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Date: Thu, 29 Feb 2024 17:00:13 -0600
From: Bjorn Helgaas <helgaas@kernel.org>
To: Edmund Raile <edmund.raile@proton.me>
Cc: linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2] PCI: Mark LSI FW643 to avoid bus reset
Message-ID: <20240229230013.GA369538@bhelgaas>
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In-Reply-To: <20240227131401.17913-1-edmund.raile@proton.me>

On Tue, Feb 27, 2024 at 01:14:18PM +0000, Edmund Raile wrote:
> Using LSI / Agere FW643 with vfio-pci will exhaust all
> pci_reset_fn_methods, the bus reset at the end causes a broken link
> only recoverable by removing power
> (power-off / suspend + rescan).
> Prevent this bus reset.
> With this change, the device can be assigned to VMs with VFIO.
> Note that it will not be reset, resulting in leaking state between VMs
> and host.
> 
> Signed-off-by: Edmund Raile <edmund.raile@proton.me>

Applied to pci/virtualization for v6.9, thank you!

> ---
> 
> I sincerely thank you for your patience and explaining
> the background of pci resets which I lacked.
> The commit message and comment now describe it correctly.
> The comment on leaking states was added.
> 
> Usefulness:
> 
> The LSI FW643 PCIe->FireWire 800 interface may be EOL but it is
> the only one that does not use a PCIe->PCI bridge.
> It is reliable and enables FireWire audio interfaces to be used
> on modern machines.
> 
> Virtualization allows for flexible access to professional audio
> software.
> 
> It has been used in at least the following Apple machines:
> MacBookPro10,1
> MacBookPro9,2
> MacBookPro6,2
> MacBookPro5,1
> Macmini6,1
> Macmini3,1
> iMac12,2
> iMac9,1
> iMac8,1
> 
> Implementation:
> 
> PCI_VENDOR_ID_ATT was reused as they are identical.
> 
>  drivers/pci/quirks.c | 13 +++++++++++++
>  1 file changed, 13 insertions(+)
> 
> diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
> index d797df6e5f3e..e0e4ad9e6d50 100644
> --- a/drivers/pci/quirks.c
> +++ b/drivers/pci/quirks.c
> @@ -3765,6 +3765,19 @@ DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_ATHEROS, 0x003e, quirk_no_bus_reset);
>   */
>  DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_CAVIUM, 0xa100, quirk_no_bus_reset);
>  
> +/*
> + * Using LSI / Agere FW643 with vfio-pci will exhaust all
> + * pci_reset_fn_methods, the bus reset at the end causes a broken link
> + * only recoverable by removing power
> + * (power-off / suspend + rescan).
> + * Prevent this bus reset.
> + * With this change, the device can be assigned to VMs with VFIO.
> + * Note that it will not be reset, resulting in leaking state between VMs
> + * and host.
> + */
> +DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_ATT, 0x5900, quirk_no_bus_reset);
> +DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_ATT, 0x5901, quirk_no_bus_reset);
> +
>  /*
>   * Some TI KeyStone C667X devices do not support bus/hot reset.  The PCIESS
>   * automatically disables LTSSM when Secondary Bus Reset is received and
> -- 
> 2.43.0
> 
>