xusbfixer

This is a bug fixing filter driver for Microsoft Windows xusb22.sys Xbox gamepad driver (version 06/12/2019 10.0.19041.1).

Description

Windows xusb22.sys driver interacting with dwm.exe (Desktop Window Manager) can sometimes cause a very long (possibly infinite) loop where dwm.exe and the driver are consuming 100% CPU. Especially when running Windows 10/11 in a QEMU/KVM virtual machine and using the ViGEm Bus driver, the system is rendered unusable as soon as a gamepad is connected.

The looping occurs in an xusb22.sys function called ProcessWaitRequests (named according to the published PDB file) similar to the following pseudocode:

while (TRUE) {
    WDFREQUEST request:
    WdfIoQueueRetrieveNextRequest(queue, &request);
    if (!request)
        break;

    // ... processing ...

    WdfRequestCompleteWithInformation(request, STATUS_SUCCESS, 29);
}

The request above originates from dwm.exe sending IOCTL 0x8000E3AC (WaitForInput, to get gamepad stick and button state etc). Apparently, as soon as the request is completed, dwm.exe sends a new IOCTL request to the driver which inserts it into the same queue which is being processed by the loop above. It can happen that the new request gets inserted into queue before next WdfIoQueueRetrieveNextRequest call and this can repeat apparently indefinitely.

The (hopefully temporary) solution

The xusbfixer driver is intended to be a temporary solution until Microsoft fixes xusb22. It is both an upper and lower filter driver where the driver stack ends up looking like:

1. xusbfixer
2. xusb22
3. xusbfixer
4. ViGEmBus

The upper xusbfixer manages IOCTL 0x8000E3AC requests and doesn't let them pass while the ProcessWaitRequests loop is running in xusb22. The lower xusbfixer monitors USB interrupt transfer requests and their completion in an attempt to detect when the ProcessWaitRequests loop is going to start and has finished.

Installing

Unpack the release zip file containing the inf and sys files. In file explorer, right click on the inf file and select Install.

Alternative xusb21 mode

Another way to fix the infinite looping in xusb22 ProcessWaitRequests is to install the previous version of Microsoft's driver, xusb21. That version does not support the IOCTL 0x8000E3AC and doesn't have the ProcessWaitRequests function. However, some applications won't be able to use gamepads anymore (such as Windows start and settings menus.) The xusbfixer driver has an alternative simple mode that mimics xusb21 and responds with invalid parameter status to the IOCTL 0x8000E004 (GetCapabilities). To turn on this alternative mode, simply remove xusbfixer from the lower filter list in Windows registry (cf. step 5 below in the uninstalling section.) To restore the default behaviour, add xusbfixer back.

Uninstalling

Run the included PowerShell script uninstall-xusbfixer.ps1 as an administrator and reboot. Alternatively, you can uninstall manually:

1. In command prompt, run pnputil /enum-drivers and note the "Published name" (e.g. oemXX.inf filename) for xusbfixer.inf,
2. Run pnputil /delete-driver oemXX.inf where oemXX.inf is from the previous step,
3. Delete file C:\Windows\System32\drivers\xusbfixer.sys,
4. Run regedit.exe and delete key HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\xusbfixer,
5. Delete also LowerFilters and UpperFilters properties under the HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Class\{d61ca365-5af4-4486-998b-9db4734c6ca3} key,
6. Reboot.

Caveat

This driver is only self-signed so you will have to use test mode or disable Windows driver signature enforcement. Either

1. Disable Secure Boot in UEFI settings, enable test mode using the command bcdedit /set testsigning on and reboot, or
2. Reboot Windows by pressing Shift and clicking Restart from start menu, then select Troubleshoot / Advanced options / Start-up Settings and restart. When the boot menu shows up, select "Disable driver signature enforcement". You can make the boot menu show up on every boot by running the command bcdedit /set advancedoptions on.

How to build

To build the driver from source code, install Visual Studio 2022, Windows SDK and Windows Driver Kit.

(Tip: if VS2022 starts consuming 100% cpu and the UI freezes for a while whenever you start editing a file (like it does for me with version 17.8.5), try setting "Tools -> Options -> Text Editor -> C/C++ -> Advanced -> Disable Database Auto Updates" to True.)

License

The project is licensed under the MIT License. See LICENSE.txt for details.

Related software

• ViGEm Bus driver
• Application software to accompany the bus driver:
  • Xb2XInput
  • x360ce