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Re: [Qemu-devel] [PATCH v7 00/13] Vhost and vhost-net support for usersp
From: |
Antonios Motakis |
Subject: |
Re: [Qemu-devel] [PATCH v7 00/13] Vhost and vhost-net support for userspace based backends |
Date: |
Mon, 10 Feb 2014 17:02:24 +0100 |
Hello,
On Mon, Feb 10, 2014 at 9:57 AM, Michael S. Tsirkin <address@hidden> wrote:
>
> 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?
You haven't missed it; we just wanted to push our intermediate changes
for review, while we were still implementing the in-tree test. The
next version (v8), which we will post quite soon, will include it.
>
>
> > 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
> >
--
Antonios Motakis
Virtual Open Systems