ionic: implement xdp frags support

Add support for using scatter-gather / frags in XDP in both
Rx and Tx paths.

Co-developed-by: Brett Creeley <brett.creeley@amd.com>
Signed-off-by: Brett Creeley <brett.creeley@amd.com>
Signed-off-by: Shannon Nelson <shannon.nelson@amd.com>
Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Author: emusln

drivers/net/ethernet/pensando/ionic/ionic_lif.c

@@ -881,7 +881,8 @@ static int ionic_lif_rxq_init(struct ionic_lif *lif, struct ionic_qcq *qcq)
 	q->partner = &lif->txqcqs[q->index]->q;
 	q->partner->partner = q;
 
-	if (!lif->xdp_prog)
+	if (!lif->xdp_prog ||
+	    (lif->xdp_prog->aux && lif->xdp_prog->aux->xdp_has_frags))
 		ctx.cmd.q_init.flags |= cpu_to_le16(IONIC_QINIT_F_SG);
 
 	if (qcq->flags & IONIC_QCQ_F_CMB_RINGS) {
@@ -1651,7 +1652,9 @@ static int ionic_init_nic_features(struct ionic_lif *lif)
 
 	netdev->xdp_features = NETDEV_XDP_ACT_BASIC    |
 			       NETDEV_XDP_ACT_REDIRECT |
-			       NETDEV_XDP_ACT_NDO_XMIT;
+			       NETDEV_XDP_ACT_RX_SG    |
+			       NETDEV_XDP_ACT_NDO_XMIT |
+			       NETDEV_XDP_ACT_NDO_XMIT_SG;
 
 	return 0;
 }
@@ -1799,6 +1802,9 @@ static bool ionic_xdp_is_valid_mtu(struct ionic_lif *lif, u32 mtu,
 	if (mtu <= IONIC_XDP_MAX_LINEAR_MTU)
 		return true;
 
+	if (xdp_prog->aux && xdp_prog->aux->xdp_has_frags)
+		return true;
+
 	return false;
 }
 
@@ -2812,7 +2818,7 @@ static int ionic_xdp_config(struct net_device *netdev, struct netdev_bpf *bpf)
 	}
 
 	maxfs = __le32_to_cpu(lif->identity->eth.max_frame_size) - VLAN_ETH_HLEN;
-	if (bpf->prog)
+	if (bpf->prog && !(bpf->prog->aux && bpf->prog->aux->xdp_has_frags))
 		maxfs = min_t(u32, maxfs, IONIC_XDP_MAX_LINEAR_MTU);
 	netdev->max_mtu = maxfs;
 

drivers/net/ethernet/pensando/ionic/ionic_txrx.c

@@ -15,6 +15,13 @@ static int ionic_maybe_stop_tx(struct ionic_queue *q, int ndescs);
 static dma_addr_t ionic_tx_map_single(struct ionic_queue *q,
 				      void *data, size_t len);
 
+static dma_addr_t ionic_tx_map_frag(struct ionic_queue *q,
+				    const skb_frag_t *frag,
+				    size_t offset, size_t len);
+
+static void ionic_tx_desc_unmap_bufs(struct ionic_queue *q,
+				     struct ionic_desc_info *desc_info);
+
 static void ionic_tx_clean(struct ionic_queue *q,
 			   struct ionic_desc_info *desc_info,
 			   struct ionic_cq_info *cq_info,
@@ -313,6 +320,7 @@ static void ionic_xdp_tx_desc_clean(struct ionic_queue *q,
 	unsigned int nbufs = desc_info->nbufs;
 	struct ionic_buf_info *buf_info;
 	struct device *dev = q->dev;
+	int i;
 
 	if (!nbufs)
 		return;
@@ -324,6 +332,15 @@ static void ionic_xdp_tx_desc_clean(struct ionic_queue *q,
 		__free_pages(buf_info->page, 0);
 	buf_info->page = NULL;
 
+	buf_info++;
+	for (i = 1; i < nbufs + 1 && buf_info->page; i++, buf_info++) {
+		dma_unmap_page(dev, buf_info->dma_addr,
+			       buf_info->len, DMA_TO_DEVICE);
+		if (desc_info->act == XDP_TX)
+			__free_pages(buf_info->page, 0);
+		buf_info->page = NULL;
+	}
+
 	if (desc_info->act == XDP_REDIRECT)
 		xdp_return_frame(desc_info->xdpf);
 
@@ -364,8 +381,38 @@ static int ionic_xdp_post_frame(struct net_device *netdev,
 	desc_info->xdpf = frame;
 	desc_info->act = act;
 
+	if (xdp_frame_has_frags(frame)) {
+		struct ionic_txq_sg_elem *elem;
+		struct skb_shared_info *sinfo;
+		struct ionic_buf_info *bi;
+		skb_frag_t *frag;
+		int i;
+
+		bi = &buf_info[1];
+		sinfo = xdp_get_shared_info_from_frame(frame);
+		frag = sinfo->frags;
+		elem = desc_info->txq_sg_desc->elems;
+		for (i = 0; i < sinfo->nr_frags; i++, frag++, bi++) {
+			dma_addr = ionic_tx_map_frag(q, frag, 0, skb_frag_size(frag));
+			if (dma_mapping_error(q->dev, dma_addr)) {
+				stats->dma_map_err++;
+				ionic_tx_desc_unmap_bufs(q, desc_info);
+				return -EIO;
+			}
+			bi->dma_addr = dma_addr;
+			bi->len = skb_frag_size(frag);
+			bi->page = skb_frag_page(frag);
+
+			elem->addr = cpu_to_le64(bi->dma_addr);
+			elem->len = cpu_to_le16(bi->len);
+			elem++;
+
+			desc_info->nbufs++;
+		}
+	}
+
 	cmd = encode_txq_desc_cmd(IONIC_TXQ_DESC_OPCODE_CSUM_NONE,
-				  0, 0, buf_info->dma_addr);
+				  0, (desc_info->nbufs - 1), buf_info->dma_addr);
 	desc->cmd = cpu_to_le64(cmd);
 	desc->len = cpu_to_le16(len);
 	desc->csum_start = 0;
@@ -449,18 +496,58 @@ static bool ionic_run_xdp(struct ionic_rx_stats *stats,
 	struct ionic_queue *txq;
 	struct netdev_queue *nq;
 	struct xdp_frame *xdpf;
+	int remain_len;
+	int frag_len;
 	int err = 0;
 
 	xdp_init_buff(&xdp_buf, IONIC_PAGE_SIZE, rxq->xdp_rxq_info);
+	frag_len = min_t(u16, len, IONIC_XDP_MAX_LINEAR_MTU + VLAN_ETH_HLEN);
 	xdp_prepare_buff(&xdp_buf, ionic_rx_buf_va(buf_info),
-			 XDP_PACKET_HEADROOM, len, false);
+			 XDP_PACKET_HEADROOM, frag_len, false);
 
 	dma_sync_single_range_for_cpu(rxq->dev, ionic_rx_buf_pa(buf_info),
 				      XDP_PACKET_HEADROOM, len,
 				      DMA_FROM_DEVICE);
 
 	prefetchw(&xdp_buf.data_hard_start);
 
+	/*  We limit MTU size to one buffer if !xdp_has_frags, so
+	 *  if the recv len is bigger than one buffer
+	 *     then we know we have frag info to gather
+	 */
+	remain_len = len - frag_len;
+	if (remain_len) {
+		struct skb_shared_info *sinfo;
+		struct ionic_buf_info *bi;
+		skb_frag_t *frag;
+
+		bi = buf_info;
+		sinfo = xdp_get_shared_info_from_buff(&xdp_buf);
+		sinfo->nr_frags = 0;
+		sinfo->xdp_frags_size = 0;
+		xdp_buff_set_frags_flag(&xdp_buf);
+
+		do {
+			if (unlikely(sinfo->nr_frags >= MAX_SKB_FRAGS)) {
+				err = -ENOSPC;
+				goto out_xdp_abort;
+			}
+
+			frag = &sinfo->frags[sinfo->nr_frags];
+			sinfo->nr_frags++;
+			bi++;
+			frag_len = min_t(u16, remain_len, ionic_rx_buf_size(bi));
+			dma_sync_single_range_for_cpu(rxq->dev, ionic_rx_buf_pa(bi),
+						      0, frag_len, DMA_FROM_DEVICE);
+			skb_frag_fill_page_desc(frag, bi->page, 0, frag_len);
+			sinfo->xdp_frags_size += frag_len;
+			remain_len -= frag_len;
+
+			if (page_is_pfmemalloc(bi->page))
+				xdp_buff_set_frag_pfmemalloc(&xdp_buf);
+		} while (remain_len > 0);
+	}
+
 	xdp_action = bpf_prog_run_xdp(xdp_prog, &xdp_buf);
 
 	switch (xdp_action) {