Fix incorrect relative mouse xinput2 reports

[iacore]

How to file a helpful issue

Qubes OS release

r4.1

Brief summary

RawMotion in X represents relative motion of mouse. However, the current linux client gui agent put absolute positions for the fields. It makes some games think you are moving the mouse ridiculously fast.

Steps to reproduce

1. Run xinput test-xi2 in a client VM
2. Maximize the terminal window
3. Move the mouse slowly

Expected behavior

You should see something like the following in the terminal.

EVENT type 17 (RawMotion)
    device: 2 (6)
    detail: 0
    flags: 
    valuators:
          0: 0.43 (0.43)
          1: -0.10 (-0.10)

"valuators" are (x, y) pixels moved relative to the last RawMotion event

Actual behavior

EVENT type 17 (RawMotion)
    device: 2 (6)
    detail: 0
    flags: 
    valuators:
          0: 1000.00 (1000.00)
          1: 510.00 (510.00)

"valuators" are the same as Motion "valuators". This is clearly not right.

[iacore]

RawMotion and Motion events in VM (xinput test-xi2) do not come from the same device. This means Xorg thinks there are two mice. This is also true for Button* and RawButton* events and key events. Sometimes, RawButton* and RawMotion would have the same device id.

In dom0, the mouse events have one device id, keyboard events have one device id.

[iacore]

This is definitely a driver issue, either xfree86's support for absolute pointing device is buggy, or the qubes fake device driver is somehow buggy (I can't find a issue yet).

I tried to use relative mouse motion in https://github.com/locriacyber/qubes-gui-agent-linux/tree/relative-motion, and it kind of worked. The absolute position is way off. We need to send RawMotion from dom0.

[DemiMarie]

This is definitely a driver issue, either xfree86's support for absolute pointing device is buggy, or the qubes fake device driver is somehow buggy (I can't find a issue yet).

If you can figure it out that would be amazing!