/hw/platform/usb_pmapper.c
+++ b/devicemodel/hw/platform/usb_pmapper.c
@@ -855,6 +855,65 @@ out:
 	return xfer->status;
 }
 
+int
+usb_dev_is_hub(void *pdata)
+{
+	struct libusb_device *ldev;
+	struct libusb_device_descriptor desc;
+	int rc;
+
+	assert(pdata);
+
+	ldev = pdata;
+	rc = libusb_get_device_descriptor(ldev, &desc);
+
+	if (rc)
+		return USB_TYPE_INVALID;
+
+	if (desc.bDeviceClass == LIBUSB_CLASS_HUB)
+		return USB_HUB;
+	else
+		return USB_DEV;
+
+}
+
+enum usb_native_dev_type
+usb_get_parent_dev_type(void *pdata, uint16_t *bus, uint16_t *port)
+{
+	struct libusb_device *ldev;
+	struct libusb_device *libdev;
+	struct libusb_device_descriptor desc;
+	int rc;
+
+	assert(pdata);
+	assert(bus);
+	assert(port);
+
+	ldev = pdata;
+	libdev = libusb_get_parent(ldev);
+
+	if (libdev == NULL) {
+		UPRINTF(LWRN, "libusb_get_parent return NULL\r\n");
+		return USB_TYPE_INVALID;
+	}
+
+	*bus = libusb_get_bus_number(libdev);
+	*port = libusb_get_port_number(libdev);
+
+	rc = libusb_get_device_descriptor(libdev, &desc);
+	if (rc) {
+		UPRINTF(LWRN, "libusb_get_device_descriptor error %d\r\n", rc);
+		return USB_TYPE_INVALID;
+	}
+
+	if (*port == 0)
+		return ROOT_HUB;
+	if (desc.bDeviceClass == LIBUSB_CLASS_HUB)
+		return USB_HUB;
+
+	return USB_TYPE_INVALID;
+}
+
 void *
 usb_dev_init(void *pdata, char *opt)
 {
@@ -1039,6 +1098,9 @@ usb_dev_native_sys_disconn_cb(struct libusb_context *ctx, struct libusb_device
 		*ldev, libusb_hotplug_event event, void *pdata)
 {
 	uint8_t port;
+	uint16_t pport;
+	uint16_t pbus;
+	int rc;
 
 	UPRINTF(LDBG, "disconnect event\r\n");
 
@@ -1048,6 +1110,13 @@ usb_dev_native_sys_disconn_cb(struct libusb_context *ctx, struct libusb_device
 	}
 
 	port = libusb_get_port_number(ldev);
+	rc = usb_get_parent_dev_type(ldev, &pbus, &pport);
+	if (rc == USB_TYPE_INVALID) {
+		UPRINTF(LWRN, "usb_get_parent_dev_type return %d\r\n", rc);
+		return 0;
+	} else if (rc == USB_HUB)
+		port += PORT_HUB_BASE;
+
 	if (g_ctx.disconn_cb)
 		g_ctx.disconn_cb(g_ctx.hci_data, &port);
 
diff --git a/devicemodel/include/usb_pmapper.h b/devicemodel/include/usb_pmapper.h
index 43cb09fd8..434a353e9 100644
--- a/devicemodel/include/usb_pmapper.h
+++ b/devicemodel/include/usb_pmapper.h
@@ -20,6 +20,9 @@
 #define USB_EP_NR(d) (USB_EP_ADDR(d) & 0xF)
 #define USB_EP_ERR_TYPE 0xFF
 
+/* hub port start address */
+#define PORT_HUB_BASE	0x0A
+
 enum {
 	USB_INFO_VERSION,
 	USB_INFO_SPEED,
@@ -29,6 +32,15 @@ enum {
 	USB_INFO_PID
 };
 
+enum usb_native_dev_type {
+	ROOT_HUB,
+	USB_HUB,
+	USB_DEV,
+	USB_VALID_SUB_DEV,
+	USB_INVALID_SUB_DEV,
+	USB_TYPE_INVALID
+};
+
 struct usb_dev_ep {
 	uint8_t pid;
 	uint8_t type;
@@ -119,4 +131,7 @@ int usb_dev_info(void *pdata, int type, void *value, int size);
 int usb_dev_request(void *pdata, struct usb_data_xfer *xfer);
 int usb_dev_reset(void *pdata);
 int usb_dev_data(void *pdata, struct usb_data_xfer *xfer, int dir, int epctx);
+enum usb_native_dev_type usb_get_parent_dev_type(void *pdata, uint16_t *bus,
+		uint16_t *port);
+int usb_dev_is_hub(void *pdata);
 #endif