On Fri, Sep 09, 2016 at 01:50:16PM +0800, Tan, Jianfeng wrote: > On 9/9/2016 12:19 PM, Yuanhan Liu wrote: > > >> > >> > >> Never mind, above fix on the vhost side will not take effect on > >> existing > >> vpp-vhost implementations. > >> > >> Actually, I was talking about the DPDK vhost implementation :) > >> > >> > >>This patch is talking about vpp's native vhost implementation, not > >>dpdk-vhost, > >>and not the way vpp uses dpdk-vhost. > >Yes, I know. What I meant is there was a "workaround" in DPDK vhost > >implementation, and since you bring this issue on the table again, > >it's a chance to think about how can we fix it. > > > >A rough idea come to my mind is we could check all the per-vring message > >at the begining of vhost_user_msg_handler() and allocate related vq when > >necessary (when it's the first vring message we got). > > > >Yeah, I know it's a bit ugly, but it at least gets rid of that > >"not-that-true" > >assumption. > > Sounds workable. So we'd define those vq-specific msgs, like: > VHOST_USER_SET_VRING_NUM, > VHOST_USER_SET_VRING_ADDR, > VHOST_USER_SET_VRING_BASE, > VHOST_USER_GET_VRING_BASE(?), > VHOST_USER_SET_VRING_KICK, > VHOST_USER_SET_VRING_CALL, > VHOST_USER_SET_VRING_ENABLE,
Yes. > >> Still not working. VPP needs SET_VRING_CALL to create vq firstly. > >> > >> Didn't get it. In the proposal, SET_FEATURES is sent before every other > >> messages, thus it should not cause the issue you described in this > >> patch. > >> > >> > >>OK. Let me try to explain. We take three vhost implementations into > >>consideration: dpdk-2.2-vhost, dpdk-master-vhost, vpp-native-vhost. > >> > >>If set_feature before set_vring_call, dpdk-2.2-vhost will fail: inside > >>set_feature handler, assigning header length to VQs which will be created in > >>set_vring_call handler. > >Oh, right. That was an in-correct implementation. > > > >>So we need to keep set_vring_call firstly. > >>Then set_feature needs to be sent > >>before any other msgs, this is what vpp-native-vhost requires. In all, the > >>sequence is like this: > >>1. set_vring_call, > >>2. set_feature, > >>3. other msgs > >> > >> > >> Besides, haven't we already sent SET_VRING_CALL before other messages > >> (well, execept the SET_FEATURES and SET_MEM_TABLE message)? > >> > >> > >>Yes, set_vring_call is already in the first place, but we need to plugin > >>set_feature between set_vring_call and other msgs. Previously, > >>set_vring_call > >>and other msgs are together. > >Okay. Another thing I noticed is that virtio-user lacks some feature > >negotiations, like GET_FEATURES and GET_PROTOCOL_FEATURES. I think you > >might need add them back somewhen? > > GET_FEATURES has been done in virtio_user_dev_init(). Oh, sorry, I missed that. > GET_PROTOCOL_FEATURES > is not supported yet. I see those features in PROTOCOL_FEATURES is for live > migration (right?). Not exactly. PROTOCOL_FEATURES was firstly introduced while MQ was enabled. Thus it's no wonder MQ is the first protocol feature vhost user supports: [yliu at yliu-dev ~/dpdk]$ gg PROTOCOL_F_ lib/librte_vhost/ lib/librte_vhost/vhost_user.h:46:#define VHOST_USER_PROTOCOL_F_MQ 0 lib/librte_vhost/vhost_user.h:47:#define VHOST_USER_PROTOCOL_F_LOG_SHMFD 1 lib/librte_vhost/vhost_user.h:48:#define VHOST_USER_PROTOCOL_F_RARP 2 --yliu > Assuming that, anyone using container/process now > enables live migration so far? I don't think so. > > Thanks, > Jianfeng > > > > > > --yliu