[bpf-next V1-RFC PATCH 02/14] xdp/mlx5: setup xdp_rxq_info and extend with qtype

[Jesper Dangaard Brouer <brouer@redhat.com>]

The mlx5 driver have a special drop-RQ queue (one per interface) that
simply drops all incoming traffic. It helps driver keep other HW
objects (flow steering) alive upon down/up operations.  It is
temporarily pointed by flow steering objects during the interface
setup, and when interface is down. It lacks many fields that are set
in a regular RQ (for example its state is never switched to
MLX5_RQC_STATE_RDY). (Thanks to Tariq Toukan for explaination).

The XDP RX-queue info API is extended with a queue-type, and mlx5 uses
this kind of drop/sink-type (RXQ_TYPE_SINK) for this kind of sink queue.

Driver hook points for xdp_rxq_info:
 * init+reg: mlx5e_alloc_rq()
 * init+reg: mlx5e_alloc_drop_rq()
 * unreg   : mlx5e_free_rq()

Tested on actual hardware with samples/bpf program

Cc: Saeed Mahameed <saeedm@mellanox.com>
Cc: Matan Barak <matanb@mellanox.com>
Cc: Tariq Toukan <tariqt@mellanox.com>
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
---
 drivers/net/ethernet/mellanox/mlx5/core/en.h      |    4 ++++
 drivers/net/ethernet/mellanox/mlx5/core/en_main.c |   14 +++++++++++++
 drivers/net/ethernet/mellanox/mlx5/core/en_rx.c   |    1 +
 include/net/xdp.h                                 |   23 +++++++++++++++++++++
 net/core/xdp.c                                    |    6 +++++
 5 files changed, 48 insertions(+)

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en.h b/drivers/net/ethernet/mellanox/mlx5/core/en.h
index c0872b3284cb..fe10a042783b 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/en.h
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en.h
@@ -46,6 +46,7 @@
 #include <linux/mlx5/transobj.h>
 #include <linux/rhashtable.h>
 #include <net/switchdev.h>
+#include <net/xdp.h>
 #include "wq.h"
 #include "mlx5_core.h"
 #include "en_stats.h"
@@ -568,6 +569,9 @@ struct mlx5e_rq {
 	u32                    rqn;
 	struct mlx5_core_dev  *mdev;
 	struct mlx5_core_mkey  umr_mkey;
+
+	/* XDP read-mostly */
+	struct xdp_rxq_info xdp_rxq;
 } ____cacheline_aligned_in_smp;
 
 struct mlx5e_channel {
diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_main.c b/drivers/net/ethernet/mellanox/mlx5/core/en_main.c
index 0f5c012de52e..ea44b5f25e11 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/en_main.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en_main.c
@@ -582,6 +582,12 @@ static int mlx5e_alloc_rq(struct mlx5e_channel *c,
 	rq->ix      = c->ix;
 	rq->mdev    = mdev;
 
+	/* XDP RX-queue info */
+	xdp_rxq_info_init(&rq->xdp_rxq);
+	rq->xdp_rxq.dev		= rq->netdev;
+	rq->xdp_rxq.queue_index = rq->ix;
+	xdp_rxq_info_reg(&rq->xdp_rxq);
+
 	rq->xdp_prog = params->xdp_prog ? bpf_prog_inc(params->xdp_prog) : NULL;
 	if (IS_ERR(rq->xdp_prog)) {
 		err = PTR_ERR(rq->xdp_prog);
@@ -695,6 +701,7 @@ static int mlx5e_alloc_rq(struct mlx5e_channel *c,
 err_rq_wq_destroy:
 	if (rq->xdp_prog)
 		bpf_prog_put(rq->xdp_prog);
+	xdp_rxq_info_unreg(&rq->xdp_rxq);
 	mlx5_wq_destroy(&rq->wq_ctrl);
 
 	return err;
@@ -707,6 +714,8 @@ static void mlx5e_free_rq(struct mlx5e_rq *rq)
 	if (rq->xdp_prog)
 		bpf_prog_put(rq->xdp_prog);
 
+	xdp_rxq_info_unreg(&rq->xdp_rxq);
+
 	switch (rq->wq_type) {
 	case MLX5_WQ_TYPE_LINKED_LIST_STRIDING_RQ:
 		mlx5e_rq_free_mpwqe_info(rq);
@@ -2768,6 +2777,11 @@ static int mlx5e_alloc_drop_rq(struct mlx5_core_dev *mdev,
 	if (err)
 		return err;
 
+	/* XDP RX-queue info for "Drop-RQ", packets never reach XDP */
+	xdp_rxq_info_init(&rq->xdp_rxq);
+	xdp_rxq_info_type(&rq->xdp_rxq, RXQ_TYPE_SINK);
+	xdp_rxq_info_reg(&rq->xdp_rxq);
+
 	rq->mdev = mdev;
 
 	return 0;
diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c b/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c
index 5b499c7a698f..7b38480811d4 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en_rx.c
@@ -812,6 +812,7 @@ static inline int mlx5e_xdp_handle(struct mlx5e_rq *rq,
 	xdp_set_data_meta_invalid(&xdp);
 	xdp.data_end = xdp.data + *len;
 	xdp.data_hard_start = va;
+	xdp.rxq = &rq->xdp_rxq;
 
 	act = bpf_prog_run_xdp(prog, &xdp);
 	switch (act) {
diff --git a/include/net/xdp.h b/include/net/xdp.h
index e4acd198fd60..5be560d943e1 100644
--- a/include/net/xdp.h
+++ b/include/net/xdp.h
@@ -36,10 +36,33 @@ struct xdp_rxq_info {
 	struct net_device *dev;
 	u32 queue_index;
 	u32 reg_state;
+	u32 qtype;
 } ____cacheline_aligned; /* perf critical, avoid false-sharing */
 
 void xdp_rxq_info_init(struct xdp_rxq_info *xdp_rxq);
 void xdp_rxq_info_reg(struct xdp_rxq_info *xdp_rxq);
 void xdp_rxq_info_unreg(struct xdp_rxq_info *xdp_rxq);
 
+/**
+ * DOC: XDP RX-queue type
+ *
+ * The XDP RX-queue info can have associated a type.
+ *
+ * @RXQ_TYPE_DEFAULT: default no specifik queue type need to be specified
+ *
+ * @RXQ_TYPE_SINK: indicate a fake queue that never reach XDP RX
+ *	code.  Some drivers have a need to maintain a lower layer
+ *	RX-queue as a sink queue, while reconfiguring other RX-queues.
+ */
+#define RXQ_TYPE_DEFAULT	0
+#define RXQ_TYPE_SINK		1
+#define RXQ_TYPE_MAX		RXQ_TYPE_SINK
+
+static inline
+void xdp_rxq_info_type(struct xdp_rxq_info *xdp_rxq, u32 qtype)
+{
+	BUILD_BUG_ON(qtype > RXQ_TYPE_MAX);
+	xdp_rxq->qtype = qtype;
+}
+
 #endif /* __LINUX_NET_XDP_H__ */
diff --git a/net/core/xdp.c b/net/core/xdp.c
index a9d2dd7b1ede..2a111f5987f6 100644
--- a/net/core/xdp.c
+++ b/net/core/xdp.c
@@ -32,8 +32,14 @@ EXPORT_SYMBOL_GPL(xdp_rxq_info_init);
 
 void xdp_rxq_info_reg(struct xdp_rxq_info *xdp_rxq)
 {
+	if (xdp_rxq->qtype == RXQ_TYPE_SINK)
+		goto skip_content_check;
+
+	/* Check information setup by driver code */
 	WARN(!xdp_rxq->dev, "Missing net_device from driver");
 	WARN(xdp_rxq->queue_index == U32_MAX, "Miss queue_index from driver");
+
+skip_content_check:
 	WARN(!(xdp_rxq->reg_state == REG_STATE_NEW),"API violation, miss init");
 	xdp_rxq->reg_state = REG_STATE_REGISTRED;
 }