[PATCH net-next 4/4] igb: add AF_XDP zero-copy Tx support

Tony Nguyen
2024-08-08T18:36:08Z

From: Sriram Yagnaraman <sriram.yagnaraman@est.tech>

Add support for AF_XDP zero-copy transmit path.

A new TX buffer type IGB_TYPE_XSK is introduced to indicate that the Tx
frame was allocated from the xsk buff pool, so igb_clean_tx_ring and
igb_clean_tx_irq can clean the buffers correctly based on type.

igb_xmit_zc performs the actual packet transmit when AF_XDP zero-copy is
enabled. We share the TX ring between slow path, XDP and AF_XDP
zero-copy, so we use the netdev queue lock to ensure mutual exclusion.

Signed-off-by: Sriram Yagnaraman <sriram.yagnaraman@est.tech>
[Kurt: Set olinfo_status in igb_xmit_zc() so that frames are transmitted]
Signed-off-by: Kurt Kanzenbach <kurt@linutronix.de>
Tested-by: Chandan Kumar Rout <chandanx.rout@intel.com> (A Contingent Worker at Intel)
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>
---
drivers/net/ethernet/intel/igb/igb.h | 2 +
drivers/net/ethernet/intel/igb/igb_main.c | 56 +++++++++++++++++++----
drivers/net/ethernet/intel/igb/igb_xsk.c | 53 +++++++++++++++++++++
3 files changed, 102 insertions(+), 9 deletions(-)

diff --git a/drivers/net/ethernet/intel/igb/igb.h b/drivers/net/ethernet/intel/igb/igb.h
index 4983a6ec718e..9ee18ac1ba47 100644
--- a/drivers/net/ethernet/intel/igb/igb.h
+++ b/drivers/net/ethernet/intel/igb/igb.h
@@ -257,6 +257,7 @@ enum igb_tx_flags {
enum igb_tx_buf_type {
IGB_TYPE_SKB = 0,
IGB_TYPE_XDP,
+ IGB_TYPE_XSK
};

/* wrapper around a pointer to a socket buffer,
@@ -836,6 +837,7 @@ int igb_xsk_pool_setup(struct igb_adapter *adapter,
bool igb_alloc_rx_buffers_zc(struct igb_ring *rx_ring, u16 count);
void igb_clean_rx_ring_zc(struct igb_ring *rx_ring);
int igb_clean_rx_irq_zc(struct igb_q_vector *q_vector, const int budget);
+bool igb_xmit_zc(struct igb_ring *tx_ring);
int igb_xsk_wakeup(struct net_device *dev, u32 qid, u32 flags);

#endif /* _IGB_H_ */
diff --git a/drivers/net/ethernet/intel/igb/igb_main.c b/drivers/net/ethernet/intel/igb/igb_main.c
index 0b779b2ca9ea..1ebd67981978 100644
--- a/drivers/net/ethernet/intel/igb/igb_main.c
+++ b/drivers/net/ethernet/intel/igb/igb_main.c
@@ -2996,6 +2996,9 @@ static int igb_xdp_xmit(struct net_device *dev, int n,
if (unlikely(!tx_ring))
return -ENXIO;

+ if (unlikely(test_bit(IGB_RING_FLAG_TX_DISABLED, &tx_ring->flags)))
+ return -ENXIO;
+
nq = txring_txq(tx_ring);
__netif_tx_lock(nq, cpu);

@@ -4917,15 +4920,20 @@ void igb_clean_tx_ring(struct igb_ring *tx_ring)
{
u16 i = tx_ring->next_to_clean;
struct igb_tx_buffer *tx_buffer = &tx_ring->tx_buffer_info[i];
+ u32 xsk_frames = 0;

while (i != tx_ring->next_to_use) {
union e1000_adv_tx_desc *eop_desc, *tx_desc;

/* Free all the Tx ring sk_buffs or xdp frames */
- if (tx_buffer->type == IGB_TYPE_SKB)
+ if (tx_buffer->type == IGB_TYPE_SKB) {
dev_kfree_skb_any(tx_buffer->skb);
- else
+ } else if (tx_buffer->type == IGB_TYPE_XDP) {
xdp_return_frame(tx_buffer->xdpf);
+ } else if (tx_buffer->type == IGB_TYPE_XSK) {
+ xsk_frames++;
+ goto skip_for_xsk;
+ }

/* unmap skb header data */
dma_unmap_single(tx_ring->dev,
@@ -4956,6 +4964,7 @@ void igb_clean_tx_ring(struct igb_ring *tx_ring)
DMA_TO_DEVICE);
}

+skip_for_xsk:
tx_buffer->next_to_watch = NULL;

/* move us one more past the eop_desc for start of next pkt */
@@ -4970,6 +4979,9 @@ void igb_clean_tx_ring(struct igb_ring *tx_ring)
/* reset BQL for queue */
netdev_tx_reset_queue(txring_txq(tx_ring));

+ if (tx_ring->xsk_pool && xsk_frames)
+ xsk_tx_completed(tx_ring->xsk_pool, xsk_frames);
+
/* reset next_to_use and next_to_clean */
tx_ring->next_to_use = 0;
tx_ring->next_to_clean = 0;
@@ -6503,6 +6515,9 @@ netdev_tx_t igb_xmit_frame_ring(struct sk_buff *skb,
return NETDEV_TX_BUSY;
}

+ if (unlikely(test_bit(IGB_RING_FLAG_TX_DISABLED, &tx_ring->flags)))
+ return NETDEV_TX_BUSY;
+
/* record the location of the first descriptor for this packet */
first = &tx_ring->tx_buffer_info[tx_ring->next_to_use];
first->type = IGB_TYPE_SKB;
@@ -8263,13 +8278,17 @@ static int igb_poll(struct napi_struct *napi, int budget)
**/
static bool igb_clean_tx_irq(struct igb_q_vector *q_vector, int napi_budget)
{
- struct igb_adapter *adapter = q_vector->adapter;
- struct igb_ring *tx_ring = q_vector->tx.ring;
- struct igb_tx_buffer *tx_buffer;
- union e1000_adv_tx_desc *tx_desc;
unsigned int total_bytes = 0, total_packets = 0;
+ struct igb_adapter *adapter = q_vector->adapter;
unsigned int budget = q_vector->tx.work_limit;
+ struct igb_ring *tx_ring = q_vector->tx.ring;
unsigned int i = tx_ring->next_to_clean;
+ union e1000_adv_tx_desc *tx_desc;
+ struct igb_tx_buffer *tx_buffer;
+ int cpu = smp_processor_id();
+ bool xsk_xmit_done = true;
+ struct netdev_queue *nq;
+ u32 xsk_frames = 0;

if (test_bit(__IGB_DOWN, &adapter->state))
return true;
@@ -8300,10 +8319,14 @@ static bool igb_clean_tx_irq(struct igb_q_vector *q_vector, int napi_budget)
total_packets += tx_buffer->gso_segs;

/* free the skb */
- if (tx_buffer->type == IGB_TYPE_SKB)
+ if (tx_buffer->type == IGB_TYPE_SKB) {
napi_consume_skb(tx_buffer->skb, napi_budget);
- else
+ } else if (tx_buffer->type == IGB_TYPE_XDP) {
xdp_return_frame(tx_buffer->xdpf);
+ } else if (tx_buffer->type == IGB_TYPE_XSK) {
+ xsk_frames++;
+ goto skip_for_xsk;
+ }

/* unmap skb header data */
dma_unmap_single(tx_ring->dev,
@@ -8335,6 +8358,7 @@ static bool igb_clean_tx_irq(struct igb_q_vector *q_vector, int napi_budget)
}
}

+skip_for_xsk:
/* move us one more past the eop_desc for start of next pkt */
tx_buffer++;
tx_desc++;
@@ -8363,6 +8387,20 @@ static bool igb_clean_tx_irq(struct igb_q_vector *q_vector, int napi_budget)
q_vector->tx.total_bytes += total_bytes;
q_vector->tx.total_packets += total_packets;

+ if (tx_ring->xsk_pool) {
+ if (xsk_frames)
+ xsk_tx_completed(tx_ring->xsk_pool, xsk_frames);
+ if (xsk_uses_need_wakeup(tx_ring->xsk_pool))
+ xsk_set_tx_need_wakeup(tx_ring->xsk_pool);
+
+ nq = txring_txq(tx_ring);
+ __netif_tx_lock(nq, cpu);
+ /* Avoid transmit queue timeout since we share it with the slow path */
+ txq_trans_cond_update(nq);
+ xsk_xmit_done = igb_xmit_zc(tx_ring);
+ __netif_tx_unlock(nq);
+ }
+
if (test_bit(IGB_RING_FLAG_TX_DETECT_HANG, &tx_ring->flags)) {
struct e1000_hw *hw = &adapter->hw;

@@ -8425,7 +8463,7 @@ static bool igb_clean_tx_irq(struct igb_q_vector *q_vector, int napi_budget)
}
}

- return !!budget;
+ return !!budget && xsk_xmit_done;
}

/**
diff --git a/drivers/net/ethernet/intel/igb/igb_xsk.c b/drivers/net/ethernet/intel/igb/igb_xsk.c
index 66cdc30e9b6e..4e530e1eb3c0 100644
--- a/drivers/net/ethernet/intel/igb/igb_xsk.c
+++ b/drivers/net/ethernet/intel/igb/igb_xsk.c
@@ -431,6 +431,59 @@ int igb_clean_rx_irq_zc(struct igb_q_vector *q_vector, const int budget)
return failure ? budget : (int)total_packets;
}

+bool igb_xmit_zc(struct igb_ring *tx_ring)
+{
+ unsigned int budget = igb_desc_unused(tx_ring);
+ struct xsk_buff_pool *pool = tx_ring->xsk_pool;
+ u32 cmd_type, olinfo_status, nb_pkts, i = 0;
+ struct xdp_desc *descs = pool->tx_descs;
+ union e1000_adv_tx_desc *tx_desc = NULL;
+ struct igb_tx_buffer *tx_buffer_info;
+ unsigned int total_bytes = 0;
+ dma_addr_t dma;
+
+ nb_pkts = xsk_tx_peek_release_desc_batch(pool, budget);
+ if (!nb_pkts)
+ return true;
+
+ while (nb_pkts-- > 0) {
+ dma = xsk_buff_raw_get_dma(pool, descs[i].addr);
+ xsk_buff_raw_dma_sync_for_device(pool, dma, descs[i].len);
+
+ tx_buffer_info = &tx_ring->tx_buffer_info[tx_ring->next_to_use];
+ tx_buffer_info->bytecount = descs[i].len;
+ tx_buffer_info->type = IGB_TYPE_XSK;
+ tx_buffer_info->xdpf = NULL;
+ tx_buffer_info->gso_segs = 1;
+ tx_buffer_info->time_stamp = jiffies;
+
+ tx_desc = IGB_TX_DESC(tx_ring, tx_ring->next_to_use);
+ tx_desc->read.buffer_addr = cpu_to_le64(dma);
+
+ /* put descriptor type bits */
+ cmd_type = E1000_ADVTXD_DTYP_DATA | E1000_ADVTXD_DCMD_DEXT |
+ E1000_ADVTXD_DCMD_IFCS;
+ olinfo_status = descs[i].len << E1000_ADVTXD_PAYLEN_SHIFT;
+
+ cmd_type |= descs[i].len | IGB_TXD_DCMD;
+ tx_desc->read.cmd_type_len = cpu_to_le32(cmd_type);
+ tx_desc->read.olinfo_status = cpu_to_le32(olinfo_status);
+
+ total_bytes += descs[i].len;
+
+ i++;
+ tx_ring->next_to_use++;
+ tx_buffer_info->next_to_watch = tx_desc;
+ if (tx_ring->next_to_use == tx_ring->count)
+ tx_ring->next_to_use = 0;
+ }
+
+ netdev_tx_sent_queue(txring_txq(tx_ring), total_bytes);
+ igb_xdp_ring_update_tail(tx_ring);
+
+ return nb_pkts < budget;
+}
+
int igb_xsk_wakeup(struct net_device *dev, u32 qid, u32 flags)
{
struct igb_adapter *adapter = netdev_priv(dev);
--
2.42.0