[PATCH RFC bpf-next 13/52] libbpf: add ability to set the meta threshold on setting XDP prog

[Alexander Lobakin <alexandr.lobakin@xxxxxxxxx>]

Covered functions:
 * bpf_link_create() - via &bpf_link_create_ops;
 * bpf_link_update() - via &bpf_link_update_ops;
 * bpf_xdp_attach() - via &bpf_xdp_attach_ops;
 * bpf_set_link_xdp_fd_opts() - via &bpf_xdp_set_link_opts;

No support for bpf_get_link_xdp_info()/&xdp_link_info as we store
additional data in the kernel in BPF link mode only.

Signed-off-by: Alexander Lobakin <alexandr.lobakin@xxxxxxxxx>
---
 tools/lib/bpf/bpf.c     |  3 +++
 tools/lib/bpf/bpf.h     |  8 +++++++-
 tools/lib/bpf/libbpf.h  |  4 ++--
 tools/lib/bpf/netlink.c | 10 ++++++++++
 4 files changed, 22 insertions(+), 3 deletions(-)

diff --git a/tools/lib/bpf/bpf.c b/tools/lib/bpf/bpf.c
index 6036dc75cc7b..e7c713a418f6 100644
--- a/tools/lib/bpf/bpf.c
+++ b/tools/lib/bpf/bpf.c
@@ -807,6 +807,9 @@ int bpf_link_create(int prog_fd, int target_fd,
 		break;
 	case BPF_XDP:
 		attr.link_create.xdp.btf_id = OPTS_GET(opts, xdp.btf_id, 0);
+		attr.link_create.xdp.meta_thresh = OPTS_GET(opts,
+							    xdp.meta_thresh,
+							    0);
 		if (!OPTS_ZEROED(opts, xdp))
 			return libbpf_err(-EINVAL);
 		break;
diff --git a/tools/lib/bpf/bpf.h b/tools/lib/bpf/bpf.h
index 4e17995fdaff..c0f54f24d675 100644
--- a/tools/lib/bpf/bpf.h
+++ b/tools/lib/bpf/bpf.h
@@ -385,6 +385,8 @@ struct bpf_link_create_opts {
 		struct {
 			/* target metadata BTF + type ID */
 			__aligned_u64 btf_id;
+			/* frame size to start composing XDP metadata from */
+			__u32 meta_thresh;
 		} xdp;
 	};
 	size_t :0;
@@ -408,11 +410,15 @@ struct bpf_link_update_opts {
 		struct {
 			/* new target metadata BTF + type ID */
 			__aligned_u64 new_btf_id;
+			/* new frame size to start composing XDP
+			 * metadata from
+			 */
+			__u32 new_meta_thresh;
 		} xdp;
 	};
 	size_t :0;
 };
-#define bpf_link_update_opts__last_field xdp.new_btf_id
+#define bpf_link_update_opts__last_field xdp.new_meta_thresh
 
 LIBBPF_API int bpf_link_update(int link_fd, int new_prog_fd,
 			       const struct bpf_link_update_opts *opts);
diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h
index 4f77128ba770..99ac94f148fc 100644
--- a/tools/lib/bpf/libbpf.h
+++ b/tools/lib/bpf/libbpf.h
@@ -1193,7 +1193,7 @@ struct xdp_link_info {
 struct bpf_xdp_set_link_opts {
 	size_t sz;
 	int old_fd;
-	__u32 :32;
+	__u32 meta_thresh;
 	__u64 btf_id;
 	size_t :0;
 };
@@ -1213,7 +1213,7 @@ LIBBPF_API int bpf_get_link_xdp_info(int ifindex, struct xdp_link_info *info,
 struct bpf_xdp_attach_opts {
 	size_t sz;
 	int old_prog_fd;
-	__u32 :32;
+	__u32 meta_thresh;
 	__u64 btf_id;
 	size_t :0;
 };
diff --git a/tools/lib/bpf/netlink.c b/tools/lib/bpf/netlink.c
index 104a809d5fb2..ac2a87243ecd 100644
--- a/tools/lib/bpf/netlink.c
+++ b/tools/lib/bpf/netlink.c
@@ -236,6 +236,7 @@ struct __bpf_set_link_xdp_fd_opts {
 	int old_fd;
 	__u32 flags;
 	__u64 btf_id;
+	__u32 meta_thresh;
 };
 
 static int
@@ -276,6 +277,13 @@ __bpf_set_link_xdp_fd_replace(const struct __bpf_set_link_xdp_fd_opts *opts)
 		if (ret < 0)
 			return ret;
 	}
+	if (opts->meta_thresh) {
+		ret = nlattr_add(&req, IFLA_XDP_META_THRESH,
+				 &opts->meta_thresh,
+				 sizeof(opts->meta_thresh));
+		if (ret < 0)
+			return ret;
+	}
 	nlattr_end_nested(&req, nla);
 
 	return libbpf_netlink_send_recv(&req, NULL, NULL, NULL);
@@ -300,6 +308,7 @@ int bpf_xdp_attach(int ifindex, int prog_fd, __u32 flags, const struct bpf_xdp_a
 		sl_opts.old_fd = -1;
 
 	sl_opts.btf_id = OPTS_GET(opts, btf_id, 0);
+	sl_opts.meta_thresh = OPTS_GET(opts, meta_thresh, 0);
 
 	err = __bpf_set_link_xdp_fd_replace(&sl_opts);
 	return libbpf_err(err);
@@ -330,6 +339,7 @@ int bpf_set_link_xdp_fd_opts(int ifindex, int fd, __u32 flags,
 	}
 
 	sl_opts.btf_id = OPTS_GET(opts, btf_id, 0);
+	sl_opts.meta_thresh = OPTS_GET(opts, meta_thresh, 0);
 
 	ret = __bpf_set_link_xdp_fd_replace(&sl_opts);
 	return libbpf_err(ret);
-- 
2.36.1