On 04/27/2017 10:24 AM, Yang, Zhiyong wrote:
Hi, Maxime:
-----Original Message-----
From: Maxime Coquelin [mailto:maxime.coque...@redhat.com]
Sent: Thursday, April 27, 2017 4:05 PM
To: Yang, Zhiyong <zhiyong.y...@intel.com>; dev@dpdk.org
Cc: yuanhan....@linux.intel.com; Loftus, Ciara <ciara.lof...@intel.com>; Marc-
André Lureau <mlur...@redhat.com>
Subject: Re: [PATCH] vhost: fix MQ fails to startup
On 04/27/2017 09:56 AM, Maxime Coquelin wrote:
Hi Zhiyong,
+Marc-André
On 04/27/2017 08:34 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 works in the right way.
I'm looking at Qemu's vhost_user_set_mem_table() function, but fail to
see how it could wait for the reply-ack if it didn't send the
VHOST_USER_SET_MEM_TABLE request before.
Oh, sorry, I get it now.
Are you working for a fix in Qemu, or have you already reported the problem?
I will send bug fix patch to Qemu.
The same wrong code has also been used when Qemu2.9 introduce the MTU
negotiation with DPDK.
I will fix them at the same time in qemu.
I think the problem must be fixed generally and not per request.
Maybe in vhost_user_write() if one-time request, just clear the
VHOST_USER_NEED_REPLY flag. Then, in process_message_reply(), return
early if this flag isn't set.
But that is not enough because as said, even if fixed, the backend has
no way to know about it.
Thanks
Zhiyong
Thanks,
Maxime
