Re: [PATCH v7 13/15] io_uring/zcrx: set pp memory provider for an rx queue

[Mina Almasry <almasrymina@google.com>]

On Tue, Oct 29, 2024 at 4:06 PM David Wei <dw@davidwei.uk> wrote:
>
> From: David Wei <davidhwei@meta.com>
>
> Set the page pool memory provider for the rx queue configured for zero
> copy to io_uring. Then the rx queue is reset using
> netdev_rx_queue_restart() and netdev core + page pool will take care of
> filling the rx queue from the io_uring zero copy memory provider.
>
> For now, there is only one ifq so its destruction happens implicitly
> during io_uring cleanup.
>
> Signed-off-by: David Wei <dw@davidwei.uk>
> ---
>  io_uring/zcrx.c | 86 +++++++++++++++++++++++++++++++++++++++++++++++--
>  io_uring/zcrx.h |  2 ++
>  2 files changed, 86 insertions(+), 2 deletions(-)
>
> diff --git a/io_uring/zcrx.c b/io_uring/zcrx.c
> index 477b0d1b7b91..3f4625730dbd 100644
> --- a/io_uring/zcrx.c
> +++ b/io_uring/zcrx.c
> @@ -8,6 +8,7 @@
>  #include <net/page_pool/helpers.h>
>  #include <net/page_pool/memory_provider.h>
>  #include <trace/events/page_pool.h>
> +#include <net/netdev_rx_queue.h>
>  #include <net/tcp.h>
>  #include <net/rps.h>
>
> @@ -36,6 +37,65 @@ static inline struct io_zcrx_area *io_zcrx_iov_to_area(const struct net_iov *nio
>         return container_of(owner, struct io_zcrx_area, nia);
>  }
>
> +static int io_open_zc_rxq(struct io_zcrx_ifq *ifq, unsigned ifq_idx)
> +{
> +       struct netdev_rx_queue *rxq;
> +       struct net_device *dev = ifq->dev;
> +       int ret;
> +
> +       ASSERT_RTNL();
> +
> +       if (ifq_idx >= dev->num_rx_queues)
> +               return -EINVAL;
> +       ifq_idx = array_index_nospec(ifq_idx, dev->num_rx_queues);
> +
> +       rxq = __netif_get_rx_queue(ifq->dev, ifq_idx);
> +       if (rxq->mp_params.mp_priv)
> +               return -EEXIST;
> +
> +       ifq->if_rxq = ifq_idx;
> +       rxq->mp_params.mp_ops = &io_uring_pp_zc_ops;
> +       rxq->mp_params.mp_priv = ifq;
> +       ret = netdev_rx_queue_restart(ifq->dev, ifq->if_rxq);
> +       if (ret)
> +               goto fail;
> +       return 0;
> +fail:
> +       rxq->mp_params.mp_ops = NULL;
> +       rxq->mp_params.mp_priv = NULL;
> +       ifq->if_rxq = -1;
> +       return ret;
> +}
> +

I don't see a CAP_NET_ADMIN check. Likely I missed it. Is that done
somewhere? Binding user memory to an rx queue needs to be a privileged
operation.

-- 
Thanks,
Mina