+DPDK vhost:
+-----------
+
+DPDK 2.0 supports two types of vhost:
+
+1. vhost-user
+2. vhost-cuse
+
+Whatever type of vhost is enabled in the DPDK build specified, is the type
+that will be enabled in OVS. By default, vhost-user is enabled in DPDK.
+Therefore, unless vhost-cuse has been enabled in DPDK, vhost-user ports
+will be enabled in OVS.
+Please note that support for vhost-cuse is intended to be deprecated in OVS
+in a future release.
+
+DPDK vhost-user:
+----------------
+
+The following sections describe the use of vhost-user 'dpdkvhostuser' ports
+with OVS.
+
+DPDK vhost-user Prerequisites:
+-------------------------
+
+1. DPDK 2.0 with vhost support enabled as documented in the "Building and
+ Installing section"
+
+2. QEMU version v2.1.0+
+
+ QEMU v2.1.0 will suffice, but it is recommended to use v2.2.0 if providing
+ your VM with memory greater than 1GB due to potential issues with memory
+ mapping larger areas.
+
+Adding DPDK vhost-user ports to the Switch:
+--------------------------------------
+
+Following the steps above to create a bridge, you can now add DPDK vhost-user
+as a port to the vswitch. Unlike DPDK ring ports, DPDK vhost-user ports can
+have arbitrary names.
+
+ - For vhost-user, the name of the port type is `dpdkvhostuser`
+
+ ```
+ ovs-ofctl add-port br0 vhost-user-1 -- set Interface vhost-user-1
+ type=dpdkvhostuser
+ ```
+
+ This action creates a socket located at
+ `/usr/local/var/run/openvswitch/vhost-user-1`, which you must provide
+ to your VM on the QEMU command line. More instructions on this can be
+ found in the next section "DPDK vhost-user VM configuration"
+ Note: If you wish for the vhost-user sockets to be created in a
+ directory other than `/usr/local/var/run/openvswitch`, you may specify
+ another location on the ovs-vswitchd command line like so:
+
+ `./vswitchd/ovs-vswitchd --dpdk -vhost_sock_dir /my-dir -c 0x1 ...`
+
+DPDK vhost-user VM configuration:
+---------------------------------
+Follow the steps below to attach vhost-user port(s) to a VM.
+
+1. Configure sockets.
+ Pass the following parameters to QEMU to attach a vhost-user device:
+
+ ```
+ -chardev socket,id=char1,path=/usr/local/var/run/openvswitch/vhost-user-1
+ -netdev type=vhost-user,id=mynet1,chardev=char1,vhostforce
+ -device virtio-net-pci,mac=00:00:00:00:00:01,netdev=mynet1
+ ```
+
+ ...where vhost-user-1 is the name of the vhost-user port added
+ to the switch.
+ Repeat the above parameters for multiple devices, changing the
+ chardev path and id as necessary. Note that a separate and different
+ chardev path needs to be specified for each vhost-user device. For
+ example you have a second vhost-user port named 'vhost-user-2', you
+ append your QEMU command line with an additional set of parameters:
+
+ ```
+ -chardev socket,id=char2,path=/usr/local/var/run/openvswitch/vhost-user-2
+ -netdev type=vhost-user,id=mynet2,chardev=char2,vhostforce
+ -device virtio-net-pci,mac=00:00:00:00:00:02,netdev=mynet2
+ ```
+
+2. Configure huge pages.
+ QEMU must allocate the VM's memory on hugetlbfs. vhost-user ports access
+ a virtio-net device's virtual rings and packet buffers mapping the VM's
+ physical memory on hugetlbfs. To enable vhost-user ports to map the VM's
+ memory into their process address space, pass the following paramters
+ to QEMU:
+
+ ```
+ -object memory-backend-file,id=mem,size=4096M,mem-path=/dev/hugepages,
+ share=on
+ -numa node,memdev=mem -mem-prealloc
+ ```
+
+DPDK vhost-cuse:
+----------------
+
+The following sections describe the use of vhost-cuse 'dpdkvhostcuse' ports
+with OVS.
+
+DPDK vhost-cuse Prerequisites:
+-------------------------
+
+1. DPDK 2.0 with vhost support enabled as documented in the "Building and
+ Installing section"
+ As an additional step, you must enable vhost-cuse in DPDK by setting the
+ following additional flag in `config/common_linuxapp`:
+
+ `CONFIG_RTE_LIBRTE_VHOST_USER=n`
+
+ Following this, rebuild DPDK as per the instructions in the "Building and
+ Installing" section. Finally, rebuild OVS as per step 3 in the "Building
+ and Installing" section - OVS will detect that DPDK has vhost-cuse libraries
+ compiled and in turn will enable support for it in the switch and disable
+ vhost-user support.
+
+2. Insert the Cuse module:
+
+ `modprobe cuse`
+
+3. Build and insert the `eventfd_link` module:
+
+ ```
+ cd $DPDK_DIR/lib/librte_vhost/eventfd_link/
+ make
+ insmod $DPDK_DIR/lib/librte_vhost/eventfd_link.ko
+ ```
+
+4. QEMU version v2.1.0+
+
+ vhost-cuse will work with QEMU v2.1.0 and above, however it is recommended to
+ use v2.2.0 if providing your VM with memory greater than 1GB due to potential
+ issues with memory mapping larger areas.
+ Note: QEMU v1.6.2 will also work, with slightly different command line parameters,
+ which are specified later in this document.
+
+Adding DPDK vhost-cuse ports to the Switch:
+--------------------------------------
+
+Following the steps above to create a bridge, you can now add DPDK vhost-cuse
+as a port to the vswitch. Unlike DPDK ring ports, DPDK vhost-cuse ports can have
+arbitrary names.
+
+ - For vhost-cuse, the name of the port type is `dpdkvhostcuse`
+
+ ```
+ ovs-ofctl add-port br0 vhost-cuse-1 -- set Interface vhost-cuse-1
+ type=dpdkvhostcuse
+ ```
+
+ When attaching vhost-cuse ports to QEMU, the name provided during the
+ add-port operation must match the ifname parameter on the QEMU command
+ line. More instructions on this can be found in the next section.
+
+DPDK vhost-cuse VM configuration:
+---------------------------------
+
+ vhost-cuse ports use a Linux* character device to communicate with QEMU.
+ By default it is set to `/dev/vhost-net`. It is possible to reuse this
+ standard device for DPDK vhost, which makes setup a little simpler but it
+ is better practice to specify an alternative character device in order to
+ avoid any conflicts if kernel vhost is to be used in parallel.
+
+1. This step is only needed if using an alternative character device.
+
+ The new character device filename must be specified on the vswitchd
+ commandline:
+
+ `./vswitchd/ovs-vswitchd --dpdk --cuse_dev_name my-vhost-net -c 0x1 ...`
+
+ Note that the `--cuse_dev_name` argument and associated string must be the first
+ arguments after `--dpdk` and come before the EAL arguments. In the example
+ above, the character device to be used will be `/dev/my-vhost-net`.
+
+2. This step is only needed if reusing the standard character device. It will
+ conflict with the kernel vhost character device so the user must first
+ remove it.
+
+ `rm -rf /dev/vhost-net`
+
+3a. Configure virtio-net adaptors:
+ The following parameters must be passed to the QEMU binary:
+
+ ```
+ -netdev tap,id=<id>,script=no,downscript=no,ifname=<name>,vhost=on
+ -device virtio-net-pci,netdev=net1,mac=<mac>
+ ```
+
+ Repeat the above parameters for multiple devices.
+
+ The DPDK vhost library will negiotiate its own features, so they
+ need not be passed in as command line params. Note that as offloads are
+ disabled this is the equivalent of setting:
+
+ `csum=off,gso=off,guest_tso4=off,guest_tso6=off,guest_ecn=off`
+
+3b. If using an alternative character device. It must be also explicitly
+ passed to QEMU using the `vhostfd` argument:
+
+ ```
+ -netdev tap,id=<id>,script=no,downscript=no,ifname=<name>,vhost=on,
+ vhostfd=<open_fd>
+ -device virtio-net-pci,netdev=net1,mac=<mac>
+ ```
+
+ The open file descriptor must be passed to QEMU running as a child
+ process. This could be done with a simple python script.
+
+ ```
+ #!/usr/bin/python
+ fd = os.open("/dev/usvhost", os.O_RDWR)
+ subprocess.call("qemu-system-x86_64 .... -netdev tap,id=vhostnet0,\
+ vhost=on,vhostfd=" + fd +"...", shell=True)
+
+ Alternatively the the `qemu-wrap.py` script can be used to automate the
+ requirements specified above and can be used in conjunction with libvirt if
+ desired. See the "DPDK vhost VM configuration with QEMU wrapper" section
+ below.
+
+4. Configure huge pages:
+ QEMU must allocate the VM's memory on hugetlbfs. Vhost ports access a
+ virtio-net device's virtual rings and packet buffers mapping the VM's
+ physical memory on hugetlbfs. To enable vhost-ports to map the VM's
+ memory into their process address space, pass the following parameters
+ to QEMU:
+
+ `-object memory-backend-file,id=mem,size=4096M,mem-path=/dev/hugepages,
+ share=on -numa node,memdev=mem -mem-prealloc`
+
+ Note: For use with an earlier QEMU version such as v1.6.2, use the
+ following to configure hugepages instead:
+
+ `-mem-path /dev/hugepages -mem-prealloc`
+
+DPDK vhost-cuse VM configuration with QEMU wrapper:
+---------------------------------------------------
+The QEMU wrapper script automatically detects and calls QEMU with the
+necessary parameters. It performs the following actions:
+
+ * Automatically detects the location of the hugetlbfs and inserts this
+ into the command line parameters.
+ * Automatically open file descriptors for each virtio-net device and
+ inserts this into the command line parameters.
+ * Calls QEMU passing both the command line parameters passed to the
+ script itself and those it has auto-detected.
+
+Before use, you **must** edit the configuration parameters section of the
+script to point to the correct emulator location and set additional
+settings. Of these settings, `emul_path` and `us_vhost_path` **must** be
+set. All other settings are optional.
+
+To use directly from the command line simply pass the wrapper some of the
+QEMU parameters: it will configure the rest. For example:
+
+```
+qemu-wrap.py -cpu host -boot c -hda <disk image> -m 4096 -smp 4
+ --enable-kvm -nographic -vnc none -net none -netdev tap,id=net1,
+ script=no,downscript=no,ifname=if1,vhost=on -device virtio-net-pci,
+ netdev=net1,mac=00:00:00:00:00:01
+```
+
+DPDK vhost-cuse VM configuration with libvirt:
+----------------------------------------------
+
+If you are using libvirt, you must enable libvirt to access the character
+device by adding it to controllers cgroup for libvirtd using the following
+steps.
+
+ 1. In `/etc/libvirt/qemu.conf` add/edit the following lines:
+
+ ```
+ 1) clear_emulator_capabilities = 0
+ 2) user = "root"
+ 3) group = "root"
+ 4) cgroup_device_acl = [
+ "/dev/null", "/dev/full", "/dev/zero",
+ "/dev/random", "/dev/urandom",
+ "/dev/ptmx", "/dev/kvm", "/dev/kqemu",
+ "/dev/rtc", "/dev/hpet", "/dev/net/tun",
+ "/dev/<my-vhost-device>",
+ "/dev/hugepages"]
+ ```
+
+ <my-vhost-device> refers to "vhost-net" if using the `/dev/vhost-net`
+ device. If you have specificed a different name on the ovs-vswitchd
+ commandline using the "--cuse_dev_name" parameter, please specify that
+ filename instead.
+
+ 2. Disable SELinux or set to permissive mode
+
+ 3. Restart the libvirtd process
+ For example, on Fedora:
+
+ `systemctl restart libvirtd.service`
+
+After successfully editing the configuration, you may launch your
+vhost-enabled VM. The XML describing the VM can be configured like so
+within the <qemu:commandline> section:
+
+ 1. Set up shared hugepages:
+
+ ```
+ <qemu:arg value='-object'/>
+ <qemu:arg value='memory-backend-file,id=mem,size=4096M,mem-path=/dev/hugepages,share=on'/>
+ <qemu:arg value='-numa'/>
+ <qemu:arg value='node,memdev=mem'/>
+ <qemu:arg value='-mem-prealloc'/>
+ ```
+
+ 2. Set up your tap devices:
+
+ ```
+ <qemu:arg value='-netdev'/>
+ <qemu:arg value='type=tap,id=net1,script=no,downscript=no,ifname=vhost0,vhost=on'/>
+ <qemu:arg value='-device'/>
+ <qemu:arg value='virtio-net-pci,netdev=net1,mac=00:00:00:00:00:01'/>
+ ```
+
+ Repeat for as many devices as are desired, modifying the id, ifname
+ and mac as necessary.
+
+ Again, if you are using an alternative character device (other than
+ `/dev/vhost-net`), please specify the file descriptor like so:
+
+ `<qemu:arg value='type=tap,id=net3,script=no,downscript=no,ifname=vhost0,vhost=on,vhostfd=<open_fd>'/>`
+
+ Where <open_fd> refers to the open file descriptor of the character device.
+ Instructions of how to retrieve the file descriptor can be found in the
+ "DPDK vhost VM configuration" section.
+ Alternatively, the process is automated with the qemu-wrap.py script,
+ detailed in the next section.
+
+Now you may launch your VM using virt-manager, or like so:
+
+ `virsh create my_vhost_vm.xml`
+
+DPDK vhost-cuse VM configuration with libvirt and QEMU wrapper:
+----------------------------------------------------------
+
+To use the qemu-wrapper script in conjuntion with libvirt, follow the
+steps in the previous section before proceeding with the following steps:
+
+ 1. Place `qemu-wrap.py` in libvirtd's binary search PATH ($PATH)
+ Ideally in the same directory that the QEMU binary is located.
+
+ 2. Ensure that the script has the same owner/group and file permissions
+ as the QEMU binary.
+
+ 3. Update the VM xml file using "virsh edit VM.xml"
+
+ 1. Set the VM to use the launch script.
+ Set the emulator path contained in the `<emulator><emulator/>` tags.
+ For example, replace:
+
+ `<emulator>/usr/bin/qemu-kvm<emulator/>`
+
+ with:
+
+ `<emulator>/usr/bin/qemu-wrap.py<emulator/>`
+
+ 4. Edit the Configuration Parameters section of the script to point to
+ the correct emulator location and set any additional options. If you are
+ using a alternative character device name, please set "us_vhost_path" to the
+ location of that device. The script will automatically detect and insert
+ the correct "vhostfd" value in the QEMU command line arguments.
+
+ 5. Use virt-manager to launch the VM
+
+Running ovs-vswitchd with DPDK backend inside a VM
+--------------------------------------------------
+
+Please note that additional configuration is required if you want to run
+ovs-vswitchd with DPDK backend inside a QEMU virtual machine. Ovs-vswitchd
+creates separate DPDK TX queues for each CPU core available. This operation
+fails inside QEMU virtual machine because, by default, VirtIO NIC provided
+to the guest is configured to support only single TX queue and single RX
+queue. To change this behavior, you need to turn on 'mq' (multiqueue)
+property of all virtio-net-pci devices emulated by QEMU and used by DPDK.
+You may do it manually (by changing QEMU command line) or, if you use Libvirt,
+by adding the following string:
+
+`<driver name='vhost' queues='N'/>`
+
+to <interface> sections of all network devices used by DPDK. Parameter 'N'
+determines how many queues can be used by the guest.
+
projects / cascardo / ovs.git / blobdiff