[PATCH net-next v6 2/3] netdev-genl: Add an XSK attribute to queues

[Joe Damato <jdamato@fastly.com>]

Expose a new per-queue nest attribute, xsk, which will be present for
queues that are being used for AF_XDP. If the queue is not being used for
AF_XDP, the nest will not be present.

In the future, this attribute can be extended to include more data about
XSK as it is needed.

Signed-off-by: Joe Damato <jdamato@fastly.com>
Suggested-by: Jakub Kicinski <kuba@kernel.org>
---
 v6:
   - Added ifdefs to netdev_nl_queue_fill_one for CONFIG_XDP_SOCKETS.

 v5:
   - Removed unused variable, ret, from netdev_nl_queue_fill_one.

 v4:
   - Updated netdev_nl_queue_fill_one to use the empty nest helper added
     in patch 1.

 v2:
   - Patch adjusted to include an attribute, xsk, which is an empty nest
     and exposed for queues which have a pool.

 Documentation/netlink/specs/netdev.yaml | 13 ++++++++++++-
 include/uapi/linux/netdev.h             |  6 ++++++
 net/core/netdev-genl.c                  | 12 ++++++++++++
 tools/include/uapi/linux/netdev.h       |  6 ++++++
 4 files changed, 36 insertions(+), 1 deletion(-)

diff --git a/Documentation/netlink/specs/netdev.yaml b/Documentation/netlink/specs/netdev.yaml
index 288923e965ae..85402a2e289c 100644
--- a/Documentation/netlink/specs/netdev.yaml
+++ b/Documentation/netlink/specs/netdev.yaml
@@ -276,6 +276,9 @@ attribute-sets:
         doc: The timeout, in nanoseconds, of how long to suspend irq
              processing, if event polling finds events
         type: uint
+  -
+    name: xsk-info
+    attributes: []
   -
     name: queue
     attributes:
@@ -294,6 +297,9 @@ attribute-sets:
       -
         name: type
         doc: Queue type as rx, tx. Each queue type defines a separate ID space.
+             XDP TX queues allocated in the kernel are not linked to NAPIs and
+             thus not listed. AF_XDP queues will have more information set in
+             the xsk attribute.
         type: u32
         enum: queue-type
       -
@@ -309,7 +315,11 @@ attribute-sets:
         doc: io_uring memory provider information.
         type: nest
         nested-attributes: io-uring-provider-info
-
+      -
+        name: xsk
+        doc: XSK information for this queue, if any.
+        type: nest
+        nested-attributes: xsk-info
   -
     name: qstats
     doc: |
@@ -652,6 +662,7 @@ operations:
             - ifindex
             - dmabuf
             - io-uring
+            - xsk
       dump:
         request:
           attributes:
diff --git a/include/uapi/linux/netdev.h b/include/uapi/linux/netdev.h
index 6c6ee183802d..4e82f3871473 100644
--- a/include/uapi/linux/netdev.h
+++ b/include/uapi/linux/netdev.h
@@ -136,6 +136,11 @@ enum {
 	NETDEV_A_NAPI_MAX = (__NETDEV_A_NAPI_MAX - 1)
 };
 
+enum {
+	__NETDEV_A_XSK_INFO_MAX,
+	NETDEV_A_XSK_INFO_MAX = (__NETDEV_A_XSK_INFO_MAX - 1)
+};
+
 enum {
 	NETDEV_A_QUEUE_ID = 1,
 	NETDEV_A_QUEUE_IFINDEX,
@@ -143,6 +148,7 @@ enum {
 	NETDEV_A_QUEUE_NAPI_ID,
 	NETDEV_A_QUEUE_DMABUF,
 	NETDEV_A_QUEUE_IO_URING,
+	NETDEV_A_QUEUE_XSK,
 
 	__NETDEV_A_QUEUE_MAX,
 	NETDEV_A_QUEUE_MAX = (__NETDEV_A_QUEUE_MAX - 1)
diff --git a/net/core/netdev-genl.c b/net/core/netdev-genl.c
index 0dcd4faefd8d..49b2b2248821 100644
--- a/net/core/netdev-genl.c
+++ b/net/core/netdev-genl.c
@@ -400,11 +400,23 @@ netdev_nl_queue_fill_one(struct sk_buff *rsp, struct net_device *netdev,
 		if (params->mp_ops &&
 		    params->mp_ops->nl_fill(params->mp_priv, rsp, rxq))
 			goto nla_put_failure;
+#ifdef CONFIG_XDP_SOCKETS
+		if (rxq->pool)
+			if (nla_put_empty_nest(rsp, NETDEV_A_QUEUE_XSK))
+				goto nla_put_failure;
+#endif
+
 		break;
 	case NETDEV_QUEUE_TYPE_TX:
 		txq = netdev_get_tx_queue(netdev, q_idx);
 		if (nla_put_napi_id(rsp, txq->napi))
 			goto nla_put_failure;
+#ifdef CONFIG_XDP_SOCKETS
+		if (txq->pool)
+			if (nla_put_empty_nest(rsp, NETDEV_A_QUEUE_XSK))
+				goto nla_put_failure;
+#endif
+		break;
 	}
 
 	genlmsg_end(rsp, hdr);
diff --git a/tools/include/uapi/linux/netdev.h b/tools/include/uapi/linux/netdev.h
index 6c6ee183802d..4e82f3871473 100644
--- a/tools/include/uapi/linux/netdev.h
+++ b/tools/include/uapi/linux/netdev.h
@@ -136,6 +136,11 @@ enum {
 	NETDEV_A_NAPI_MAX = (__NETDEV_A_NAPI_MAX - 1)
 };
 
+enum {
+	__NETDEV_A_XSK_INFO_MAX,
+	NETDEV_A_XSK_INFO_MAX = (__NETDEV_A_XSK_INFO_MAX - 1)
+};
+
 enum {
 	NETDEV_A_QUEUE_ID = 1,
 	NETDEV_A_QUEUE_IFINDEX,
@@ -143,6 +148,7 @@ enum {
 	NETDEV_A_QUEUE_NAPI_ID,
 	NETDEV_A_QUEUE_DMABUF,
 	NETDEV_A_QUEUE_IO_URING,
+	NETDEV_A_QUEUE_XSK,
 
 	__NETDEV_A_QUEUE_MAX,
 	NETDEV_A_QUEUE_MAX = (__NETDEV_A_QUEUE_MAX - 1)
-- 
2.43.0