Enable Launch Time Control (LTC) support to XDP zero copy via XDP Tx metadata framework.

This patch is tested with tools/testing/selftests/bpf/xdp_hw_metadata on Intel Tiger Lake platform. Below are the test steps and result.

Test Steps: 1. Add mqprio qdisc: $ sudo tc qdisc add dev enp2s0 handle 8001: parent root mqprio num_tc 4 map 3 2 1 0 0 0 0 0 0 0 0 0 0 0 0 0 queues 1@0 1@1 1@2 1@3 hw 0

2. Enable launch time hardware offload on hardware queue 1: $ sudo tc qdisc replace dev enp2s0 parent 8001:2 etf offload clockid CLOCK_TAI delta 500000

3. Change RSS to route all incoming IP packets into hardware queue 1: $ sudo ethtool -X enp2s0 start 1 equal 1

4. Start xdp_hw_metadata selftest application: $ sudo ./xdp_hw_metadata enp2s0 -l 1000000000

5. Send an UDP packet to port 9091 of DUT. $ echo -n xdp | nc -u -q0 169.254.1.1 9091

When launch time is set to 1s in the future, the delta between launch time and transmit hardware timestamp is equal to 0.016us, as shown in result below: 0x562ff5dc8880: rx_desc[4]->addr=84110 addr=84110 comp_addr=84110 EoP rx_hash: 0xE343384 with RSS type:0x1 HW RX-time: 1734578015467548904 (sec:1734578015.4675) delta to User RX-time sec:0.0002 (183.103 usec) XDP RX-time: 1734578015467651698 (sec:1734578015.4677) delta to User RX-time sec:0.0001 (80.309 usec) No rx_vlan_tci or rx_vlan_proto, err=-95 0x562ff5dc8880: ping-pong with csum=561c (want c7dd) csum_start=34 csum_offset=6 HW RX-time: 1734578015467548904 (sec:1734578015.4675) delta to HW Launch-time sec:1.0000 (1000000.000 usec) 0x562ff5dc8880: complete tx idx=4 addr=4018 HW Launch-time: 1734578016467548904 (sec:1734578016.4675) delta to HW TX-complete-time sec:0.0000 (0.016 usec) HW TX-complete-time: 1734578016467548920 (sec:1734578016.4675) delta to User TX-complete-time sec:0.0000 (32.546 usec) XDP RX-time: 1734578015467651698 (sec:1734578015.4677) delta to User TX-complete-time sec:0.9999 (999929.768 usec) HW RX-time: 1734578015467548904 (sec:1734578015.4675) delta to HW TX-complete-time sec:1.0000 (1000000.016 usec) 0x562ff5dc8880: complete rx idx=132 addr=84110

Signed-off-by: Song Yoong Siang yoong.siang.song@intel.com --- drivers/net/ethernet/intel/igc/igc_main.c | 78 ++++++++++++++++------- 1 file changed, 56 insertions(+), 22 deletions(-)

diff --git a/drivers/net/ethernet/intel/igc/igc_main.c b/drivers/net/ethernet/intel/igc/igc_main.c index 27872bdea9bd..6857f5f5b4b2 100644 --- a/drivers/net/ethernet/intel/igc/igc_main.c +++ b/drivers/net/ethernet/intel/igc/igc_main.c @@ -1566,6 +1566,26 @@ static bool igc_request_tx_tstamp(struct igc_adapter *adapter, struct sk_buff *s return false; }

+static void igc_insert_empty_packet(struct igc_ring *tx_ring) +{ + struct igc_tx_buffer *empty_info; + struct sk_buff *empty; + void *data; + + empty_info = &tx_ring->tx_buffer_info[tx_ring->next_to_use]; + empty = alloc_skb(IGC_EMPTY_FRAME_SIZE, GFP_ATOMIC); + if (!empty) + return; + + data = skb_put(empty, IGC_EMPTY_FRAME_SIZE); + memset(data, 0, IGC_EMPTY_FRAME_SIZE); + + igc_tx_ctxtdesc(tx_ring, 0, false, 0, 0, 0); + + if (igc_init_tx_empty_descriptor(tx_ring, empty, empty_info) < 0) + dev_kfree_skb_any(empty); +} + static netdev_tx_t igc_xmit_frame_ring(struct sk_buff *skb, struct igc_ring *tx_ring) { @@ -1603,26 +1623,8 @@ static netdev_tx_t igc_xmit_frame_ring(struct sk_buff *skb, skb->tstamp = ktime_set(0, 0); launch_time = igc_tx_launchtime(tx_ring, txtime, &first_flag, &insert_empty);

- if (insert_empty) { - struct igc_tx_buffer *empty_info; - struct sk_buff *empty; - void *data; - - empty_info = &tx_ring->tx_buffer_info[tx_ring->next_to_use]; - empty = alloc_skb(IGC_EMPTY_FRAME_SIZE, GFP_ATOMIC); - if (!empty) - goto done; - - data = skb_put(empty, IGC_EMPTY_FRAME_SIZE); - memset(data, 0, IGC_EMPTY_FRAME_SIZE); - - igc_tx_ctxtdesc(tx_ring, 0, false, 0, 0, 0); - - if (igc_init_tx_empty_descriptor(tx_ring, - empty, - empty_info) < 0) - dev_kfree_skb_any(empty); - } + if (insert_empty) + igc_insert_empty_packet(tx_ring);

done: /* record the location of the first descriptor for this packet */ @@ -2955,9 +2957,33 @@ static u64 igc_xsk_fill_timestamp(void *_priv) return *(u64 *)_priv; }

+static void igc_xsk_request_launch_time(u64 launch_time, void *_priv) +{ + struct igc_metadata_request *meta_req = _priv; + struct igc_ring *tx_ring = meta_req->tx_ring; + __le32 launch_time_offset; + bool insert_empty = false; + bool first_flag = false; + + if (!tx_ring->launchtime_enable) + return; + + launch_time_offset = igc_tx_launchtime(tx_ring, + ns_to_ktime(launch_time), + &first_flag, &insert_empty); + if (insert_empty) { + igc_insert_empty_packet(tx_ring); + meta_req->tx_buffer = + &tx_ring->tx_buffer_info[tx_ring->next_to_use]; + } + + igc_tx_ctxtdesc(tx_ring, launch_time_offset, first_flag, 0, 0, 0); +} + const struct xsk_tx_metadata_ops igc_xsk_tx_metadata_ops = { .tmo_request_timestamp = igc_xsk_request_timestamp, .tmo_fill_timestamp = igc_xsk_fill_timestamp, + .tmo_request_launch_time = igc_xsk_request_launch_time, };

static void igc_xdp_xmit_zc(struct igc_ring *ring) @@ -2980,7 +3006,7 @@ static void igc_xdp_xmit_zc(struct igc_ring *ring) ntu = ring->next_to_use; budget = igc_desc_unused(ring);

- while (xsk_tx_peek_desc(pool, &xdp_desc) && budget--) { + while (xsk_tx_peek_desc(pool, &xdp_desc) && budget >= 4) { struct igc_metadata_request meta_req; struct xsk_tx_metadata *meta = NULL; struct igc_tx_buffer *bi; @@ -3004,6 +3030,12 @@ static void igc_xdp_xmit_zc(struct igc_ring *ring) xsk_tx_metadata_request(meta, &igc_xsk_tx_metadata_ops, &meta_req);

+ /* xsk_tx_metadata_request() may have updated next_to_use */ + ntu = ring->next_to_use; + + /* xsk_tx_metadata_request() may have updated Tx buffer info */ + bi = meta_req.tx_buffer; + tx_desc = IGC_TX_DESC(ring, ntu); tx_desc->read.cmd_type_len = cpu_to_le32(meta_req.cmd_type); tx_desc->read.olinfo_status = cpu_to_le32(olinfo_status); @@ -3021,9 +3053,11 @@ static void igc_xdp_xmit_zc(struct igc_ring *ring) ntu++; if (ntu == ring->count) ntu = 0; + + ring->next_to_use = ntu; + budget = igc_desc_unused(ring); }

- ring->next_to_use = ntu; if (tx_desc) { igc_flush_tx_descriptors(ring); xsk_tx_release(pool);