Re: [Qemu-devel] [PATCH 00/10] vhost-user: simple reconnection support

[Victor Kaplansky]

Hi MST, I've reviewed the patches and they are fine.
>From my perspective we can pull them into upstream.


On Mon, Jun 06, 2016 at 06:44:58PM +0200, address@hidden wrote:
> From: Marc-André Lureau <address@hidden>
> 
> Hi,
> 
> In a previous series "RFCv2: vhost-user: shutdown and reconnection", I
> proposed to add a new slave request to handle graceful shutdown, for
> both qemu configuration, server or client, while keeping the guest
> running with link down status.
> 
> However, for the simple case where qemu is configured as server, and
> the backend processes packets in order and disconnects, it is possible
> for the backend to recover after reconnection by discarding the qemu
> SET_VRING_BASE value and resuming from the used->index instead. This
> simplifies the reconnection support in this particular situation (it
> would make sense to have the backend declare this behaviour with an
> extra flag)
> 
> The guest won't be notified of link status change and queues may not
> be processed in a timely manner, also qemu may assert if some
> vhost-user commands are happening while the backend is disconnected.
> So the reconnection must happen "quickly enough" here. In order to
> keep the series relatively small, these further problems will be
> addressed later.
> 
> These series demonstrates a simple reconnect support for vubr
> (configured as client and qemu as server), includes some nice to
> have fixes and a simple test.
> 
> rfcv3->v1:
> - rebased
> - added add a dummy vhost_net_get_acked_features()
>   implementation for !VHOST_NET
> - changed vubr->tests/vhost-user-bridge in summary
> - made the test silent by using a subprocess
> - added s-o-b/tested-by/r-b tags
> 
> Marc-André Lureau (8):
>   tests/vhost-user-bridge: add client mode
>   tests/vhost-user-bridge: workaround stale vring base
>   vhost-user: disconnect on start failure
>   vhost-net: do not crash if backend is not present
>   vhost-net: save & restore vhost-user acked features
>   vhost-net: save & restore vring enable state
>   tests: append i386 tests
>   test: start vhost-user reconnect test
> 
> Tetsuya Mukawa (2):
>   vhost-user: add ability to know vhost-user backend disconnection
>   qemu-char: add qemu_chr_disconnect to close a fd accepted by listen fd
> 
>  hw/net/vhost_net.c        |  45 ++++++++++++++-
>  include/net/net.h         |   1 +
>  include/net/vhost-user.h  |   1 +
>  include/net/vhost_net.h   |   3 +
>  include/sysemu/char.h     |   7 +++
>  net/vhost-user.c          |  32 ++++++++++-
>  qemu-char.c               |   8 +++
>  tests/Makefile            |   2 +-
>  tests/vhost-user-bridge.c |  45 +++++++++++----
>  tests/vhost-user-test.c   | 136 
> ++++++++++++++++++++++++++++++++++++++++------
>  10 files changed, 247 insertions(+), 33 deletions(-)
> 
> -- 
> 2.7.4
> 
>