gve: Add header split ethtool stats

To record the stats of header split packets, three stats are added in
the driver's ethtool stats.

- rx_hsplit_pkt is the split packets count with header split
- rx_hsplit_bytes is the received header bytes count with header split
- rx_hsplit_unsplit_pkt is the unsplit packet count due to header buffer
  overflow or zero header length when header split is enabled

Currently, it's entering the stats_update critical section more than
once per packet. We have plans to avoid that in the future change to let
all the stats_update happen in one place at the end of
`gve_rx_poll_dqo`.
Co-developed-by: Ziwei Xiao <ziweixiao@google.com>
Signed-off-by: Ziwei Xiao <ziweixiao@google.com>
Signed-off-by: Jeroen de Borst <jeroendb@google.com>
Reviewed-by: Praveen Kaligineedi <pkaligineedi@google.com>
Reviewed-by: Harshitha Ramamurthy <hramamurthy@google.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/google/gve/gve.h

@@ -269,15 +269,19 @@ struct gve_rx_ring {
 	};
 
 	u64 rbytes; /* free-running bytes received */
+	u64 rx_hsplit_bytes; /* free-running header bytes received */
 	u64 rpackets; /* free-running packets received */
 	u32 cnt; /* free-running total number of completed packets */
 	u32 fill_cnt; /* free-running total number of descs and buffs posted */
 	u32 mask; /* masks the cnt and fill_cnt to the size of the ring */
+	u64 rx_hsplit_pkt; /* free-running packets with headers split */
 	u64 rx_copybreak_pkt; /* free-running count of copybreak packets */
 	u64 rx_copied_pkt; /* free-running total number of copied packets */
 	u64 rx_skb_alloc_fail; /* free-running count of skb alloc fails */
 	u64 rx_buf_alloc_fail; /* free-running count of buffer alloc fails */
 	u64 rx_desc_err_dropped_pkt; /* free-running count of packets dropped by descriptor error */
+	/* free-running count of unsplit packets due to header buffer overflow or hdr_len is 0 */
+	u64 rx_hsplit_unsplit_pkt;
 	u64 rx_cont_packet_cnt; /* free-running multi-fragment packets received */
 	u64 rx_frag_flip_cnt; /* free-running count of rx segments where page_flip was used */
 	u64 rx_frag_copy_cnt; /* free-running count of rx segments copied */

drivers/net/ethernet/google/gve/gve_ethtool.c

@@ -39,17 +39,18 @@ static u32 gve_get_msglevel(struct net_device *netdev)
  * as declared in enum xdp_action inside file uapi/linux/bpf.h .
  */
 static const char gve_gstrings_main_stats[][ETH_GSTRING_LEN] = {
-	"rx_packets", "tx_packets", "rx_bytes", "tx_bytes",
-	"rx_dropped", "tx_dropped", "tx_timeouts",
+	"rx_packets", "rx_hsplit_pkt", "tx_packets", "rx_bytes",
+	"tx_bytes", "rx_dropped", "tx_dropped", "tx_timeouts",
 	"rx_skb_alloc_fail", "rx_buf_alloc_fail", "rx_desc_err_dropped_pkt",
+	"rx_hsplit_unsplit_pkt",
 	"interface_up_cnt", "interface_down_cnt", "reset_cnt",
 	"page_alloc_fail", "dma_mapping_error", "stats_report_trigger_cnt",
 };
 
 static const char gve_gstrings_rx_stats[][ETH_GSTRING_LEN] = {
-	"rx_posted_desc[%u]", "rx_completed_desc[%u]", "rx_consumed_desc[%u]", "rx_bytes[%u]",
-	"rx_cont_packet_cnt[%u]", "rx_frag_flip_cnt[%u]", "rx_frag_copy_cnt[%u]",
-	"rx_frag_alloc_cnt[%u]",
+	"rx_posted_desc[%u]", "rx_completed_desc[%u]", "rx_consumed_desc[%u]",
+	"rx_bytes[%u]", "rx_hsplit_bytes[%u]", "rx_cont_packet_cnt[%u]",
+	"rx_frag_flip_cnt[%u]", "rx_frag_copy_cnt[%u]", "rx_frag_alloc_cnt[%u]",
 	"rx_dropped_pkt[%u]", "rx_copybreak_pkt[%u]", "rx_copied_pkt[%u]",
 	"rx_queue_drop_cnt[%u]", "rx_no_buffers_posted[%u]",
 	"rx_drops_packet_over_mru[%u]", "rx_drops_invalid_checksum[%u]",
@@ -153,11 +154,13 @@ static void
 gve_get_ethtool_stats(struct net_device *netdev,
 		      struct ethtool_stats *stats, u64 *data)
 {
-	u64 tmp_rx_pkts, tmp_rx_bytes, tmp_rx_skb_alloc_fail,
-		tmp_rx_buf_alloc_fail, tmp_rx_desc_err_dropped_pkt,
+	u64 tmp_rx_pkts, tmp_rx_hsplit_pkt, tmp_rx_bytes, tmp_rx_hsplit_bytes,
+		tmp_rx_skb_alloc_fail, tmp_rx_buf_alloc_fail,
+		tmp_rx_desc_err_dropped_pkt, tmp_rx_hsplit_unsplit_pkt,
 		tmp_tx_pkts, tmp_tx_bytes;
-	u64 rx_buf_alloc_fail, rx_desc_err_dropped_pkt, rx_pkts,
-		rx_skb_alloc_fail, rx_bytes, tx_pkts, tx_bytes, tx_dropped;
+	u64 rx_buf_alloc_fail, rx_desc_err_dropped_pkt, rx_hsplit_unsplit_pkt,
+		rx_pkts, rx_hsplit_pkt, rx_skb_alloc_fail, rx_bytes, tx_pkts, tx_bytes,
+		tx_dropped;
 	int stats_idx, base_stats_idx, max_stats_idx;
 	struct stats *report_stats;
 	int *rx_qid_to_stats_idx;
@@ -184,8 +187,10 @@ gve_get_ethtool_stats(struct net_device *netdev,
 		kfree(rx_qid_to_stats_idx);
 		return;
 	}
-	for (rx_pkts = 0, rx_bytes = 0, rx_skb_alloc_fail = 0,
-	     rx_buf_alloc_fail = 0, rx_desc_err_dropped_pkt = 0, ring = 0;
+	for (rx_pkts = 0, rx_bytes = 0, rx_hsplit_pkt = 0,
+	     rx_skb_alloc_fail = 0, rx_buf_alloc_fail = 0,
+	     rx_desc_err_dropped_pkt = 0, rx_hsplit_unsplit_pkt = 0,
+	     ring = 0;
 	     ring < priv->rx_cfg.num_queues; ring++) {
 		if (priv->rx) {
 			do {
@@ -194,18 +199,23 @@ gve_get_ethtool_stats(struct net_device *netdev,
 				start =
 				  u64_stats_fetch_begin(&priv->rx[ring].statss);
 				tmp_rx_pkts = rx->rpackets;
+				tmp_rx_hsplit_pkt = rx->rx_hsplit_pkt;
 				tmp_rx_bytes = rx->rbytes;
 				tmp_rx_skb_alloc_fail = rx->rx_skb_alloc_fail;
 				tmp_rx_buf_alloc_fail = rx->rx_buf_alloc_fail;
 				tmp_rx_desc_err_dropped_pkt =
 					rx->rx_desc_err_dropped_pkt;
+				tmp_rx_hsplit_unsplit_pkt =
+					rx->rx_hsplit_unsplit_pkt;
 			} while (u64_stats_fetch_retry(&priv->rx[ring].statss,
 						       start));
 			rx_pkts += tmp_rx_pkts;
+			rx_hsplit_pkt += tmp_rx_hsplit_pkt;
 			rx_bytes += tmp_rx_bytes;
 			rx_skb_alloc_fail += tmp_rx_skb_alloc_fail;
 			rx_buf_alloc_fail += tmp_rx_buf_alloc_fail;
 			rx_desc_err_dropped_pkt += tmp_rx_desc_err_dropped_pkt;
+			rx_hsplit_unsplit_pkt += tmp_rx_hsplit_unsplit_pkt;
 		}
 	}
 	for (tx_pkts = 0, tx_bytes = 0, tx_dropped = 0, ring = 0;
@@ -226,6 +236,7 @@ gve_get_ethtool_stats(struct net_device *netdev,
 
 	i = 0;
 	data[i++] = rx_pkts;
+	data[i++] = rx_hsplit_pkt;
 	data[i++] = tx_pkts;
 	data[i++] = rx_bytes;
 	data[i++] = tx_bytes;
@@ -237,6 +248,7 @@ gve_get_ethtool_stats(struct net_device *netdev,
 	data[i++] = rx_skb_alloc_fail;
 	data[i++] = rx_buf_alloc_fail;
 	data[i++] = rx_desc_err_dropped_pkt;
+	data[i++] = rx_hsplit_unsplit_pkt;
 	data[i++] = priv->interface_up_cnt;
 	data[i++] = priv->interface_down_cnt;
 	data[i++] = priv->reset_cnt;
@@ -276,6 +288,7 @@ gve_get_ethtool_stats(struct net_device *netdev,
 				start =
 				  u64_stats_fetch_begin(&priv->rx[ring].statss);
 				tmp_rx_bytes = rx->rbytes;
+				tmp_rx_hsplit_bytes = rx->rx_hsplit_bytes;
 				tmp_rx_skb_alloc_fail = rx->rx_skb_alloc_fail;
 				tmp_rx_buf_alloc_fail = rx->rx_buf_alloc_fail;
 				tmp_rx_desc_err_dropped_pkt =
@@ -283,6 +296,7 @@ gve_get_ethtool_stats(struct net_device *netdev,
 			} while (u64_stats_fetch_retry(&priv->rx[ring].statss,
 						       start));
 			data[i++] = tmp_rx_bytes;
+			data[i++] = tmp_rx_hsplit_bytes;
 			data[i++] = rx->rx_cont_packet_cnt;
 			data[i++] = rx->rx_frag_flip_cnt;
 			data[i++] = rx->rx_frag_copy_cnt;

drivers/net/ethernet/google/gve/gve_rx_dqo.c

@@ -720,6 +720,8 @@ static int gve_rx_dqo(struct napi_struct *napi, struct gve_rx_ring *rx,
 
 	/* Copy the header into the skb in the case of header split */
 	if (hsplit) {
+		int unsplit = 0;
+
 		if (hdr_len && !hbo) {
 			rx->ctx.skb_head = gve_rx_copy_data(priv->dev, napi,
 							    rx->dqo.hdr_bufs.data +
@@ -728,7 +730,14 @@ static int gve_rx_dqo(struct napi_struct *napi, struct gve_rx_ring *rx,
 			if (unlikely(!rx->ctx.skb_head))
 				goto error;
 			rx->ctx.skb_tail = rx->ctx.skb_head;
+		} else {
+			unsplit = 1;
 		}
+		u64_stats_update_begin(&rx->statss);
+		rx->rx_hsplit_pkt++;
+		rx->rx_hsplit_unsplit_pkt += unsplit;
+		rx->rx_hsplit_bytes += hdr_len;
+		u64_stats_update_end(&rx->statss);
 	}
 
 	/* Sync the portion of dma buffer for CPU to read. */