Re: [bugzilla-daemon@kernel.org: [Bug 219765] New: Regression: VFIO NVIDIA GPU Passthrough Fails in Linux 6.13.0 (GPU Reset & Audio Controller Disappears)]

[Bjorn Helgaas <helgaas@kernel.org>]

[+cc Ilpo, Jonathan]

On Mon, Feb 10, 2025 at 11:07:15AM -0600, Bjorn Helgaas wrote:
> #regzbot link: https://bugzilla.kernel.org/show_bug.cgi?id=219765
> 
> I don't see an obvious culprit between v6.12 and v6.13, suggested
> bisection if possible.
> 
> Workaround: boot with pcie_port_pm=off

Update: pcie_port_pm=off turned out *not* to be a workaround, possibly
a red herring due to configuration differences.

> Given the workaround, maybe it's worth trying a revert of this:
> 
>   dc421bb3c0db ("PCI: Enable runtime PM of the host bridge")

Reporter bisected to 665745f27487 ("PCI/bwctrl: Re-add BW notification
portdrv as PCIe BW controller").

Bisect log in bugzilla.  GPU passthrough works correctly after
reverting these commits:

  665745f27487 ("PCI/bwctrl: Re-add BW notification portdrv as PCIe BW controller")
  de9a6c8d5dbf ("PCI/bwctrl: Add pcie_set_target_speed() to set PCIe Link Speed")
  
> ----- Forwarded message from bugzilla-daemon@kernel.org -----
> 
> https://bugzilla.kernel.org/show_bug.cgi?id=219765
> 
> Created attachment 307599
>   --> https://bugzilla.kernel.org/attachment.cgi?id=307599&action=edit
> dmesg logs for the kernel in which gpu passthrough works
> 
> After upgrading from Linux 6.12.10 to Linux 6.13.0, VFIO GPU passthrough fails
> for an NVIDIA GPU (AD107). The GPU is not passed through to the VM, and its
> audio device (01:00.1) disappears from Virt-Manager. This issue does not occur
> in Linux 6.12.10.
> 
> I have attached the logs.