Preparing nodes for SR-IOV

To use SR-IOV capabilities, check that the network adapter that you want to pass through supports them, and then enable IOMMU. For NVIDIA Mellanox network adapters, you need to additionally enable SR-IOV in firmware.

To check that a network adapter supports 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)

To enable IOMMU on a node

Run the pci-helper.py script, and then 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.

You can check that IOMMU is successfully enabled in the dmesg output:

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

To enable SR-IOV in firmware for NVIDIA Mellanox network adapters

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.