[PATCH net-next 4/4] gve: Add Rx HWTS metadata to AF_XDP ZC mode

[joshwash@google.com]

From: Tim Hostetler <thostet@google.com>

By overlaying the struct gve_xdp_buff on top of the struct xdp_buff_xsk
that AF_XDP utilizes, the driver records the 32 bit timestamp via the
completion descriptor and the cached 64 bit NIC timestamp via gve_priv.

The driver's implementation of xmo_rx_timestamp extends the timestamp to
the full and up to date 64 bit timestamp and returns it to the user.

gve_rx_xsk_dqo is modified to accept a pointer to the completion
descriptor and no longer takes a buf_len explicitly as it can be pulled
out of the descriptor.

With this patch gve now supports bpf_xdp_metadata_rx_timestamp.

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_main.c   |  7 +++++++
 drivers/net/ethernet/google/gve/gve_rx_dqo.c | 16 ++++++++++++++--
 2 files changed, 21 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/google/gve/gve_main.c b/drivers/net/ethernet/google/gve/gve_main.c
index 2b41a42fb516..a5a2b18d309b 100644
--- a/drivers/net/ethernet/google/gve/gve_main.c
+++ b/drivers/net/ethernet/google/gve/gve_main.c
@@ -2348,6 +2348,10 @@ static void gve_set_netdev_xdp_features(struct gve_priv *priv)
 	xdp_set_features_flag_locked(priv->dev, xdp_features);
 }
 
+static const struct xdp_metadata_ops gve_xdp_metadata_ops = {
+	.xmo_rx_timestamp	= gve_xdp_rx_timestamp,
+};
+
 static int gve_init_priv(struct gve_priv *priv, bool skip_describe_device)
 {
 	int num_ntfy;
@@ -2443,6 +2447,9 @@ static int gve_init_priv(struct gve_priv *priv, bool skip_describe_device)
 	}
 
 	gve_set_netdev_xdp_features(priv);
+	if (!gve_is_gqi(priv))
+		priv->dev->xdp_metadata_ops = &gve_xdp_metadata_ops;
+
 	err = gve_setup_device_resources(priv);
 	if (err)
 		goto err_free_xsk_bitmap;
diff --git a/drivers/net/ethernet/google/gve/gve_rx_dqo.c b/drivers/net/ethernet/google/gve/gve_rx_dqo.c
index f20d1b1d06e6..f1bd8f5d5732 100644
--- a/drivers/net/ethernet/google/gve/gve_rx_dqo.c
+++ b/drivers/net/ethernet/google/gve/gve_rx_dqo.c
@@ -240,6 +240,11 @@ int gve_rx_alloc_ring_dqo(struct gve_priv *priv,
 		rx->rx_headroom = 0;
 	}
 
+	/* struct gve_xdp_buff is overlaid on struct xdp_buff_xsk and utilizes
+	 * the 24 byte field cb to store gve specific data.
+	 */
+	XSK_CHECK_PRIV_TYPE(struct gve_xdp_buff);
+
 	rx->dqo.num_buf_states = cfg->raw_addressing ? buffer_queue_slots :
 		gve_get_rx_pages_per_qpl_dqo(cfg->ring_size);
 	rx->dqo.buf_states = kvcalloc_node(rx->dqo.num_buf_states,
@@ -701,16 +706,23 @@ static void gve_xdp_done_dqo(struct gve_priv *priv, struct gve_rx_ring *rx,
 }
 
 static int gve_rx_xsk_dqo(struct napi_struct *napi, struct gve_rx_ring *rx,
-			  struct gve_rx_buf_state_dqo *buf_state, int buf_len,
+			  const struct gve_rx_compl_desc_dqo *compl_desc,
+			  struct gve_rx_buf_state_dqo *buf_state,
 			  struct bpf_prog *xprog)
 {
 	struct xdp_buff *xdp = buf_state->xsk_buff;
+	int buf_len = compl_desc->packet_len;
 	struct gve_priv *priv = rx->gve;
+	struct gve_xdp_buff *gve_xdp;
 	int xdp_act;
 
 	xdp->data_end = xdp->data + buf_len;
 	xsk_buff_dma_sync_for_cpu(xdp);
 
+	gve_xdp = (void *)xdp;
+	gve_xdp->gve = priv;
+	gve_xdp->compl_desc = compl_desc;
+
 	if (xprog) {
 		xdp_act = bpf_prog_run_xdp(xprog, xdp);
 		buf_len = xdp->data_end - xdp->data;
@@ -800,7 +812,7 @@ static int gve_rx_dqo(struct napi_struct *napi, struct gve_rx_ring *rx,
 
 	xprog = READ_ONCE(priv->xdp_prog);
 	if (buf_state->xsk_buff)
-		return gve_rx_xsk_dqo(napi, rx, buf_state, buf_len, xprog);
+		return gve_rx_xsk_dqo(napi, rx, compl_desc, buf_state, xprog);
 
 	/* Page might have not been used for awhile and was likely last written
 	 * by a different thread.
-- 
2.51.2.1041.gc1ab5b90ca-goog