[vfio-users] Convenience script for binding to vfio-pci

[Alex Williamson]

Hi Andre,

On Mon, 2015-09-14 at 14:23 +0000, Andre Richter wrote:
> Hi,
> 
> just in case anybody is interested, I want to share a little convenience
> script of mine:
> 
> https://github.com/andre-richter/vfio-pci-bind
> 
> This script takes a Bus:Device:Function string of the form "00:00.0"
> as command line argument and:
> 
> 1. Unbinds all devices that are in the same iommu group as the supplied
> device from their current driver (except PCIe bridges).
> 
> 2. Binds to vfio-pci:
>   1. The supplied device.
>   2. All unbound devices that have the same device_id and vendor_id as the
> supplied device.
>   3. All devices that are in the same iommu group.
> 
> 3. Transfers ownership of the respective iommu groups inside /dev/vfio to
> $SUDO_USER
> 
> Script must be executed via sudo!


This looks fragile:

unless File.exist?('/sys/bus/pci/devices/0000:00:00.0/iommu/')
  puts 'No signs of an IOMMU. Check your hardware and/or linux cmdline parameters.'
  puts 'Use intel_iommu=on or iommu=pt iommu=1'
  exit
end

Why not check the iommu link for the device to be attached, or look
in /sys/class/iommu rather than assume device 0000:00:00.0?

TARGET_DEV_SYSFS_PATH = "/sys/bus/pci/devices/0000:#{bdf}/"

You're assuming domain 0000.

# Do not care about bridges
dev_sysfs_paths.delete_if { |dsp| File.read(dsp + '/class')[0..5] == '0x0604' }

Testing for HEADER_TYPE 0 would be more compatible and match the patch I
proposed for whitelisting all bridges, not just those w/o a driver or
bound to pcieport.  Ex


if [ $(( 0x$(setpci -s 0000:00:1c.0 0e.b) & 0x7f )) -ne 0 ]; then
    echo bridge
fi


  # Add id to vfio-pci driver
  File.write('/sys/bus/pci/drivers/vfio-pci/new_id', devid)

If you used /sys/bus/pci/devices/ssss:bb:dd.f/driver_override you could
avoid the "feature" of binding all devices with the same vendor:device
ID.

# Adjust ownership
ids = ENV['SUDO_UID'] + ':' + ENV['SUDO_GID']
Dir.glob('/dev/vfio/[0-9]*').each { |f| `chown #{ids} #{f}` }

Is this changing the ownership of *all* the groups to the current user?
Why not just the group affected?  Thanks,

Alex