[PATCH net-next v2 1/2] netdev: expose io_uring rx_page_order order via netlink

[Dragos Tatulea <dtatulea@nvidia.com>]

This adds observability for the io_uring zcrx rx-buf-len configuration.

Signed-off-by: Dragos Tatulea <dtatulea@nvidia.com>
Reviewed-by: Yael Chemla <ychemla@nvidia.com>
Reviewed-by: Tariq Toukan <tariqt@nvidia.com>
---
 Documentation/netlink/specs/netdev.yaml | 9 ++++++++-
 include/uapi/linux/netdev.h             | 2 ++
 io_uring/zcrx.c                         | 8 ++++++++
 tools/include/uapi/linux/netdev.h       | 2 ++
 4 files changed, 20 insertions(+), 1 deletion(-)

diff --git a/Documentation/netlink/specs/netdev.yaml b/Documentation/netlink/specs/netdev.yaml
index 49862b666d7d..5f143da7458c 100644
--- a/Documentation/netlink/specs/netdev.yaml
+++ b/Documentation/netlink/specs/netdev.yaml
@@ -127,7 +127,14 @@ attribute-sets:
         enum: xsk-flags
   -
     name: io-uring-provider-info
-    attributes: []
+    attributes:
+      -
+        name: rx-buf-len
+        type: uint
+        doc: |
+          RX buffer length in bytes for this io_uring memory provider.
+          Reflects the rx_buf_len passed at io_uring zerocopy rx
+          registration time.
   -
     name: page-pool
     attributes:
diff --git a/include/uapi/linux/netdev.h b/include/uapi/linux/netdev.h
index 7df1056a35fd..2f3ab75e8cc0 100644
--- a/include/uapi/linux/netdev.h
+++ b/include/uapi/linux/netdev.h
@@ -97,6 +97,8 @@ enum {
 };
 
 enum {
+	NETDEV_A_IO_URING_PROVIDER_INFO_RX_BUF_LEN = 1,
+
 	__NETDEV_A_IO_URING_PROVIDER_INFO_MAX,
 	NETDEV_A_IO_URING_PROVIDER_INFO_MAX = (__NETDEV_A_IO_URING_PROVIDER_INFO_MAX - 1)
 };
diff --git a/io_uring/zcrx.c b/io_uring/zcrx.c
index 19837e0b5e91..c7b167c2d4e4 100644
--- a/io_uring/zcrx.c
+++ b/io_uring/zcrx.c
@@ -1156,6 +1156,7 @@ static void io_pp_zc_destroy(struct page_pool *pp)
 static int io_pp_nl_fill(void *mp_priv, struct sk_buff *rsp,
 			 struct netdev_rx_queue *rxq)
 {
+	struct io_zcrx_ifq *ifq = mp_priv;
 	struct nlattr *nest;
 	int type;
 
@@ -1163,6 +1164,13 @@ static int io_pp_nl_fill(void *mp_priv, struct sk_buff *rsp,
 	nest = nla_nest_start(rsp, type);
 	if (!nest)
 		return -EMSGSIZE;
+
+	if (nla_put_uint(rsp, NETDEV_A_IO_URING_PROVIDER_INFO_RX_BUF_LEN,
+			 1ULL << ifq->niov_shift)) {
+		nla_nest_cancel(rsp, nest);
+		return -EMSGSIZE;
+	}
+
 	nla_nest_end(rsp, nest);
 
 	return 0;
diff --git a/tools/include/uapi/linux/netdev.h b/tools/include/uapi/linux/netdev.h
index 7df1056a35fd..2f3ab75e8cc0 100644
--- a/tools/include/uapi/linux/netdev.h
+++ b/tools/include/uapi/linux/netdev.h
@@ -97,6 +97,8 @@ enum {
 };
 
 enum {
+	NETDEV_A_IO_URING_PROVIDER_INFO_RX_BUF_LEN = 1,
+
 	__NETDEV_A_IO_URING_PROVIDER_INFO_MAX,
 	NETDEV_A_IO_URING_PROVIDER_INFO_MAX = (__NETDEV_A_IO_URING_PROVIDER_INFO_MAX - 1)
 };
-- 
2.54.0