[Help Wanted] passthrough-ed touchpad mistakenly treated as tablet

[Patrick Young]

Hello, I've recently deployed a QEMU-based infra using Proxmox VE.

And Trying to use evdev passthrough to pass my Synaptics Touchpad to a
guest VM which is running Arch Linux. The Arch guest VM runs XFCE and
using libinput driver as log suggests.

The touchpad seems be passthrough-ed as tablet, whose device name
shown in guest is "QEMU QEMU USB Tablet". This wrong behavior which
not identified touchpad correctly make the touchpad doesn't work well.
It is always using absolute positioning instead of relative one. The
double-click-as-tap feature and disable-while-typing is totally not
working at all.

How can I do to let QEMU treat it as touchpad?