[PATCH net-next v5 09/11] igc: Add support for Frame Preemption verification

Vinicius Costa Gomes
2022-05-20T01:16:40Z

Add support for sending/receiving Frame Preemption verification
frames.

The i225 hardware doesn't implement the process of verification
internally, this is left to the driver.

Add a simple implementation of the state machine defined in IEEE
802.3-2018, Section 99.4.7.

For now, the state machine is started manually by the user, when
enabling verification. Example:

$ ethtool --set-frame-preemption IFACE disable-verify off

The "verified" condition is set to true when the SMD-V frame is sent,
and the SMD-R frame is received. So, it only tracks the transmission
side. This seems to be what's expected from IEEE 802.3-2018.

Signed-off-by: Vinicius Costa Gomes <vinicius.gomes@intel.com>
---
drivers/net/ethernet/intel/igc/igc.h | 16 ++
drivers/net/ethernet/intel/igc/igc_defines.h | 13 +
drivers/net/ethernet/intel/igc/igc_ethtool.c | 37 ++-
drivers/net/ethernet/intel/igc/igc_main.c | 243 +++++++++++++++++++
4 files changed, 307 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/intel/igc/igc.h b/drivers/net/ethernet/intel/igc/igc.h
index 11da66bd9c2c..be4a8362d6d7 100644
--- a/drivers/net/ethernet/intel/igc/igc.h
+++ b/drivers/net/ethernet/intel/igc/igc.h
@@ -131,6 +131,13 @@ struct igc_ring {
struct xsk_buff_pool *xsk_pool;
} ____cacheline_internodealigned_in_smp;

+enum frame_preemption_state {
+ FRAME_PREEMPTION_STATE_FAILED,
+ FRAME_PREEMPTION_STATE_DONE,
+ FRAME_PREEMPTION_STATE_START,
+ FRAME_PREEMPTION_STATE_SENT,
+};
+
/* Board specific private data structure */
struct igc_adapter {
struct net_device *netdev;
@@ -184,6 +191,7 @@ struct igc_adapter {
ktime_t base_time;
ktime_t cycle_time;
bool frame_preemption_active;
+ bool frame_preemption_requested;
u32 add_frag_size;

/* OS defined structs */
@@ -250,6 +258,14 @@ struct igc_adapter {
struct timespec64 start;
struct timespec64 period;
} perout[IGC_N_PEROUT];
+
+ struct delayed_work fp_verification_work;
+ unsigned long fp_start;
+ bool fp_received_smd_v;
+ bool fp_received_smd_r;
+ unsigned int fp_verify_cnt;
+ enum frame_preemption_state fp_tx_state;
+ bool fp_disable_verify;
};

void igc_up(struct igc_adapter *adapter);
diff --git a/drivers/net/ethernet/intel/igc/igc_defines.h b/drivers/net/ethernet/intel/igc/igc_defines.h
index 68faca584e34..63fc76a0b72a 100644
--- a/drivers/net/ethernet/intel/igc/igc_defines.h
+++ b/drivers/net/ethernet/intel/igc/igc_defines.h
@@ -307,6 +307,8 @@
#define IGC_TXD_DTYP_C 0x00000000 /* Context Descriptor */
#define IGC_TXD_POPTS_IXSM 0x01 /* Insert IP checksum */
#define IGC_TXD_POPTS_TXSM 0x02 /* Insert TCP/UDP checksum */
+#define IGC_TXD_POPTS_SMD_V 0x10 /* Transmitted packet is a SMD-Verify */
+#define IGC_TXD_POPTS_SMD_R 0x20 /* Transmitted packet is a SMD-Response */
#define IGC_TXD_CMD_EOP 0x01000000 /* End of Packet */
#define IGC_TXD_CMD_IC 0x04000000 /* Insert Checksum */
#define IGC_TXD_CMD_DEXT 0x20000000 /* Desc extension (0 = legacy) */
@@ -366,9 +368,20 @@

#define IGC_RXDEXT_STATERR_LB 0x00040000

+#define IGC_RXD_STAT_SMD_V 0x2000 /* Received packet is SMD-Verify packet */
+#define IGC_RXD_STAT_SMD_R 0x4000 /* Received packet is SMD-Response packet */
+
/* Advanced Receive Descriptor bit definitions */
#define IGC_RXDADV_STAT_TSIP 0x08000 /* timestamp in packet */

+#define IGC_RXDADV_STAT_SMD_TYPE_MASK 0x06000
+#define IGC_RXDADV_STAT_SMD_TYPE_SHIFT 13
+
+#define IGC_SMD_TYPE_SFD 0x0
+#define IGC_SMD_TYPE_SMD_V 0x1
+#define IGC_SMD_TYPE_SMD_R 0x2
+#define IGC_SMD_TYPE_COMPLETE 0x3
+
#define IGC_RXDEXT_STATERR_L4E 0x20000000
#define IGC_RXDEXT_STATERR_IPE 0x40000000
#define IGC_RXDEXT_STATERR_RXE 0x80000000
diff --git a/drivers/net/ethernet/intel/igc/igc_ethtool.c b/drivers/net/ethernet/intel/igc/igc_ethtool.c
index 401d2cdb3e81..9a80e2569dc3 100644
--- a/drivers/net/ethernet/intel/igc/igc_ethtool.c
+++ b/drivers/net/ethernet/intel/igc/igc_ethtool.c
@@ -1680,6 +1680,8 @@ static int igc_ethtool_get_preempt(struct net_device *netdev,

fpcmd->enabled = adapter->frame_preemption_active;
fpcmd->add_frag_size = adapter->add_frag_size;
+ fpcmd->verified = adapter->fp_tx_state == FRAME_PREEMPTION_STATE_DONE;
+ fpcmd->disable_verify = adapter->fp_disable_verify;

for (i = 0; i < adapter->num_tx_queues; i++) {
struct igc_ring *ring = adapter->tx_ring[i];
@@ -1698,6 +1700,7 @@ static int igc_ethtool_set_preempt(struct net_device *netdev,
struct netlink_ext_ack *extack)
{
struct igc_adapter *adapter = netdev_priv(netdev);
+ bool verified = false, mask_changed = false;
u32 mask;
int i;

@@ -1706,17 +1709,47 @@ static int igc_ethtool_set_preempt(struct net_device *netdev,
return -EINVAL;
}

- adapter->frame_preemption_active = fpcmd->enabled;
+ adapter->frame_preemption_requested = fpcmd->enabled;
adapter->add_frag_size = fpcmd->add_frag_size;
mask = fpcmd->preemptible_mask;

for (i = 0; i < adapter->num_tx_queues; i++) {
struct igc_ring *ring = adapter->tx_ring[i];
+ bool preemptible = mask & BIT(i);
+
+ if (ring->preemptible != preemptible)
+ mask_changed = true;

ring->preemptible = (mask & BIT(i));
}

- return igc_tsn_offload_apply(adapter);
+ if (!fpcmd->disable_verify && adapter->fp_disable_verify) {
+ adapter->fp_tx_state = FRAME_PREEMPTION_STATE_START;
+ schedule_delayed_work(&adapter->fp_verification_work,
+ msecs_to_jiffies(10));
+ }
+
+ adapter->fp_disable_verify = fpcmd->disable_verify;
+
+ verified = adapter->fp_tx_state == FRAME_PREEMPTION_STATE_DONE;
+
+ /* If the verification was not done, we want to enable frame
+ * preemption and we have not finished it, wait for it to
+ * finish.
+ */
+ if (!verified && !adapter->fp_disable_verify && adapter->frame_preemption_requested)
+ return 0;
+
+ if (adapter->frame_preemption_active != adapter->frame_preemption_requested ||
+ adapter->add_frag_size != fpcmd->add_frag_size ||
+ mask_changed) {
+ adapter->frame_preemption_active = adapter->frame_preemption_requested;
+ adapter->add_frag_size = fpcmd->add_frag_size;
+
+ return igc_tsn_offload_apply(adapter);
+ }
+
+ return 0;
}

static int igc_ethtool_begin(struct net_device *netdev)
diff --git a/drivers/net/ethernet/intel/igc/igc_main.c b/drivers/net/ethernet/intel/igc/igc_main.c
index 5dd7140bac82..69e96e9a3ec8 100644
--- a/drivers/net/ethernet/intel/igc/igc_main.c
+++ b/drivers/net/ethernet/intel/igc/igc_main.c
@@ -30,6 +30,11 @@
#define IGC_XDP_TX BIT(1)
#define IGC_XDP_REDIRECT BIT(2)

+#define IGC_FP_TIMEOUT msecs_to_jiffies(100)
+#define IGC_MAX_VERIFY_CNT 3
+
+#define IGC_FP_SMD_FRAME_SIZE 60
+
static int debug = -1;

MODULE_AUTHOR("Intel Corporation, <linux.nics@intel.com>");
@@ -2190,6 +2195,79 @@ static int igc_xdp_init_tx_descriptor(struct igc_ring *ring,
return 0;
}

+static int igc_fp_init_smd_frame(struct igc_ring *ring, struct igc_tx_buffer *buffer,
+ struct sk_buff *skb)
+{
+ dma_addr_t dma;
+ unsigned int size;
+
+ size = skb_headlen(skb);
+
+ dma = dma_map_single(ring->dev, skb->data, size, DMA_TO_DEVICE);
+ if (dma_mapping_error(ring->dev, dma)) {
+ netdev_err_once(ring->netdev, "Failed to map DMA for TX\n");
+ return -ENOMEM;
+ }
+
+ buffer->skb = skb;
+ buffer->protocol = 0;
+ buffer->bytecount = skb->len;
+ buffer->gso_segs = 1;
+ buffer->time_stamp = jiffies;
+ dma_unmap_len_set(buffer, len, skb->len);
+ dma_unmap_addr_set(buffer, dma, dma);
+
+ return 0;
+}
+
+static int igc_fp_init_tx_descriptor(struct igc_ring *ring,
+ struct sk_buff *skb, int type)
+{
+ struct igc_tx_buffer *buffer;
+ union igc_adv_tx_desc *desc;
+ u32 cmd_type, olinfo_status;
+ int err;
+
+ if (!igc_desc_unused(ring))
+ return -EBUSY;
+
+ buffer = &ring->tx_buffer_info[ring->next_to_use];
+ err = igc_fp_init_smd_frame(ring, buffer, skb);
+ if (err)
+ return err;
+
+ cmd_type = IGC_ADVTXD_DTYP_DATA | IGC_ADVTXD_DCMD_DEXT |
+ IGC_ADVTXD_DCMD_IFCS | IGC_TXD_DCMD |
+ buffer->bytecount;
+ olinfo_status = buffer->bytecount << IGC_ADVTXD_PAYLEN_SHIFT;
+
+ switch (type) {
+ case IGC_SMD_TYPE_SMD_V:
+ olinfo_status |= (IGC_TXD_POPTS_SMD_V << 8);
+ break;
+ case IGC_SMD_TYPE_SMD_R:
+ olinfo_status |= (IGC_TXD_POPTS_SMD_R << 8);
+ break;
+ default:
+ return -EINVAL;
+ }
+
+ desc = IGC_TX_DESC(ring, ring->next_to_use);
+ desc->read.cmd_type_len = cpu_to_le32(cmd_type);
+ desc->read.olinfo_status = cpu_to_le32(olinfo_status);
+ desc->read.buffer_addr = cpu_to_le64(dma_unmap_addr(buffer, dma));
+
+ netdev_tx_sent_queue(txring_txq(ring), skb->len);
+
+ buffer->next_to_watch = desc;
+
+ ring->next_to_use++;
+ if (ring->next_to_use == ring->count)
+ ring->next_to_use = 0;
+
+ return 0;
+}
+
static struct igc_ring *igc_xdp_get_tx_ring(struct igc_adapter *adapter,
int cpu)
{
@@ -2317,6 +2395,43 @@ static void igc_update_rx_stats(struct igc_q_vector *q_vector,
q_vector->rx.total_bytes += bytes;
}

+static int igc_rx_desc_smd_type(union igc_adv_rx_desc *rx_desc)
+{
+ u32 status = le32_to_cpu(rx_desc->wb.upper.status_error);
+
+ return (status & IGC_RXDADV_STAT_SMD_TYPE_MASK)
+ >> IGC_RXDADV_STAT_SMD_TYPE_SHIFT;
+}
+
+static bool igc_check_smd_frame(void *pktbuf, unsigned int size)
+{
+#if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)
+ const u32 *b;
+#else
+ const u16 *b;
+#endif
+ int i;
+
+ if (size != 60)
+ return false;
+
+ /* The SMD frames (V and R) have the preamble, the SMD tag, 60
+ * octects of zeroes and the mCRC. At this point the hardware
+ * already discarded most of that, so we only need to check
+ * the "contents" of the frame.
+ */
+ b = pktbuf;
+ for (i = 16 / sizeof(*b); i < size / sizeof(*b); i++)
+ /* FIXME: i226 seems to insert some garbage
+ * (timestamps?) in SMD frames, ignore the first 16
+ * bytes (4 words). Investigate better.
+ */
+ if (b[i] != 0)
+ return false;
+
+ return true;
+}
+
static int igc_clean_rx_irq(struct igc_q_vector *q_vector, const int budget)
{
unsigned int total_bytes = 0, total_packets = 0;
@@ -2333,6 +2448,7 @@ static int igc_clean_rx_irq(struct igc_q_vector *q_vector, const int budget)
ktime_t timestamp = 0;
struct xdp_buff xdp;
int pkt_offset = 0;
+ int smd_type;
void *pktbuf;

/* return some buffers to hardware, one at a time is too slow */
@@ -2364,6 +2480,22 @@ static int igc_clean_rx_irq(struct igc_q_vector *q_vector, const int budget)
size -= IGC_TS_HDR_LEN;
}

+ smd_type = igc_rx_desc_smd_type(rx_desc);
+
+ if (unlikely(smd_type == IGC_SMD_TYPE_SMD_V || smd_type == IGC_SMD_TYPE_SMD_R)) {
+ if (igc_check_smd_frame(pktbuf, size)) {
+ adapter->fp_received_smd_v = smd_type == IGC_SMD_TYPE_SMD_V;
+ adapter->fp_received_smd_r = smd_type == IGC_SMD_TYPE_SMD_R;
+ schedule_delayed_work(&adapter->fp_verification_work, 0);
+ }
+
+ /* Advance the ring next-to-clean */
+ igc_is_non_eop(rx_ring, rx_desc);
+
+ cleaned_count++;
+ continue;
+ }
+
if (!skb) {
xdp_init_buff(&xdp, truesize, &rx_ring->xdp_rxq);
xdp_prepare_buff(&xdp, pktbuf - igc_rx_offset(rx_ring),
@@ -6003,6 +6135,116 @@ static int igc_tsn_enable_cbs(struct igc_adapter *adapter,
return igc_tsn_offload_apply(adapter);
}

+/* I225 doesn't send the SMD frames automatically, we need to handle
+ * them ourselves.
+ */
+static int igc_xmit_smd_frame(struct igc_adapter *adapter, int type)
+{
+ int cpu = smp_processor_id();
+ struct netdev_queue *nq;
+ struct igc_ring *ring;
+ struct sk_buff *skb;
+ void *data;
+ int err;
+
+ if (!netif_running(adapter->netdev))
+ return -ENOTCONN;
+
+ /* FIXME: rename this function to something less specific, as
+ * it can be used outside XDP.
+ */
+ ring = igc_xdp_get_tx_ring(adapter, cpu);
+ nq = txring_txq(ring);
+
+ skb = alloc_skb(IGC_FP_SMD_FRAME_SIZE, GFP_KERNEL);
+ if (!skb)
+ return -ENOMEM;
+
+ data = skb_put(skb, IGC_FP_SMD_FRAME_SIZE);
+ memset(data, 0, IGC_FP_SMD_FRAME_SIZE);
+
+ __netif_tx_lock_bh(nq);
+
+ err = igc_fp_init_tx_descriptor(ring, skb, type);
+
+ igc_flush_tx_descriptors(ring);
+
+ __netif_tx_unlock_bh(nq);
+
+ return err;
+}
+
+static void igc_fp_verification_work(struct work_struct *work)
+{
+ struct delayed_work *dwork = to_delayed_work(work);
+ struct igc_adapter *adapter;
+ int err;
+
+ adapter = container_of(dwork, struct igc_adapter, fp_verification_work);
+
+ if (adapter->fp_disable_verify)
+ goto done;
+
+ switch (adapter->fp_tx_state) {
+ case FRAME_PREEMPTION_STATE_START:
+ adapter->fp_received_smd_r = false;
+ err = igc_xmit_smd_frame(adapter, IGC_SMD_TYPE_SMD_V);
+ if (err < 0)
+ netdev_err(adapter->netdev, "Error sending SMD-V frame\n");
+
+ adapter->fp_tx_state = FRAME_PREEMPTION_STATE_SENT;
+ adapter->fp_start = jiffies;
+ schedule_delayed_work(&adapter->fp_verification_work, IGC_FP_TIMEOUT);
+ break;
+
+ case FRAME_PREEMPTION_STATE_SENT:
+ if (adapter->fp_received_smd_r) {
+ /* Verifcation has finished successfully, we
+ * can enable frame preemption in the hw now
+ */
+ adapter->fp_tx_state = FRAME_PREEMPTION_STATE_DONE;
+ adapter->fp_received_smd_r = false;
+
+ if (adapter->frame_preemption_requested) {
+ adapter->frame_preemption_active = true;
+ igc_tsn_offload_apply(adapter);
+ }
+
+ break;
+ }
+
+ if (time_is_before_jiffies(adapter->fp_start + IGC_FP_TIMEOUT)) {
+ adapter->fp_verify_cnt++;
+ netdev_warn(adapter->netdev, "Timeout waiting for SMD-R frame\n");
+
+ if (adapter->fp_verify_cnt > IGC_MAX_VERIFY_CNT) {
+ adapter->fp_verify_cnt = 0;
+ adapter->fp_tx_state = FRAME_PREEMPTION_STATE_FAILED;
+ netdev_err(adapter->netdev,
+ "Exceeded number of attempts for frame preemption verification\n");
+ } else {
+ adapter->fp_tx_state = FRAME_PREEMPTION_STATE_START;
+ }
+ schedule_delayed_work(&adapter->fp_verification_work, IGC_FP_TIMEOUT);
+ }
+
+ break;
+
+ case FRAME_PREEMPTION_STATE_FAILED:
+ case FRAME_PREEMPTION_STATE_DONE:
+ break;
+ }
+
+done:
+ if (adapter->fp_received_smd_v) {
+ err = igc_xmit_smd_frame(adapter, IGC_SMD_TYPE_SMD_R);
+ if (err < 0)
+ netdev_err(adapter->netdev, "Error sending SMD-R frame\n");
+
+ adapter->fp_received_smd_v = false;
+ }
+}
+
static int igc_setup_tc(struct net_device *dev, enum tc_setup_type type,
void *type_data)
{
@@ -6369,6 +6611,7 @@ static int igc_probe(struct pci_dev *pdev,

INIT_WORK(&adapter->reset_task, igc_reset_task);
INIT_WORK(&adapter->watchdog_task, igc_watchdog_task);
+ INIT_DELAYED_WORK(&adapter->fp_verification_work, igc_fp_verification_work);

/* Initialize link properties that are user-changeable */
adapter->fc_autoneg = true;
--
2.35.3