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bpftool: Specify XDP Hints ifname when loading program
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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
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@walking-machine @qmonnet
walking-machine authored and qmonnet committed May 26, 2023
1 parent 57fc1ef commit 3270b21
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Showing 5 changed files with 64 additions and 20 deletions.
7 changes: 4 additions & 3 deletions bash-completion/bpftool
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Original file line number Diff line number Diff line change
Expand Up @@ -278,7 +278,7 @@ _bpftool()
_bpftool_get_prog_tags
return 0
;;
dev)
dev|offload_dev|xdpmeta_dev)
_sysfs_get_netdevs
return 0
;;
Expand Down Expand Up @@ -508,7 +508,8 @@ _bpftool()
;;
*)
COMPREPLY=( $( compgen -W "map" -- "$cur" ) )
_bpftool_once_attr 'type dev pinmaps autoattach'
_bpftool_once_attr 'type pinmaps autoattach'
_bpftool_one_of_list 'offload_dev xdpmeta_dev'
return 0
;;
esac
Expand Down Expand Up @@ -733,7 +734,7 @@ _bpftool()
esac
;;
*)
_bpftool_once_attr 'type key value entries name flags dev'
_bpftool_once_attr 'type key value entries name flags offload_dev'
if _bpftool_search_list 'array_of_maps' 'hash_of_maps'; then
_bpftool_once_attr 'inner_map'
fi
Expand Down
8 changes: 4 additions & 4 deletions docs/bpftool-map.rst
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Original file line number Diff line number Diff line change
Expand Up @@ -28,7 +28,7 @@ MAP COMMANDS
| **bpftool** **map** { **show** | **list** } [*MAP*]
| **bpftool** **map create** *FILE* **type** *TYPE* **key** *KEY_SIZE* **value** *VALUE_SIZE* \
| **entries** *MAX_ENTRIES* **name** *NAME* [**flags** *FLAGS*] [**inner_map** *MAP*] \
| [**dev** *NAME*]
| [**offload_dev** *NAME*]
| **bpftool** **map dump** *MAP*
| **bpftool** **map update** *MAP* [**key** *DATA*] [**value** *VALUE*] [*UPDATE_FLAGS*]
| **bpftool** **map lookup** *MAP* [**key** *DATA*]
Expand Down Expand Up @@ -73,7 +73,7 @@ DESCRIPTION
maps. On such kernels bpftool will automatically emit this
information as well.

**bpftool map create** *FILE* **type** *TYPE* **key** *KEY_SIZE* **value** *VALUE_SIZE* **entries** *MAX_ENTRIES* **name** *NAME* [**flags** *FLAGS*] [**inner_map** *MAP*] [**dev** *NAME*]
**bpftool map create** *FILE* **type** *TYPE* **key** *KEY_SIZE* **value** *VALUE_SIZE* **entries** *MAX_ENTRIES* **name** *NAME* [**flags** *FLAGS*] [**inner_map** *MAP*] [**offload_dev** *NAME*]
Create a new map with given parameters and pin it to *bpffs*
as *FILE*.

Expand All @@ -86,8 +86,8 @@ DESCRIPTION
kernel needs it to collect metadata related to the inner maps
that the new map will work with.

Keyword **dev** expects a network interface name, and is used
to request hardware offload for the map.
Keyword **offload_dev** expects a network interface name,
and is used to request hardware offload for the map.

**bpftool map dump** *MAP*
Dump all entries in a given *MAP*. In case of **name**,
Expand Down
11 changes: 7 additions & 4 deletions docs/bpftool-prog.rst
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Original file line number Diff line number Diff line change
Expand Up @@ -31,7 +31,7 @@ PROG COMMANDS
| **bpftool** **prog dump xlated** *PROG* [{ **file** *FILE* | [**opcodes**] [**linum**] [**visual**] }]
| **bpftool** **prog dump jited** *PROG* [{ **file** *FILE* | [**opcodes**] [**linum**] }]
| **bpftool** **prog pin** *PROG* *FILE*
| **bpftool** **prog** { **load** | **loadall** } *OBJ* *PATH* [**type** *TYPE*] [**map** {**idx** *IDX* | **name** *NAME*} *MAP*] [**dev** *NAME*] [**pinmaps** *MAP_DIR*] [**autoattach**]
| **bpftool** **prog** { **load** | **loadall** } *OBJ* *PATH* [**type** *TYPE*] [**map** { **idx** *IDX* | **name** *NAME* } *MAP*] [{ **offload_dev** | **xdpmeta_dev** } *NAME*] [**pinmaps** *MAP_DIR*] [**autoattach**]
| **bpftool** **prog attach** *PROG* *ATTACH_TYPE* [*MAP*]
| **bpftool** **prog detach** *PROG* *ATTACH_TYPE* [*MAP*]
| **bpftool** **prog tracelog**
Expand Down Expand Up @@ -129,7 +129,7 @@ DESCRIPTION
contain a dot character ('.'), which is reserved for future
extensions of *bpffs*.

**bpftool prog { load | loadall }** *OBJ* *PATH* [**type** *TYPE*] [**map** {**idx** *IDX* | **name** *NAME*} *MAP*] [**dev** *NAME*] [**pinmaps** *MAP_DIR*] [**autoattach**]
**bpftool prog { load | loadall }** *OBJ* *PATH* [**type** *TYPE*] [**map** { **idx** *IDX* | **name** *NAME* } *MAP*] [{ **offload_dev** | **xdpmeta_dev** } *NAME*] [**pinmaps** *MAP_DIR*] [**autoattach**]
Load bpf program(s) from binary *OBJ* and pin as *PATH*.
**bpftool prog load** pins only the first program from the
*OBJ* as *PATH*. **bpftool prog loadall** pins all programs
Expand All @@ -143,8 +143,11 @@ DESCRIPTION
to be replaced in the ELF file counting from 0, while *NAME*
allows to replace a map by name. *MAP* specifies the map to
use, referring to it by **id** or through a **pinned** file.
If **dev** *NAME* is specified program will be loaded onto
given networking device (offload).
If **offload_dev** *NAME* is specified program will be loaded
onto given networking device (offload).
If **xdpmeta_dev** *NAME* is specified program will become
device-bound without offloading, this facilitates access
to XDP metadata.
Optional **pinmaps** argument can be provided to pin all
maps under *MAP_DIR* directory.

Expand Down
7 changes: 6 additions & 1 deletion src/map.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1287,6 +1287,11 @@ static int do_create(int argc, char **argv)
"flags"))
goto exit;
} else if (is_prefix(*argv, "dev")) {
p_info("Warning: 'bpftool map create [...] dev <ifname>' syntax is deprecated.\n"
"Going further, please use 'offload_dev <ifname>' to request hardware offload for the map.");
goto offload_dev;
} else if (is_prefix(*argv, "offload_dev")) {
offload_dev:
NEXT_ARG();

if (attr.map_ifindex) {
Expand Down Expand Up @@ -1431,7 +1436,7 @@ static int do_help(int argc, char **argv)
"Usage: %1$s %2$s { show | list } [MAP]\n"
" %1$s %2$s create FILE type TYPE key KEY_SIZE value VALUE_SIZE \\\n"
" entries MAX_ENTRIES name NAME [flags FLAGS] \\\n"
" [inner_map MAP] [dev NAME]\n"
" [inner_map MAP] [offload_dev NAME]\n"
" %1$s %2$s dump MAP\n"
" %1$s %2$s update MAP [key DATA] [value VALUE] [UPDATE_FLAGS]\n"
" %1$s %2$s lookup MAP [key DATA]\n"
Expand Down
51 changes: 43 additions & 8 deletions src/prog.c
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Original file line number Diff line number Diff line change
Expand Up @@ -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;

Expand Down Expand Up @@ -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;
Expand Down Expand Up @@ -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);
Expand Down Expand Up @@ -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);
Expand Down Expand Up @@ -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"
Expand Down

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