usb-bus: Don't allow speed mismatch while attaching devices

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>

hw/usb-bus.c

diff --git a/hw/usb-bus.c b/hw/usb-bus.c
index fc72018..2abce12 100644
--- a/hw/usb-bus.c
+++ b/hw/usb-bus.c
@@ -200,6 +200,11 @@
     } else {
         port = QTAILQ_FIRST(&bus->free);
     }
+    if (!(port->speedmask & dev->speedmask)) {
+        error_report("Warning: speed mismatch trying to attach usb device %s to bus %s\n",
+                dev->product_desc, bus->qbus.name);
+        return -1;
+    }
 
     dev->attached++;
     QTAILQ_REMOVE(&bus->free, port, next);