#!/bin/sh

# SPDX-FileCopyrightText: 2023 - 2024 Benjamin Grande M. S. <ben.grande.b@gmail.com
#
# SPDX-License-Identifier: GPL-3.0-or-later

## Credits: https://www.qubes-os.org/doc/how-to-use-pci-devices/#bringing-pci-devices-back-to-dom0
##
## After attaching a PCI device and detaching it, the device is not available
## in Dom0 anymore. This is an intended feature. A device which was previously
## assigned to a less trusted qube could attack dom0 if it were automatically
## reassigned there. In order to re-enable the device in dom0, either reboot
## physical machine or run the following script.
##
## This is useful for testing purposes when testing PCI devices, not
## recommended for users to attach a device to Dom0.

set -eu

usage(){
  printf '%s\n' "Usage: ${0##*/} --i-like-danger <DEVICE>"
  printf '%s\n' "Example: ${0##*/} --i-like-danger 0000:00:1b.0"
  printf '%s\n' "Warning: Strongly discouraged to reattach PCI devices to"
  printf '%s\n' "Warning:  dom0, especially if it doesn't support resetting!"
  exit 1
}

case "${1-}" in
  --i-like-danger) ;;
  *) usage;;
esac
case "${2-}" in
  "") usage;;
  *) device="${2}"
esac

uid="$(id -u)"
test "${uid}" = "0" || exec sudo "${0}"

printf '%s\n' "${device}" | tee -- /sys/bus/pci/drivers/pciback/unbind
modalias="$(cat -- "/sys/bus/pci/devices/${device}/modalias")"
module="$(modprobe -R "${modalias}" | head -n 1)"
printf '%s\n' "${device}" | tee -- "/sys/bus/pci/drivers/${module}/bind"