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 script, and then reboot the node to apply the changes:

# /usr/libexec/vstorage-ui-agent/bin/ 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

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

    # wget
    # tar -xvzf mft-4.17.0-106-x86_64-rpm.tgz
  2. Install the package, and then start Mellanox Software Tools (MST):

    # yum install rpm-build
    # . mft-4.17.0-106-x86_64-rpm/
    # mst start
  3. Determine the MST device path:

    # mst status
  4. Query the current configuration:

    # mlxconfig -d /dev/mst/mt4119_pciconf0 q
             NUM_OF_VFS            4               # Number of activated VFs
             SRIOV_EN              True(1)         # SR-IOV is enabled
  5. 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
  6. Reboot the node to apply the changes.