diff --git a/devicemodel/hw/pci/xhci.c b/devicemodel/hw/pci/xhci.c
index 869fc6eba..56ae8d08f 100644
--- a/devicemodel/hw/pci/xhci.c
+++ b/devicemodel/hw/pci/xhci.c
@@ -500,15 +500,6 @@ pci_xhci_native_usb_dev_conn_cb(void *hci_data, void *dev_data)
 	UPRINTF(LDBG, "%04x:%04x %d-%d connecting.\r\n",
 			native_vid, native_pid, native_bus, native_port);
 
-	/* FIXME: will support usb3 in future */
-	if (xdev->native_assign_ports[native_bus] &&
-			usb_native_is_ss_port(native_bus)) {
-		UPRINTF(LDBG, "%04x:%04x %d-%d be ignored due to superspeed"
-				" device hasn't support yet\r\n", native_vid,
-				native_pid, native_bus, native_port);
-		goto errout;
-	}
-
 	if (!xdev->native_assign_ports[native_bus] ||
 			!xdev->native_assign_ports[native_bus][native_port]) {
 		UPRINTF(LDBG, "%04x:%04x %d-%d doesn't belong to this vm, bye."
@@ -783,7 +774,6 @@ pci_xhci_port_chg(struct pci_xhci_vdev *xdev, int port, int conn)
 		return -1;
 	}
 
-	/* TODO: add USB 3.0 port state */
 	if (conn == 0) {
 		reg->portsc &= ~XHCI_PS_CCS;
 		reg->portsc |= (XHCI_PS_CSC |
diff --git a/devicemodel/hw/platform/usb_pmapper.c b/devicemodel/hw/platform/usb_pmapper.c
index 175bf1d2f..8b772d6ec 100644
--- a/devicemodel/hw/platform/usb_pmapper.c
+++ b/devicemodel/hw/platform/usb_pmapper.c
@@ -762,9 +762,9 @@ usb_dev_init(void *pdata, char *opt)
 	if (port == 0)
 		goto errout;
 
-	switch (desc.bcdUSB) {	/* TODO: implemnt USB3.0 */
+	switch (desc.bcdUSB) {
 	case 0x300:
-		ver = 2; break;
+		ver = 3; break;
 	case 0x200:
 	case 0x110:
 		ver = 2; break;
diff --git a/devicemodel/include/usb_core.h b/devicemodel/include/usb_core.h
index b652a1196..64ca72458 100644
--- a/devicemodel/include/usb_core.h
+++ b/devicemodel/include/usb_core.h
@@ -34,7 +34,15 @@
 #include <stdbool.h>
 #include "types.h"
 
-#define	USB_MAX_XFER_BLOCKS	256
+/* FIXME:
+ * There are some huge data requests which need more than 256 TRBs in a single
+ * transfer, so it is neccessary to expand it.
+ * But this is not final solution, this size should be dynamically changed
+ * according to the native xhci driver's adjust of trb segements.
+ * By default, the native xhci driver use two segments which contain 2 * 256
+ * trbs, so 1024 is enough currently.
+ */
+#define	USB_MAX_XFER_BLOCKS	1024
 
 #define	USB_XFER_OUT		0
 #define	USB_XFER_IN		1