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diff --git a/doc/guides/nics/virtio.rst b/doc/guides/nics/virtio.rst new file mode 100644 index 00000000..06ca433a --- /dev/null +++ b/doc/guides/nics/virtio.rst @@ -0,0 +1,213 @@ +.. BSD LICENSE + Copyright(c) 2010-2015 Intel Corporation. All rights reserved. + All rights reserved. + + Redistribution and use in source and binary forms, with or without + modification, are permitted provided that the following conditions + are met: + + * Redistributions of source code must retain the above copyright + notice, this list of conditions and the following disclaimer. + * Redistributions in binary form must reproduce the above copyright + notice, this list of conditions and the following disclaimer in + the documentation and/or other materials provided with the + distribution. + * Neither the name of Intel Corporation nor the names of its + contributors may be used to endorse or promote products derived + from this software without specific prior written permission. + + THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS + "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT + LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR + A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT + OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, + SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT + LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, + DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY + THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT + (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE + OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + +Poll Mode Driver for Emulated Virtio NIC +======================================== + +Virtio is a para-virtualization framework initiated by IBM, and supported by KVM hypervisor. +In the Data Plane Development Kit (DPDK), +we provide a virtio Poll Mode Driver (PMD) as a software solution, comparing to SRIOV hardware solution, +for fast guest VM to guest VM communication and guest VM to host communication. + +Vhost is a kernel acceleration module for virtio qemu backend. +The DPDK extends kni to support vhost raw socket interface, +which enables vhost to directly read/ write packets from/to a physical port. +With this enhancement, virtio could achieve quite promising performance. + +In future release, we will also make enhancement to vhost backend, +releasing peak performance of virtio PMD driver. + +For basic qemu-KVM installation and other Intel EM poll mode driver in guest VM, +please refer to Chapter "Driver for VM Emulated Devices". + +In this chapter, we will demonstrate usage of virtio PMD driver with two backends, +standard qemu vhost back end and vhost kni back end. + +Virtio Implementation in DPDK +----------------------------- + +For details about the virtio spec, refer to Virtio PCI Card Specification written by Rusty Russell. + +As a PMD, virtio provides packet reception and transmission callbacks virtio_recv_pkts and virtio_xmit_pkts. + +In virtio_recv_pkts, index in range [vq->vq_used_cons_idx , vq->vq_ring.used->idx) in vring is available for virtio to burst out. + +In virtio_xmit_pkts, same index range in vring is available for virtio to clean. +Virtio will enqueue to be transmitted packets into vring, advance the vq->vq_ring.avail->idx, +and then notify the host back end if necessary. + +Features and Limitations of virtio PMD +-------------------------------------- + +In this release, the virtio PMD driver provides the basic functionality of packet reception and transmission. + +* It supports merge-able buffers per packet when receiving packets and scattered buffer per packet + when transmitting packets. The packet size supported is from 64 to 1518. + +* It supports multicast packets and promiscuous mode. + +* The descriptor number for the RX/TX queue is hard-coded to be 256 by qemu. + If given a different descriptor number by the upper application, + the virtio PMD generates a warning and fall back to the hard-coded value. + +* Features of mac/vlan filter are supported, negotiation with vhost/backend are needed to support them. + When backend can't support vlan filter, virtio app on guest should disable vlan filter to make sure + the virtio port is configured correctly. E.g. specify '--disable-hw-vlan' in testpmd command line. + +* RTE_PKTMBUF_HEADROOM should be defined larger than sizeof(struct virtio_net_hdr), which is 10 bytes. + +* Virtio does not support runtime configuration. + +* Virtio supports Link State interrupt. + +* Virtio supports software vlan stripping and inserting. + +* Virtio supports using port IO to get PCI resource when uio/igb_uio module is not available. + +Prerequisites +------------- + +The following prerequisites apply: + +* In the BIOS, turn VT-x and VT-d on + +* Linux kernel with KVM module; vhost module loaded and ioeventfd supported. + Qemu standard backend without vhost support isn't tested, and probably isn't supported. + +Virtio with kni vhost Back End +------------------------------ + +This section demonstrates kni vhost back end example setup for Phy-VM Communication. + +.. _figure_host_vm_comms: + +.. figure:: img/host_vm_comms.* + + Host2VM Communication Example Using kni vhost Back End + + +Host2VM communication example + +#. Load the kni kernel module: + + .. code-block:: console + + insmod rte_kni.ko + + Other basic DPDK preparations like hugepage enabling, uio port binding are not listed here. + Please refer to the *DPDK Getting Started Guide* for detailed instructions. + +#. Launch the kni user application: + + .. code-block:: console + + examples/kni/build/app/kni -c 0xf -n 4 -- -p 0x1 -P --config="(0,1,3)" + + This command generates one network device vEth0 for physical port. + If specify more physical ports, the generated network device will be vEth1, vEth2, and so on. + + For each physical port, kni creates two user threads. + One thread loops to fetch packets from the physical NIC port into the kni receive queue. + The other user thread loops to send packets in the kni transmit queue. + + For each physical port, kni also creates a kernel thread that retrieves packets from the kni receive queue, + place them onto kni's raw socket's queue and wake up the vhost kernel thread to exchange packets with the virtio virt queue. + + For more details about kni, please refer to :ref:`kni`. + +#. Enable the kni raw socket functionality for the specified physical NIC port, + get the generated file descriptor and set it in the qemu command line parameter. + Always remember to set ioeventfd_on and vhost_on. + + Example: + + .. code-block:: console + + echo 1 > /sys/class/net/vEth0/sock_en + fd=`cat /sys/class/net/vEth0/sock_fd` + exec qemu-system-x86_64 -enable-kvm -cpu host \ + -m 2048 -smp 4 -name dpdk-test1-vm1 \ + -drive file=/data/DPDKVMS/dpdk-vm.img \ + -netdev tap, fd=$fd,id=mynet_kni, script=no,vhost=on \ + -device virtio-net-pci,netdev=mynet_kni,bus=pci.0,addr=0x3,ioeventfd=on \ + -vnc:1 -daemonize + + In the above example, virtio port 0 in the guest VM will be associated with vEth0, which in turns corresponds to a physical port, + which means received packets come from vEth0, and transmitted packets is sent to vEth0. + +#. In the guest, bind the virtio device to the uio_pci_generic kernel module and start the forwarding application. + When the virtio port in guest bursts rx, it is getting packets from the raw socket's receive queue. + When the virtio port bursts tx, it is sending packet to the tx_q. + + .. code-block:: console + + modprobe uio + echo 512 > /sys/devices/system/node/node0/hugepages/hugepages-2048kB/nr_hugepages + modprobe uio_pci_generic + python tools/dpdk_nic_bind.py -b uio_pci_generic 00:03.0 + + We use testpmd as the forwarding application in this example. + + .. figure:: img/console.* + + Running testpmd + +#. Use IXIA packet generator to inject a packet stream into the KNI physical port. + + The packet reception and transmission flow path is: + + IXIA packet generator->82599 PF->KNI rx queue->KNI raw socket queue->Guest VM virtio port 0 rx burst->Guest VM virtio port 0 tx burst-> KNI tx queue->82599 PF-> IXIA packet generator + +Virtio with qemu virtio Back End +-------------------------------- + +.. _figure_host_vm_comms_qemu: + +.. figure:: img/host_vm_comms_qemu.* + + Host2VM Communication Example Using qemu vhost Back End + + +.. code-block:: console + + qemu-system-x86_64 -enable-kvm -cpu host -m 2048 -smp 2 -mem-path /dev/ + hugepages -mem-prealloc + -drive file=/data/DPDKVMS/dpdk-vm1 + -netdev tap,id=vm1_p1,ifname=tap0,script=no,vhost=on + -device virtio-net-pci,netdev=vm1_p1,bus=pci.0,addr=0x3,ioeventfd=on + -device pci-assign,host=04:10.1 \ + +In this example, the packet reception flow path is: + + IXIA packet generator->82599 PF->Linux Bridge->TAP0's socket queue-> Guest VM virtio port 0 rx burst-> Guest VM 82599 VF port1 tx burst-> IXIA packet generator + +The packet transmission flow is: + + IXIA packet generator-> Guest VM 82599 VF port1 rx burst-> Guest VM virtio port 0 tx burst-> tap -> Linux Bridge->82599 PF-> IXIA packet generator |