Subject: Re: [PATCH 20/33] virtio_net: xsk: introduce virtnet_rq_bind_xsk_pool()

From: "Michael S. Tsirkin" <[email-masked]>
Date: Fri, 3 Feb 2023 03:48:33 -0500

On Thu, Feb 02, 2023 at 07:00:45PM +0800, Xuan Zhuo wrote:
> This function is used to bind or unbind xsk pool to virtnet rq.
> 
> Signed-off-by: Xuan Zhuo <[email-masked]>
> ---
>  drivers/net/virtio/Makefile     |  2 +-
>  drivers/net/virtio/main.c       |  8 ++---
>  drivers/net/virtio/virtio_net.h | 16 ++++++++++
>  drivers/net/virtio/xsk.c        | 56 +++++++++++++++++++++++++++++++++
>  4 files changed, 76 insertions(+), 6 deletions(-)
>  create mode 100644 drivers/net/virtio/xsk.c
> 
> diff --git a/drivers/net/virtio/Makefile b/drivers/net/virtio/Makefile
> index 15ed7c97fd4f..8c2a884d2dba 100644
> --- a/drivers/net/virtio/Makefile
> +++ b/drivers/net/virtio/Makefile
> @@ -5,4 +5,4 @@
>  
>  obj-$(CONFIG_VIRTIO_NET) += virtio_net.o
>  
> -virtio_net-y := main.o
> +virtio_net-y := main.o xsk.o
> diff --git a/drivers/net/virtio/main.c b/drivers/net/virtio/main.c
> index 049a3bb9d88d..0ee23468b795 100644
> --- a/drivers/net/virtio/main.c
> +++ b/drivers/net/virtio/main.c
> @@ -110,7 +110,6 @@ struct padded_vnet_hdr {
>  	char padding[12];
>  };
>  
> -static void virtnet_rq_free_unused_buf(struct virtqueue *vq, void *buf);
>  static void virtnet_sq_free_unused_buf(struct virtqueue *vq, void *buf);
>  
>  static void *xdp_to_ptr(struct xdp_frame *ptr)
> @@ -1351,8 +1350,7 @@ static int add_recvbuf_mergeable(struct virtnet_info *vi,
>   * before we're receiving packets, or from refill_work which is
>   * careful to disable receiving (using napi_disable).
>   */
> -static bool try_fill_recv(struct virtnet_info *vi, struct receive_queue *rq,
> -			  gfp_t gfp)
> +bool try_fill_recv(struct virtnet_info *vi, struct receive_queue *rq, gfp_t gfp)
>  {
>  	int err;
>  	bool oom;
> @@ -1388,7 +1386,7 @@ static void skb_recv_done(struct virtqueue *rvq)
>  	virtqueue_napi_schedule(&rq->napi, rvq);
>  }
>  
> -static void virtnet_napi_enable(struct virtqueue *vq, struct napi_struct *napi)
> +void virtnet_napi_enable(struct virtqueue *vq, struct napi_struct *napi)
>  {
>  	napi_enable(napi);
>  
> @@ -3284,7 +3282,7 @@ static void virtnet_sq_free_unused_buf(struct virtqueue *vq, void *buf)
>  		xdp_return_frame(ptr_to_xdp(buf));
>  }
>  
> -static void virtnet_rq_free_unused_buf(struct virtqueue *vq, void *buf)
> +void virtnet_rq_free_unused_buf(struct virtqueue *vq, void *buf)

If you are making this an API now you better document
what it does. Same applies to other stuff you are
making non-static.

>  {
>  	struct virtnet_info *vi = vq->vdev->priv;
>  	int i = vq2rxq(vq);
> diff --git a/drivers/net/virtio/virtio_net.h b/drivers/net/virtio/virtio_net.h
> index b46f083a630a..4a7633714802 100644
> --- a/drivers/net/virtio/virtio_net.h
> +++ b/drivers/net/virtio/virtio_net.h
> @@ -168,6 +168,12 @@ struct send_queue {
>  
>  	/* Record whether sq is in reset state. */
>  	bool reset;
> +
> +	struct {
> +		struct xsk_buff_pool __rcu *pool;
> +
> +		dma_addr_t hdr_dma_address;
> +	} xsk;
>  };
>  
>  /* Internal representation of a receive virtqueue */
> @@ -200,6 +206,13 @@ struct receive_queue {
>  	char name[16];
>  
>  	struct xdp_rxq_info xdp_rxq;
> +
> +	struct {
> +		struct xsk_buff_pool __rcu *pool;
> +
> +		/* xdp rxq used by xsk */
> +		struct xdp_rxq_info xdp_rxq;
> +	} xsk;
>  };
>  
>  static inline bool is_xdp_raw_buffer_queue(struct virtnet_info *vi, int q)
> @@ -274,4 +287,7 @@ int virtnet_xdp_handler(struct bpf_prog *xdp_prog, struct xdp_buff *xdp,
>  			unsigned int *xdp_xmit,
>  			struct virtnet_rq_stats *stats);
>  int virtnet_tx_reset(struct virtnet_info *vi, struct send_queue *sq);
> +bool try_fill_recv(struct virtnet_info *vi, struct receive_queue *rq, gfp_t gfp);
> +void virtnet_napi_enable(struct virtqueue *vq, struct napi_struct *napi);
> +void virtnet_rq_free_unused_buf(struct virtqueue *vq, void *buf);
>  #endif
> diff --git a/drivers/net/virtio/xsk.c b/drivers/net/virtio/xsk.c
> new file mode 100644
> index 000000000000..e01ff2abea11
> --- /dev/null
> +++ b/drivers/net/virtio/xsk.c
> @@ -0,0 +1,56 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +/*
> + * virtio-net xsk
> + */
> +
> +#include "virtio_net.h"
> +
> +static int virtnet_rq_bind_xsk_pool(struct virtnet_info *vi, struct receive_queue *rq,
> +				    struct xsk_buff_pool *pool, struct net_device *dev)

This static function is unused after this patch, so compiler will
complain. Yes it's just a warning but still not nice.

> +{
> +	bool running = netif_running(vi->dev);
> +	int err, qindex;
> +
> +	qindex = rq - vi->rq;
> +
> +	if (pool) {
> +		err = xdp_rxq_info_reg(&rq->xsk.xdp_rxq, dev, qindex, rq->napi.napi_id);
> +		if (err < 0)
> +			return err;
> +
> +		err = xdp_rxq_info_reg_mem_model(&rq->xsk.xdp_rxq,
> +						 MEM_TYPE_XSK_BUFF_POOL, NULL);
> +		if (err < 0) {
> +			xdp_rxq_info_unreg(&rq->xsk.xdp_rxq);
> +			return err;
> +		}
> +
> +		xsk_pool_set_rxq_info(pool, &rq->xsk.xdp_rxq);
> +	} else {
> +		xdp_rxq_info_unreg(&rq->xsk.xdp_rxq);
> +	}
> +
> +	if (running)
> +		napi_disable(&rq->napi);
> +
> +	err = virtqueue_reset(rq->vq, virtnet_rq_free_unused_buf);
> +	if (err)
> +		netdev_err(vi->dev, "reset rx fail: rx queue index: %d err: %d\n", qindex, err);
> +
> +	if (pool) {
> +		if (err)
> +			xdp_rxq_info_unreg(&rq->xsk.xdp_rxq);
> +		else
> +			rcu_assign_pointer(rq->xsk.pool, pool);
> +	} else {
> +		rcu_assign_pointer(rq->xsk.pool, NULL);
> +	}
> +
> +	if (!try_fill_recv(vi, rq, GFP_KERNEL))
> +		schedule_delayed_work(&vi->refill, 0);
> +
> +	if (running)
> +		virtnet_napi_enable(rq->vq, &rq->napi);
> +
> +	return err;
> +}
> -- 
> 2.32.0.3.g01195cf9f