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.
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.
The problem is for DPDK to detect whether bug is fixed in Qemu. Maybe only way would be to have a new protocol feature flag, which is not really its role.
Fixes: 73c8f9f69c6c("vhost: introduce reply ack feature") Reported-by: Loftus, Ciara <ciara.lof...@intel.com> Signed-off-by: Zhiyong Yang <zhiyong.y...@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 {
Cheers, Maxime
