[dpdk-dev] [PATCH] vhost: fix MQ fails to startup

[Zhiyong Yang <zhiyong.yang@intel.com>]

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. But 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. Once Qemu bugs
have been fixed and upstreamed, we can enable it.

Fixes: 73c8f9f69c6c("vhost: introduce reply ack feature")

Reported-by: Loftus, Ciara <ciara.loftus@intel.com>
Signed-off-by: Zhiyong Yang <zhiyong.yang@intel.com>
---
 lib/librte_vhost/vhost_user.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/librte_vhost/vhost_user.h b/lib/librte_vhost/vhost_user.h
index 2ba22db..a3d2900 100644
--- a/lib/librte_vhost/vhost_user.h
+++ b/lib/librte_vhost/vhost_user.h
@@ -52,7 +52,7 @@
 #define VHOST_USER_PROTOCOL_FEATURES	((1ULL << VHOST_USER_PROTOCOL_F_MQ) | \
 					 (1ULL << VHOST_USER_PROTOCOL_F_LOG_SHMFD) |\
 					 (1ULL << VHOST_USER_PROTOCOL_F_RARP) | \
-					 (1ULL << VHOST_USER_PROTOCOL_F_REPLY_ACK) | \
+					 (0ULL << VHOST_USER_PROTOCOL_F_REPLY_ACK) | \
 					 (1ULL << VHOST_USER_PROTOCOL_F_NET_MTU))
 
 typedef enum VhostUserRequest {
-- 
2.7.4