Re: [Qemu-devel] vhost-user breaks after 96a3d98.

[Jason Wang]

On 2016年12月30日 20:41, Flavio Leitner wrote:
> Hi,
>
> While I was testing vhost-user using OVS 2.5 and DPDK 2.2.0 in the
> host and testpmd dpdk 2.2.0 in the guest, I found that the commit
> below breaks the environment and no packets gets into the guest.
>
> dpdk port --> OVS --> vhost-user --> guest --> testpmd
>                           ^--- drops here         ^--- no packets here.
>
> commit 96a3d98d2cdbd897ff5ab33427aa4cfb94077665
> Author: Jason Wang <address@hidden>
> Date:   Mon Aug 1 16:07:58 2016 +0800
>
>      vhost: don't set vring call if no vector
>      
>      We used to set vring call fd unconditionally even if guest driver does
>      not use MSIX for this vritqueue at all. This will cause lots of
>      unnecessary userspace access and other checks for drivers does not use
>      interrupt at all (e.g virtio-net pmd). So check and clean vring call
>      fd if guest does not use any vector for this virtqueue at
>      all.
> [...]
>
> Thanks,

Hi Flavio:

Thanks for reporting this issue, could this be a bug of vhost-user? (I 
believe virito-net pmd does not use interrupt for rx/tx at all)

Anyway, will try to reproduce it.