[BUG] mt7925e: MT7927 stuck in D3 after VFIO guest reboot

[Michał Wiśniewski]

Hello,
I have a MediaTek MT7927 passed through with VFIO to a Kali Linux VM.
The card works normally after starting the VM, but running systemctl
reboot inside Kali causes the VM to hang and the physical MT7927 to
stop responding.

After the failure:
PCI configuration space reads as all ff;
lspci reports Unknown header type 7f;
FLR and secondary bus reset do not recover the card;
QEMU remains in D state even after SIGKILL;
only fully disconnecting AC power from the host restores the card.

The main host messages are:
kvm: vfio: Unable to power on device, stuck in D3
pcieport 0000:00:1c.0: retraining failed
vfio-pci 0000:02:00.0: not ready 65535ms after FLR; giving up
pcieport 0000:00:1c.0: Data Link Layer Link Active not set in 100 msec

Hardware:
MediaTek MT7927
PCI ID: 14c3:7927
subsystem ID: 105b:e104

Guest:
Kali Linux 2026.2
driver: mt7925e
linux-next tag: next-20260716
commit: 1a1757b76427f6201bfe0bf1bea9f7574f332a93
uname -r: 7.2.0-rc3-next-20260716-mt7927-test

Host:
Proxmox VE 9.2.4
kernel: 7.0.14-5-pve
QEMU: 11.0.2
driver: vfio-pci

Regards,
Michał Wiśniewski