Some recent patches to the QEMU source fix a long standing problem where the PV vkbd backend was unable to function correctly without the PV fb backend, which effectively made it pointless to implement PV HID (i.e. keyboard and mouse) frontends for HVM guests.
Now that the problem has been fixed, I’m happy to announce that this commit enables enumeration of PV vkbd devices in Windows enabling use of the new XENVKBD and XENHID drivers.
Once the new drivers are installed into your Windows guest then you can disable the USB tablet (see xl.cfg manpage) pointing device in your VM configuration and still have the benefit of an absolute pointing device without the overhead of USB emulation.
If you are interested in this then please try the new driver packages and send feedback to the mailing list.