> -----Original Message-----
> From: Maciej Fijalkowski <maciej.fijalkow...@intel.com>
> Sent: Tuesday, November 24, 2020 21:52
> To: Camelia Alexandra Groza <camelia.gr...@nxp.com>
> Cc: k...@kernel.org; bro...@redhat.com; sa...@kernel.org;
> da...@davemloft.net; Madalin Bucur (OSS)
> <madalin.bu...@oss.nxp.com>; Ioana Ciornei <ioana.cior...@nxp.com>;
> netdev@vger.kernel.org
> Subject: Re: [PATCH net-next v4 4/7] dpaa_eth: add XDP_TX support
>
> On Mon, Nov 23, 2020 at 07:36:22PM +0200, Camelia Groza wrote:
> > Use an xdp_frame structure for managing the frame. Store a backpointer
> to
> > the structure at the start of the buffer before enqueueing for cleanup
> > on TX confirmation. Reserve DPAA_TX_PRIV_DATA_SIZE bytes from the
> frame
> > size shared with the XDP program for this purpose. Use the XDP
> > API for freeing the buffer when it returns to the driver on the TX
> > confirmation path.
> >
> > The frame queues are shared with the netstack.
>
> Can you also provide the info from cover letter about locklessness (is
> that even a word?) in here?
Sure.
> One question below and:
>
> Reviewed-by: Maciej Fijalkowski <maciej.fijalkow...@intel.com>
>
> >
> > This approach will be reused for XDP REDIRECT.
> >
> > Acked-by: Madalin Bucur <madalin.bu...@oss.nxp.com>
> > Signed-off-by: Camelia Groza <camelia.gr...@nxp.com>
> > ---
> > Changes in v4:
> > - call xdp_rxq_info_is_reg() before unregistering
> > - minor cleanups (remove unneeded variable, print error code)
> > - add more details in the commit message
> > - did not call qman_destroy_fq() in case of xdp_rxq_info_reg() failure
> > since it would lead to a double free of the fq resources
> >
> > drivers/net/ethernet/freescale/dpaa/dpaa_eth.c | 128
> ++++++++++++++++++++++++-
> > drivers/net/ethernet/freescale/dpaa/dpaa_eth.h | 2 +
> > 2 files changed, 125 insertions(+), 5 deletions(-)
> >
> > diff --git a/drivers/net/ethernet/freescale/dpaa/dpaa_eth.c
> b/drivers/net/ethernet/freescale/dpaa/dpaa_eth.c
> > index ee076f4..0deffcc 100644
> > --- a/drivers/net/ethernet/freescale/dpaa/dpaa_eth.c
> > +++ b/drivers/net/ethernet/freescale/dpaa/dpaa_eth.c
> > @@ -1130,6 +1130,24 @@ static int dpaa_fq_init(struct dpaa_fq *dpaa_fq,
> bool td_enable)
> >
> > dpaa_fq->fqid = qman_fq_fqid(fq);
> >
> > + if (dpaa_fq->fq_type == FQ_TYPE_RX_DEFAULT ||
> > + dpaa_fq->fq_type == FQ_TYPE_RX_PCD) {
> > + err = xdp_rxq_info_reg(&dpaa_fq->xdp_rxq, dpaa_fq-
> >net_dev,
> > + dpaa_fq->fqid);
> > + if (err) {
> > + dev_err(dev, "xdp_rxq_info_reg() = %d\n", err);
> > + return err;
> > + }
> > +
> > + err = xdp_rxq_info_reg_mem_model(&dpaa_fq->xdp_rxq,
> > + MEM_TYPE_PAGE_ORDER0,
> NULL);
> > + if (err) {
> > + dev_err(dev, "xdp_rxq_info_reg_mem_model() =
> %d\n", err);
> > + xdp_rxq_info_unreg(&dpaa_fq->xdp_rxq);
> > + return err;
> > + }
> > + }
> > +
> > return 0;
> > }
> >
> > @@ -1159,6 +1177,11 @@ static int dpaa_fq_free_entry(struct device
> *dev, struct qman_fq *fq)
> > }
> > }
> >
> > + if ((dpaa_fq->fq_type == FQ_TYPE_RX_DEFAULT ||
> > + dpaa_fq->fq_type == FQ_TYPE_RX_PCD) &&
> > + xdp_rxq_info_is_reg(&dpaa_fq->xdp_rxq))
> > + xdp_rxq_info_unreg(&dpaa_fq->xdp_rxq);
> > +
> > qman_destroy_fq(fq);
> > list_del(&dpaa_fq->list);
> >
> > @@ -1625,6 +1648,9 @@ static int dpaa_eth_refill_bpools(struct dpaa_priv
> *priv)
> > *
> > * Return the skb backpointer, since for S/G frames the buffer containing
> > it
> > * gets freed here.
> > + *
> > + * No skb backpointer is set when transmitting XDP frames. Cleanup the
> buffer
> > + * and return NULL in this case.
> > */
> > static struct sk_buff *dpaa_cleanup_tx_fd(const struct dpaa_priv *priv,
> > const struct qm_fd *fd, bool ts)
> > @@ -1664,13 +1690,21 @@ static struct sk_buff
> *dpaa_cleanup_tx_fd(const struct dpaa_priv *priv,
> > }
> > } else {
> > dma_unmap_single(priv->tx_dma_dev, addr,
> > - priv->tx_headroom +
> qm_fd_get_length(fd),
> > + qm_fd_get_offset(fd) +
> qm_fd_get_length(fd),
> > dma_dir);
> > }
> >
> > swbp = (struct dpaa_eth_swbp *)vaddr;
> > skb = swbp->skb;
> >
> > + /* No skb backpointer is set when running XDP. An xdp_frame
> > + * backpointer is saved instead.
> > + */
> > + if (!skb) {
> > + xdp_return_frame(swbp->xdpf);
> > + return NULL;
> > + }
> > +
> > /* DMA unmapping is required before accessing the HW provided
> info */
> > if (ts && priv->tx_tstamp &&
> > skb_shinfo(skb)->tx_flags & SKBTX_HW_TSTAMP) {
> > @@ -2350,11 +2384,76 @@ static enum qman_cb_dqrr_result
> rx_error_dqrr(struct qman_portal *portal,
> > return qman_cb_dqrr_consume;
> > }
> >
> > +static int dpaa_xdp_xmit_frame(struct net_device *net_dev,
> > + struct xdp_frame *xdpf)
> > +{
> > + struct dpaa_priv *priv = netdev_priv(net_dev);
> > + struct rtnl_link_stats64 *percpu_stats;
> > + struct dpaa_percpu_priv *percpu_priv;
> > + struct dpaa_eth_swbp *swbp;
> > + struct netdev_queue *txq;
> > + void *buff_start;
> > + struct qm_fd fd;
> > + dma_addr_t addr;
> > + int err;
> > +
> > + percpu_priv = this_cpu_ptr(priv->percpu_priv);
> > + percpu_stats = &percpu_priv->stats;
> > +
> > + if (xdpf->headroom < DPAA_TX_PRIV_DATA_SIZE) {
> > + err = -EINVAL;
> > + goto out_error;
> > + }
> > +
> > + buff_start = xdpf->data - xdpf->headroom;
> > +
> > + /* Leave empty the skb backpointer at the start of the buffer.
> > + * Save the XDP frame for easy cleanup on confirmation.
> > + */
> > + swbp = (struct dpaa_eth_swbp *)buff_start;
> > + swbp->skb = NULL;
> > + swbp->xdpf = xdpf;
> > +
> > + qm_fd_clear_fd(&fd);
> > + fd.bpid = FSL_DPAA_BPID_INV;
> > + fd.cmd |= cpu_to_be32(FM_FD_CMD_FCO);
> > + qm_fd_set_contig(&fd, xdpf->headroom, xdpf->len);
> > +
> > + addr = dma_map_single(priv->tx_dma_dev, buff_start,
> > + xdpf->headroom + xdpf->len,
> > + DMA_TO_DEVICE);
>
> Not sure if I asked that. What is the purpose for including the headroom
> in frame being set? I would expect to take into account only frame from
> xdpf->data.
The xdpf headroom becomes the fd's offset, the area before the data where the
backpointers for cleanup are stored. This area isn't sent out with the frame.
> > + if (unlikely(dma_mapping_error(priv->tx_dma_dev, addr))) {
> > + err = -EINVAL;
> > + goto out_error;
> > + }
> > +
> > + qm_fd_addr_set64(&fd, addr);
> > +
> > + /* Bump the trans_start */
> > + txq = netdev_get_tx_queue(net_dev, smp_processor_id());
> > + txq->trans_start = jiffies;
> > +
> > + err = dpaa_xmit(priv, percpu_stats, smp_processor_id(), &fd);
> > + if (err) {
> > + dma_unmap_single(priv->tx_dma_dev, addr,
> > + qm_fd_get_offset(&fd) +
> qm_fd_get_length(&fd),
> > + DMA_TO_DEVICE);
> > + goto out_error;
> > + }
> > +
> > + return 0;
> > +
> > +out_error:
> > + percpu_stats->tx_errors++;
> > + return err;
> > +}
> > +
> > static u32 dpaa_run_xdp(struct dpaa_priv *priv, struct qm_fd *fd, void
> *vaddr,
> > - unsigned int *xdp_meta_len)
> > + struct dpaa_fq *dpaa_fq, unsigned int
> *xdp_meta_len)
> > {
> > ssize_t fd_off = qm_fd_get_offset(fd);
> > struct bpf_prog *xdp_prog;
> > + struct xdp_frame *xdpf;
> > struct xdp_buff xdp;
> > u32 xdp_act;
> >
> > @@ -2370,7 +2469,8 @@ static u32 dpaa_run_xdp(struct dpaa_priv *priv,
> struct qm_fd *fd, void *vaddr,
> > xdp.data_meta = xdp.data;
> > xdp.data_hard_start = xdp.data - XDP_PACKET_HEADROOM;
> > xdp.data_end = xdp.data + qm_fd_get_length(fd);
> > - xdp.frame_sz = DPAA_BP_RAW_SIZE;
> > + xdp.frame_sz = DPAA_BP_RAW_SIZE - DPAA_TX_PRIV_DATA_SIZE;
> > + xdp.rxq = &dpaa_fq->xdp_rxq;
> >
> > xdp_act = bpf_prog_run_xdp(xdp_prog, &xdp);
> >
> > @@ -2381,6 +2481,22 @@ static u32 dpaa_run_xdp(struct dpaa_priv *priv,
> struct qm_fd *fd, void *vaddr,
> > case XDP_PASS:
> > *xdp_meta_len = xdp.data - xdp.data_meta;
> > break;
> > + case XDP_TX:
> > + /* We can access the full headroom when sending the frame
> > + * back out
> > + */
> > + xdp.data_hard_start = vaddr;
> > + xdp.frame_sz = DPAA_BP_RAW_SIZE;
> > + xdpf = xdp_convert_buff_to_frame(&xdp);
> > + if (unlikely(!xdpf)) {
> > + free_pages((unsigned long)vaddr, 0);
> > + break;
> > + }
> > +
> > + if (dpaa_xdp_xmit_frame(priv->net_dev, xdpf))
> > + xdp_return_frame_rx_napi(xdpf);
> > +
> > + break;
> > default:
> > bpf_warn_invalid_xdp_action(xdp_act);
> > fallthrough;
> > @@ -2415,6 +2531,7 @@ static enum qman_cb_dqrr_result
> rx_default_dqrr(struct qman_portal *portal,
> > u32 fd_status, hash_offset;
> > struct qm_sg_entry *sgt;
> > struct dpaa_bp *dpaa_bp;
> > + struct dpaa_fq *dpaa_fq;
> > struct dpaa_priv *priv;
> > struct sk_buff *skb;
> > int *count_ptr;
> > @@ -2423,9 +2540,10 @@ static enum qman_cb_dqrr_result
> rx_default_dqrr(struct qman_portal *portal,
> > u32 hash;
> > u64 ns;
> >
> > + dpaa_fq = container_of(fq, struct dpaa_fq, fq_base);
> > fd_status = be32_to_cpu(fd->status);
> > fd_format = qm_fd_get_format(fd);
> > - net_dev = ((struct dpaa_fq *)fq)->net_dev;
> > + net_dev = dpaa_fq->net_dev;
> > priv = netdev_priv(net_dev);
> > dpaa_bp = dpaa_bpid2pool(dq->fd.bpid);
> > if (!dpaa_bp)
> > @@ -2494,7 +2612,7 @@ static enum qman_cb_dqrr_result
> rx_default_dqrr(struct qman_portal *portal,
> >
> > if (likely(fd_format == qm_fd_contig)) {
> > xdp_act = dpaa_run_xdp(priv, (struct qm_fd *)fd, vaddr,
> > - &xdp_meta_len);
> > + dpaa_fq, &xdp_meta_len);
> > if (xdp_act != XDP_PASS) {
> > percpu_stats->rx_packets++;
> > percpu_stats->rx_bytes += qm_fd_get_length(fd);
> > diff --git a/drivers/net/ethernet/freescale/dpaa/dpaa_eth.h
> b/drivers/net/ethernet/freescale/dpaa/dpaa_eth.h
> > index 94e8613..5c8d52a 100644
> > --- a/drivers/net/ethernet/freescale/dpaa/dpaa_eth.h
> > +++ b/drivers/net/ethernet/freescale/dpaa/dpaa_eth.h
> > @@ -68,6 +68,7 @@ struct dpaa_fq {
> > u16 channel;
> > u8 wq;
> > enum dpaa_fq_type fq_type;
> > + struct xdp_rxq_info xdp_rxq;
> > };
> >
> > struct dpaa_fq_cbs {
> > @@ -150,6 +151,7 @@ struct dpaa_buffer_layout {
> > */
> > struct dpaa_eth_swbp {
> > struct sk_buff *skb;
> > + struct xdp_frame *xdpf;
> > };
> >
> > struct dpaa_priv {
> > --
> > 1.9.1
> >
