[dpdk-dev,v2] vhost: workaround MQ fails to startup

  vhost since dpdk17.02 + qemu2.7 and above will 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 dealing 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. DPDK code indeed works in the right way.
   The feature VHOST_USER_PROTOCOL_F_REPLY_ACK has to be disabled
by default at the dpdk side in order to avoid the feature support of
DPDK + qemu at the same time. if doing like that, MQ can works well.

Cc: stable@dpdk.org

Reported-by: Ciara Loftus <ciara.loftus@intel.com>
Signed-off-by: Zhiyong Yang <zhiyong.yang@intel.com>
Tested-by: Ciara Loftus <ciara.loftus@intel.com>
---

changes in V2
1. modify "workaround" instead of "fix" in the title.
2. add a simple comment suggested by yuanhan

 lib/librte_vhost/vhost_user.h | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)
  

On 04/27/2017 11:41 AM, Zhiyong Yang wrote:
>    vhost since dpdk17.02 + qemu2.7 and above will 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 dealing 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. DPDK code indeed works in the right way.
>     The feature VHOST_USER_PROTOCOL_F_REPLY_ACK has to be disabled
> by default at the dpdk side in order to avoid the feature support of
> DPDK + qemu at the same time. if doing like that, MQ can works well.
> 
> Cc: stable@dpdk.org
> 
> Reported-by: Ciara Loftus <ciara.loftus@intel.com>
> Signed-off-by: Zhiyong Yang <zhiyong.yang@intel.com>
> Tested-by: Ciara Loftus <ciara.loftus@intel.com>
> ---
> 
> changes in V2
> 1. modify "workaround" instead of "fix" in the title.
> 2. add a simple comment suggested by yuanhan
> 
>   lib/librte_vhost/vhost_user.h | 6 +++++-
>   1 file changed, 5 insertions(+), 1 deletion(-)
> 

Reviewed-by: Maxime Coquelin <maxime.coquelin@redhat.com>

Thanks,
Maxime
  

On Thu, Apr 27, 2017 at 12:00:52PM +0200, Maxime Coquelin wrote:
> 
> 
> On 04/27/2017 11:41 AM, Zhiyong Yang wrote:
> >   vhost since dpdk17.02 + qemu2.7 and above will 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 dealing 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. DPDK code indeed works in the right way.
> >    The feature VHOST_USER_PROTOCOL_F_REPLY_ACK has to be disabled
> >by default at the dpdk side in order to avoid the feature support of
> >DPDK + qemu at the same time. if doing like that, MQ can works well.
> >
> >Cc: stable@dpdk.org
> >
> >Reported-by: Ciara Loftus <ciara.loftus@intel.com>
> >Signed-off-by: Zhiyong Yang <zhiyong.yang@intel.com>
> >Tested-by: Ciara Loftus <ciara.loftus@intel.com>
> >---
> >
> >changes in V2
> >1. modify "workaround" instead of "fix" in the title.
> >2. add a simple comment suggested by yuanhan
> >
> >  lib/librte_vhost/vhost_user.h | 6 +++++-
> >  1 file changed, 5 insertions(+), 1 deletion(-)
> >
> 
> Reviewed-by: Maxime Coquelin <maxime.coquelin@redhat.com>

Applied to dpdk-next-virtio.

Thanks.

	--yliu
  

Hi, all:

       The patch  which is used to fix the Qemu bug has been accepted in qemu community.
http://patchwork.ozlabs.org/patch/760118/

Thanks
Zhiyong

> -----Original Message-----
> From: Yuanhan Liu [mailto:yuanhan.liu@linux.intel.com]
> Sent: Friday, April 28, 2017 12:29 PM
> To: Maxime Coquelin <maxime.coquelin@redhat.com>
> Cc: Yang, Zhiyong <zhiyong.yang@intel.com>; dev@dpdk.org; Loftus, Ciara
> <ciara.loftus@intel.com>; stable@dpdk.org
> Subject: Re: [PATCH v2] vhost: workaround MQ fails to startup
> 
> On Thu, Apr 27, 2017 at 12:00:52PM +0200, Maxime Coquelin wrote:
> >
> >
> > On 04/27/2017 11:41 AM, Zhiyong Yang wrote:
> > >   vhost since dpdk17.02 + qemu2.7 and above will 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 dealing 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. DPDK code indeed works in the right way.
> > >    The feature VHOST_USER_PROTOCOL_F_REPLY_ACK has to be disabled by
> > >default at the dpdk side in order to avoid the feature support of
> > >DPDK + qemu at the same time. if doing like that, MQ can works well.
> > >
> > >Cc: stable@dpdk.org
> > >
> > >Reported-by: Ciara Loftus <ciara.loftus@intel.com>
> > >Signed-off-by: Zhiyong Yang <zhiyong.yang@intel.com>
> > >Tested-by: Ciara Loftus <ciara.loftus@intel.com>
> > >---
> > >
> > >changes in V2
> > >1. modify "workaround" instead of "fix" in the title.
> > >2. add a simple comment suggested by yuanhan
> > >
> > >  lib/librte_vhost/vhost_user.h | 6 +++++-
> > >  1 file changed, 5 insertions(+), 1 deletion(-)
> > >
> >
> > Reviewed-by: Maxime Coquelin <maxime.coquelin@redhat.com>
> 
> Applied to dpdk-next-virtio.
> 
> Thanks.
> 
> 	--yliu