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

[Eddie Yen]

Sorry about delay reply.

Same reason as Kyle. We have 2 NICs which had same VID:PID. And want to
passthrough one of them into VM.
The script can use, but need to unbind device from NIC driver first as
premise.

echo $DEV > /sys/bus/pci/devices/$DEV/unbind
echo $DEV > /sys/bus/pci/drivers/vfio-pci/new_id
(Can't remember the second command path.)


if using

echo vfio-pci > /sys/bus/pci/devices/$DEV/driver_override

lspci -k will shows NIC driver still occupied this NIC.


I'ii try Kyle's method but need to think about how to transfer this method
for Ubuntu (Debian)...

2018-05-18 1:43 GMT+08:00 Alex Williamson <alex.williamson at redhat.com>:

> On Thu, 17 May 2018 13:12:07 -0400
> Kyle Marek <psppsn96 at gmail.com> 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:
> >
> > # 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.
>
> Yes, this is a good demonstration of how userspace can easily
> accomplish this through modprobe.d softdeps and custom install
> options.  A more persistence focused version of the above might do the
> same knowing that we're looking for all devices device downstream of
> the root port at 0000:00:01.0, and would look something like:
>
> install vfio-pci for dev in $(find /sys/devices/pci0000:00/0000:00:01.0/
> -maxdepth 1 -mindepth 1 -type d -name "????:??:??.?"); do echo vfio-pci >
> $dev/driver_override; done; modprobe --ignore-install...
>
> or even
>
> for override in $(find /sys/devices/pci0000:00/0000:00:01.0/ -mindepth
> 2 -name driver_override); do echo vfio-pci > $override; done...
>
> There are countless ways to do this, including ways that take advantage
> of PCI slots information provided through ACPI if the system supports
> it.  Thanks,
>
> Alex
>
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