Commit a9c2a608 authored by Stanislav Fomichev's avatar Stanislav Fomichev Committed by Martin KaFai Lau
Browse files

bpf: expose information about supported xdp metadata kfunc 



Add new xdp-rx-metadata-features member to netdev netlink
which exports a bitmask of supported kfuncs. Most of the patch
is autogenerated (headers), the only relevant part is netdev.yaml
and the changes in netdev-genl.c to marshal into netlink.

Example output on veth:

$ ip link add veth0 type veth peer name veth1 # ifndex == 12
$ ./tools/net/ynl/samples/netdev 12

Select ifc ($ifindex; or 0 = dump; or -2 ntf check): 12
   veth1[12]    xdp-features (23): basic redirect rx-sg xdp-rx-metadata-features (3): timestamp hash xdp-zc-max-segs=0

Cc: netdev@vger.kernel.org
Cc: Willem de Bruijn <willemb@google.com>
Signed-off-by: default avatarStanislav Fomichev <sdf@google.com>
Link: https://lore.kernel.org/r/20230913171350.369987-3-sdf@google.com


Signed-off-by: default avatarMartin KaFai Lau <martin.lau@kernel.org>
parent fc45c5b6

Documentation/netlink/specs/netdev.yaml

+21 −0
Original line number Diff line number Diff line
@@ -42,6 +42,19 @@ definitions: 
        doc:

          This feature informs if netdev implements non-linear XDP buffer

          support in ndo_xdp_xmit callback.

  -

    type: flags

    name: xdp-rx-metadata

    render-max: true

    entries:

      -

        name: timestamp

        doc:

          Device is capable of exposing receive HW timestamp via bpf_xdp_metadata_rx_timestamp().

      -

        name: hash

        doc:

          Device is capable of exposing receive packet hash via bpf_xdp_metadata_rx_hash().



attribute-sets:

  -
@@ -68,6 +81,13 @@ attribute-sets: 
        type: u32

        checks:

          min: 1

      -

        name: xdp-rx-metadata-features

        doc: Bitmask of supported XDP receive metadata features.

             See Documentation/networking/xdp-rx-metadata.rst for more details.

        type: u64

        enum: xdp-rx-metadata

        enum-as-flags: true



operations:

  list:
@@ -84,6 +104,7 @@ operations: 
            - ifindex

            - xdp-features

            - xdp-zc-max-segs

            - xdp-rx-metadata-features

      dump:

        reply: *dev-all

    -

Documentation/networking/xdp-rx-metadata.rst

+7 −0
Original line number Diff line number Diff line
@@ -105,6 +105,13 @@ bpf_tail_call 
Adding programs that access metadata kfuncs to the ``BPF_MAP_TYPE_PROG_ARRAY``

is currently not supported.



Supported Devices

=================



It is possible to query which kfunc the particular netdev implements via

netlink. See ``xdp-rx-metadata-features`` attribute set in

``Documentation/netlink/specs/netdev.yaml``.



Example

=======

include/net/xdp.h

+4 −1
Original line number Diff line number Diff line
@@ -386,19 +386,22 @@ void xdp_attachment_setup(struct xdp_attachment_info *info, 
/* Define the relationship between xdp-rx-metadata kfunc and

 * various other entities:

 * - xdp_rx_metadata enum

 * - netdev netlink enum (Documentation/netlink/specs/netdev.yaml)

 * - kfunc name

 * - xdp_metadata_ops field

 */

#define XDP_METADATA_KFUNC_xxx	\

	XDP_METADATA_KFUNC(XDP_METADATA_KFUNC_RX_TIMESTAMP, \

			   NETDEV_XDP_RX_METADATA_TIMESTAMP, \

			   bpf_xdp_metadata_rx_timestamp, \

			   xmo_rx_timestamp) \

	XDP_METADATA_KFUNC(XDP_METADATA_KFUNC_RX_HASH, \

			   NETDEV_XDP_RX_METADATA_HASH, \

			   bpf_xdp_metadata_rx_hash, \

			   xmo_rx_hash) \



enum xdp_rx_metadata {

#define XDP_METADATA_KFUNC(name, _, __) name,

#define XDP_METADATA_KFUNC(name, _, __, ___) name,

XDP_METADATA_KFUNC_xxx

#undef XDP_METADATA_KFUNC

MAX_XDP_METADATA_KFUNC,

include/uapi/linux/netdev.h

+16 −0
Original line number Diff line number Diff line
@@ -38,11 +38,27 @@ enum netdev_xdp_act { 
	NETDEV_XDP_ACT_MASK = 127,

};



/**

 * enum netdev_xdp_rx_metadata

 * @NETDEV_XDP_RX_METADATA_TIMESTAMP: Device is capable of exposing receive HW

 *   timestamp via bpf_xdp_metadata_rx_timestamp().

 * @NETDEV_XDP_RX_METADATA_HASH: Device is capable of exposing receive packet

 *   hash via bpf_xdp_metadata_rx_hash().

 */

enum netdev_xdp_rx_metadata {

	NETDEV_XDP_RX_METADATA_TIMESTAMP = 1,

	NETDEV_XDP_RX_METADATA_HASH = 2,



	/* private: */

	NETDEV_XDP_RX_METADATA_MASK = 3,

};



enum {

	NETDEV_A_DEV_IFINDEX = 1,

	NETDEV_A_DEV_PAD,

	NETDEV_A_DEV_XDP_FEATURES,

	NETDEV_A_DEV_XDP_ZC_MAX_SEGS,

	NETDEV_A_DEV_XDP_RX_METADATA_FEATURES,



	__NETDEV_A_DEV_MAX,

	NETDEV_A_DEV_MAX = (__NETDEV_A_DEV_MAX - 1)

kernel/bpf/offload.c

+1 −1
Original line number Diff line number Diff line
@@ -845,7 +845,7 @@ void *bpf_dev_bound_resolve_kfunc(struct bpf_prog *prog, u32 func_id) 
	if (!ops)

		goto out;



#define XDP_METADATA_KFUNC(name, _, xmo) \

#define XDP_METADATA_KFUNC(name, _, __, xmo) \

	if (func_id == bpf_xdp_metadata_kfunc_id(name)) p = ops->xmo;

	XDP_METADATA_KFUNC_xxx

#undef XDP_METADATA_KFUNC