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net: dpaa2-eth: AF_XDP TX zero copy support
authorRobert-Ionut Alexa <robert-ionut.alexa@nxp.com>
Tue, 18 Oct 2022 14:19:00 +0000 (17:19 +0300)
committerDavid S. Miller <davem@davemloft.net>
Mon, 24 Oct 2022 08:22:11 +0000 (09:22 +0100)
Add support in dpaa2-eth for packet processing on the Tx path using
AF_XDP zero copy mode.

The newly added dpaa2_xsk_tx() function will handle enqueuing AF_XDP Tx
packets into the appropriate queue and update any necessary statistics.

On a more detailed note, the dpaa2_xsk_tx_build_fd() function handles
creating a Scatter-Gather frame descriptor with only one data buffer.
This is needed because otherwise we would need to impose a headroom in
the Tx buffer to store our software annotation structures.
This tactic is already used on the normal data path of the dpaa2-eth
driver, thus we are reusing the dpaa2_eth_sgt_get/dpaa2_eth_sgt_recycle
functions in order to allocate and recycle the Scatter-Gather table
buffers.

In case we have reached the maximum number of Tx XSK packets to be sent
in a NAPI cycle, we'll exit the dpaa2_eth_poll() and hope to be
rescheduled again.

On the XSK Tx confirmation path, we are just unmapping the SGT buffer
and recycle it for further use.

Signed-off-by: Robert-Ionut Alexa <robert-ionut.alexa@nxp.com>
Signed-off-by: Ioana Ciornei <ioana.ciornei@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.c
drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.h
drivers/net/ethernet/freescale/dpaa2/dpaa2-xsk.c

index 4c340f7..31eebea 100644 (file)
@@ -858,7 +858,7 @@ static void dpaa2_eth_enable_tx_tstamp(struct dpaa2_eth_priv *priv,
        }
 }
 
-static void *dpaa2_eth_sgt_get(struct dpaa2_eth_priv *priv)
+void *dpaa2_eth_sgt_get(struct dpaa2_eth_priv *priv)
 {
        struct dpaa2_eth_sgt_cache *sgt_cache;
        void *sgt_buf = NULL;
@@ -880,7 +880,7 @@ static void *dpaa2_eth_sgt_get(struct dpaa2_eth_priv *priv)
        return sgt_buf;
 }
 
-static void dpaa2_eth_sgt_recycle(struct dpaa2_eth_priv *priv, void *sgt_buf)
+void dpaa2_eth_sgt_recycle(struct dpaa2_eth_priv *priv, void *sgt_buf)
 {
        struct dpaa2_eth_sgt_cache *sgt_cache;
 
@@ -1115,9 +1115,10 @@ static int dpaa2_eth_build_single_fd(struct dpaa2_eth_priv *priv,
  * This can be called either from dpaa2_eth_tx_conf() or on the error path of
  * dpaa2_eth_tx().
  */
-static void dpaa2_eth_free_tx_fd(struct dpaa2_eth_priv *priv,
-                                struct dpaa2_eth_fq *fq,
-                                const struct dpaa2_fd *fd, bool in_napi)
+void dpaa2_eth_free_tx_fd(struct dpaa2_eth_priv *priv,
+                         struct dpaa2_eth_channel *ch,
+                         struct dpaa2_eth_fq *fq,
+                         const struct dpaa2_fd *fd, bool in_napi)
 {
        struct device *dev = priv->net_dev->dev.parent;
        dma_addr_t fd_addr, sg_addr;
@@ -1184,6 +1185,10 @@ static void dpaa2_eth_free_tx_fd(struct dpaa2_eth_priv *priv,
 
                        if (!swa->tso.is_last_fd)
                                should_free_skb = 0;
+               } else if (swa->type == DPAA2_ETH_SWA_XSK) {
+                       /* Unmap the SGT Buffer */
+                       dma_unmap_single(dev, fd_addr, swa->xsk.sgt_size,
+                                        DMA_BIDIRECTIONAL);
                } else {
                        skb = swa->single.skb;
 
@@ -1201,6 +1206,12 @@ static void dpaa2_eth_free_tx_fd(struct dpaa2_eth_priv *priv,
                return;
        }
 
+       if (swa->type == DPAA2_ETH_SWA_XSK) {
+               ch->xsk_tx_pkts_sent++;
+               dpaa2_eth_sgt_recycle(priv, buffer_start);
+               return;
+       }
+
        if (swa->type != DPAA2_ETH_SWA_XDP && in_napi) {
                fq->dq_frames++;
                fq->dq_bytes += fd_len;
@@ -1375,7 +1386,7 @@ err_alloc_tso_hdr:
 err_sgt_get:
        /* Free all the other FDs that were already fully created */
        for (i = 0; i < index; i++)
-               dpaa2_eth_free_tx_fd(priv, NULL, &fd_start[i], false);
+               dpaa2_eth_free_tx_fd(priv, NULL, NULL, &fd_start[i], false);
 
        return err;
 }
@@ -1491,7 +1502,7 @@ static netdev_tx_t __dpaa2_eth_tx(struct sk_buff *skb,
        if (unlikely(err < 0)) {
                percpu_stats->tx_errors++;
                /* Clean up everything, including freeing the skb */
-               dpaa2_eth_free_tx_fd(priv, fq, fd, false);
+               dpaa2_eth_free_tx_fd(priv, NULL, fq, fd, false);
                netdev_tx_completed_queue(nq, 1, fd_len);
        } else {
                percpu_stats->tx_packets += total_enqueued;
@@ -1584,7 +1595,7 @@ static void dpaa2_eth_tx_conf(struct dpaa2_eth_priv *priv,
 
        /* Check frame errors in the FD field */
        fd_errors = dpaa2_fd_get_ctrl(fd) & DPAA2_FD_TX_ERR_MASK;
-       dpaa2_eth_free_tx_fd(priv, fq, fd, true);
+       dpaa2_eth_free_tx_fd(priv, ch, fq, fd, true);
 
        if (likely(!fd_errors))
                return;
@@ -1929,6 +1940,7 @@ static int dpaa2_eth_poll(struct napi_struct *napi, int budget)
        struct dpaa2_eth_fq *fq, *txc_fq = NULL;
        struct netdev_queue *nq;
        int store_cleaned, work_done;
+       bool work_done_zc = false;
        struct list_head rx_list;
        int retries = 0;
        u16 flowid;
@@ -1941,6 +1953,15 @@ static int dpaa2_eth_poll(struct napi_struct *napi, int budget)
        INIT_LIST_HEAD(&rx_list);
        ch->rx_list = &rx_list;
 
+       if (ch->xsk_zc) {
+               work_done_zc = dpaa2_xsk_tx(priv, ch);
+               /* If we reached the XSK Tx per NAPI threshold, we're done */
+               if (work_done_zc) {
+                       work_done = budget;
+                       goto out;
+               }
+       }
+
        do {
                err = dpaa2_eth_pull_channel(ch);
                if (unlikely(err))
@@ -1993,6 +2014,11 @@ static int dpaa2_eth_poll(struct napi_struct *napi, int budget)
 out:
        netif_receive_skb_list(ch->rx_list);
 
+       if (ch->xsk_tx_pkts_sent) {
+               xsk_tx_completed(ch->xsk_pool, ch->xsk_tx_pkts_sent);
+               ch->xsk_tx_pkts_sent = 0;
+       }
+
        if (txc_fq && txc_fq->dq_frames) {
                nq = netdev_get_tx_queue(priv->net_dev, txc_fq->flowid);
                netdev_tx_completed_queue(nq, txc_fq->dq_frames,
@@ -2989,7 +3015,11 @@ static void dpaa2_eth_cdan_cb(struct dpaa2_io_notification_ctx *ctx)
        /* Update NAPI statistics */
        ch->stats.cdan++;
 
-       napi_schedule(&ch->napi);
+       /* NAPI can also be scheduled from the AF_XDP Tx path. Mark a missed
+        * so that it can be rescheduled again.
+        */
+       if (!napi_if_scheduled_mark_missed(&ch->napi))
+               napi_schedule(&ch->napi);
 }
 
 /* Allocate and configure a DPCON object */
index 38f67b9..5d0fc43 100644 (file)
  */
 #define DPAA2_ETH_TXCONF_PER_NAPI      256
 
+/* Maximum number of Tx frames to be processed in a single NAPI
+ * call when AF_XDP is running. Bind it to DPAA2_ETH_TXCONF_PER_NAPI
+ * to maximize the throughput.
+ */
+#define DPAA2_ETH_TX_ZC_PER_NAPI       DPAA2_ETH_TXCONF_PER_NAPI
+
 /* Buffer qouta per channel. We want to keep in check number of ingress frames
  * in flight: for small sized frames, congestion group taildrop may kick in
  * first; for large sizes, Rx FQ taildrop threshold will ensure only a
@@ -154,6 +160,7 @@ struct dpaa2_eth_swa {
                } xdp;
                struct {
                        struct xdp_buff *xdp_buff;
+                       int sgt_size;
                } xsk;
                struct {
                        struct sk_buff *skb;
@@ -495,6 +502,7 @@ struct dpaa2_eth_channel {
        int recycled_bufs_cnt;
 
        bool xsk_zc;
+       int xsk_tx_pkts_sent;
        struct xsk_buff_pool *xsk_pool;
        struct dpaa2_eth_bp *bp;
 };
@@ -531,7 +539,7 @@ struct dpaa2_eth_trap_data {
 
 #define DPAA2_ETH_DEFAULT_COPYBREAK    512
 
-#define DPAA2_ETH_ENQUEUE_MAX_FDS      200
+#define DPAA2_ETH_ENQUEUE_MAX_FDS      256
 struct dpaa2_eth_fds {
        struct dpaa2_fd array[DPAA2_ETH_ENQUEUE_MAX_FDS];
 };
@@ -836,4 +844,16 @@ void dpaa2_eth_xdp_enqueue(struct dpaa2_eth_priv *priv,
 int dpaa2_xsk_wakeup(struct net_device *dev, u32 qid, u32 flags);
 int dpaa2_xsk_setup_pool(struct net_device *dev, struct xsk_buff_pool *pool, u16 qid);
 
+void dpaa2_eth_free_tx_fd(struct dpaa2_eth_priv *priv,
+                         struct dpaa2_eth_channel *ch,
+                         struct dpaa2_eth_fq *fq,
+                         const struct dpaa2_fd *fd, bool in_napi);
+bool dpaa2_xsk_tx(struct dpaa2_eth_priv *priv,
+                 struct dpaa2_eth_channel *ch);
+
+/* SGT (Scatter-Gather Table) cache management */
+void *dpaa2_eth_sgt_get(struct dpaa2_eth_priv *priv);
+
+void dpaa2_eth_sgt_recycle(struct dpaa2_eth_priv *priv, void *sgt_buf);
+
 #endif /* __DPAA2_H */
index 2df7bff..7313188 100644 (file)
@@ -196,6 +196,7 @@ static int dpaa2_xsk_disable_pool(struct net_device *dev, u16 qid)
 
        ch->xsk_zc = false;
        ch->xsk_pool = NULL;
+       ch->xsk_tx_pkts_sent = 0;
        ch->bp = priv->bp[DPAA2_ETH_DEFAULT_BP_IDX];
 
        dpaa2_eth_setup_consume_func(priv, ch, DPAA2_RX_FQ, dpaa2_eth_rx);
@@ -325,3 +326,125 @@ int dpaa2_xsk_wakeup(struct net_device *dev, u32 qid, u32 flags)
 
        return 0;
 }
+
+static int dpaa2_xsk_tx_build_fd(struct dpaa2_eth_priv *priv,
+                                struct dpaa2_eth_channel *ch,
+                                struct dpaa2_fd *fd,
+                                struct xdp_desc *xdp_desc)
+{
+       struct device *dev = priv->net_dev->dev.parent;
+       struct dpaa2_sg_entry *sgt;
+       struct dpaa2_eth_swa *swa;
+       void *sgt_buf = NULL;
+       dma_addr_t sgt_addr;
+       int sgt_buf_size;
+       dma_addr_t addr;
+       int err = 0;
+
+       /* Prepare the HW SGT structure */
+       sgt_buf_size = priv->tx_data_offset + sizeof(struct dpaa2_sg_entry);
+       sgt_buf = dpaa2_eth_sgt_get(priv);
+       if (unlikely(!sgt_buf))
+               return -ENOMEM;
+       sgt = (struct dpaa2_sg_entry *)(sgt_buf + priv->tx_data_offset);
+
+       /* Get the address of the XSK Tx buffer */
+       addr = xsk_buff_raw_get_dma(ch->xsk_pool, xdp_desc->addr);
+       xsk_buff_raw_dma_sync_for_device(ch->xsk_pool, addr, xdp_desc->len);
+
+       /* Fill in the HW SGT structure */
+       dpaa2_sg_set_addr(sgt, addr);
+       dpaa2_sg_set_len(sgt, xdp_desc->len);
+       dpaa2_sg_set_final(sgt, true);
+
+       /* Store the necessary info in the SGT buffer */
+       swa = (struct dpaa2_eth_swa *)sgt_buf;
+       swa->type = DPAA2_ETH_SWA_XSK;
+       swa->xsk.sgt_size = sgt_buf_size;
+
+       /* Separately map the SGT buffer */
+       sgt_addr = dma_map_single(dev, sgt_buf, sgt_buf_size, DMA_BIDIRECTIONAL);
+       if (unlikely(dma_mapping_error(dev, sgt_addr))) {
+               err = -ENOMEM;
+               goto sgt_map_failed;
+       }
+
+       /* Initialize FD fields */
+       memset(fd, 0, sizeof(struct dpaa2_fd));
+       dpaa2_fd_set_offset(fd, priv->tx_data_offset);
+       dpaa2_fd_set_format(fd, dpaa2_fd_sg);
+       dpaa2_fd_set_addr(fd, sgt_addr);
+       dpaa2_fd_set_len(fd, xdp_desc->len);
+       dpaa2_fd_set_ctrl(fd, FD_CTRL_PTA);
+
+       return 0;
+
+sgt_map_failed:
+       dpaa2_eth_sgt_recycle(priv, sgt_buf);
+
+       return err;
+}
+
+bool dpaa2_xsk_tx(struct dpaa2_eth_priv *priv,
+                 struct dpaa2_eth_channel *ch)
+{
+       struct xdp_desc *xdp_descs = ch->xsk_pool->tx_descs;
+       struct dpaa2_eth_drv_stats *percpu_extras;
+       struct rtnl_link_stats64 *percpu_stats;
+       int budget = DPAA2_ETH_TX_ZC_PER_NAPI;
+       int total_enqueued, enqueued;
+       int retries, max_retries;
+       struct dpaa2_eth_fq *fq;
+       struct dpaa2_fd *fds;
+       int batch, i, err;
+
+       percpu_stats = this_cpu_ptr(priv->percpu_stats);
+       percpu_extras = this_cpu_ptr(priv->percpu_extras);
+       fds = (this_cpu_ptr(priv->fd))->array;
+
+       /* Use the FQ with the same idx as the affine CPU */
+       fq = &priv->fq[ch->nctx.desired_cpu];
+
+       batch = xsk_tx_peek_release_desc_batch(ch->xsk_pool, budget);
+       if (!batch)
+               return false;
+
+       /* Create a FD for each XSK frame to be sent */
+       for (i = 0; i < batch; i++) {
+               err = dpaa2_xsk_tx_build_fd(priv, ch, &fds[i], &xdp_descs[i]);
+               if (err) {
+                       batch = i;
+                       break;
+               }
+       }
+
+       /* Enqueue all the created FDs */
+       max_retries = batch * DPAA2_ETH_ENQUEUE_RETRIES;
+       total_enqueued = 0;
+       enqueued = 0;
+       retries = 0;
+       while (total_enqueued < batch && retries < max_retries) {
+               err = priv->enqueue(priv, fq, &fds[total_enqueued], 0,
+                                   batch - total_enqueued, &enqueued);
+               if (err == -EBUSY) {
+                       retries++;
+                       continue;
+               }
+
+               total_enqueued += enqueued;
+       }
+       percpu_extras->tx_portal_busy += retries;
+
+       /* Update statistics */
+       percpu_stats->tx_packets += total_enqueued;
+       for (i = 0; i < total_enqueued; i++)
+               percpu_stats->tx_bytes += dpaa2_fd_get_len(&fds[i]);
+       for (i = total_enqueued; i < batch; i++) {
+               dpaa2_eth_free_tx_fd(priv, ch, fq, &fds[i], false);
+               percpu_stats->tx_errors++;
+       }
+
+       xsk_tx_release(ch->xsk_pool);
+
+       return total_enqueued == budget ? true : false;
+}