Re: [Qemu-devel] [PATCH v1 0/4] Add feature to start QEMU without vhost-user backend

[Tetsuya Mukawa <mukawa@igel.co.jp>]

On 2015/05/29 13:42, Tetsuya Mukawa wrote:
> Hi guys,
>
> Here are patches to add feature to start QEMU without vhost-user backend.
> Currently, if we want to use vhost-user backend, the backend must start before
> QEMU. Also, if QEMU or the backend is closed unexpectedly, there is no way to
> recover without restarting both applications. Practically, it's not useful.
>
> This patch series adds following features.
>  - QEMU can start before the backend.
>  - QEMU or the backend can restart anytime.
>    connectivity will be recovered automatically, when app starts again.
>    (if QEMU is server, QEMU just wait reconnection)
>    while lost connection, link status of virtio-net device is down,
>    so virtio-net driver on the guest can know it
>
> To work like above, the patch introduces flags to specify features vhost-user
> backend will support.
>
> Here are examples.
> ('backend_mrg_rxbuf' is an one of new flags. To know all, check the last patch)
>
>     * QEMU is configured as vhost-user client.
>      -chardev socket,id=chr0,path=/tmp/sock,reconnect=3 \
>      -netdev vhost-user,id=net0,chardev=chr0,vhostforce,backend_mrg_rxbuf \
>      -device virtio-net-pci,netdev=net0 \
>
>     * QEMU is configured as vhost-user server.
>      -chardev socket,id=chr0,path=/tmp/sock,server,nowait \
>      -netdev vhost-user,id=net0,chardev=chr0,vhostforce,backend_mrg_rxbuf \
>      -device virtio-net-pci,netdev=net0 \
>
> When virtio-net device is configured by virtio-net driver, QEMU should know
> vhost-user backend features. But if QEMU starts without the backend, QEMU cannot
> know it. So above the feature values specified by user will be used as features
> the backend will support.
>
> When connection between QEMU and the backend is established, QEMU checkes feature
> values of the backend to make sure the expected features are provided.
> If it doesn't, the connection will be closed by QEMU.
>
> Regards,
> Tetsuya
>
> ----------
> Changes
> ----------
> - Changes from RFC patch
>   The last patch of this series was changed like below.
>    - Rebase to latest master.
>    - Remove needless has_backend_feature variable.
>    - Change user interface to be able to specify each feature by name.
>    - Add (Since 2.4) to schema file.
>    - Fix commit title and body.
>
>
> Tetsuya Mukawa (4):
>   vhost-user: Add ability to know vhost-user backend disconnection
>   vhost-user: Shutdown vhost-user connection when wrong messages are
>     passed
>   vhost-user: Enable 'nowait' and 'reconnect' option
>   vhost-user: Add new option to specify vhost-user backend features
>
>  hw/net/vhost_net.c             |   6 ++-
>  hw/net/virtio-net.c            |  13 +++++
>  hw/scsi/vhost-scsi.c           |   2 +-
>  hw/virtio/vhost-user.c         |  24 ++++++---
>  hw/virtio/vhost.c              |   7 ++-
>  include/hw/virtio/vhost.h      |   3 +-
>  include/hw/virtio/virtio-net.h |   1 +
>  include/net/net.h              |   3 ++
>  include/net/vhost_net.h        |   1 +
>  include/sysemu/char.h          |   7 +++
>  net/net.c                      |   9 ++++
>  net/tap.c                      |   1 +
>  net/vhost-user.c               |  69 ++++++++++++++++++++++++-
>  qapi-schema.json               | 114 +++++++++++++++++++++++++++++++++++------
>  qemu-char.c                    |  15 ++++++
>  qemu-options.hx                |  10 ++++
>  16 files changed, 256 insertions(+), 29 deletions(-)
>

Ping.

Could someone please review this patches?
http://patchwork.ozlabs.org/project/qemu-devel/list/?submitter=66139

Regards,
Tetsuya