On Tue Oct 15 2024, Maciej Fijalkowski wrote:
> On Fri, Oct 11, 2024 at 11:01:04AM +0200, Kurt Kanzenbach wrote:
>> From: Sriram Yagnaraman <sriram.yagnara...@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.yagnara...@est.tech>
>> [Kurt: Set olinfo_status in igb_xmit_zc() so that frames are transmitted,
>> Use READ_ONCE() for xsk_pool and check Tx disabled and carrier in
>> igb_xmit_zc(), Add FIXME for RS bit]
>> Signed-off-by: Kurt Kanzenbach <k...@linutronix.de>
>> Reviewed-by: Maciej Fijalkowski <maciej.fijalkow...@intel.com>
>> ---
>> drivers/net/ethernet/intel/igb/igb.h | 2 +
>> drivers/net/ethernet/intel/igb/igb_main.c | 61 ++++++++++++++++++++++++-----
>> drivers/net/ethernet/intel/igb/igb_xsk.c | 64
>> +++++++++++++++++++++++++++++++
>> 3 files changed, 117 insertions(+), 10 deletions(-)
>>
>> diff --git a/drivers/net/ethernet/intel/igb/igb.h
>> b/drivers/net/ethernet/intel/igb/igb.h
>> index e4a85867aa18..f6ac74327bb3 100644
>> --- a/drivers/net/ethernet/intel/igb/igb.h
>> +++ b/drivers/net/ethernet/intel/igb/igb.h
>> @@ -258,6 +258,7 @@ 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,
>> @@ -859,6 +860,7 @@ bool igb_alloc_rx_buffers_zc(struct igb_ring *rx_ring,
>> void igb_clean_rx_ring_zc(struct igb_ring *rx_ring);
>> int igb_clean_rx_irq_zc(struct igb_q_vector *q_vector,
>> struct xsk_buff_pool *xsk_pool, 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 711b60cab594..5f396c02e3b9 100644
>> --- a/drivers/net/ethernet/intel/igb/igb_main.c
>> +++ b/drivers/net/ethernet/intel/igb/igb_main.c
>> @@ -2979,6 +2979,9 @@ 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);
>>
>> @@ -3326,7 +3329,8 @@ static int igb_probe(struct pci_dev *pdev, const
>> struct pci_device_id *ent)
>> netdev->priv_flags |= IFF_SUPP_NOFCS;
>>
>> netdev->priv_flags |= IFF_UNICAST_FLT;
>> - netdev->xdp_features = NETDEV_XDP_ACT_BASIC | NETDEV_XDP_ACT_REDIRECT;
>> + netdev->xdp_features = NETDEV_XDP_ACT_BASIC | NETDEV_XDP_ACT_REDIRECT |
>> + NETDEV_XDP_ACT_XSK_ZEROCOPY;
>>
>> /* MTU range: 68 - 9216 */
>> netdev->min_mtu = ETH_MIN_MTU;
>> @@ -4900,15 +4904,20 @@ 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,
>> @@ -4939,6 +4948,7 @@ 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 */
>> @@ -4953,6 +4963,9 @@ 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;
>> @@ -6486,6 +6499,9 @@ 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;
>> @@ -8260,13 +8276,18 @@ 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;
>> + struct xsk_buff_pool *xsk_pool;
>> + 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;
>> @@ -8297,10 +8318,14 @@ 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,
>> @@ -8332,6 +8357,7 @@ 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++;
>> @@ -8360,6 +8386,21 @@ 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;
>>
>> + xsk_pool = READ_ONCE(tx_ring->xsk_pool);
>> + if (xsk_pool) {
>> + if (xsk_frames)
>> + xsk_tx_completed(xsk_pool, xsk_frames);
>> + if (xsk_uses_need_wakeup(xsk_pool))
>> + xsk_set_tx_need_wakeup(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;
>>
>> @@ -8422,7 +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 22d234db0fab..d962c5e22b71 100644
>> --- a/drivers/net/ethernet/intel/igb/igb_xsk.c
>> +++ b/drivers/net/ethernet/intel/igb/igb_xsk.c
>> @@ -465,6 +465,70 @@ int igb_clean_rx_irq_zc(struct igb_q_vector *q_vector,
>> 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;
>
> Ughh that's another read of pool ptr, you should have passed it by arg to
> igb_xmit_zc()...Ups, missed that somehow. Thanks! Thanks, Kurt
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