netdev - Re: [PATCH net-next v4] xen networking: add basic XDP support for xen-netfront

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Date:   Mon, 16 Mar 2020 16:44:35 +0100
From:   Jesper Dangaard Brouer <brouer@...hat.com>
To:     Denis Kirjanov <kda@...ux-powerpc.org>
Cc:     brouer@...hat.com, netdev@...r.kernel.org, jgross@...e.com,
        ilias.apalodimas@...aro.org, wei.liu@...nel.org, paul@....org
Subject: Re: [PATCH net-next v4] xen networking: add basic XDP support for
 xen-netfront

On Mon, 16 Mar 2020 16:09:36 +0300
Denis Kirjanov <kda@...ux-powerpc.org> wrote:

> diff --git a/drivers/net/xen-netfront.c b/drivers/net/xen-netfront.c
> index 482c6c8..c06ae57 100644
> --- a/drivers/net/xen-netfront.c
> +++ b/drivers/net/xen-netfront.c
[...]
> @@ -778,6 +790,52 @@ static int xennet_get_extras(struct netfront_queue *queue,
>  	return err;
>  }
>  
> +u32 xennet_run_xdp(struct netfront_queue *queue, struct page *pdata,
> +		   struct xen_netif_rx_response *rx, struct bpf_prog *prog,
> +		   struct xdp_buff *xdp)
> +{
> +	struct xdp_frame *xdpf;
> +	u32 len = rx->status;
> +	u32 act = XDP_PASS;
> +	int err;
> +
> +	xdp->data_hard_start = page_address(pdata);
> +	xdp->data = xdp->data_hard_start + XDP_PACKET_HEADROOM;
> +	xdp_set_data_meta_invalid(xdp);
> +	xdp->data_end = xdp->data + len;
> +	xdp->rxq = &queue->xdp_rxq;
> +	xdp->handle = 0;
> +
> +	act = bpf_prog_run_xdp(prog, xdp);
> +	switch (act) {
> +	case XDP_TX:
> +		xdpf = convert_to_xdp_frame(xdp);
> +		err = xennet_xdp_xmit(queue->info->netdev, 1,
> +				&xdpf, 0);

Strange line wrap, I don't think this is needed, please fix.


> +		if (unlikely(err < 0))
> +			trace_xdp_exception(queue->info->netdev, prog, act);
> +		break;
> +	case XDP_REDIRECT:
> +		err = xdp_do_redirect(queue->info->netdev, xdp, prog);

What is the frame size of the packet memory?


> +		if (unlikely(err))
> +			trace_xdp_exception(queue->info->netdev, prog, act);
> +		xdp_do_flush();
> +		break;
> +	case XDP_PASS:
> +	case XDP_DROP:
> +		break;
> +
> +	case XDP_ABORTED:
> +		trace_xdp_exception(queue->info->netdev, prog, act);
> +		break;
> +
> +	default:
> +		bpf_warn_invalid_xdp_action(act);
> +	}
> +
> +	return act;
> +}
> +

-- 
Best regards,
  Jesper Dangaard Brouer
  MSc.CS, Principal Kernel Engineer at Red Hat
  LinkedIn: http://www.linkedin.com/in/brouer