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Adding SR-IOV to Tripleo

Blueprint URL:

SR-IOV is a specification that extends the PCI Express specification and allows a PCIe device to appear to be multiple separate physical PCIe devices.

SR-IOV provides one or more Virtual Functions (VFs) and a Physical Function(PF)

  • Virtual Functions (VF’s) are ‘lightweight’ PCIe functions that contain the resources necessary for data movement but have a carefully minimized set of configuration resources.
  • Physical Function (PF) are full PCIe functions that include the SR-IOV Extended Capability. This capability is used to configure and manage the SR-IOV functionality.

The VF’s could be attached to VMs like a dedicated PCIe device and thereby the usage of SR-IOV NICs boosts the networking performance considerably.

Problem Description

  • Today the installation and configuration of SR-IOV feature is done manually after overcloud deployment. It shall be automated via tripleo.
  • Identification of the hardware capabilities for SR-IOV were all done manually today and the same shall be automated during introspection. The hardware detection also provides the operator, the data needed for configuring Heat templates.

Proposed Change


  • Ironic Python Agent will discover the below hardware details and store it in swift blob -

    • SR-IOV capable NICs: Shall read /sys/bus/pci/devices/.../sriov_totalvfs and check if its non zero, inorder to identify if the NIC is SR-IOV capable
    • VT-d or IOMMU support in BIOS: The CPU flags shall be read to identify the support.
  • DIB shall include the package by default - openstack-neutron-sriov-nic-agent.

  • The nodes without any of the above mentioned capabilities can’t be used for COMPUTE role with SR-IOV

  • SR-IOV drivers shall be loaded during bootup via persistent module loading scripts. These persistent module loading scripts shall be created by the puppet manifests.

  • T-H-T shall provide the below details

    • supported_pci_vendor_devs - configure the vendor-id/product-id couples in the nodes running neutron-server
    • max number of vf’s - persistent across reboots
    • physical device mappings - Add physical device mappings ml2_conf_sriov.ini file in compute node
  • On the nodes running the Neutron server, puppet shall

    • enable sriovnicswitch in the /etc/neutron/plugin.ini file mechanism_drivers = openvswitch,sriovnicswitch This configuration enables the SR-IOV mechanism driver alongside OpenvSwitch.
    • Set the VLAN range for SR-IOV in the file /etc/neutron/plugin.ini, present in the network node network_vlan_ranges = <physical network name SR-IOV interface>:<VLAN min> :<VLAN max> Ex : network_vlan_ranges = fabric0:15:20
    • Configure the vendor-id/product-id couples if it differs from “15b3:1004,8086:10ca” in /etc/neutron/plugins/ml2/ml2_conf_sriov.ini supported_pci_vendor_devs = 15b3:1004,8086:10ca,<vendor-id:product-id>
    • Configure neutron-server.service to use the ml2_conf_sriov.ini file [Service] Type=notify User=neutron ExecStart=/usr/bin/neutron-server –config-file /usr/share/neutron/neutron-dist.conf –config-file /etc/neutron/neutron.conf –config-file /etc/neutron/plugin.ini –config-file /etc/neutron/plugins/ml2/ml2_conf_sriov.ini –log-file /var/log/neutron/server.log
  • In the nodes running nova scheduler, puppet shall

    • add PciPassthroughFilter filter to the list of scheduler_default_filters. This needs to be done to allow proper scheduling of SR-IOV devices
  • On each COMPUTE+SRIOV node, puppet shall configure /etc/nova/nova.conf

    • Associate the available VFs with each physical network Ex: pci_passthrough_whitelist={“devname”: “enp5s0f1”, “physical_network”:”fabric0”}

      PCI passthrough whitelist entries use the following syntax: [“device_id”: “<id>”,] [“product_id”: “<id>”,] [“address”: “[[[[<domain>]:]<bus>]:][<slot>][.[<function>]]” | “devname”: “Ethernet Interface Name”,] “physical_network”:”Network label string”

      VF’s that needs to be excluded from agent configuration shall be added in [sriov_nic]/exclude_devices. T-H-T shall configure this.

      Multiple whitelist entries per host are supported.

  • Puppet shall

    • Setup max number of VF’s to be configured by the operator echo required_max_vfs > /sys/bus/pci/devices/.../sriov_numvfs Puppet will also validate the required_max_vfs, so that it does not go beyond the supported max on the device.

    • Enable NoopFirewallDriver in the ‘/etc/neutron/plugins/ml2/sriov_agent.ini’ file.

      [securitygroup] firewall_driver = neutron.agent.firewall.NoopFirewallDriver

    • Add mappings to the /etc/neutron/plugins/ml2/sriov_agent.ini file. Ex: physical_device_mappings = fabric0:enp4s0f1 In this example, fabric0 is the physical network, and enp4s0f1 is the physical function

  • Puppet shall start the SR-IOV agent on Compute

    • systemctl enable neutron-sriov-nic-agent.service
    • systemctl start neutron-sriov-nic-agent.service



Security impact

  • We have no firewall drivers which support SR-IOV at present. Security groups will be disabled only for SR-IOV ports in compute hosts.

Other End User Impact


Performance Impact

  • SR-IOV provides near native I/O performance for each virtual machine on a physical server. Refer -

Other Deployer Impact

  • The operator shall ensure that the BIOS supports VT-d/IOMMU virtualization technology on the compute nodes.
  • IOMMU needs to be enabled in the Compute+SR-IOV nodes. Boot parameters (intel_iommu=on or amd_iommu=pt) shall be added in the grub.conf, using the first boot scripts (THT).
  • Post deployment, operator shall
    • Create neutron ports prior to creating VM’s (nova boot) neutron port-create fabric0_0 –name sr-iov –binding:vnic-type direct
    • Create the VM with the required flavor and SR-IOV port id Ex: nova boot –flavor m1.small –image <image id> –nic port-id=<port id> vnf0

Developer Impact




Primary assignees:

  • karthiks
  • sanjayu

Work Items

  • Documented above in the Proposed changes



  • Since SR-IOV needs specific hardware support, this feature cant be tested under CI. We will need third party CI for validating it.

Documentation Impact

  • Manual steps that needs to be done by the operator shall be documented. Ex: configuring BIOS for VT-d, IOMMU, post deploymenent configurations.