[PATCH net-next 3/4] gve: Prepare bpf_xdp_metadata_rx_timestamp support

[joshwash@google.com]

From: Tim Hostetler <thostet@google.com>

Support populating XDP RX metadata with hardware RX timestamps. This
patch utilizes the same underlying logic to calculate hardware
timestamps as the regular RX path.

xdp_metadata_ops is registered with the net_device in a future patch.

gve_rx_calculate_hwtstamp was pulled out so as to not duplicate logic
between gve_xdp_rx_timestamp and gve_rx_hwtstamp.

Signed-off-by: Tim Hostetler <thostet@google.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Reviewed-by: Harshitha Ramamurthy <hramamurthy@google.com>
Signed-off-by: Joshua Washington <joshwash@google.com>
---
 drivers/net/ethernet/google/gve/gve.h        |  2 +
 drivers/net/ethernet/google/gve/gve_dqo.h    |  1 +
 drivers/net/ethernet/google/gve/gve_rx_dqo.c | 41 +++++++++++++++-----
 3 files changed, 34 insertions(+), 10 deletions(-)

diff --git a/drivers/net/ethernet/google/gve/gve.h b/drivers/net/ethernet/google/gve/gve.h
index a21e599cf710..970d5ca8cdde 100644
--- a/drivers/net/ethernet/google/gve/gve.h
+++ b/drivers/net/ethernet/google/gve/gve.h
@@ -208,6 +208,8 @@ struct gve_rx_buf_state_dqo {
 /* Wrapper for XDP Rx metadata */
 struct gve_xdp_buff {
 	struct xdp_buff xdp;
+	struct gve_priv *gve;
+	const struct gve_rx_compl_desc_dqo *compl_desc;
 };
 
 /* `head` and `tail` are indices into an array, or -1 if empty. */
diff --git a/drivers/net/ethernet/google/gve/gve_dqo.h b/drivers/net/ethernet/google/gve/gve_dqo.h
index 6eb442096e02..5871f773f0c7 100644
--- a/drivers/net/ethernet/google/gve/gve_dqo.h
+++ b/drivers/net/ethernet/google/gve/gve_dqo.h
@@ -36,6 +36,7 @@ netdev_tx_t gve_tx_dqo(struct sk_buff *skb, struct net_device *dev);
 netdev_features_t gve_features_check_dqo(struct sk_buff *skb,
 					 struct net_device *dev,
 					 netdev_features_t features);
+int gve_xdp_rx_timestamp(const struct xdp_md *_ctx, u64 *timestamp);
 bool gve_tx_poll_dqo(struct gve_notify_block *block, bool do_clean);
 bool gve_xdp_poll_dqo(struct gve_notify_block *block);
 bool gve_xsk_tx_poll_dqo(struct gve_notify_block *block, int budget);
diff --git a/drivers/net/ethernet/google/gve/gve_rx_dqo.c b/drivers/net/ethernet/google/gve/gve_rx_dqo.c
index 76b26896f572..f20d1b1d06e6 100644
--- a/drivers/net/ethernet/google/gve/gve_rx_dqo.c
+++ b/drivers/net/ethernet/google/gve/gve_rx_dqo.c
@@ -456,20 +456,38 @@ static void gve_rx_skb_hash(struct sk_buff *skb,
  * Note that this means if the time delta between packet reception and the last
  * clock read is greater than ~2 seconds, this will provide invalid results.
  */
+static ktime_t gve_rx_get_hwtstamp(struct gve_priv *gve, u32 hwts)
+{
+	u64 last_read = READ_ONCE(gve->last_sync_nic_counter);
+	u32 low = (u32)last_read;
+	s32 diff = hwts - low;
+
+	return ns_to_ktime(last_read + diff);
+}
+
 static void gve_rx_skb_hwtstamp(struct gve_rx_ring *rx,
 				const struct gve_rx_compl_desc_dqo *desc)
 {
-	u64 last_read = READ_ONCE(rx->gve->last_sync_nic_counter);
 	struct sk_buff *skb = rx->ctx.skb_head;
-	u32 ts, low;
-	s32 diff;
-
-	if (desc->ts_sub_nsecs_low & GVE_DQO_RX_HWTSTAMP_VALID) {
-		ts = le32_to_cpu(desc->ts);
-		low = (u32)last_read;
-		diff = ts - low;
-		skb_hwtstamps(skb)->hwtstamp = ns_to_ktime(last_read + diff);
-	}
+
+	if (desc->ts_sub_nsecs_low & GVE_DQO_RX_HWTSTAMP_VALID)
+		skb_hwtstamps(skb)->hwtstamp =
+			gve_rx_get_hwtstamp(rx->gve, le32_to_cpu(desc->ts));
+}
+
+int gve_xdp_rx_timestamp(const struct xdp_md *_ctx, u64 *timestamp)
+{
+	const struct gve_xdp_buff *ctx = (void *)_ctx;
+
+	if (!ctx->gve->nic_ts_report)
+		return -ENODATA;
+
+	if (!(ctx->compl_desc->ts_sub_nsecs_low & GVE_DQO_RX_HWTSTAMP_VALID))
+		return -ENODATA;
+
+	*timestamp = gve_rx_get_hwtstamp(ctx->gve,
+					 le32_to_cpu(ctx->compl_desc->ts));
+	return 0;
 }
 
 static void gve_rx_free_skb(struct napi_struct *napi, struct gve_rx_ring *rx)
@@ -851,6 +869,9 @@ static int gve_rx_dqo(struct napi_struct *napi, struct gve_rx_ring *rx,
 				 buf_state->page_info.page_offset,
 				 buf_state->page_info.pad,
 				 buf_len, false);
+		gve_xdp.gve = priv;
+		gve_xdp.compl_desc = compl_desc;
+
 		old_data = gve_xdp.xdp.data;
 		xdp_act = bpf_prog_run_xdp(xprog, &gve_xdp.xdp);
 		buf_state->page_info.pad += gve_xdp.xdp.data - old_data;
-- 
2.51.2.1041.gc1ab5b90ca-goog