[RFC 00/27] Add VDUSE support to Vhost library

[Maxime Coquelin]

This series introduces a new type of backend, VDUSE,
to the Vhost library.

VDUSE stands for vDPA device in Userspace, it enables
implementing a Virtio device in userspace and have it
attached to the Kernel vDPA bus.

Once attached to the vDPA bus, it can be used either by
Kernel Virtio drivers, like virtio-net in our case, via
the virtio-vdpa driver. Doing that, the device is visible
to the Kernel networking stack and is exposed to userspace
as a regular netdev.

It can also be exposed to userspace thanks to the
vhost-vdpa driver, via a vhost-vdpa chardev that can be
passed to QEMU or Virtio-user PMD.

While VDUSE support is already available in upstream
Kernel, a couple of patches are required to support
network device type:

https://gitlab.com/mcoquelin/linux/-/tree/vduse_networking_poc

In order to attach the created VDUSE device to the vDPA
bus, a recent iproute2 version containing the vdpa tool is
required.

Usage:
======

1. Probe required Kernel modules
# modprobe vdpa
# modprobe vduse
# modprobe virtio-vdpa

2. Build (require vduse kernel headers to be available)
# meson build
# ninja -C build

3. Create a VDUSE device (vduse0) using Vhost PMD with
testpmd (with 4 queue pairs in this example)
# ./build/app/dpdk-testpmd --no-pci --vdev=net_vhost0,iface=/dev/vduse/vduse0,queues=4 --log-level=*:9  -- -i --txq=4 --rxq=4
 
4. Attach the VDUSE device to the vDPA bus
# vdpa dev add name vduse0 mgmtdev vduse
=> The virtio-net netdev shows up (eth0 here)
# ip l show eth0
21: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP mode DEFAULT group default qlen 1000
    link/ether c2:73:ea:a7:68:6d brd ff:ff:ff:ff:ff:ff

5. Start/stop traffic in testpmd
testpmd> start
testpmd> show port stats 0
  ######################## NIC statistics for port 0  ########################
  RX-packets: 11         RX-missed: 0          RX-bytes:  1482
  RX-errors: 0
  RX-nombuf:  0
  TX-packets: 1          TX-errors: 0          TX-bytes:  62

  Throughput (since last show)
  Rx-pps:            0          Rx-bps:            0
  Tx-pps:            0          Tx-bps:            0
  ############################################################################
testpmd> stop

6. Detach the VDUSE device from the vDPA bus
# vdpa dev del vduse0

7. Quit testpmd
testpmd> quit

Known issues & remaining work:
==============================
- Fix issue in FD manager (still polling while FD has been removed)
- Add Netlink support in Vhost library
- Support device reconnection
- Support packed ring
- Enable & test more Virtio features
- Provide performance benchmark results


Maxime Coquelin (27):
  vhost: fix missing guest notif stat increment
  vhost: fix invalid call FD handling
  vhost: fix IOTLB entries overlap check with previous entry
  vhost: add helper of IOTLB entries coredump
  vhost: add helper for IOTLB entries shared page check
  vhost: don't dump unneeded pages with IOTLB
  vhost: change to single IOTLB cache per device
  vhost: add offset field to IOTLB entries
  vhost: add page size info to IOTLB entry
  vhost: retry translating IOVA after IOTLB miss
  vhost: introduce backend ops
  vhost: add IOTLB cache entry removal callback
  vhost: add helper for IOTLB misses
  vhost: add helper for interrupt injection
  vhost: add API to set max queue pairs
  net/vhost: use API to set max queue pairs
  vhost: add control virtqueue support
  vhost: add VDUSE device creation and destruction
  vhost: add VDUSE callback for IOTLB miss
  vhost: add VDUSE callback for IOTLB entry removal
  vhost: add VDUSE callback for IRQ injection
  vhost: add VDUSE events handler
  vhost: add support for virtqueue state get event
  vhost: add support for VDUSE status set event
  vhost: add support for VDUSE IOTLB update event
  vhost: add VDUSE device startup
  vhost: add multiqueue support to VDUSE

 doc/guides/prog_guide/vhost_lib.rst |   4 +
 drivers/net/vhost/rte_eth_vhost.c   |   3 +
 lib/vhost/iotlb.c                   | 333 +++++++++--------
 lib/vhost/iotlb.h                   |  45 ++-
 lib/vhost/meson.build               |   5 +
 lib/vhost/rte_vhost.h               |  17 +
 lib/vhost/socket.c                  |  72 +++-
 lib/vhost/vduse.c                   | 553 ++++++++++++++++++++++++++++
 lib/vhost/vduse.h                   |  33 ++
 lib/vhost/version.map               |   3 +
 lib/vhost/vhost.c                   |  51 ++-
 lib/vhost/vhost.h                   |  90 +++--
 lib/vhost/vhost_user.c              |  53 ++-
 lib/vhost/vhost_user.h              |   2 +-
 lib/vhost/virtio_net_ctrl.c         | 282 ++++++++++++++
 lib/vhost/virtio_net_ctrl.h         |  10 +
 16 files changed, 1317 insertions(+), 239 deletions(-)
 create mode 100644 lib/vhost/vduse.c
 create mode 100644 lib/vhost/vduse.h
 create mode 100644 lib/vhost/virtio_net_ctrl.c
 create mode 100644 lib/vhost/virtio_net_ctrl.h

-- 
2.39.2