Virtual Functions
NVIDIA DOCA Virtual Functions User Guide
This document provides an overview and configuration of virtual functions for NVIDIA® BlueField® DPU and demonstrates a use case for running the DOCA Applications over x86 host.
Single root IO virtualization (SR-IOV) is a technology that allows a physical PCIe device to present itself multiple times through the PCIe bus. This technology enables multiple virtual instances of the device with separate resources. NVIDIA adapters are able to expose virtual instances or functions (VFs) for each port individually. These virtual functions can then be provisioned separately.
Each VF can be seen as an additional device connected to the physical interface or function (PF). It shares the same resources with the PF, and its number of ports equals those of the PF.
SR-IOV is commonly used in conjunction with an SR-IOV-enabled hypervisor to provide virtual machines direct hardware access to network resources, thereby increasing its performance.
There are several benefits to running applications on the host. For example, one may want to utilize a strong and high-resource host machine, or to start DOCA integration on the host before offloading it to the BlueField DPU.
The configuration in this document allows the entire application to run on the host's memory, while utilizing the HW accelerators on BlueField (e.g., using RegEx the accelerator on BlueField via a daemon running on it).
When VFs are enabled on the host, VF representors are visible on the Arm side which can be bridged to corresponding PF representors (e.g., the uplink representor and the host representor). This allows the application to only scan traffic forwarded to the VFs as configured by the user and to behave as a simple "bump-on-the-wire". DOCA installed on the host allows access to the hardware capabilities of the BlueField DPU without comprising features such as the stateful table (SFT) which uses HW offload and additional HW steering elements embedded inside the eSwitch.
Running applications on the host and using the RegEx accelerator on the BlueField requires enabling the RegEx engine.
To run all the reference applications over the host, you must install the host DOCA package. Refer to NVIDIA DOCA Installation Guide for more information on host installation. VFs must be configured as trusted for the hardware jump action to work as intended. The following steps configure "trusted" mode for VFs:
- Delete all existing VFs/SFs.
- To delete all VFs on a PF run the following on the host:
$ echo 0 > /sys/class/net/<physical_function>/device/sriov_numvfs
$ echo 0 > /sys/class/net/ens1f0/device/sriov_numvfs
- Refer to Scalable Function Setup Guide for instructions on deleting SFs.
- To delete all VFs on a PF run the following on the host:
- Stop the main driver on the host:
/etc/init.d/openibd stop
- Before creating the VFs, set them to "trusted" mode on the device by running the following commands on the Arm side.
- Setting VFs on port 0:
$ mlxreg -d /dev/mst/mt41686_pciconf0 --reg_id 0xc007 --reg_len 0x40 --indexes "0x0.0:32=0x80000000" --yes --set "0x4.0:32=0x1"
- Setting VFs on port 1:
$ mlxreg -d /dev/mst/mt41686_pciconf0.1 --reg_id 0xc007 --reg_len 0x40 --indexes "0x0.0:32=0x80000000" --yes --set "0x4.0:32=0x1"
Note:These commands set trusted mode for all created VFs/SFs after their execution on Arm.
Note:Setting trusted mode should be performed once per reboot.
- Setting VFs on port 0:
- Restart the main driver on the host by running the following command:
/etc/init.d/openibd restart
- Enable SR-IOV. Run:
host$ mlxconfig -y -d /dev/mst/mt41686_pciconf0 s SRIOV_EN=1
- Set number of VFs. Run:
host$ mlxconfig -y -d /dev/mst/mt41686_pciconf0 s NUM_OF_VFS=X
Note:Requires reboot.
host$ echo X > /sys/class/net/<physical_function>/device/sriov_numvfs
$ mlxconfig -y -d /dev/mst/mt41686_pciconf0 s NUM_OF_VFS=2 $ echo 2 > /sys/class/net/ens1f0/device/sriov_numvfs
After enabling VF, the representor appears on the DPU. The function itself is seen at the x86 side.
- To verify that the VFs have been created. Run:
$ lspci | grep Mellanox 05:00.0 Ethernet controller: Mellanox Technologies Device a2d6 05:00.1 Ethernet controller: Mellanox Technologies Device a2d6 05:00.2 DMA controller: Mellanox Technologies Device c2d3 05:00.3 Ethernet controller: Mellanox Technologies MT28850 05:00.4 Ethernet controller: Mellanox Technologies MT28850
Note:2 new virtual Ethernet devices are created in this example.
The following steps are required only if the application utilizes the RegEx engine:
- Stop the driver on the host. Run:
host$ sudo /etc/init.d/openibd stop
- On the Arm, start the driver. Run:
dpu$ sudo /etc/init.d/openibd start
- On the Arm, enable RegEx (only if the application requires it). Run:
dpu$ echo 1 > /sys/class/net/p0/smart_nic/pf/regex_en
- On the Arm, add 200 huge pages. Run:
dpu$ current_huge='cat /sys/kernel/mm/hugepages/hugepages-2048kB/nr_hugepages' dpu$ echo $((200 + current_huge)) > /sys/kernel/mm/hugepages/hugepages-2048kB/nr_hugepages
- On the Arm, start mlx RegEx. Run:
dpu$ systemctl start mlx-regex
Note:If it has not been set before, the previous value of huge pages should be 2048 or higher (depending on the number of cores).
- Verify that the service is running. Run:
dpu$ systemctl status mlx-regex
- The host can now run RegEx. Run:
host$ sudo /etc/init.d/openibd start
Running DPDK over the host requires configuring huge pages.
By default, a DPDK application initializes all the cores of the device. This is usually unnecessary and may even cause unforeseeable issues. It is recommended to limit the number of cores, especially when using an AMD-based system, to 16 cores using the -c flag when running DPDK.
The following is a CLI example for running a reference application over the host using VF:
./opt/mellanox/doca/applications/**/bin/*executable* -a "pci address VF0" -a "pci address VF1" -c 0xff -- "application flags"
The following is a topology example for running the application over the host.
Configure the OVS on BlueField as follows:
Bridge ovsbr1
Port ovsbr1
Interface ovsbr1
type: internal
Port pf0hpf
Interface pf0hpf
Port pf0vf1
Interface pf0vf1
Bridge vf_br
Port p0
Interface p0
Port vf_br
Interface vf_br
type: internal
Port pf0vf0
Interface pf0vf0
When enabling a new VF over the host, VF representors are created on the Arm side. The first OVS bridge connects the uplink connection (p0) to the new VF representor (pf0vf0), and the second bridge connects the second VF representor (pf0vf1) to the host representors (pf0phf). On the host, the 2 PCIe addresses of the newly created function must be initialized when running the applications.
When traffic is received (e.g., from the uplink), the following occurs:
- Traffic is received over
p0. - Traffic is forwarded to
pf0vf0. - Application "listens" to
pf0vf0andpf0vf1and can, therefore, acquire the traffic frompf0vf0, inspect it, and forward topf0vf1. - Traffic is forwarded from
pf0vf1topf0hpf.
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