[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [Qemu-devel] [PATCH v7 00/13] Vhost and vhost-net support for usersp
From: |
Michael S. Tsirkin |
Subject: |
Re: [Qemu-devel] [PATCH v7 00/13] Vhost and vhost-net support for userspace based backends |
Date: |
Mon, 10 Feb 2014 10:57:14 +0200 |
On Fri, Jan 31, 2014 at 06:34:29PM +0100, Antonios Motakis wrote:
> In this patch series we would like to introduce our approach for putting a
> virtio-net backend in an external userspace process. Our eventual target is to
> run the network backend in the Snabbswitch ethernet switch, while receiving
> traffic from a guest inside QEMU/KVM which runs an unmodified virtio-net
> implementation.
>
> For this, we are working into extending vhost to allow equivalent
> functionality
> for userspace. Vhost already passes control of the data plane of virtio-net to
> the host kernel; we want to realize a similar model, but for userspace.
>
> In this patch series the concept of a vhost-backend is introduced.
>
> We define two vhost backend types - vhost-kernel and vhost-user. The former is
> the interface to the current kernel module implementation. Its control plane
> is
> ioctl based. The data plane is the kernel directly accessing the QEMU
> allocated,
> guest memory.
>
> In the new vhost-user backend, the control plane is based on communication
> between QEMU and another userspace process using a unix domain socket. This
> allows to implement a virtio backend for a guest running in QEMU, inside the
> other userspace process. For this communication we use a chardev with a unix
> socket
> backend. Vhost-user is client/server agnostic regarding the chardev, however
> it does not support the 'nowait' and 'telnet' options.
>
> We change -mem-path to QemuOpts and add prealloc and share as properties
> to it. HugeTLBFS is required for this option to work.
>
> The data path is realized by directly accessing the vrings and the buffer data
> off the guest's memory.
>
> The current user of vhost-user is only vhost-net. We add new netdev backend
> that is intended to initialize vhost-net with vhost-user backend.
You mentioned that there will be an in-tree utility that can
communicate over this channel from the other side.
Did I miss it in this patchset or is it not included yet?
> Example usage:
>
> qemu -m 1024 -mem-path /hugetlbfs,share=on \
> -chardev socket,id=chr0,path=/path/to/socket \
> -netdev type=vhost-user,id=net0,chardev=chr0 \
> -device virtio-net-pci,netdev=net0
>
> This code can be pulled from address@hidden:virtualopensystems/qemu.git
> vhost-user-v7
>
> A reference vhost-user slave for testing is available from
> address@hidden:virtualopensystems/vapp.git
>
> TODOs include:
> - Include a test in QEMU to avoid regressions
> - Slave reconnection and nowait support
>
> Changes from v6:
> - Remove the 'unlink' property of '-mem-path'
> - Extend qemu-char: blocking read, send fds, monitor for connection close
> - Vhost-user uses chardev as a backend
> - Poll and reconnect removed (no VHOST_USER_ECHO).
> - Disconnect is deteced by the chardev (G_IO_HUP event)
> - vhost-backend.c split to vhost-user.c
>
> Changes from v5:
> - Split -mem-path unlink option to a separate patch
> - Fds are passed only in the ancillary data
> - Stricter message size checks on receive/send
> - Netdev vhost-user now includes path and poll_time options
> - The connection probing interval is configurable
>
> Changes from v4:
> - Use error_report for errors
> - VhostUserMsg has new field `size` indicating the following payload length.
> Field `flags` now has version and reply bits. The structure is packed.
> - Send data is of variable length (`size` field in message)
> - Receive in 2 steps, header and payload
> - Add new message type VHOST_USER_ECHO, to check connection status
>
> Changes from v3:
> - Convert -mem-path to QemuOpts with prealloc, share and unlink properties
> - Set 1 sec timeout when read/write to the unix domain socket
> - Fix file descriptor leak
>
> Changes from v2:
> - Reconnect when the backend disappears
>
> Changes from v1:
> - Implementation of vhost-user netdev backend
> - Code improvements
>
> Antonios Motakis (13):
> Convert -mem-path to QemuOpts and add prealloc and share properties
> Add chardev API qemu_chr_fe_read_all
> Add chardev API qemu_chr_fe_set_msgfds
> Add G_IO_HUP handler for socket chardev
> vhost_net should call the poll callback only when it is set
> Refactor virtio-net to use a generic get_vhost_net
> vhost_net_init will use VhostNetOptions to get all its arguments
> Add vhost_ops to the vhost_dev struct and replace all relevant ioctls
> Add vhost-backend and VhostBackendType
> Add vhost-user as a vhost backend.
> Add new vhost-user netdev backend
> Add the vhost-user netdev backend to command line
> Add vhost-user protocol documentation
>
> docs/specs/vhost-user.txt | 249 ++++++++++++++++++++++++++++
> exec.c | 30 +++-
> hmp-commands.hx | 4 +-
> hw/net/vhost_net.c | 142 +++++++++++-----
> hw/net/virtio-net.c | 42 ++---
> hw/scsi/vhost-scsi.c | 20 ++-
> hw/virtio/Makefile.objs | 2 +-
> hw/virtio/vhost-backend.c | 71 ++++++++
> hw/virtio/vhost-user.c | 331
> ++++++++++++++++++++++++++++++++++++++
> hw/virtio/vhost.c | 55 ++++---
> include/exec/cpu-all.h | 3 -
> include/hw/virtio/vhost-backend.h | 38 +++++
> include/hw/virtio/vhost.h | 8 +-
> include/net/vhost-user.h | 17 ++
> include/net/vhost_net.h | 11 +-
> include/sysemu/char.h | 28 ++++
> net/Makefile.objs | 2 +-
> net/clients.h | 3 +
> net/hub.c | 1 +
> net/net.c | 2 +
> net/tap.c | 18 ++-
> net/vhost-user.c | 217 +++++++++++++++++++++++++
> qapi-schema.json | 18 ++-
> qemu-char.c | 185 ++++++++++++++++++++-
> qemu-options.hx | 25 ++-
> vl.c | 37 ++++-
> 26 files changed, 1425 insertions(+), 134 deletions(-)
> create mode 100644 docs/specs/vhost-user.txt
> create mode 100644 hw/virtio/vhost-backend.c
> create mode 100644 hw/virtio/vhost-user.c
> create mode 100644 include/hw/virtio/vhost-backend.h
> create mode 100644 include/net/vhost-user.h
> create mode 100644 net/vhost-user.c
>
> --
> 1.8.3.2
>
- Re: [Qemu-devel] [PATCH v7 00/13] Vhost and vhost-net support for userspace based backends,
Michael S. Tsirkin <=