Re: [Qemu-devel] [PATCH v2] hw/virtio: fix vhost user fails to startup when MQ

From: "Michael S. Tsirkin" <mst@redhat.com>
To: Maxime Coquelin <maxime.coquelin@redhat.com>
Cc: Zhiyong Yang <zhiyong.yang@intel.com>,
	qemu-devel@nongnu.org, marcandre.lureau@gmail.com,
	qemu-stable <qemu-stable@nongnu.org>
Subject: Re: [Qemu-devel] [PATCH v2] hw/virtio: fix vhost user fails to startup when MQ
Date: Fri, 5 May 2017 23:37:06 +0300	[thread overview]
Message-ID: <20170505233700-mutt-send-email-mst@kernel.org> (raw)
In-Reply-To: <74adb9e5-a8cc-9335-3547-6c59fb74a752@redhat.com>

On Fri, May 05, 2017 at 09:34:14AM +0200, Maxime Coquelin wrote:
> Hi,
> 
> On 05/04/2017 06:25 PM, Zhiyong Yang wrote:
> >   Qemu2.7~2.9 and vhost user for dpdk 17.02 release work together
> > to cause failures of new connection when negotiating to set MQ.
> > (one queue pair works well).
> >     Because there exist some bugs in qemu code when introducing
> > VHOST_USER_PROTOCOL_F_REPLY_ACK to qemu. When vhost_user_set_mem_table
> > is invoked to deal with the vhost message VHOST_USER_SET_MEM_TABLE
> > for the second time, qemu indeed doesn't send the messge (The message
> > needs to be sent only once)but still will be waiting for dpdk's reply
> > ack, then, qemu is always freezing, while DPDK is always waiting for
> > next vhost message from qemu.
> >    The patch aims to fix the bug, MQ can work well.
> >    The same bug is found in function vhost_user_net_set_mtu, it is fixed
> > at the same time.
> >    DPDK related patch is as following:
> >    http://www.dpdk.org/dev/patchwork/patch/23955/
> > 
> > Signed-off-by: Zhiyong Yang <zhiyong.yang@intel.com>
> > ---
> > 
> > Changes in V2:
> > Thanks for Maxime's suggestion, if one-time request, clear the
> > VHOST_USER_NEED_REPLY flag in function vhost_user_write,
> > in process_message_reply(), return early, if this flag isn't set.
> > 
> >   hw/virtio/vhost-user.c | 21 +++++++++++++--------
> >   1 file changed, 13 insertions(+), 8 deletions(-)
> > 
> 
> Thanks for the quick fix, it looks good to me.
> I forgot to ask you to cc qemu-stable, and reference the faulty commit:
> 
> Cc: qemu-stable@nongnu.org
> Fixes: ca525ce5618b ("vhost-user: Introduce a new protocol feature
> REPLY_ACK.")
> 
> Maybe this can be amended when applied. Michael?

Sure. np.

> Other than that, feel free to add my:
> Reviewed-by: Maxime Coquelin <maxime.coquelin@redhat.com>
> 
> Thanks,
> Maxime