VirtIO-net Emulated Devices

Virtio-net device emulation enables users to create VirtIO-net emulated PCIe devices in the system where the NVIDIA® BlueField® 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 PCIe VF Ethernet NIC devices in the host system where the DPU is plugged in.

DPU software also enables users to create virtio block PCIe PF and SR-IOV PCIe VF devices. This is covered in the NVIDIA BlueField SNAP and virtio-blk SNAP Documentation.

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. Refer to section "Scalable Functions" for more information.

Each virtio-net PF/VF requires a dedicated SF and it should be reserved from mlxconfig (see section "VirtIO-net PF Device Configuration"). However, since an SF is a shared resource on the system, there may be other application-created SFs as well. In that case, PF_TOTAL_SF must be updated to consider those SFs. Otherwise, virtio-net is not able to create enough configured PF/VF.

SystemD Service

Controller systemd service is enabled by default and runs automatically if VIRTIO_NET_EMULATION_ENABLE is true from mlxconfig.

1. To check controller service status, run:

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   $ systemctl status virtio-net-controller.service
           

2. To reload the service, make sure to unload virtio-net/virtio-pcie drivers on host. Then run:

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   $ systemctl restart virtio-net-controller.service
           

3. To monitor log output of the controller service, run:

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   $ journalctl -u virtio-net-controller -f
           

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 is 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_p0 – RDMA device (e.g., mlx5_0) used to create SF on port 0. This port is the EMU manager when is_lag is 0. Default value is mlx5_0.

• ib_dev_p1 – RDMA device (e.g., mlx5_1) used to create SF on port 1. Default value is mlx5_1.

• ib_dev_lag – RDMA LAG device (e.g., mlx5_bond_0) used to create SF on LAG. Default value is mlx5_bond_0. This port is EMU manager when is_lag is 1. ib_dev_lag and ib_dev_p0/ib_dev_p1 cannot be configured simultaneously.

• ib_dev_for_static_pf – the RDMA device (e.g., mlx5_0) which the static virtio PF is created on

• is_lag – specifies whether LAG is used. Note that if LAG is used, make sure to use the correct IB dev for static PF.

• static_pf –
  

  • mac_base – base MAC address for static PFs. MACs are automatically assigned with the following pattern: pf_mac→pf_0, pf_mac+1→pf_1, etc.

    Note

    Note that the controller does not validate the MAC address (other than its length). The user must ensure MAC is valid and unique.

  • features – virtio spec-defined feature bits for static PFs. If unsure, leave features out of the JSON file and a default value is automatically assigned.

• vf –

  • mac_base – base MAC address for static PFs. MACs are automatically assigned with the following pattern: pf_mac→pf_0, pf_mac+1→pf_1, etc.

  • features – virtio spec-defined feature bits for static VFs. If unsure, leave features out of the JSON file and a default value is automatically assigned.

  • vfs_per_pf – number of VFs to create on each PF. This is mandatory if mac_base is specified.

    Note

    This value does not equal VIRTIO_NET_EMULATION_NUM_VF in mlxconfig. vfs_per_pf ≤ VIRTIO_NET_EMULATION_NUM_VF.

  • qp_num – number of QPs for each VF. If not specified, then the QP number assigned is taken from its parent PF.

• recovery – specifies whether recovery is enabled. If unspecified, recovery is enabled by default. To disable it, set recovery to 0.

• sf_pool_percent – determines the initial SF pool size as the percentage of PF_TOTAL_SF of mlxconfig. Valid range: [0, 100]. For instance, if the value is 5, it means an SF pool with 5% of PF_TOTAL_SF is created. 0 means no SF pool is reserved beforehand (default).

  Note

  PF_TOTAL_SF is shared by all applications. User must ensure the percent request is guaranteed or else the controller will not be able to reserve the requested SFs resulting in failure.

• sf_pool_force_destroy – specifies whether to destroy the SF pool. When set to 1, the controller destroys the SF pool when stopped/restarted (and the SF pool is recreated if sf_pool_percent is not 0 when starting), otherwise it does not. Default value is 0.

For example, the following definition has all static PFs using mlx5_0 (port 0) as the data path device in a non-lag configuration:

            

            
{
  "ib_dev_p0": "mlx5_0",
  "ib_dev_p1": "mlx5_1",
  "ib_dev_for_static_pf": "mlx5_0",
  "is_lag": 0,
  "recovery": 1,
  "sf_pool_percent": 0,
  "sf_pool_force_destroy": 0,
  "static_pf": {
    "mac_base": "11:22:33:44:55:66",
    "features": "0x230047082b"
  },
  "vf": {
    "mac_base": "CC:48:15:FF:00:00",
    "features": "0x230047082b",
    "vfs_per_pf": 100,
    "qp_num": 4
  }
}
        

The following is an example for LAG configuration:

            

            
{
  "ib_dev_lag": "mlx5_bond_0",
  "ib_dev_for_static_pf": "mlx5_bond_0",
  "is_lag": 1,
  "recovery": 1,
  "sf_pool_percent": 0,
  "sf_pool_force_destroy": 0
}
        

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
        

To operate a particular device, either the VUID or device index can be used to locate the device. Both attributes can be fetched from command "virtnet list". For example, to modify the MAC of a specific VF, you may run either of the following commands:

            

            
# virtnet modify -p 0 –v 0 device -m 0C:C4:7A:FF:22:98
        

Or:

            

            
# virtnet modify -u <VUID-string> device -m 0C:C4:7A:FF:22:98
        

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:

            

            
{
  "port_ib_dev": "mlx5_0",
  "pf_id": 0,
  "function_type": "pf",
  "bdf_raw": 26624,
  "device_type": "hotplug",
  "mac": "0c:c4:7a:ff:22:93",
  "pf_num": 0,
  "sf_num": 2000,
  "mq": 1
}
        

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 Live Update

Live update minimizes network interface down time by performing online upgrade of the virtio-net controller without necessitating a full restart.

To perform a live update, you must install a newer version of the controller either using the rpm or deb package (depending on the OS distro used). Run:

            

            
dpkg --force-all -i virtio-net-controller-x.y.z-1.mlnx.aarch64.deb
        

            

            
rpm -Uvh virtio-net-controller-x.y.z-1.mlnx.aarch64.rpm --force
        

It is recommended to use the following command to verify the versions of the controller currently running and the one just installed:

            

            
virtnet version
        

If the versions that are correct, issue the following command to start the live update process:

            

            
virtnet update --start
virtnet update -s
        

During the update process, the following command may be used to check the update status:

            

            
virtnet update status
virtnet update -t
        

During the update, all existing virtnet commands (e.g., list, query, modify) are still supported. VF creation/deletion works as well.

When the update process completes successfully, the command virtnet update status will reflect the status accordingly.

This section covers managing virtio-net PCIe PF devices using virtio-net controller.

VirtIO-net PF Device Configuration

1. Run the following command on the DPU:

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   $ mlxconfig -d /dev/mst/mt41686_pciconf0 s INTERNAL_CPU_MODEL=1
           

2. Add the following kernel boot parameters to the Linux boot arguments:

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   pci=realloc
           

3. Cold reboot the host system.

4. Apply the following configuration on the DPU:

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   $ 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 \
   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
           

5. Cold reboot the host system a second time.

Creating Modern 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.

1. Create a hotplug virtio-net device. Run:

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   $ virtnet hotplug -i mlx5_0 -f 0x0 -m 0C:C4:7A:FF:22:93 -t 1500 -n 3 -s 1024
           

   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

   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:

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   {
     "bdf": "85:00.0",
     "vuid": "VNETS1D0F0",
     "id": 3,
     "sf_rep_net_device": "en3f0pf0sf2000",
     "mac": "0C:C4:7A:FF:22:93"
   }
           

2. Add the representor port of the device to the OVS bridge and bring it up. Run:

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   $ ovs-vsctl add-port <bridge> en3f0pf0sf2000
   $ ip link set dev en3f0pf0sf2000 up
           

   Once steps 1-3 are completed, virtio-net device should be available in the host system.

3. To query all the device configurations of virtio-net device that you created, run:

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   $ virtnet query –p 0
           

4. To list all the virtio-net devices, run:

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   $ virtnet list
           

5. To modify device attributes, for example, changing its MAC address, run:

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   $ virtnet modify -p 0 device -m 0C:C4:7A:FF:22:98
           

6. Once usage is complete, to hot-unplug a virtio-net device, run:

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   $ virtnet unplug -p 0
           

Creating Transitional Hotplug VirtIO-net PF Device

A transitional device is a virtio device which supports drivers conforming to virtio specification 1.x and legacy drivers operating under virtio specification 0.95 (i.e., legacy mode) so that servers with old Linux kernels can still utilize virtio-based technology.

1. Run the following command on the DPU:

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   $ mst start 
   $ mlxconfig -d /dev/mst/mt41686_pciconf0 s \
     VIRTIO_NET_EMULATION_PF_PCI_LAYOUT=1 \
     VIRTIO_EMULATION_HOTPLUG_TRANS=1
           

2. Add the following parameters to the Linux boot arguments on the guest OS (host OS or VM) side:

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   virtio_pci.force_legacy=1 intel_iommu=off
           

   Refer to the known limitations below.

3. Cold reboot the host system.

4. If virtio_pci is a kernel module rather than built-in from the guest OS, run the following command after both the host and DPU OSes are up:

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   modprobe –rv virtio_pci
   modprobe –v virtio_pci force_legacy=1
           

5. To create a transitional hotplug virtio-net device. Run the following command on the DPU (with additional -l/--legacy):

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   $ virtnet hotplug -i mlx5_0 -f 0x0 -m 0C:C4:7A:FF:22:93 -t 1500 -n 3 -s 1024 -l
           

6. Proceed from step 2 of section "Creating Modern Hotplug VirtIO-net PF Device" for the rest of configuration.

This section covers managing virtio-net PCIe SR-IOV VF devices using virtio-net-controller.

Virtio-net SR-IOV VF Device Configuration

1. On the DPU, make sure virtio-net-controller service is enabled so that it starts automatically. Run:

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   systemctl status virtio-net-controller.service
           

2. On the 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=realloc" exist in grub.conf file.

3. 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.

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   pci 0000:84:00.0: [1af4:1041] type 7f class 0xffffff
   pci 0000:84:00.0: unknown header type 7f, ignoring device
           

4. Run the following command on the DPU:

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   mst start && mlxconfig -d /dev/mst/mt41686_pciconf0 s INTERNAL_CPU_MODEL=1
           

5. Add the following kernel boot parameters to the Linux boot arguments:

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   intel_iommu=on iommu=pt pci=realloc
           

6. Cold reboot the host system.

7. Apply the following configuration on the DPU in three steps to support up to 125 VFs per PF (500 VFs in total).

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      $ mst start && mlxconfig -d /dev/mst/mt41686_pciconf0 s PF_BAR2_ENABLE=0 PER_PF_NUM_SF=1
              

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      $ mlxconfig -d /dev/mst/mt41686_pciconf0 s \
      PCI_SWITCH_EMULATION_ENABLE=0 \
      PCI_SWITCH_EMULATION_NUM_PORT=0 \
      VIRTIO_NET_EMULATION_ENABLE=1 \
      VIRTIO_NET_EMULATION_NUM_VF=126 \
      VIRTIO_NET_EMULATION_NUM_PF=4 \
      VIRTIO_NET_EMULATION_NUM_MSIX=4 \
      SRIOV_EN=1 \
      PF_SF_BAR_SIZE=8 \
      PF_TOTAL_SF=508 \
      NUM_OF_VFS=0
              

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      $ mlxconfig -d /dev/mst/mt41686_pciconf0.1 s PF_TOTAL_SF=1 PF_SF_BAR_SIZE=8
              

8. Cold reboot the host system.

Creating Virtio-net SR-IOV VF Devices

1. On the host, make sure the static virtio network device presents. Run:

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   # lspci | grep -i virtio
   85:00.3 Network controller: Red Hat, Inc. Virtio network device
           

2. On the host, make sure virtio_pci and virtio_net are loaded. Run:

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   # lsmod | grep virtio
           

   The net device should be created:

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   # 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
           

3. To create SR-IOV VF devices on the host, run:

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   # echo 2 > /sys/bus/pci/drivers/virtio-pci/0000\:85\:00.3/sriov_numvfs
           

   Note

   When the number of VFs created is high, SR-IOV enablement may take several minutes.

   2 VFs should be created from the host:

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   # 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
           

4. From the DPU virtio-net controller, run the following command to get VF information.

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   # virtnet list
   {
       "vf_id": 0,
       "parent_pf_id": 0,
       "function_type": "VF",
       "vuid": "VNETS0D0F2VF1",
       "bdf": "83:00.6",
       "sf_num": 3000,
       "sf_parent_device": "mlx5_0",
       "sf_rep_net_device": "en3f0pf0sf3000",
       "sf_rep_net_ifindex": 19,
       "sf_rdma_device": "mlx5_7",
       "sf_vhca_id": "0x192",
       "msix_config_vector": "0x0",
       "num_msix": 10,
       "max_queues": 4,
       "max_queues_size": 256,
       "net_mac": "5A:94:07:04:F6:1C",
       "net_mtu": 1500
   },
           

   You may use the pci-bdf to match the PF/VF on the host to the information showing on DPU.

   To query all the device configurations of the virtio-net device of that VF, run:

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   $ virtnet query -p 0 -v 0
           

   Add the corresponding SF representor to the OVS bridge and bring it up. Run:

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   # ovs-vsctl add-port <bridge> en3f0pf0sf1004
   # ip link set dev en3f0pf0sf1004 up
           

   Now the VF is 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.

5. To destroy SR-IOV VF devices on the host, run:

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   # echo 0 > /sys/bus/pci/drivers/virtio-pci/0000\:85\:00.3/sriov_numvfs
           

   Note

   When the command returns from the host OS, it does not necessarily mean the controller finished its operations. Look at controller log from the DPU and make sure you see a log like below before removing virtio kernel modules or recreate VFs.

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   # virtio-net-controller[3544]: [INFO]  virtnet.c:617:virtnet_device_vfs_unload: PF(0): Unload (4) VFs finished
           

   Once VFs are destroyed, created SFs from the DPU side are not destroyed but are saved into the SF pool to be reused later.

Transitional VirtIO-net VF Device Support

Transitional virtio-net VF devices are not currently supported.

Virtio VF PCIe devices can be attached to the guest VM using vhost acceleration software stack. This enables performing live migration of guest VMs.

This section describes the steps to enable VM live migration using virtio VF PCIe devices along with vhost acceleration software.

Prerequisites

• Minimum hypervisor kernel version – Linux kernel 5.7 (for VFIO SR-IOV support)

Install vHost Acceleration Software Stack

Vhost acceleration software stack is built using open-source BSD licensed DPDK.

To install vhost acceleration software:

1. Clone the software source code.

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   git clone https://github.com/Mellanox/dpdk-vhost-vfe
           

   Info

   Latest release tag is vfe-1.0.

2. Build software:

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   apt-get install libev-dev
   yum install -y numactl-devel libev-devel
   meson build -Dexamples=vdpa
   ninja -C build
           

To install QEMU:

1. Clone QEMU sources.

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   git clone https://github.com/Mellanox/qemu -b stable-8.1-presetup
           

   Info

   Latest release tag is vfe-0.4.

2. Build QEMU.

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   mkdir bin
   cd bin
   ../configure --target-list=x86_64-softmmu --enable-kvm
   make -j24
           

Configure vHost and DPU System

1. Set the DPU nvconfig.

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   mlxconfig -d /dev/mst/mt41686_pciconf0 s \
   VIRTIO_NET_EMULATION_ENABLE=1 VIRTIO_NET_EMULATION_NUM_PF=1 VIRTIO_NET_EMULATION_NUM_VF=16 \
   VIRTIO_BLK_EMULATION_ENABLE=1 VIRTIO_BLK_EMULATION_NUM_PF=1 VIRTIO_BLK_EMULATION_NUM_VF=16 \
   VIRTIO_NET_EMULATION_NUM_MSIX=64 VIRTIO_BLK_EMULATION_NUM_MSIX=64 NUM_VF_MSIX=64
           

2. Cold reboot the system after above configuration.

3. Setup the hypervisor system:

   1. Configure hugepages and libvirt VM XML (see OVS Hardware Offloads Configuration for information on doing that).

   2. Add a virtio-net interface and a virtio-blk interface in VM XML.

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      <qemu:commandline>
      <qemu:arg value='-chardev'/>
      <qemu:arg value='socket,id=char0,path=/tmp/vfe-net0,server=on'/>
      <qemu:arg value='-netdev'/>
      <qemu:arg value='type=vhost-user,id=vdpa,chardev=char0,queues=4'/>
      <qemu:arg value='-device'/>
      <qemu:arg value='virtio-net-pci,netdev=vdpa,mac=00:00:00:00:33:00,page-per-vq=on,rx_queue_size=1024,tx_queue_size=1024,mq=on'/>
      <qemu:arg value='-chardev'/>
      <qemu:arg value='socket,id=char1,path=/tmp/vfe-blk0,server=on'/>
      <qemu:arg value='-device'/>
      <qemu:arg value='vhost-user-blk-pci,chardev=char1,page-per-vq=on,num-queues=4,disable-legacy=on,disable-modern=off'/>
      </qemu:commandline>
              

4. Create block device on the DPU:

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   spdk_rpc.py bdev_null_create Null0 1024 512
   snap_rpc.py controller_virtio_blk_create --pf_id 0 --bdev_type spdk mlx5_0 --bdev Null0 --num_queues 1 --admin_q --force_in_order
           

5. On BlueField-3 SNAP:

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   spdk_rpc.py bdev_null_create Null0 1024 512
   snap_rpc.py virtio_blk_controller_create --pf_id 0 --bdev Null0 --num_queues 1 --admin_q --force_in_order
           

Run vHost Acceleration Service

1. Bind the virtio PF devices to vfio-pci driver:

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   modprobe vfio vfio_pci
   echo 1 > /sys/module/vfio_pci/parameters/enable_sriov
    
   echo 0x1af4 0x1041 > /sys/bus/pci/drivers/vfio-pci/new_id
   echo 0x1af4 0x1042 > /sys/bus/pci/drivers/vfio-pci/new_id
    
   echo 0000:af:00.2 > /sys/bus/pci/drivers/vfio-pci/bind
   echo 0000:af:00.3 > /sys/bus/pci/drivers/vfio-pci/bind
    
   lspci -vvv -s 0000:af:00.3 | grep "Kernel driver"
   Kernel driver in use: vfio-pci
   lspci -vvv -s 0000:af:00.2 | grep "Kernel driver"
   Kernel driver in use: vfio-pci
           

2. Enable SR-IOV and create a VF(s):

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   echo 1 > /sys/bus/pci/devices/0000:af:00.2/sriov_numvfs
   echo 1 > /sys/bus/pci/devices/0000:af:00.3/sriov_numvfs
    
   lspci | grep Virtio
   af:00.2 Ethernet controller: Red Hat, Inc. Virtio network device
   af:00.3 Non-Volatile memory controller: Red Hat, Inc. Virtio block device
   af:04.5 Ethernet controller: Red Hat, Inc. Virtio network device
   af:05.1 Non-Volatile memory controller: Red Hat, Inc. Virtio block device
           

3. Add a VF representor to the OVS bridge on the DPU:

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   virtnet query -p 0 -v 0 | grep sf_rep_net_device
   "sf_rep_net_device": "en3f0pf0sf3000",
    
    ovs-vsctl add-port ovsbr1 en3f0pf0sf3000
           

4. Run the vhost acceleration software service:

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   cd dpdk-vhost-vfe
   sudo ./build/app/dpdk-vfe-vdpa -a 0000:00:00.0 --log-level=.,8 --vfio-vf-token=cdc786f0-59d4-41d9-b554-fed36ff5e89f -- --client
           

5. Provision the virtio-net PF and VF.

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   cd dpdk-vhost-vfe
    
   python ./app/vfe-vdpa/vhostmgmt mgmtpf -a 0000:af:00.2
   # Wait on virtio-net-controller finishing handle PF FLR
    
   # On DPU, change VF MAC address or other device options
   virtnet modify -p 0 -v 0 device -m 00:00:00:00:33:00
   python ./app/vfe-vdpa/vhostmgmt vf -a 0000:af:04.5 -v /tmp/vfe-net0
           

6. Provision the virtio-blk PF and VF.

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   cd dpdk-vhost-vfe
    
   python ./app/vfe-vdpa/vhostmgmt mgmtpf -a 0000:af:00.3
   # Wait on SNAP controller to finish handling PF FLR
    
   # On DPU, the user must create a VF device controller before adding the VF device to the
   # vhostmgmt upon pf or vf device delete from vhostmgmt, or vhostmgmt restart:
   #       For BlueField-3, the VF controller is automatically recreated 
   #       For BlueField-2, the VF controller must be manually recreated
   # Use snap_rpc.py controller_list to check for controller exsistence and create controller if it's not there
   snap_rpc.py controller_virtio_blk_create mlx5_0 --pf_id 0 --vf_id 0 --bdev_type spdk --bdev Null0 --force_in_order 
   python ./app/vfe-vdpa/vhostmgmt vf -a 0000:af:05.1 -v /tmp/vfe-blk0
           

   Note

   If the SR-IOV is disabled and reenabled, the user must re-provision the VFs.

Start the VM

            

            
virsh start <domain-name>
        

Simple Live Migration

Prepare two identical hosts and perform the provisioning of the virtio device to DPDK on both.

Boot the VM on one server:

            

            
virsh migrate --verbose --live --persistent gen-l-vrt-440-162-CentOS-7.4 qemu+ssh://gen-l-vrt-439/system --unsafe
        

Remove Device

When finished with using the virtio device, use following commands to remove them from DPDK:

            

            
python ./app/vfe-vdpa/vhostmgmt vf -r 0000:af:04.5
python ./app/vfe-vdpa/vhostmgmt mgmtpf -r 0000:af:00.2
 
python ./app/vfe-vdpa/vhostmgmt vf -r 0000:af:05.1
python ./app/vfe-vdpa/vhostmgmt mgmtpf -r 0000:af:00.3