Configuring SR-IOV support

Limitations

Virtual machines with attached PCI devices cannot be live migrated.

Prerequisites

To authorize further OpenStack commands, the OpenStack command-line client must be configured, as outlined in Connecting to OpenStack command-line interface.

Procedure overview

Prepare a compute node for SR-IOV support.
Reconfigure the compute cluster to enable SR-IOV support.
Create a virtual machine with an SR-IOV network port.

To prepare a node for SR-IOV

List all network adapters on a node and obtain their VID and PID:

# lspci -nnD | grep Ethernet
0000:00:03.0 Ethernet controller [0200]: Mellanox Technologies MT27800 Family [ConnectX-5] [15b3:1017]
0000:00:04.0 Ethernet controller [0200]: Mellanox Technologies MT27800 Family [ConnectX-5] [15b3:1017]

[15b3:1017] is the VID and PID of the network adapter.

Check that the chosen network adapter supports SR-IOV by using its VID and PID:

# lspci -vv -d 15b3:1017 | grep SR-IOV
Capabilities: [180 v1] Single Root I/O Virtualization (SR-IOV)
Capabilities: [180 v1] Single Root I/O Virtualization (SR-IOV)

Enable IOMMU on the node by running the pci-helper.py enable-iommu script and reboot the node to apply the changes:
```
# /usr/libexec/vstorage-ui-agent/bin/pci-helper.py enable-iommu
# reboot
```
The script works for both Intel and AMD processors.

Verify that IOMMU is enabled in the dmesg output:

# dmesg | grep -e DMAR -e IOMMU
[    0.000000] DMAR: IOMMU enabled

[For NVIDIA Mellanox network adapters] Enable SR-IOV in firmware:

Download Mellanox Firmware Tools (MFT) from the official website and extract the archive on the node. For example:

# wget https://www.mellanox.com/downloads/MFT/mft-4.17.0-106-x86_64-rpm.tgz
# tar -xvzf mft-4.17.0-106-x86_64-rpm.tgz

Install the package, and then start Mellanox Software Tools (MST):

# yum install rpm-build
# . mft-4.17.0-106-x86_64-rpm/install.sh
# mst start

Determine the MST device path:
```
# mst status
```

Query the current configuration:

# mlxconfig -d /dev/mst/mt4119_pciconf0 q
...
Configurations:
...
         NUM_OF_VFS            4               # Number of activated VFs
         SRIOV_EN              True(1)         # SR-IOV is enabled
...

Set the desired values, if necessary. For example, to increase the number of virtual functions to 8, run:
```
# mlxconfig -d /dev/mst/mt4119_pciconf0 set SRIOV_EN=1 NUM_OF_VFS=8
```
Reboot the node to apply the changes.

To enable SR-IOV support for the compute cluster

Create a configuration file in the YAML format. For example:
```
# cat << EOF > pci-passthrough.yaml
- node_id: c3b2321a-7c12-8456-42ce-8005ff937e12
  devices:
    - device_type: sriov
      device: enp2s0
      physical_network: sriovnet
      num_vfs: 8
EOF
```
In this example:
- node_id is the UUID of the compute node that hosts a network adapter
- sriov is the device type for a network adapter
- enp2s0 is the device name of a network adapter
- sriovnet is an arbitrary name that will be used as an alias for a network adapter
- num_vfs is the number of virtual functions to create for a network adapter
The maximum number of virtual functions supported by a PCI device is specified in the /sys/class/net/<device_name>/device/sriov_totalvfs file. For example:
```
# cat /sys/class/net/enp2s0/device/sriov_totalvfs
63
```

Reconfigure the compute cluster by using this configuration file:

# vinfra service compute set --pci-passthrough-config pci-passthrough.yaml
+---------+--------------------------------------+
| Field   | Value                                |
+---------+--------------------------------------+
| task_id | 89c8a6c4-f480-424e-ab44-c2f4e2976eb9 |
+---------+--------------------------------------+

Check the status of the task:

# vinfra task show 89c8a6c4-f480-424e-ab44-c2f4e2976eb9

To create a virtual machine with an SR-IOV network port

Create a physical compute network specifying the network adapter alias from the pci-passthrough.yaml file and the default vNIC type direct. You also need to disable the built-in DHCP server and specify the desired IP address range. For example, to create the sriov-network network with the 10.10.10.0/24 CIDR, run:
```
# vinfra service compute network create sriov-network --physical-network sriovnet --default-vnic-type direct \
--no-dhcp --cidr 10.10.10.0/24
```

Create a virtual machine specifying the new network. For example, to create the VM sriov-vm from the template centos7 and with the large flavor, run:

# vinfra service compute server create sriov-vm --network id=sriov-network --volume source=image,size=11,id=centos7 --flavor large