Re: QCA6174 pcie wifi: Add pci quirks

From: Bjorn Helgaas <helgaas@kernel.org>
To: Ingmar Klein <ingmar_klein@web.de>
Cc: bhelgaas@google.com, linux-pci@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: Re: QCA6174 pcie wifi: Add pci quirks
Date: Tue, 14 Sep 2021 16:11:23 -0500	[thread overview]
Message-ID: <20210914211123.GA1457901@bjorn-Precision-5520> (raw)
In-Reply-To: <08982e05-b6e8-5a8d-24ab-da1488ee50a8@web.de>

On Fri, Apr 09, 2021 at 11:26:33AM +0200, Ingmar Klein wrote:
> Edit: Retry, as I did not consider, that my mail-client would make this
> party html.
> 
> Dear maintainers,
> I recently encountered an issue on my Proxmox server system, that
> includes a Qualcomm QCA6174 m.2 PCIe wifi module.
> https://deviwiki.com/wiki/AIRETOS_AFX-QCA6174-NX
> 
> On system boot and subsequent virtual machine start (with passed-through
> QCA6174), the VM would just freeze/hang, at the point where the ath10k
> driver loads.
> Quick search in the proxmox related topics, brought me to the following
> discussion, which suggested a PCI quirk entry for the QCA6174 in the kernel:
> https://forum.proxmox.com/threads/pcie-passthrough-freezes-proxmox.27513/
> 
> I then went ahead, got the Proxmox kernel source (v5.4.106) and applied
> the attached patch.
> Effect was as hoped, that the VM hangs are now gone. System boots and
> runs as intended.
> 
> Judging by the existing quirk entries for Atheros, I would think, that
> my proposed "fix" could be included in the vanilla kernel.
> As far as I saw, there is no entry yet, even in the latest kernel sources.
> 
> Thank you very much!
> Best regards,
> Ingmar

I wrote a commit log and applied this to pci/virtualization for v5.16
with Pali's reviewed-by and your signed-off-by from
https://lore.kernel.org/r/408e5b45-3eaa-fa13-318d-48f7d1ecdacf@web.de

    PCI: Mark Atheros QCA6174 to avoid bus reset

    When passing the Atheros QCA6174 through to a virtual machine, the VM hangs
    at the point where the ath10k driver loads.

    Add a quirk to avoid bus resets on this device, which avoids the hang.

    [bhelgaas: commit log]
    Link: https://lore.kernel.org/r/08982e05-b6e8-5a8d-24ab-da1488ee50a8@web.de
    Signed-off-by: Ingmar Klein <ingmar_klein@web.de>
    Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
    Reviewed-by: Pali Rohár <pali@kernel.org>
    Cc: stable@vger.kernel.org

Thank you!

> diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
> index 706f27a86a8e..ecfe80ec5b9c 100644
> --- a/drivers/pci/quirks.c
> +++ b/drivers/pci/quirks.c
> @@ -3584,6 +3584,7 @@ DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_ATHEROS, 0x0032, quirk_no_bus_reset);
>  DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_ATHEROS, 0x003c, quirk_no_bus_reset);
>  DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_ATHEROS, 0x0033, quirk_no_bus_reset);
>  DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_ATHEROS, 0x0034, quirk_no_bus_reset);
> +DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_ATHEROS, 0x003e, quirk_no_bus_reset);
>  
>  /*
>   * Root port on some Cavium CN8xxx chips do not successfully complete a bus