VFIO cannot reset device no reset mechanism found

Question

I'm trying to passthrough my USB controller to macOS (in QEMU). My USB controller is in this IOMMU group:

IOMMU Group 4:
00:14.0 USB controller [0c03]: Intel Corporation 100 Series/C230 Series Chipset Family USB 3.0 xHCI Controller [8086:a12f] (rev 31)
00:14.2 Signal processing controller [1180]: Intel Corporation 100 Series/C230 Series Chipset Family Thermal Subsystem [8086:a131] (rev 31)

I get this error when trying to start the VM:

qemu-system-x86_64: vfio: Cannot reset device 0000:00:14.2, no available reset mechanism.
qemu-system-x86_64: vfio: Cannot reset device 0000:00:14.0, no available reset mechanism.
qemu-system-x86_64: vfio: Cannot reset device 0000:00:14.2, no available reset mechanism.
qemu-system-x86_64: vfio: Cannot reset device 0000:00:14.0, no available reset mechanism.

The same error appears twice for some reason. Is there a way to start the VM anyway, despite there not being a reset mechanism? I'm totally fine with rebooting my computer everytime I want to reset it.

I'm using Arch Linux, kernel without vfio-pci, and I'm using https://github.com/foxlet/macOS-Simple-KVM for my QEMU macOS setup.

Answer 1

I solved it. I don't know what exactly I did or why it worked, but I'm going to do my best to recall what I did:

1. In your mkinitcpio.conf, make sure that all the VFIO modules are listed BEFORE anything else like intel_agp and i915

2. When you start the VM, the errors will still show and the display will be blank, but the display starts up eventually after a bit of waiting (took like 30 seconds for me)

You will probably not be able to start the VM again after you stop it once, unless you reboot your computer.