[ovs-dev] [PATCH 1/1] dpdk: Deprecate vhost-user dequeue zero-copy.

[Maxime Coquelin]

On 8/6/20 7:18 PM, Ian Stokes wrote:
> Dequeue zero-copy is no longer supported for vhost-user client mode
> in DPDK due to commit [1].
> 
> In addition to this, zero-copy mode has been proposed to be marked
> deprecated in [2] with removal in the next DPDK LTS release.
> 
> This commit deprecates support for vhost-user dequeue zero-copy in OVS
> with its removal expected in the next OVS release.
> 
> [1] 715070ea10e6 ("vhost: prevent zero-copy with incompatible client
>     mode")
> [2] http://mails.dpdk.org/archives/dev/2020-August/177236.html
> 
> Signed-off-by: Ian Stokes <ian.stokes at intel.com>
> ---
>  Documentation/topics/dpdk/vhost-user.rst | 5 +++++
>  NEWS                                     | 2 ++
>  lib/netdev-dpdk.c                        | 2 ++
>  3 files changed, 9 insertions(+)
> 
> diff --git a/Documentation/topics/dpdk/vhost-user.rst b/Documentation/topics/dpdk/vhost-user.rst
> index b1eb5d9da..4af738d11 100644
> --- a/Documentation/topics/dpdk/vhost-user.rst
> +++ b/Documentation/topics/dpdk/vhost-user.rst
> @@ -556,6 +556,11 @@ shown with::
>  vhost-user Dequeue Zero Copy (experimental)
>  -------------------------------------------
>  
> +.. warning::
> +
> +   vhost-user Dequeue Zero Copy is deprecated in OVS and will be removed in
> +   the next release.
> +
>  Normally when dequeuing a packet from a vHost User device, a memcpy operation
>  must be used to copy that packet from guest address space to host address
>  space. This memcpy can be removed by enabling dequeue zero-copy like so::
> diff --git a/NEWS b/NEWS
> index dceda95a3..5d6489f26 100644
> --- a/NEWS
> +++ b/NEWS
> @@ -22,6 +22,8 @@ v2.14.0 - xx xxx xxxx
>         CVE-2020-10726, this DPDK version is strongly recommended to be used.
>       * New 'ovs-appctl dpdk/log-list' and 'ovs-appctl dpdk/log-set' commands
>         to list and change log levels in DPDK components.
> +     * Vhost-user Dequeue zero-copy support is deprecated and will be removed
> +       in the next release.
>     - Linux datapath:
>       * Support for kernel versions up to 5.5.x.
>     - AF_XDP:
> diff --git a/lib/netdev-dpdk.c b/lib/netdev-dpdk.c
> index 44ebf96da..27bf3b6ed 100644
> --- a/lib/netdev-dpdk.c
> +++ b/lib/netdev-dpdk.c
> @@ -5079,6 +5079,8 @@ netdev_dpdk_vhost_client_reconfigure(struct netdev *netdev)
>                        dev->up.name, dev->vhost_id);
>              if (zc_enabled) {
>                  VLOG_INFO("Zero copy enabled for vHost port %s", dev->up.name);
> +                VLOG_WARN("Zero copy support is deprecated and will be "
> +                          "removed in the next OVS release.");
>              }
>          }
>  
> 

Acked-by: Maxime Coquelin <maxime.coquelin at redhat.com>

Thanks!
Maxime