On Fri, Aug 05, 2016 at 11:36:42AM +0000, Jianfeng Tan wrote: > When virtio_user is used with VPP's native vhost user, it cannot > send/receive any packets. > > The root cause is that vpp-vhost-user translates the message > VHOST_USER_SET_FEATURES as puting this device into init state, > aka, zero all related structures. However, previous code > puts this message at last in the whole initialization process, > which leads to all previous information are zeroed. > > To fix this issue, we rearrange the sequence of those messages. > - step 0, send VHOST_USER_SET_VRING_CALL so that vhost allocates > virtqueue structures;
Yes, it is. However, it's not that right to do that (you see there is a FIXME in vhost_user_set_vring_call()). That means it need be fixed: we should not rely on fact that it's the first per-vring message we will get in the current QEMU implementation as the truth. That also means, naming a function like virtio_user_create_queue() based on above behaviour is wrong. > - step 1, send VHOST_USER_SET_FEATURES to confirm the features; > - step 2, send VHOST_USER_SET_MEM_TABLE to share mem regions; > - step 3, send VHOST_USER_SET_VRING_NUM, VHOST_USER_SET_VRING_BASE, > VHOST_USER_SET_VRING_ADDR, VHOST_USER_SET_VRING_KICK for each > queue; > - ... > > Fixes: 37a7eb2ae816 ("net/virtio-user: add device emulation layer") > > Reported-by: Zhihong Wang <zhihong.wang at intel.com> > Signed-off-by: Jianfeng Tan <jianfeng.tan at intel.com> > --- > drivers/net/virtio/virtio_user/virtio_user_dev.c | 120 > ++++++++++++++--------- > 1 file changed, 72 insertions(+), 48 deletions(-) That's too much of code for a bug fix. I'm wondering how about just moving VHOST_USER_GET_PROTOCOL_FEATURES ahead, to the begining of virtio_user_start_device()? It should fix this issue. --yliu