[PATCH net-next 3/4] igb: add AF_XDP zero-copy Rx support

Tony Nguyen
2024-08-08T18:36:06Z

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

Add support for AF_XDP zero-copy receive path.

When AF_XDP zero-copy is enabled, the rx buffers are allocated from the
xsk buff pool using igb_alloc_rx_buffers_zc.

Use xsk_pool_get_rx_frame_size to set SRRCTL rx buf size when zero-copy
is enabled.

Signed-off-by: Sriram Yagnaraman <sriram.yagnaraman@est.tech>
[Kurt: Port to v6.10 and provide napi_id for xdp_rxq_info_reg()]
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 | 4 +
drivers/net/ethernet/intel/igb/igb_main.c | 95 ++++++--
drivers/net/ethernet/intel/igb/igb_xsk.c | 261 +++++++++++++++++++++-
3 files changed, 337 insertions(+), 23 deletions(-)

diff --git a/drivers/net/ethernet/intel/igb/igb.h b/drivers/net/ethernet/intel/igb/igb.h
index 053130c01480..4983a6ec718e 100644
--- a/drivers/net/ethernet/intel/igb/igb.h
+++ b/drivers/net/ethernet/intel/igb/igb.h
@@ -87,6 +87,7 @@ struct igb_adapter;
#define IGB_XDP_CONSUMED BIT(0)
#define IGB_XDP_TX BIT(1)
#define IGB_XDP_REDIR BIT(2)
+#define IGB_XDP_EXIT BIT(3)

struct vf_data_storage {
unsigned char vf_mac_addresses[ETH_ALEN];
@@ -832,6 +833,9 @@ struct xsk_buff_pool *igb_xsk_pool(struct igb_adapter *adapter,
int igb_xsk_pool_setup(struct igb_adapter *adapter,
struct xsk_buff_pool *pool,
u16 qid);
+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);
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 b6f23bbeff71..0b779b2ca9ea 100644
--- a/drivers/net/ethernet/intel/igb/igb_main.c
+++ b/drivers/net/ethernet/intel/igb/igb_main.c
@@ -472,12 +472,17 @@ static void igb_dump(struct igb_adapter *adapter)

for (i = 0; i < rx_ring->count; i++) {
const char *next_desc;
- struct igb_rx_buffer *buffer_info;
- buffer_info = &rx_ring->rx_buffer_info[i];
+ dma_addr_t dma = (dma_addr_t)0;
+ struct igb_rx_buffer *buffer_info = NULL;
rx_desc = IGB_RX_DESC(rx_ring, i);
u0 = (struct my_u0 *)rx_desc;
staterr = le32_to_cpu(rx_desc->wb.upper.status_error);

+ if (!rx_ring->xsk_pool) {
+ buffer_info = &rx_ring->rx_buffer_info[i];
+ dma = buffer_info->dma;
+ }
+
if (i == rx_ring->next_to_use)
next_desc = " NTU";
else if (i == rx_ring->next_to_clean)
@@ -497,11 +502,11 @@ static void igb_dump(struct igb_adapter *adapter)
"R ", i,
le64_to_cpu(u0->a),
le64_to_cpu(u0->b),
- (u64)buffer_info->dma,
+ (u64)dma,
next_desc);

if (netif_msg_pktdata(adapter) &&
- buffer_info->dma && buffer_info->page) {
+ buffer_info && dma && buffer_info->page) {
print_hex_dump(KERN_INFO, "",
DUMP_PREFIX_ADDRESS,
16, 1,
@@ -1983,7 +1988,10 @@ static void igb_configure(struct igb_adapter *adapter)
*/
for (i = 0; i < adapter->num_rx_queues; i++) {
struct igb_ring *ring = adapter->rx_ring[i];
- igb_alloc_rx_buffers(ring, igb_desc_unused(ring));
+ if (ring->xsk_pool)
+ igb_alloc_rx_buffers_zc(ring, igb_desc_unused(ring));
+ else
+ igb_alloc_rx_buffers(ring, igb_desc_unused(ring));
}
}

@@ -3335,7 +3343,8 @@ 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;
@@ -4423,7 +4432,8 @@ int igb_setup_rx_resources(struct igb_ring *rx_ring)
if (xdp_rxq_info_is_reg(&rx_ring->xdp_rxq))
xdp_rxq_info_unreg(&rx_ring->xdp_rxq);
res = xdp_rxq_info_reg(&rx_ring->xdp_rxq, rx_ring->netdev,
- rx_ring->queue_index, 0);
+ rx_ring->queue_index,
+ rx_ring->q_vector->napi.napi_id);
if (res < 0) {
dev_err(dev, "Failed to register xdp_rxq index %u\n",
rx_ring->queue_index);
@@ -4719,12 +4729,17 @@ void igb_setup_srrctl(struct igb_adapter *adapter, struct igb_ring *ring)
struct e1000_hw *hw = &adapter->hw;
int reg_idx = ring->reg_idx;
u32 srrctl = 0;
+ u32 buf_size;

- srrctl = IGB_RX_HDR_LEN << E1000_SRRCTL_BSIZEHDRSIZE_SHIFT;
- if (ring_uses_large_buffer(ring))
- srrctl |= IGB_RXBUFFER_3072 >> E1000_SRRCTL_BSIZEPKT_SHIFT;
+ if (ring->xsk_pool)
+ buf_size = xsk_pool_get_rx_frame_size(ring->xsk_pool);
+ else if (ring_uses_large_buffer(ring))
+ buf_size = IGB_RXBUFFER_3072;
else
- srrctl |= IGB_RXBUFFER_2048 >> E1000_SRRCTL_BSIZEPKT_SHIFT;
+ buf_size = IGB_RXBUFFER_2048;
+
+ srrctl = IGB_RX_HDR_LEN << E1000_SRRCTL_BSIZEHDRSIZE_SHIFT;
+ srrctl |= buf_size >> E1000_SRRCTL_BSIZEPKT_SHIFT;
srrctl |= E1000_SRRCTL_DESCTYPE_ADV_ONEBUF;
if (hw->mac.type >= e1000_82580)
srrctl |= E1000_SRRCTL_TIMESTAMP;
@@ -4756,9 +4771,17 @@ void igb_configure_rx_ring(struct igb_adapter *adapter,
u32 rxdctl = 0;

xdp_rxq_info_unreg_mem_model(&ring->xdp_rxq);
- WARN_ON(xdp_rxq_info_reg_mem_model(&ring->xdp_rxq,
- MEM_TYPE_PAGE_SHARED, NULL));
ring->xsk_pool = igb_xsk_pool(adapter, ring);
+ if (ring->xsk_pool) {
+ WARN_ON(xdp_rxq_info_reg_mem_model(&ring->xdp_rxq,
+ MEM_TYPE_XSK_BUFF_POOL,
+ NULL));
+ xsk_pool_set_rxq_info(ring->xsk_pool, &ring->xdp_rxq);
+ } else {
+ WARN_ON(xdp_rxq_info_reg_mem_model(&ring->xdp_rxq,
+ MEM_TYPE_PAGE_SHARED,
+ NULL));
+ }

/* disable the queue */
wr32(E1000_RXDCTL(reg_idx), 0);
@@ -4785,9 +4808,12 @@ void igb_configure_rx_ring(struct igb_adapter *adapter,
rxdctl |= IGB_RX_HTHRESH << 8;
rxdctl |= IGB_RX_WTHRESH << 16;

- /* initialize rx_buffer_info */
- memset(ring->rx_buffer_info, 0,
- sizeof(struct igb_rx_buffer) * ring->count);
+ if (ring->xsk_pool)
+ memset(ring->rx_buffer_info_zc, 0,
+ sizeof(*ring->rx_buffer_info_zc) * ring->count);
+ else
+ memset(ring->rx_buffer_info, 0,
+ sizeof(*ring->rx_buffer_info) * ring->count);

/* initialize Rx descriptor 0 */
rx_desc = IGB_RX_DESC(ring, 0);
@@ -4974,8 +5000,13 @@ void igb_free_rx_resources(struct igb_ring *rx_ring)

rx_ring->xdp_prog = NULL;
xdp_rxq_info_unreg(&rx_ring->xdp_rxq);
- vfree(rx_ring->rx_buffer_info);
- rx_ring->rx_buffer_info = NULL;
+ if (rx_ring->xsk_pool) {
+ vfree(rx_ring->rx_buffer_info_zc);
+ rx_ring->rx_buffer_info_zc = NULL;
+ } else {
+ vfree(rx_ring->rx_buffer_info);
+ rx_ring->rx_buffer_info = NULL;
+ }

/* if not set, then don't free */
if (!rx_ring->desc)
@@ -5013,6 +5044,11 @@ void igb_clean_rx_ring(struct igb_ring *rx_ring)
dev_kfree_skb(rx_ring->skb);
rx_ring->skb = NULL;

+ if (rx_ring->xsk_pool) {
+ igb_clean_rx_ring_zc(rx_ring);
+ goto skip_for_xsk;
+ }
+
/* Free all the Rx ring sk_buffs */
while (i != rx_ring->next_to_alloc) {
struct igb_rx_buffer *buffer_info = &rx_ring->rx_buffer_info[i];
@@ -5040,6 +5076,7 @@ void igb_clean_rx_ring(struct igb_ring *rx_ring)
i = 0;
}

+skip_for_xsk:
rx_ring->next_to_alloc = 0;
rx_ring->next_to_clean = 0;
rx_ring->next_to_use = 0;
@@ -8195,7 +8232,9 @@ static int igb_poll(struct napi_struct *napi, int budget)
clean_complete = igb_clean_tx_irq(q_vector, budget);

if (q_vector->rx.ring) {
- int cleaned = igb_clean_rx_irq(q_vector, budget);
+ int cleaned = q_vector->rx.ring->xsk_pool ?
+ igb_clean_rx_irq_zc(q_vector, budget) :
+ igb_clean_rx_irq(q_vector, budget);

work_done += cleaned;
if (cleaned >= budget)
@@ -8603,8 +8642,15 @@ struct sk_buff *igb_run_xdp(struct igb_adapter *adapter,
break;
case XDP_REDIRECT:
err = xdp_do_redirect(adapter->netdev, xdp, xdp_prog);
- if (err)
+ if (err) {
+ if (rx_ring->xsk_pool &&
+ xsk_uses_need_wakeup(rx_ring->xsk_pool) &&
+ err == -ENOBUFS)
+ result = IGB_XDP_EXIT;
+ else
+ result = IGB_XDP_CONSUMED;
goto out_failure;
+ }
result = IGB_XDP_REDIR;
break;
default:
@@ -8861,12 +8907,14 @@ static void igb_put_rx_buffer(struct igb_ring *rx_ring,

static int igb_clean_rx_irq(struct igb_q_vector *q_vector, const int budget)
{
+ unsigned int total_bytes = 0, total_packets = 0;
struct igb_adapter *adapter = q_vector->adapter;
struct igb_ring *rx_ring = q_vector->rx.ring;
- struct sk_buff *skb = rx_ring->skb;
- unsigned int total_bytes = 0, total_packets = 0;
u16 cleaned_count = igb_desc_unused(rx_ring);
+ struct sk_buff *skb = rx_ring->skb;
+ int cpu = smp_processor_id();
unsigned int xdp_xmit = 0;
+ struct netdev_queue *nq;
struct xdp_buff xdp;
u32 frame_sz = 0;
int rx_buf_pgcnt;
@@ -8994,7 +9042,10 @@ static int igb_clean_rx_irq(struct igb_q_vector *q_vector, const int budget)
if (xdp_xmit & IGB_XDP_TX) {
struct igb_ring *tx_ring = igb_xdp_tx_queue_mapping(adapter);

+ nq = txring_txq(tx_ring);
+ __netif_tx_lock(nq, cpu);
igb_xdp_ring_update_tail(tx_ring);
+ __netif_tx_unlock(nq);
}

u64_stats_update_begin(&rx_ring->rx_syncp);
diff --git a/drivers/net/ethernet/intel/igb/igb_xsk.c b/drivers/net/ethernet/intel/igb/igb_xsk.c
index 925bf97f7caa..66cdc30e9b6e 100644
--- a/drivers/net/ethernet/intel/igb/igb_xsk.c
+++ b/drivers/net/ethernet/intel/igb/igb_xsk.c
@@ -66,7 +66,10 @@ static void igb_txrx_ring_enable(struct igb_adapter *adapter, u16 qid)
* at least 1 descriptor unused to make sure
* next_to_use != next_to_clean
*/
- igb_alloc_rx_buffers(rx_ring, igb_desc_unused(rx_ring));
+ if (rx_ring->xsk_pool)
+ igb_alloc_rx_buffers_zc(rx_ring, igb_desc_unused(rx_ring));
+ else
+ igb_alloc_rx_buffers(rx_ring, igb_desc_unused(rx_ring));

/* Rx/Tx share the same napi context. */
napi_enable(&rx_ring->q_vector->napi);
@@ -172,6 +175,262 @@ int igb_xsk_pool_setup(struct igb_adapter *adapter,
igb_xsk_pool_disable(adapter, qid);
}

+static u16 igb_fill_rx_descs(struct xsk_buff_pool *pool, struct xdp_buff **xdp,
+ union e1000_adv_rx_desc *rx_desc, u16 count)
+{
+ dma_addr_t dma;
+ u16 buffs;
+ int i;
+
+ /* nothing to do */
+ if (!count)
+ return 0;
+
+ buffs = xsk_buff_alloc_batch(pool, xdp, count);
+ for (i = 0; i < buffs; i++) {
+ dma = xsk_buff_xdp_get_dma(*xdp);
+ rx_desc->read.pkt_addr = cpu_to_le64(dma);
+ rx_desc->wb.upper.length = 0;
+
+ rx_desc++;
+ xdp++;
+ }
+
+ return buffs;
+}
+
+bool igb_alloc_rx_buffers_zc(struct igb_ring *rx_ring, u16 count)
+{
+ u32 nb_buffs_extra = 0, nb_buffs = 0;
+ union e1000_adv_rx_desc *rx_desc;
+ u16 ntu = rx_ring->next_to_use;
+ u16 total_count = count;
+ struct xdp_buff **xdp;
+
+ rx_desc = IGB_RX_DESC(rx_ring, ntu);
+ xdp = &rx_ring->rx_buffer_info_zc[ntu];
+
+ if (ntu + count >= rx_ring->count) {
+ nb_buffs_extra = igb_fill_rx_descs(rx_ring->xsk_pool, xdp,
+ rx_desc,
+ rx_ring->count - ntu);
+ if (nb_buffs_extra != rx_ring->count - ntu) {
+ ntu += nb_buffs_extra;
+ goto exit;
+ }
+ rx_desc = IGB_RX_DESC(rx_ring, 0);
+ xdp = rx_ring->rx_buffer_info_zc;
+ ntu = 0;
+ count -= nb_buffs_extra;
+ }
+
+ nb_buffs = igb_fill_rx_descs(rx_ring->xsk_pool, xdp, rx_desc, count);
+ ntu += nb_buffs;
+ if (ntu == rx_ring->count)
+ ntu = 0;
+
+ /* clear the length for the next_to_use descriptor */
+ rx_desc = IGB_RX_DESC(rx_ring, ntu);
+ rx_desc->wb.upper.length = 0;
+
+exit:
+ if (rx_ring->next_to_use != ntu) {
+ rx_ring->next_to_use = ntu;
+
+ /* Force memory writes to complete before letting h/w
+ * know there are new descriptors to fetch. (Only
+ * applicable for weak-ordered memory model archs,
+ * such as IA-64).
+ */
+ wmb();
+ writel(ntu, rx_ring->tail);
+ }
+
+ return total_count == (nb_buffs + nb_buffs_extra);
+}
+
+void igb_clean_rx_ring_zc(struct igb_ring *rx_ring)
+{
+ u16 ntc = rx_ring->next_to_clean;
+ u16 ntu = rx_ring->next_to_use;
+
+ while (ntc != ntu) {
+ struct xdp_buff *xdp = rx_ring->rx_buffer_info_zc[ntc];
+
+ xsk_buff_free(xdp);
+ ntc++;
+ if (ntc >= rx_ring->count)
+ ntc = 0;
+ }
+}
+
+static struct sk_buff *igb_construct_skb_zc(struct igb_ring *rx_ring,
+ struct xdp_buff *xdp,
+ ktime_t timestamp)
+{
+ unsigned int totalsize = xdp->data_end - xdp->data_meta;
+ unsigned int metasize = xdp->data - xdp->data_meta;
+ struct sk_buff *skb;
+
+ net_prefetch(xdp->data_meta);
+
+ /* allocate a skb to store the frags */
+ skb = napi_alloc_skb(&rx_ring->q_vector->napi, totalsize);
+ if (unlikely(!skb))
+ return NULL;
+
+ if (timestamp)
+ skb_hwtstamps(skb)->hwtstamp = timestamp;
+
+ memcpy(__skb_put(skb, totalsize), xdp->data_meta,
+ ALIGN(totalsize, sizeof(long)));
+
+ if (metasize) {
+ skb_metadata_set(skb, metasize);
+ __skb_pull(skb, metasize);
+ }
+
+ return skb;
+}
+
+static void igb_update_ntc(struct igb_ring *rx_ring)
+{
+ u32 ntc = rx_ring->next_to_clean + 1;
+
+ /* fetch, update, and store next to clean */
+ ntc = (ntc < rx_ring->count) ? ntc : 0;
+ rx_ring->next_to_clean = ntc;
+
+ prefetch(IGB_RX_DESC(rx_ring, ntc));
+}
+
+int igb_clean_rx_irq_zc(struct igb_q_vector *q_vector, const int budget)
+{
+ struct igb_adapter *adapter = q_vector->adapter;
+ unsigned int total_bytes = 0, total_packets = 0;
+ struct igb_ring *rx_ring = q_vector->rx.ring;
+ int cpu = smp_processor_id();
+ unsigned int xdp_xmit = 0;
+ struct netdev_queue *nq;
+ bool failure = false;
+ u16 entries_to_alloc;
+ struct sk_buff *skb;
+
+ while (likely(total_packets < budget)) {
+ union e1000_adv_rx_desc *rx_desc;
+ struct xdp_buff *xdp;
+ ktime_t timestamp = 0;
+ unsigned int size;
+
+ rx_desc = IGB_RX_DESC(rx_ring, rx_ring->next_to_clean);
+ size = le16_to_cpu(rx_desc->wb.upper.length);
+ if (!size)
+ break;
+
+ /* This memory barrier is needed to keep us from reading
+ * any other fields out of the rx_desc until we know the
+ * descriptor has been written back
+ */
+ dma_rmb();
+
+ xdp = rx_ring->rx_buffer_info_zc[rx_ring->next_to_clean];
+ xsk_buff_set_size(xdp, size);
+ xsk_buff_dma_sync_for_cpu(xdp);
+
+ /* pull rx packet timestamp if available and valid */
+ if (igb_test_staterr(rx_desc, E1000_RXDADV_STAT_TSIP)) {
+ int ts_hdr_len;
+
+ ts_hdr_len = igb_ptp_rx_pktstamp(rx_ring->q_vector,
+ xdp->data,
+ &timestamp);
+
+ xdp->data += ts_hdr_len;
+ xdp->data_meta += ts_hdr_len;
+ size -= ts_hdr_len;
+ }
+
+ skb = igb_run_xdp(adapter, rx_ring, xdp);
+
+ if (IS_ERR(skb)) {
+ unsigned int xdp_res = -PTR_ERR(skb);
+
+ if (likely(xdp_res & (IGB_XDP_TX | IGB_XDP_REDIR))) {
+ xdp_xmit |= xdp_res;
+ } else if (xdp_res == IGB_XDP_EXIT) {
+ failure = true;
+ break;
+ } else if (xdp_res == IGB_XDP_CONSUMED) {
+ xsk_buff_free(xdp);
+ }
+
+ total_packets++;
+ total_bytes += size;
+
+ igb_update_ntc(rx_ring);
+ continue;
+ }
+
+ skb = igb_construct_skb_zc(rx_ring, xdp, timestamp);
+
+ /* exit if we failed to retrieve a buffer */
+ if (!skb) {
+ rx_ring->rx_stats.alloc_failed++;
+ break;
+ }
+
+ xsk_buff_free(xdp);
+ igb_update_ntc(rx_ring);
+
+ if (eth_skb_pad(skb))
+ continue;
+
+ /* probably a little skewed due to removing CRC */
+ total_bytes += skb->len;
+
+ /* populate checksum, timestamp, VLAN, and protocol */
+ igb_process_skb_fields(rx_ring, rx_desc, skb);
+
+ napi_gro_receive(&q_vector->napi, skb);
+
+ /* update budget accounting */
+ total_packets++;
+ }
+
+ if (xdp_xmit & IGB_XDP_REDIR)
+ xdp_do_flush();
+
+ if (xdp_xmit & IGB_XDP_TX) {
+ struct igb_ring *tx_ring = igb_xdp_tx_queue_mapping(adapter);
+
+ nq = txring_txq(tx_ring);
+ __netif_tx_lock(nq, cpu);
+ igb_xdp_ring_update_tail(tx_ring);
+ __netif_tx_unlock(nq);
+ }
+
+ u64_stats_update_begin(&rx_ring->rx_syncp);
+ rx_ring->rx_stats.packets += total_packets;
+ rx_ring->rx_stats.bytes += total_bytes;
+ u64_stats_update_end(&rx_ring->rx_syncp);
+ q_vector->rx.total_packets += total_packets;
+ q_vector->rx.total_bytes += total_bytes;
+
+ entries_to_alloc = igb_desc_unused(rx_ring);
+ if (entries_to_alloc >= IGB_RX_BUFFER_WRITE)
+ failure |= !igb_alloc_rx_buffers_zc(rx_ring, entries_to_alloc);
+
+ if (xsk_uses_need_wakeup(rx_ring->xsk_pool)) {
+ if (failure || rx_ring->next_to_clean == rx_ring->next_to_use)
+ xsk_set_rx_need_wakeup(rx_ring->xsk_pool);
+ else
+ xsk_clear_rx_need_wakeup(rx_ring->xsk_pool);
+
+ return (int)total_packets;
+ }
+ return failure ? budget : (int)total_packets;
+}
+
int igb_xsk_wakeup(struct net_device *dev, u32 qid, u32 flags)
{
struct igb_adapter *adapter = netdev_priv(dev);
--
2.42.0