Regression: x-igd-opregion=off ignored in VFIO IGD quirk handling

• Operating system: Arch
• kernel version: Linux 6.14.6-arch1-1 #1 SMP PREEMPT_DYNAMIC Fri, 09 May 2025 17:36:18 +0000 x86_64 GNU/Linux
• kernel module: https://github.com/strongtz/i915-sriov-dkms
• Architecture: x86_64
• QEMU flavor: qemu-system-x86_64
• QEMU version: QEMU emulator version 10.0.50 (v10.0.0-995-g757a34115e)
• QEMU command line:

  ./qemu-system-x86_64 -M q35 -m 4096 -enable-kvm -hda fedora32.qcow2 \
      -device vfio-pci,host=0000:00:02.1,romfile="/path/to/intelgopdriver_desktop.bin",x-vga=on,x-igd-opregion=off

Emulated/Virtualized environment

• Operating system: any
• OS/kernel version: any
• Architecture: x86_64

Description of problem

A regression in QEMU’s VFIO IGD initialization causes the x-igd-opregion=off parameter to be ignored, resulting in an error when passing through an Intel iGPU SR-IOV Virtual Function (VF) at PCI address 00:02.1: qemu-system-x86_64: -device vfio-pci,host=0000:00:02.1,...: Device does not supports IGD OpRegion feature: No such device Automatic detection of IGD-OpRegion assumes any Intel iGPU (including GVT-g) will have it but SR-IOV VFs do not.

Steps to reproduce

1. Configure an Intel iGPU with SR-IOV enabled, creating a VF at 00:02.1.
2. Bind the VF to the vfio-pci driver:

    echo 0000:00:02.1 > /sys/bus/pci/drivers/i915/unbind
    either:
      echo "8086 4680" > /sys/bus/pci/drivers/vfio-pci/new_id
    or:
      echo 0000:00:02.1 > /sys/bus/pci/drivers/vfio-pci/bind

3. Run QEMU with the command line above, including -device vfio-pci,host=0000:00:02.1,...,x-igd-opregion=off.

Additional information

• Hardware details:
  • 00:02.1 VGA compatible controller [0300]: Intel Corporation AlderLake-S GT1 [8086:4680] (rev 0c)
  • Host motherboard: MSI PRO Z690-A DDR4
  • CPU: Intel Core i5 12600K
• Regression cause: The issue was introduced by commit 7be29f2f, which changed vfio_pci_igd_config_quirk to detect OpRegion automatically, ignoring vdev->igd_opregion=false.
• Proposed fix: I have a patch that adds checks for vdev->igd_opregion in vfio_pci_igd_config_quirk and vfio_pci_kvmgt_config_quirk, skipping OpRegion handling when x-igd-opregion=off. The patch has been tested, confirming the VM starts without errors. I will submit it to qemu-devel@nongnu.org with a reference to this issue.