Emulated Devices
NVIDIA DOCA Emulated Devices
This document describes the ability of NVIDIA® BlueField® DPU to emulate and accelerate physical and virtual host functions.
NVIDIA mediated devices deliver flexibility in allowing to create accelerated devices without SR-IOV on the BlueField® system. These mediated devices support NIC and RDMA and offer the same level of ASAP2 offloads as SR-IOV VFs. Mediates devices are supported using mlx5 sub-function acceleration technology. Two sub-function devices are created on the BlueField device upon boot (one per port if the port is in switchdev mode) using commands from /etc/mellanox/mlnx-sf.conf:
/sbin/mlnx-sf -a create -d 0000:03:00.0 -u 61a59715-aeec-42d5-be83-f8f42ba8b049 --mac 12:11:11:11:11:11
/sbin/mlnx-sf -a create -d 0000:03:00.1 -u 5b198182-1901-4c29-97a0-6623f3d02065 --mac 12:11:11:11:11:12
The help menu for mlnx-sf is presented below:
Usage: mlnx-sf [ OPTIONS ]
OPTIONS:
-a, -action, --action <action> Perform action
action: { enable | create | configure | remove | show | set_max_mdevs | query_mdevs_num }
-d, -device, --device <device> PCI device <domain>:<bus>:<device>.<func> (E.g.: 0000:03:00.0)
-m, -max_mdevs, --max_mdevs <max mdevs number> Set maximum number of MDEVs
-u, -uuid, --uuid <uuid> UUID to create SF with
-M, -mac, --mac <MAC> MAC to create SF with
-p, -permanent, --permanent [<conf file>] Store configuration to be used after reboot and/or driver restart. Default (/etc/mellanox/mlnx-sf.conf).
-V, -version, --version Display script version and exit
-D, -dryrun, --dryrun Display commands only
-v, -verbose, --verbose Run script in verbose mode (print out every step of execution)
-h, -help, --help Display help
"/etc/mellanox/mlnx-sf.conf" can be updated manually or using "mlnx-sf" tool with "-p" parameter.
1.1. Related Configuration
Interface names are configured using the UDEV rule under /etc/udev/rules.d/82-net-setup-link.rules.
SUBSYSTEM=="net", ACTION=="add", ATTR{phys_switch_id}!="", ATTR{phys_port_name}!="", \
IMPORT{program}="/etc/infiniband/vf-net-link-name.sh $attr{phys_switch_id} $attr{phys_port_name}" \
NAME="$env{NAME}", RUN+="/sbin/ethtool -L $env{NAME} combined 4"
# MDEV network interfaces
ACTION=="add", SUBSYSTEM=="net", DEVPATH=="/devices/pci0000:00/0000:00:00.0/0000:01:00.0/0000:02:02.0/0000:03:00.0/61a59715-aeec-42d5-be83-f8f42ba8b049/net/eth[0-9]", NAME="p0m0"
ACTION=="add", SUBSYSTEM=="net", DEVPATH=="/devices/pci0000:00/0000:00:00.0/0000:01:00.0/0000:02:02.0/0000:03:00.1/5b198182-1901-4c29-97a0-6623f3d02065/net/eth[0-9]", NAME="p1m0"
NVMe SNAP uses p0m0 as its default interface. See /etc/nvme_snap/sf1.conf.
This feature enables users to create VirtIO-net emulated PCIe devices in the system where the NVIDIA® BlueField®-2 DPU is connected. This is done by the virtio-net-controller software module present in the DPU. Virtio-net emulated devices allow users to hot plug up to 31 virtio-net PCIe PF Ethernet NIC devices or 504 virtio-net PCI VF Ethernet NIC devices in the host system where the DPU is plugged in.
DPU software also enables users to create virtio block PCI PF and SR-IOV PCI VF devices. This is covered in the NVIDIA BlueField SNAP and virtio-blk SNAP Documentation.
2.1. VirtIO-net Controller
Virtio-net-controller is a systemd service running on the DPU, with a user interface frontend to communicate with the background service. An SF representor is created for each virtio-net device created on the host. Virtio-net controller only uses an SF number ≥1000.
It is important to note that since the controller provides hardware resources and ACKs the request from the host's VirtIO driver, in order to reboot the DPU and host OS, it is necessary to reboot the host OS first, and only then reboot the DPU.
SF representor name is determined by udev rules. The default name is in the format of <prefix><pf_num><sf_num>. For example: en3f0pf0sf1001.
2.1.1. SystemD Service
Controller systemd service is enabled by default and runs automatically if VIRTIO_NET_EMULATION_ENABLE is true from mlxconfig.
- To check controller service status, run:
systemctl status virtio-net-controller.service
- To reload the service, make sure to unload virtio-net/virtio-pcie drivers on host. Then run:
systemctl restart virtio-net-controller.service
- To monitor log output of the controller service, run:
journalctl -u virtio-net-controller
The controller service has an optional configuration file which allows users to customize several parameters. The configuration file should be defined on the DPU at the following path /opt/mellanox/mlnx_virtnet/virtnet.conf. This file will be read every time the controller starts. Dynamic change of virtnet.conf is not supported. It is defined as a JSON format configuration file. The currently supported options are:
- ib_dev_for_static_pf – the RDMA device (e.g, mlx5_0) which the static VirtIO PF is created on
- is_lag - whether or not LAG is used. Note that if LAG is used, make sure to use the correct IB dev for static PF.
For example, the definition below has all static PFs using mlx5_0 (port 0) as the data path device in a non-lag configuration.
{
"ib_dev_for_static_pf":"mlx5_0", 190
"is_lag":0
}
2.1.2. User Frontend
To communicate with the service, a user frontend program, virtnet, is installed on the DPU. Run the following command to check its usage:
# virtnet -h
usage: virtnet [-h] [-v] {hotplug,unplug,list,query,modify,log} ...
Nvidia virtio-net-controller command line interface v1.0.9
positional arguments:
{hotplug,unplug,list,query,modify,log}
** Use -h for sub-command usage
hotplug hotplug virtnet device
unplug unplug virtnet device
list list all virtnet devices
query query all or individual virtnet device(s)
modify modify virtnet device
log set log level
optional arguments:
-h, --help show this help message and exit
-v, --version show program's version number and exit
Note that each positional argument has its own help menu as well. For example:
# virtnet log -h
usage: virtnet log [-h] -l {info,err,debug}
optional arguments:
-h, --help show this help message and exit
-l {info,err,debug}, --level {info,err,debug}
log level: info/err/debug
2.1.3. Controller Recovery
It is possible to recover the control and data planes if communications are interrupted so the original traffic can resume. Recovery depends on the JSON files stored in /opt/mellanox/mlnx_virtnet/recovery where there is a file that corresponds to each device (either PF or VF). The following is an example of the data stored in these files:
{
{
"pf_id": 0,
"function_type": "pf",
"device_type": "hotplug",
"mac": "7e:f5:1b:79:79:75",
"pf_num": 0,
"sf_num": 1000"rx_mode": 0
}
}
These files should not be modified under normal circumstances. However, if necessary, advanced users may tune settings to meet their requirements. Users are responsible for the validity of the recovery files and should only perform this when the controller is not running.
Controller recovery is enabled by default and does not need user configuration or intervention unless a system reset is needed or BlueField configuration is changed (i.e. any of the mlxconfig options PCI_SWITCH_EMULATION_NUM_PORT, VIRTIO_NET_EMULATION_NUM_VF, or VIRTIO_NET_EMULATION_NUM_PF). To this end, the files under /opt/mellanox/mlnx_virtnet/recovery must be deleted.
2.2. VirtIO-net PF Devices
This section covers managing virtio-net PCIe PF devices using virtio-net-controller.
2.2.1. VirtIO-net PF Device Configuration
- Run the following command on the DPU:
mlxconfig -d /dev/mst/mt41686_pciconf0 s INTERNAL_CPU_MODEL=1
- Add the following kernel boot parameters to the Linux boot arguments:
intel_iommu=on iommu=pt pci=realloc
- Cold reboot the host system.
- Apply the following configuration on the DPU:
$ mst start $ mlxconfig -d /dev/mst/mt41686_pciconf0 s PF_BAR2_ENABLE=0 PER_PF_NUM_SF=1 $ mlxconfig -d /dev/mst/mt41686_pciconf0 s \ PCI_SWITCH_EMULATION_ENABLE=1 \ PCI_SWITCH_EMULATION_NUM_PORT=16 \ VIRTIO_NET_EMULATION_ENABLE=1 \ VIRTIO_NET_EMULATION_NUM_VF=0 \ VIRTIO_NET_EMULATION_NUM_PF=0 \ VIRTIO_NET_EMULATION_NUM_MSIX=10 \ VIRTIO_NET_EMULATION_VENDOR_ID=0x1af4 \ VIRTIO_NET_EMULATION_DEVICE_ID=0x1041 \ VIRTIO_NET_EMULATION_CLASS_CODE=0x028000 \ ECPF_ESWITCH_MANAGER=1 \ ECPF_PAGE_SUPPLIER=1 \ SRIOV_EN=0 \ PF_SF_BAR_SIZE=10 \ PF_TOTAL_SF=64 $ mlxconfig -d /dev/mst/mt41686_pciconf0.1 s \ PF_SF_BAR_SIZE=10 \ PF_TOTAL_SF=64
- Cold reboot the host system a second time.
2.2.2. Creating Hotplug VirtIO-net PF Device
VirtIO emulated network PCIe devices are created and destroyed using virtio-net-controller application console. When this application is terminated, all created virtio-net emulated devices are hot unplugged.
- Create a hotplug virtio-net device. Run:
virtnet hotplug -i mlx5_0 -f 0x0 -m 0C:C4:7A:FF:22:93 -t 1500 -n 3 -s 1024
This creates one hotplug virtio-net device with MAC address 0C:C4:7A:FF:22:93, MTU 1500, and 3 VirtIO queues with a depth of 1024 entries. This device is uniquely identified by its index. This index is used to query and update device attributes. If the device is created successfully, an output appears similar to the following:Note:The maximum number of virtio-net queues is bound by the minimum of the following numbers:
- VIRTIO_NET_EMULATION_NUM_MSIX from the command mlxconfig -d <mst_dev> q
- max_virtq from the command virtnet list"
"bdf": "84:0.0", "id": 1, "rep_name": "en3f0pf0sf1001", "mac": "0C:C4:7A:FF:22:93"
- Bring up the representor port of the device. Run:
ip link set dev en3f0pf0sf1001 up ovs-vsctl add-port <bridge> en3f0pf0sf1001
Once steps 1-3 are completed, virtio-net device should be available in the host system.
- To query all the device configurations of virtio-net device that you created, run:
virtnet query –p 1
- To list all the virtio-net devices, run:
virtnet list
- To modify device attributes, for example, changing its MAC address, run:
virtnet modify -p 0 device -m 0C:C4:7A:FF:22:98
- Once usage is complete, to hot-unplug a VirtIO net device, run:
virtnet unplug -p 1
2.3. VirtIO-net SR-IOV VF Devices
This section covers managing virtio-net PCIe SR-IOV VF devices using virtio-net-controller.
2.3.1. Virtio-net SR-IOV VF Device Configuration
Virtio-net SR-IOV VF is only supported with statically configured PF, hot-plugged PF is not currently supported.
- On the DPU, make sure virtio-net-controller service is enabled so that it starts automatically. Run:
systemctl status virtio-net-controller.service
- On the x86 host, enable SR-IOV. Please refer to MLNX_OFED documentation under Features Overview and Configuration > Virtualization > Single Root IO Virtualization (SR-IOV) > Setting Up SR-IOV for instructions on how to do that. Make sure the parameters
intel_iommu=on iommu=pt pci=reallocexist in grub.conf file. - It is recommended to add pci=assign-busses to the boot command line when creating more than 127 VFs. Without this option, the following errors might appear from host and the virtio driver will not probe these devices.
pci 0000:84:00.0: [1af4:1041] type 7f class 0xffffff pci 0000:84:00.0: unknown header type 7f, ignoring device
- Run the following command on the DPU:
mst start && mlxconfig -d /dev/mst/mt41686_pciconf0 s INTERNAL_CPU_MODEL=1
- Cold reboot the host system.
- Apply the following configuration on the DPU in three steps to support up to 125 VFs per PF (500 VFs in total).
-
mst start && mlxconfig -d /dev/mst/mt41686_pciconf0 s PF_BAR2_ENABLE=0 PER_PF_NUM_SF=1
-
mlxconfig -d /dev/mst/mt41686_pciconf0 s \ PCI_SWITCH_EMULATION_ENABLE=1 \ PCI_SWITCH_EMULATION_NUM_PORT=16 \ VIRTIO_NET_EMULATION_ENABLE=1 \ VIRTIO_NET_EMULATION_NUM_VF=126 \ VIRTIO_NET_EMULATION_NUM_PF=4 \ VIRTIO_NET_EMULATION_NUM_MSIX=4 \ VIRTIO_NET_EMULATION_VENDOR_ID=0x1af4 \ VIRTIO_NET_EMULATION_DEVICE_ID=0x1041 \ VIRTIO_NET_EMULATION_CLASS_CODE=0x028000 \ ECPF_ESWITCH_MANAGER=1 \ ECPF_PAGE_SUPPLIER=1 \ SRIOV_EN=1 \ PF_SF_BAR_SIZE=8 \ PF_TOTAL_SF=508 \ NUM_OF_VFS=0
-
mlxconfig -d /dev/mst/mt41686_pciconf0.1 s PF_TOTAL_SF=1 PF_SF_BAR_SIZE=8
-
- Cold reboot the host system.
2.3.2. Creating Virtio-net SR-IOV VF Devices
The virtio-net-controller application console must be kept alive to maintain the functionality of the static PF and its VFs.
- On the host, make sure the static virtio network device presents. Run:
# lspci | grep -i virtio 85:00.3 Network controller: Red Hat, Inc. Virtio network device
- On the host, make sure virtio_pci and virtio_net are loaded. Run:
# lsmod | grep virtio
# ethtool -i p7p3 driver: virtio_net version: 1.0.0 firmware-version: expansion-rom-version: bus-info: 0000:85:00.3 supports-statistics: no supports-test: no supports-eeprom-access: no supports-register-dump: no supports-priv-flags: no
- To create SR-IOV VF devices on the x86 host, run:
# echo 2 > /sys/bus/pci/drivers/virtio-pci/0000\:85\:00.3/sriov_numvfs
2 VFs should be created from the x86 host:Note:When the number of VFs created is high, SR-IOV enablement may take several minutes.
# lspci | grep -i virt 85:00.3 Network controller: Red Hat, Inc. Virtio network device 85:04.5 Network controller: Red Hat, Inc. Virtio network device 85:04.6 Network controller: Red Hat, Inc. Virtio network device
- From the DPU virtio-net controller, run the following command to get VF information.
# virnet list { "vf_id": 0, "parent_pf_id": 0, "function_type": "VF", "bdf": "85:04.5", "sf_parent_device": "mlx5_0", "sf_rep_name": "pf0sf5", "msix_config_vector": "0x0", "num_msix": 4, "max_queues": 4, "queues_size": 256, "net_mac": "1A:38:A4:55:BD:B0", "net_mtu": 1500 },
You may use the pci-bdf to match the PF/VF on the x86 host to the information showing on DPU.
To query all the device configurations of the virtio-net device of that VF, run:
$ virtnet query -p 0 -v 0
Bring up the corresponding SF and add it to the OVS bridge:# ip link set dev pf0sf5 up # ovs-vsctl add-port <bridge> pf0sf5
Now the VF should be functional.Note:When port MTU (p0/p1 of the DPU) is changed after the controller is started, you must restart controller service. It is not recommended to use jumbo MTUs because that may lead to performance degradation.
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