R-Car/Virtualization/VFIO

Device Pass-Through Using VFIO

Platform Device Pass-Through Proof-of-Concept

This is a proof-of-concept showing how to provide guest access to an R-Car GPIO controller block on the Renesas Salvator-XS board.

Host Side

• Build and boot a host kernel using:
  • Repository: git://git.kernel.org/pub/scm/linux/kernel/git/geert/renesas-drivers.git
  • Branch: "topic/rcar3-virt-gpio-passthrough"
  • Config: "renesas_defconfig"

• Configure workarounds for missing functionality:

$ echo 0 > /sys/module/vfio_platform/parameters/reset_required
$ echo 1 > /sys/module/vfio/parameters/enable_unsafe_noiommu_mode

• Unbind GPIO6 from the "gpio-rcar" driver:

$ echo e6055400.gpio > /sys/bus/platform/drivers/gpio_rcar/unbind
gpio gpiochip6: REMOVING GPIOCHIP WITH GPIOS STILL REQUESTED

• Bind GPIO6 to the "vfio-platform" driver, for pass-through to guests:

$ echo vfio-platform > /sys/bus/platform/devices/e6055400.gpio/driver_override
$ echo e6055400.gpio > /sys/bus/platform/drivers/vfio-platform/bind
iommu: Adding device e6055400.gpio to group 0
vfio-platform e6055400.gpio: Adding kernel taint for vfio-noiommu group on device