My usb 2.0 didn't show any exclamation mark but nothing worked. After reconnecting everything, rebooting, adding/removing other passthrough cards and using "rescan hardware" several times, more and more things began being recognized until they all worked fine (pendrive, keyboard and mouse). I don't really know what to say other than it seems a bit unstable. I'm using vm version 8 with EFI, if it helps.
Edit:
This is how it works:
-Booting without any usb devices: it won't detect anything you connect until you "scan for new hardware" in device manager. After that, the keyboard and pendrive work, but the generic mouse doesn't. If I connect a different one (logitech mx518), it works, and the generic mouse start working after this point. You can then unplug and plug back everything as many times as you want, everything will keep working.
-Booting with at least one usb device (any device other than the generic mouse): same result as above after scanning for new hardware. It's just this time nothing has to be scanned because I suppose that step is part of the booting sequence.
So, before it works, it has to see at least one device when scanning, and it can't be my "generic mouse"
