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

[Maxime Coquelin <maxime.coquelin@redhat.com>]

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?

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

Thanks,
Maxime