On Sun, Jul 10, 2016 at 09:17:31PM +0800, Yuanhan Liu wrote: > On Fri, Jul 08, 2016 at 02:48:56PM +0300, Ilya Maximets wrote: > > > > Another point is that crash constantly happens on queue_id=3 (second RX > > queue) in > > my scenario. It is newly allocated virtqueue while reconfiguration from > > rxq=1 to > > rxq=2. > > That's a valuable message: what's your DPDK HEAD commit while triggering > this issue?
I guess I have understood what goes wrong in you case. I would guess that your vhost has 2 queues (here I mean queue-pairs, including one Tx and Rx queue; below usage is the same) configured, so does to your QEMU. However, you just enabled 1 queue while starting testpmd inside the guest, and you want to enable 2 queues by running following testpmd commands: stop port stop all port config all rxq 2 port config all txq 2 port start all Badly, that won't work for current virtio PMD implementation, and what's worse, it triggers a vhost crash, the one you saw. Here is how it comes. Since you just enabled 1 queue while starting testpmd, it will setup 1 queue only, meaning only one queue's **valid** information will be sent to vhost. You might see SET_VRING_ADDR (and related vhost messages) for the other queue as well, but they are just the dummy messages: they don't include any valid/real information about the 2nd queue: the driver don't setup it after all. So far, so good. It became broken when you run above commands. Those commands do setup for the 2nd queue, however, they failed to trigger the QEMU virtio device to start the vhost-user negotiation, meaning no SET_VRING_ADDR will be sent for the 2nd queue, leaving vhost untold and not updated. What's worse, above commands trigger the QEMU to send SET_VRING_ENABLE messages, to enable all the vrings. And since the vrings for the 2nd queue are not properly configured, the crash happens. So maybe we should do virtio reset on port start? --yliu