bpftool: Specify XDP Hints ifname when loading program

Add ability to specify a network interface used to resolve XDP hints
kfuncs when loading program through bpftool.

Usage:

  bpftool prog load [...] xdpmeta_dev <ifname>

Writing just 'dev <ifname>' instead of 'xdpmeta_dev' is a very probable
mistake that results in not very descriptive errors,
so 'bpftool prog load [...] dev <ifname>' syntax becomes deprecated,
followed by 'bpftool map create [...] dev <ifname>' for consistency.

Now, to offload program, execute:

  bpftool prog load [...] offload_dev <ifname>

To offload map:

  bpftool map create [...] offload_dev <ifname>

'dev <ifname>' still performs offloading in the commands above, but now
triggers a warning and is excluded from bash completion.

'xdpmeta_dev' and 'offload_dev' are mutually exclusive options, because
'xdpmeta_dev' basically makes a program device-bound without loading it
onto the said device. For now, offloaded programs cannot use XDP hints [0],
but if this changes, using 'offload_dev <ifname>' should cover this case.

  [0] https://lore.kernel.org/bpf/a5a636cc-5b03-686f-4be0-000383b05cfc@linux.dev

Signed-off-by: Larysa Zaremba <larysa.zaremba@intel.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Quentin Monnet <quentin@isovalent.com>
Link: https://lore.kernel.org/bpf/20230517160103.1088185-1-larysa.zaremba@intel.com

1 files changed, 43 insertions, 8 deletions

diff --git a/tools/bpf/bpftool/prog.c b/tools/bpf/bpftool/prog.c
index 1f736dc29824..8443a149dd17 100644
--- a/tools/bpf/bpftool/prog.c
+++ b/tools/bpf/bpftool/prog.c
@@ -1517,12 +1517,13 @@ static int load_with_options(int argc, char **argv, bool first_prog_only)
 	struct bpf_program *prog = NULL, *pos;
 	unsigned int old_map_fds = 0;
 	const char *pinmaps = NULL;
+	__u32 xdpmeta_ifindex = 0;
+	__u32 offload_ifindex = 0;
 	bool auto_attach = false;
 	struct bpf_object *obj;
 	struct bpf_map *map;
 	const char *pinfile;
 	unsigned int i, j;
-	__u32 ifindex = 0;
 	const char *file;
 	int idx, err;
 
@@ -1614,17 +1615,46 @@ static int load_with_options(int argc, char **argv, bool first_prog_only)
 			map_replace[old_map_fds].fd = fd;
 			old_map_fds++;
 		} else if (is_prefix(*argv, "dev")) {
+			p_info("Warning: 'bpftool prog load [...] dev <ifname>' syntax is deprecated.\n"
+			       "Going further, please use 'offload_dev <ifname>' to offload program to device.\n"
+			       "For applications using XDP hints only, use 'xdpmeta_dev <ifname>'.");
+			goto offload_dev;
+		} else if (is_prefix(*argv, "offload_dev")) {
+offload_dev:
 			NEXT_ARG();
 
-			if (ifindex) {
-				p_err("offload device already specified");
+			if (offload_ifindex) {
+				p_err("offload_dev already specified");
+				goto err_free_reuse_maps;
+			} else if (xdpmeta_ifindex) {
+				p_err("xdpmeta_dev and offload_dev are mutually exclusive");
+				goto err_free_reuse_maps;
+			}
+			if (!REQ_ARGS(1))
+				goto err_free_reuse_maps;
+
+			offload_ifindex = if_nametoindex(*argv);
+			if (!offload_ifindex) {
+				p_err("unrecognized netdevice '%s': %s",
+				      *argv, strerror(errno));
+				goto err_free_reuse_maps;
+			}
+			NEXT_ARG();
+		} else if (is_prefix(*argv, "xdpmeta_dev")) {
+			NEXT_ARG();
+
+			if (xdpmeta_ifindex) {
+				p_err("xdpmeta_dev already specified");
+				goto err_free_reuse_maps;
+			} else if (offload_ifindex) {
+				p_err("xdpmeta_dev and offload_dev are mutually exclusive");
 				goto err_free_reuse_maps;
 			}
 			if (!REQ_ARGS(1))
 				goto err_free_reuse_maps;
 
-			ifindex = if_nametoindex(*argv);
-			if (!ifindex) {
+			xdpmeta_ifindex = if_nametoindex(*argv);
+			if (!xdpmeta_ifindex) {
 				p_err("unrecognized netdevice '%s': %s",
 				      *argv, strerror(errno));
 				goto err_free_reuse_maps;
@@ -1671,7 +1701,12 @@ static int load_with_options(int argc, char **argv, bool first_prog_only)
 				goto err_close_obj;
 		}
 
-		bpf_program__set_ifindex(pos, ifindex);
+		if (prog_type == BPF_PROG_TYPE_XDP && xdpmeta_ifindex) {
+			bpf_program__set_flags(pos, BPF_F_XDP_DEV_BOUND_ONLY);
+			bpf_program__set_ifindex(pos, xdpmeta_ifindex);
+		} else {
+			bpf_program__set_ifindex(pos, offload_ifindex);
+		}
 		if (bpf_program__type(pos) != prog_type)
 			bpf_program__set_type(pos, prog_type);
 		bpf_program__set_expected_attach_type(pos, expected_attach_type);
@@ -1709,7 +1744,7 @@ static int load_with_options(int argc, char **argv, bool first_prog_only)
 	idx = 0;
 	bpf_object__for_each_map(map, obj) {
 		if (bpf_map__type(map) != BPF_MAP_TYPE_PERF_EVENT_ARRAY)
-			bpf_map__set_ifindex(map, ifindex);
+			bpf_map__set_ifindex(map, offload_ifindex);
 
 		if (j < old_map_fds && idx == map_replace[j].idx) {
 			err = bpf_map__reuse_fd(map, map_replace[j++].fd);
@@ -2416,7 +2451,7 @@ static int do_help(int argc, char **argv)
 		"       %1$s %2$s dump jited  PROG [{ file FILE | [opcodes] [linum] }]\n"
 		"       %1$s %2$s pin   PROG FILE\n"
 		"       %1$s %2$s { load | loadall } OBJ  PATH \\\n"
-		"                         [type TYPE] [dev NAME] \\\n"
+		"                         [type TYPE] [{ offload_dev | xdpmeta_dev } NAME] \\\n"
 		"                         [map { idx IDX | name NAME } MAP]\\\n"
 		"                         [pinmaps MAP_DIR]\n"
 		"                         [autoattach]\n"