On Mon, Feb 05, 2018 at 09:57:23AM +0000, Wang, Wei W wrote: > On Friday, February 2, 2018 11:26 PM, Stefan Hajnoczi wrote: > > On Tue, Jan 30, 2018 at 08:09:19PM +0800, Wei Wang wrote: > > > Background: > > > The vhost-user negotiation is split into 2 phases currently. The 1st > > > phase happens when the connection is established, and we can find > > > what's done in the 1st phase in vhost_user_init(). The 2nd phase > > > happens when the master driver is loaded (e.g. run of virtio-net pmd) > > > and set status to the device, and we can find what's done in the 2nd > > > phase in vhost_dev_start(), which includes sending the memory info and > > > virtqueue info. The socket is connected, till one of the QEMU devices > > > exits, so pmd exiting won't end the QEMU side socket connection. > > > > > > Issues: > > > Suppose we have both the vhost and virtio-net set up, and vhost pmd > > > <-> virtio-net pmd communication works well. Now, vhost pmd exits > > > (virtio-net pmd is still there). Some time later, we re-run vhost pmd, > > > the vhost pmd doesn't know the virtqueue addresses of the virtio-net > > > pmd, unless the virtio-net pmd reloads to start the 2nd phase of the > > > vhost-user protocol. So the second run of the vhost pmd won't work. > > > > This isn't a problem for virtio-vhost-user since the vhost-pmd resets the > > virtio-vhost-user device when it restarts. The vhost-user AF_UNIX socket > > reconnects and negotiation restarts. > > I'm not sure if you've agreed that vhost-user negotiation is split into two > phases as described above. If not, it's also not difficult to check, thanks > to the RTE_LOG put at the vhost_user_msg_handler: > RTE_LOG(INFO, VHOST_CONFIG, "read message %s\n", > vhost_message_str[msg.request.master]); > It tells us what messages are received and when they are received. > > Before trying the virtio-vhost-user setup, please make sure the virtio-net > side VM doesn't have the virtio-net kernel driver loaded (blacklist the > module or disable it in .config). > VM1: the VM with virtio-vhost-user > VM2: the VM with virtio-net > > 1) After we boot VM1 and the virtio-vhost-user pmd, we boot VM2, and we will > see the following log in VM1: > VHOST_CONFIG: new device, handle is 0 > VHOST_CONFIG: read message VHOST_USER_GET_FEATURES > VHOST_CONFIG: read message VHOST_USER_GET_PROTOCOL_FEATURES > VHOST_CONFIG: read message VHOST_USER_SET_PROTOCOL_FEATURES > VHOST_CONFIG: read message VHOST_USER_GET_QUEUE_NUM > VHOST_CONFIG: read message VHOST_USER_SET_OWNER > VHOST_CONFIG: read message VHOST_USER_GET_FEATURES > VHOST_CONFIG: read message VHOST_USER_SET_VRING_CALL > VHOST_CONFIG: vring call idx:0 file:-1 > VHOST_CONFIG: read message VHOST_USER_SET_VRING_CALL > VHOST_CONFIG: vring call idx:1 file:-1 > > Those messages are what I called phase1 negotiation. They are negotiated when > the AF_UNIX socket connects. > > 2) Then in VM2 we load the virtio-net pmd, we will see phase2 messages > showing up in VM1, like: > VHOST_CONFIG: read message VHOST_USER_SET_VRING_NUM > VHOST_CONFIG: read message VHOST_USER_SET_VRING_BASE > VHOST_CONFIG: read message VHOST_USER_SET_VRING_ADDR > ... > Those messages are sent to virtio-vhost-user only when the VM2's virtio-net > pmd loads. > > AF_UNIX socket reconnection only triggers phase1 negotiation. If virtio-net > pmd in VM2 doesn't reload, virtio-vhost-user pmd won't get the above phase2 > messages. Do you agree with the issue?
I'll reply on the subthread with Michael where you posted a similar response. Stefan
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