Identify Example: Support VFIO interface for devices behind IOMMU

[cooldavid]

Devices behind IOMMU would get DMA page fault error without proper IOMMU setting. Make the identify example support setting VFIO group for those devices.

Reference document: https://www.kernel.org/doc/Documentation/vfio.txt

Usage example:

• Unbind the device: $ echo -n "0000:02:00.0" > /sys/bus/pci/devices/0000\:02\:00.0/driver/unbind
• Bind to VFIO-PCI driver: $ lspci -n -s 0000:02:00.0 02:00.0 0108: 8086:f1a8 (rev 03) $ echo -n "8086 f1a8" > /sys/bus/pci/drivers/vfio-pci/new_id *Find out and check the IOMMU group $ ls -l /sys/bus/pci/devices/0000:02:00.0/iommu_group lrwxrwxrwx 1 root root 0 May 28 12:26 /sys/bus/pci/devices/0000:02:00.0/iommu_group -> ../../../../kernel/iommu_groups/7 $ ls /dev/vfio/ 7 vfio

• Run the identify example $ build/bin/nvm-identify-userspace --ctrl=02:00.0 --vfio=7 Resetting controller and setting up admin queues... ------------- Controller information ------------- PCI Vendor ID : 86 80 PCI Subsystem Vendor ID : 86 80 NVM Express version : 1.3.0 Controller page size : 4096 Max queue entries : 256 Serial Number : BTNHXXXXXXXXXXXXX
  Model Number : INTEL SSDPEKNW512G8
  Firmware revision : 002C
  Max data transfer size : 131072 Max outstanding commands: 0 Max number of namespaces: 1 Current number of CQs : 8 Current number of SQs : 8

  Goodbye!

[enfiskutensykkel]

Thank you for this contribution.