net: atlantic: Implement xdp data plane

It supports XDP_PASS, XDP_DROP and multi buffer.

The new function aq_nic_xmit_xdpf() is used to send packet with
xdp_frame and internally it calls aq_nic_map_xdp().

AQC chip supports 32 multi-queues and 8 vectors(irq).
there are two option
1. under 8 cores and 4 tx queues per core.
2. under 4 cores and 8 tx queues per core.

Like ixgbe, these tx queues can be used only for XDP_TX, XDP_REDIRECT
queue. If so, no tx_lock is needed.
But this patchset doesn't use this strategy because getting hardware tx
queue index cost is too high.
So, tx_lock is used in the aq_nic_xmit_xdpf().

single-core, single queue, 80% cpu utilization.

  30.75%  bpf_prog_xxx_xdp_prog_tx  [k] bpf_prog_xxx_xdp_prog_tx
  10.35%  [kernel]                  [k] aq_hw_read_reg <---------- here
   4.38%  [kernel]                  [k] get_page_from_freelist

single-core, 8 queues, 100% cpu utilization, half PPS.

  45.56%  [kernel]                  [k] aq_hw_read_reg <---------- here
  17.58%  bpf_prog_xxx_xdp_prog_tx  [k] bpf_prog_xxx_xdp_prog_tx
   4.72%  [kernel]                  [k] hw_atl_b0_hw_ring_rx_receive

The new function __aq_ring_xdp_clean() is a xdp rx handler and this is
called only when XDP is attached.

Signed-off-by: Taehee Yoo <ap420073@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/aquantia/atlantic/aq_ethtool.c

@@ -97,6 +97,15 @@ static const char * const aq_ethtool_queue_rx_stat_names[] = {
 	"%sQueue[%d] AllocFails",
 	"%sQueue[%d] SkbAllocFails",
 	"%sQueue[%d] Polls",
+	"%sQueue[%d] PageFlips",
+	"%sQueue[%d] PageReuses",
+	"%sQueue[%d] PageFrees",
+	"%sQueue[%d] XdpAbort",
+	"%sQueue[%d] XdpDrop",
+	"%sQueue[%d] XdpPass",
+	"%sQueue[%d] XdpTx",
+	"%sQueue[%d] XdpInvalid",
+	"%sQueue[%d] XdpRedirect",
 };
 
 static const char * const aq_ethtool_queue_tx_stat_names[] = {

drivers/net/ethernet/aquantia/atlantic/aq_nic.c

@@ -569,6 +569,103 @@ int aq_nic_start(struct aq_nic_s *self)
 	return err;
 }
 
+static unsigned int aq_nic_map_xdp(struct aq_nic_s *self,
+				   struct xdp_frame *xdpf,
+				   struct aq_ring_s *ring)
+{
+	struct device *dev = aq_nic_get_dev(self);
+	struct aq_ring_buff_s *first = NULL;
+	unsigned int dx = ring->sw_tail;
+	struct aq_ring_buff_s *dx_buff;
+	struct skb_shared_info *sinfo;
+	unsigned int frag_count = 0U;
+	unsigned int nr_frags = 0U;
+	unsigned int ret = 0U;
+	u16 total_len;
+
+	dx_buff = &ring->buff_ring[dx];
+	dx_buff->flags = 0U;
+
+	sinfo = xdp_get_shared_info_from_frame(xdpf);
+	total_len = xdpf->len;
+	dx_buff->len = total_len;
+	if (xdp_frame_has_frags(xdpf)) {
+		nr_frags = sinfo->nr_frags;
+		total_len += sinfo->xdp_frags_size;
+	}
+	dx_buff->pa = dma_map_single(dev, xdpf->data, dx_buff->len,
+				     DMA_TO_DEVICE);
+
+	if (unlikely(dma_mapping_error(dev, dx_buff->pa)))
+		goto exit;
+
+	first = dx_buff;
+	dx_buff->len_pkt = total_len;
+	dx_buff->is_sop = 1U;
+	dx_buff->is_mapped = 1U;
+	++ret;
+
+	for (; nr_frags--; ++frag_count) {
+		skb_frag_t *frag = &sinfo->frags[frag_count];
+		unsigned int frag_len = skb_frag_size(frag);
+		unsigned int buff_offset = 0U;
+		unsigned int buff_size = 0U;
+		dma_addr_t frag_pa;
+
+		while (frag_len) {
+			if (frag_len > AQ_CFG_TX_FRAME_MAX)
+				buff_size = AQ_CFG_TX_FRAME_MAX;
+			else
+				buff_size = frag_len;
+
+			frag_pa = skb_frag_dma_map(dev, frag, buff_offset,
+						   buff_size, DMA_TO_DEVICE);
+
+			if (unlikely(dma_mapping_error(dev, frag_pa)))
+				goto mapping_error;
+
+			dx = aq_ring_next_dx(ring, dx);
+			dx_buff = &ring->buff_ring[dx];
+
+			dx_buff->flags = 0U;
+			dx_buff->len = buff_size;
+			dx_buff->pa = frag_pa;
+			dx_buff->is_mapped = 1U;
+			dx_buff->eop_index = 0xffffU;
+
+			frag_len -= buff_size;
+			buff_offset += buff_size;
+
+			++ret;
+		}
+	}
+
+	first->eop_index = dx;
+	dx_buff->is_eop = 1U;
+	dx_buff->skb = NULL;
+	dx_buff->xdpf = xdpf;
+	goto exit;
+
+mapping_error:
+	for (dx = ring->sw_tail;
+	     ret > 0;
+	     --ret, dx = aq_ring_next_dx(ring, dx)) {
+		dx_buff = &ring->buff_ring[dx];
+
+		if (!dx_buff->pa)
+			continue;
+		if (unlikely(dx_buff->is_sop))
+			dma_unmap_single(dev, dx_buff->pa, dx_buff->len,
+					 DMA_TO_DEVICE);
+		else
+			dma_unmap_page(dev, dx_buff->pa, dx_buff->len,
+				       DMA_TO_DEVICE);
+	}
+
+exit:
+	return ret;
+}
+
 unsigned int aq_nic_map_skb(struct aq_nic_s *self, struct sk_buff *skb,
 			    struct aq_ring_s *ring)
 {
@@ -697,6 +794,7 @@ unsigned int aq_nic_map_skb(struct aq_nic_s *self, struct sk_buff *skb,
 	first->eop_index = dx;
 	dx_buff->is_eop = 1U;
 	dx_buff->skb = skb;
+	dx_buff->xdpf = NULL;
 	goto exit;
 
 mapping_error:
@@ -725,6 +823,44 @@ unsigned int aq_nic_map_skb(struct aq_nic_s *self, struct sk_buff *skb,
 	return ret;
 }
 
+int aq_nic_xmit_xdpf(struct aq_nic_s *aq_nic, struct aq_ring_s *tx_ring,
+		     struct xdp_frame *xdpf)
+{
+	u16 queue_index = AQ_NIC_RING2QMAP(aq_nic, tx_ring->idx);
+	struct net_device *ndev = aq_nic_get_ndev(aq_nic);
+	struct skb_shared_info *sinfo;
+	int cpu = smp_processor_id();
+	int err = NETDEV_TX_BUSY;
+	struct netdev_queue *nq;
+	unsigned int frags = 1;
+
+	if (xdp_frame_has_frags(xdpf)) {
+		sinfo = xdp_get_shared_info_from_frame(xdpf);
+		frags += sinfo->nr_frags;
+	}
+
+	if (frags > AQ_CFG_SKB_FRAGS_MAX)
+		return err;
+
+	nq = netdev_get_tx_queue(ndev, tx_ring->idx);
+	__netif_tx_lock(nq, cpu);
+
+	aq_ring_update_queue_state(tx_ring);
+
+	/* Above status update may stop the queue. Check this. */
+	if (__netif_subqueue_stopped(aq_nic_get_ndev(aq_nic), queue_index))
+		goto out;
+
+	frags = aq_nic_map_xdp(aq_nic, xdpf, tx_ring);
+	if (likely(frags))
+		err = aq_nic->aq_hw_ops->hw_ring_tx_xmit(aq_nic->aq_hw, tx_ring,
+							 frags);
+out:
+	__netif_tx_unlock(nq);
+
+	return err;
+}
+
 int aq_nic_xmit(struct aq_nic_s *self, struct sk_buff *skb)
 {
 	struct aq_nic_cfg_s *cfg = aq_nic_get_cfg(self);

drivers/net/ethernet/aquantia/atlantic/aq_nic.h

@@ -180,6 +180,8 @@ void aq_nic_ndev_free(struct aq_nic_s *self);
 int aq_nic_start(struct aq_nic_s *self);
 unsigned int aq_nic_map_skb(struct aq_nic_s *self, struct sk_buff *skb,
 			    struct aq_ring_s *ring);
+int aq_nic_xmit_xdpf(struct aq_nic_s *aq_nic, struct aq_ring_s *tx_ring,
+		     struct xdp_frame *xdpf);
 int aq_nic_xmit(struct aq_nic_s *self, struct sk_buff *skb);
 int aq_nic_get_regs(struct aq_nic_s *self, struct ethtool_regs *regs, void *p);
 int aq_nic_get_regs_count(struct aq_nic_s *self);