[vfio-users] How to set PCI address in "options vfio-pci" ?

[Kyle Marek]

On 05/17/2018 01:12 PM, Kyle Marek wrote:
> On 05/17/2018 10:27 AM, Alex Williamson wrote:
>> On Thu, 17 May 2018 12:56:49 +0800
>> Eddie Yen <missile0407 at gmail.com> wrote:
>>
>>> Hi everyone,
>>>
>>> IME, you can set VID:PID by adding "options vfio-pci" into conf file and
>>> put at modprobe.d
>>> So that VFIO can take over the device that had same VID:PID when boot.
>>>
>>> But how can I set this option by using PCI Address without using override
>>> script?
>> There's no such module option, what's wrong with a script?  Part of the
>> reason we don't have such a module option is that PCI addresses are not
>> persistent, they can change based on devices added or removed, or even
>> motherboard BIOS updates.  Userspace has more flexibility for managing
>> this and is fully able to do so via initrd scripts and modprobe.d.
>> Thanks,
>>
>> Alex
> That's a good point.
>
> However, I had an environment where I needed to pass through one of two
> devices with the same PCI IDs. I accomplished it with an install command
> in my modprobe config.
>
> I can probably make this look at other factors before overriding the
> driver, but the following config might work well enough if the PCI IDs
> don't change:

If PCI addresses don't change*

> # For each PCI device listed in the for-loop, override their assigned driver
> # to vfio-pci, for usage with PCI-passthrough.
> #
> # Please make sure to include vfio-pci in the initrd, or some other modules
> # will likely claim the devices first. This can be done on systems that use
> # initramfs-tools by adding "vfio-pci" to /etc/initramfs-tools/modules
> install vfio-pci for dev in 0000:03:00.0 0000:03:00.1; do echo vfio-pci > "/sys/bus/pci/devices/$dev/driver_override"; done; /sbin/modprobe --ignore-install vfio-pci $CMDLINE_OPTS
>
> # Load vfio-pci before some other drivers so they don't claim devices first.
> # The pre-drm line should handle all graphics drivers.
> softdep snd_hda_intel pre: vfio-pci
> softdep drm pre: vfio-pci
>
>
> This worked well for me in dracut and initramfs-tools initrds with the
> vfio-pci module included.