Comment 0 for bug 1781891

System information:
Ubuntu 18.04 LTS (server edition) with kernel 4.15.0-24-generic x86_64
Upgraded from Ubuntu server 17.10

Software:
qemu-kvm:
  Installed: 1:2.11+dfsg-1ubuntu7.4
  Candidate: 1:2.11+dfsg-1ubuntu7.4
  Version table:
 *** 1:2.11+dfsg-1ubuntu7.4 500
        500 http://za.archive.ubuntu.com/ubuntu bionic-updates/main amd64 Packages
        100 /var/lib/dpkg/status
     1:2.11+dfsg-1ubuntu7.3 500
        500 http://security.ubuntu.com/ubuntu bionic-security/main amd64 Packages
     1:2.11+dfsg-1ubuntu7 500
        500 http://za.archive.ubuntu.com/ubuntu bionic/main amd64 Packages

Hardware:
Motherboard: X370 Killer SLI
CPU: AMD Ryzen 7 1800X

PCI device:
27:00.0 USB controller: VIA Technologies, Inc. VL805 USB 3.0 Host Controller (rev 01)
IOMMU Group 15 27:00.0 USB controller [0c03]: VIA Technologies, Inc. VL805 USB 3.0 Host Controller [1106:3483] (rev 01)

USB controller of PCI card:
Bus 003 Device 002: ID 2109:3431 VIA Labs, Inc. Hub

Loaded device drivers:

Before upgrading to Ubuntu 18.04, this PCI device was added to pci-stub.ids which allowed the device to be passed to a Windows 10 VM. In turn, all USB devices connected to this card worked in the VM and drivers could successfully be installed.

Since the upgrade from Ubuntu 17.10 to Ubuntu 18.04, I have tried several approaches to have this device not bound to the xhci driver but all in vain. (In every test I did, I always performed update-initramfs -u as well as update-grub)

pci-stub.ids does not stop xhci from grabbing device. So passing PCI card to VM does not work

Adding the device ID to /etc/modprobe.d/vfio.conf (options) does seem to load the connect the vfio driver to it, but xhci still binds to it as well, so passing PCI device to VM does not work.

Adding "0000:27:00.0,xhci" to /etc/unbindpci also did not work.

By adding the USB controller to the VM, USB devices connected to it does seem to be USB devices on the VM, but some of the drivers does not load correctly in Windows 10. For example, I need to install a device driver for a ROCKEY4 USB dongle and even though the driver installs (which must be done with device disconnected), the driver does not seem to ever bind correctly to the device because the software that uses the dongle does not recognise it.

I have successfully bound a PCI graphics adapter to the VM, so in principle PCI passthrough works, bit in the case of the USB PCI card there seems to be no way to pass the device to a VM.

Expected result:

PCI passthrough should be available to all types of PCI devices and instructions should be available from qemu or kvm documentation even though it involves different parts of the OS (such as making use of /etc/modprobe/vfio.conf, /etc/unbindpci etc)