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SubjectRe: [PATCH net-next] net: thunderx: Add support for xdp redirect
On Fri, 24 Nov 2017 15:03:26 +0300
Aleksey Makarov <aleksey.makarov@cavium.com> wrote:

> From: Sunil Goutham <sgoutham@cavium.com>
>
> This patch adds support for XDP_REDIRECT. Flush is not
> yet supported.
>
> Signed-off-by: Sunil Goutham <sgoutham@cavium.com>
> Signed-off-by: cjacob <cjacob@caviumnetworks.com>
> Signed-off-by: Aleksey Makarov <aleksey.makarov@cavium.com>
> ---
> drivers/net/ethernet/cavium/thunder/nicvf_main.c | 110 ++++++++++++++++-----
> drivers/net/ethernet/cavium/thunder/nicvf_queues.c | 11 ++-
> drivers/net/ethernet/cavium/thunder/nicvf_queues.h | 4 +
> 3 files changed, 94 insertions(+), 31 deletions(-)
>
> diff --git a/drivers/net/ethernet/cavium/thunder/nicvf_main.c b/drivers/net/ethernet/cavium/thunder/nicvf_main.c
> index a063c36c4c58..b82e28262c57 100644
> --- a/drivers/net/ethernet/cavium/thunder/nicvf_main.c
> +++ b/drivers/net/ethernet/cavium/thunder/nicvf_main.c
> @@ -65,6 +65,11 @@ module_param(cpi_alg, int, S_IRUGO);
> MODULE_PARM_DESC(cpi_alg,
> "PFC algorithm (0=none, 1=VLAN, 2=VLAN16, 3=IP Diffserv)");
>
> +struct nicvf_xdp_tx {
> + u64 dma_addr;
> + u8 qidx;
> +};
> +
[...]

> static inline bool nicvf_xdp_rx(struct nicvf *nic, struct bpf_prog *prog,
> struct cqe_rx_t *cqe_rx, struct snd_queue *sq,
> struct sk_buff **skb)
> {
> struct xdp_buff xdp;
> struct page *page;
> + struct nicvf_xdp_tx *xdp_tx = NULL;
> u32 action;
> - u16 len, offset = 0;
> + u16 len, err, offset = 0;
> u64 dma_addr, cpu_addr;
> void *orig_data;
>
> @@ -521,7 +541,7 @@ static inline bool nicvf_xdp_rx(struct nicvf *nic, struct bpf_prog *prog,
> cpu_addr = (u64)phys_to_virt(cpu_addr);
> page = virt_to_page((void *)cpu_addr);
>
> - xdp.data_hard_start = page_address(page);
> + xdp.data_hard_start = page_address(page) + RCV_BUF_HEADROOM;
> xdp.data = (void *)cpu_addr;
> xdp_set_data_meta_invalid(&xdp);
> xdp.data_end = xdp.data + len;
[...]
> @@ -564,6 +573,20 @@ static inline bool nicvf_xdp_rx(struct nicvf *nic, struct bpf_prog *prog,
> case XDP_TX:
> nicvf_xdp_sq_append_pkt(nic, sq, (u64)xdp.data, dma_addr, len);
> return true;
> + case XDP_REDIRECT:
> + /* Save DMA address for use while transmitting */
> + xdp_tx = (struct nicvf_xdp_tx *)page_address(page);
> + xdp_tx->dma_addr = dma_addr;
> + xdp_tx->qidx = nicvf_netdev_qidx(nic, cqe_rx->rq_idx);

Hey, this sucks... You cannot just invent your own in-driver usage of
the XDP packet headroom. That is specific to your driver only. In
effect you can only XDP_REDIRECT from your driver out your own driver.

The XDP_TX action is for driver/port local redirect. The XDP_REDIRECT
action is between drivers.

> +
> + err = xdp_do_redirect(nic->pnicvf->netdev, &xdp, prog);
> + if (!err)
> + return true;
> +
> + /* Free the page on error */
> + nicvf_unmap_page(nic, page, dma_addr);
> + put_page(page);
> + break;
> default:
> bpf_warn_invalid_xdp_action(action);
> /* fall through */
[...]
> @@ -1764,6 +1776,50 @@ static int nicvf_xdp(struct net_device *netdev, struct netdev_bpf *xdp)
> }
> }
>
> +static int nicvf_xdp_xmit(struct net_device *netdev, struct xdp_buff *xdp)

This is a generic ndo_xdp_xmit that other drivers can call.

> +{
> + struct nicvf *nic = netdev_priv(netdev);
> + struct nicvf *snic = nic;
> + struct nicvf_xdp_tx *xdp_tx;
> + struct snd_queue *sq;
> + struct page *page;
> + int err, qidx;
> +
> + if (!netif_running(netdev) || !nic->xdp_prog)
> + return -EINVAL;
> +
> + page = virt_to_page(xdp->data);
> + xdp_tx = (struct nicvf_xdp_tx *)page_address(page);
> + qidx = xdp_tx->qidx;

What is another driver XDP_REDIRECT a frame to your driver?

> +
> + if (xdp_tx->qidx >= nic->xdp_tx_queues)
> + return -EINVAL;
> +
> + /* Get secondary Qset's info */
> + if (xdp_tx->qidx >= MAX_SND_QUEUES_PER_QS) {
> + qidx = xdp_tx->qidx / MAX_SND_QUEUES_PER_QS;
> + snic = (struct nicvf *)nic->snicvf[qidx - 1];
> + if (!snic)
> + return -EINVAL;
> + qidx = xdp_tx->qidx % MAX_SND_QUEUES_PER_QS;
> + }
> +
> + sq = &snic->qs->sq[qidx];
> + err = nicvf_xdp_sq_append_pkt(snic, sq, (u64)xdp->data,
> + xdp_tx->dma_addr,
> + xdp->data_end - xdp->data);
> + if (err)
> + return -ENOMEM;
> +
> + nicvf_xdp_sq_doorbell(snic, sq, qidx);
> + return 0;
> +}
> +
> +static void nicvf_xdp_flush(struct net_device *dev)
> +{
> + return;
> +}
> +
> static const struct net_device_ops nicvf_netdev_ops = {
> .ndo_open = nicvf_open,
> .ndo_stop = nicvf_stop,
> @@ -1775,6 +1831,8 @@ static const struct net_device_ops nicvf_netdev_ops = {
> .ndo_fix_features = nicvf_fix_features,
> .ndo_set_features = nicvf_set_features,
> .ndo_bpf = nicvf_xdp,
> + .ndo_xdp_xmit = nicvf_xdp_xmit,
> + .ndo_xdp_flush = nicvf_xdp_flush,
> };
[...]


> diff --git a/drivers/net/ethernet/cavium/thunder/nicvf_queues.h b/drivers/net/ethernet/cavium/thunder/nicvf_queues.h
> index 67d1a3230773..178ab6e8e3c5 100644
> --- a/drivers/net/ethernet/cavium/thunder/nicvf_queues.h
> +++ b/drivers/net/ethernet/cavium/thunder/nicvf_queues.h
> @@ -11,6 +11,7 @@
>
> #include <linux/netdevice.h>
> #include <linux/iommu.h>
> +#include <linux/bpf.h>
> #include "q_struct.h"
>
> #define MAX_QUEUE_SET 128
> @@ -92,6 +93,9 @@
> #define RCV_FRAG_LEN (SKB_DATA_ALIGN(DMA_BUFFER_LEN + NET_SKB_PAD) + \
> SKB_DATA_ALIGN(sizeof(struct skb_shared_info)))
>
> +#define RCV_BUF_HEADROOM 128 /* To store dma address for XDP redirect */
> +#define XDP_HEADROOM (XDP_PACKET_HEADROOM + RCV_BUF_HEADROOM)
> +
> #define MAX_CQES_FOR_TX ((SND_QUEUE_LEN / MIN_SQ_DESC_PER_PKT_XMIT) * \
> MAX_CQE_PER_PKT_XMIT)
>



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

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