[openstack-dev] [nova][pci-passthrough] definitely specify VFIO driver as the host PCI driver for passthrough

Chen Fan fan.chen at easystack.cn
Fri Jun 24 04:27:57 UTC 2016

hi all,
      in openstack, we can use the pci passthrough feature now, refer to
      but we can't definitely specify the host pci driver is LEGACY_KVM 
or newer VFIO,
      new VFIO driver is more safer, and higher-performance user-space 
      than legacy kvm driver (pci-stub), the benefit relative to kvm 
assignment driver
      could refer to http://lwn.net/Articles/474088/.
      In additional, VFIO driver provides the GPU passthrough as primary 
card support.
      I think it is more useful for further GPU passthrough support in 

      Openstack relies on the libvirt nodedev device configuration to do 
pci passthrough,
      with managed mode, the configured device is automatically detached 
and re-attached
      with KVM or VFIO driver that depended on the host driver modules 
      so now we can't specify the driver in openstack to VFIO mode, I 
think we should need
      to add this feature support in openstack to get pci passhthrough 
more scalability.

      a simply idea is to add a option in nova.conf HOST_PCI_MODEL = 
VFIO /KVM to specify
      the pci passthrough device driver is using VFIO driver.
      any comments are welcome. :)


Chen Fan

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