[Intel-wired-lan] [PATCH bpf-next v3 1/5] netlink: specs: Add XDP RX checksum capability to XDP metadata specs

Lorenzo Bianconi
2026-02-17T08:34:42Z

Introduce XDP RX checksum capability to XDP metadata specs. XDP RX
checksum will be use by devices capable of exposing receive checksum
result via bpf_xdp_metadata_rx_checksum().
Moreover, introduce xmo_rx_checksum netdev callback in order to allow
the eBPF program bound to the device to retrieve the RX checksum result
computed by the hw NIC.

Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
---
Documentation/netlink/specs/netdev.yaml | 5 +++++
include/net/xdp.h | 13 +++++++++++++
include/uapi/linux/netdev.h | 3 +++
net/core/xdp.c | 28 ++++++++++++++++++++++++++++
tools/include/uapi/linux/netdev.h | 3 +++
5 files changed, 52 insertions(+)

diff --git a/Documentation/netlink/specs/netdev.yaml b/Documentation/netlink/specs/netdev.yaml
index 596c306ce52b8303b20680ff0cd34d4fd9db0e48..58eda634668a07860447a65d9fc2284839af6244 100644
--- a/Documentation/netlink/specs/netdev.yaml
+++ b/Documentation/netlink/specs/netdev.yaml
@@ -61,6 +61,11 @@ definitions:
doc: |
Device is capable of exposing receive packet VLAN tag via
bpf_xdp_metadata_rx_vlan_tag().
+ -
+ name: checksum
+ doc: |
+ Device is capable of exposing receive checksum result via
+ bpf_xdp_metadata_rx_checksum().
-
type: flags
name: xsk-flags
diff --git a/include/net/xdp.h b/include/net/xdp.h
index aa742f413c358575396530879af4570dc3fc18de..00abb2e1e85514b4080d0e4e6e3b8f5f67f73b61 100644
--- a/include/net/xdp.h
+++ b/include/net/xdp.h
@@ -586,6 +586,10 @@ void xdp_attachment_setup(struct xdp_attachment_info *info,
NETDEV_XDP_RX_METADATA_VLAN_TAG, \
bpf_xdp_metadata_rx_vlan_tag, \
xmo_rx_vlan_tag) \
+ XDP_METADATA_KFUNC(XDP_METADATA_KFUNC_RX_CHECKSUM, \
+ NETDEV_XDP_RX_METADATA_CHECKSUM, \
+ bpf_xdp_metadata_rx_checksum, \
+ xmo_rx_checksum)

enum xdp_rx_metadata {
#define XDP_METADATA_KFUNC(name, _, __, ___) name,
@@ -643,12 +647,21 @@ enum xdp_rss_hash_type {
XDP_RSS_TYPE_L4_IPV6_SCTP_EX = XDP_RSS_TYPE_L4_IPV6_SCTP | XDP_RSS_L3_DYNHDR,
};

+enum xdp_checksum {
+ XDP_CHECKSUM_NONE = CHECKSUM_NONE,
+ XDP_CHECKSUM_UNNECESSARY = CHECKSUM_UNNECESSARY,
+ XDP_CHECKSUM_COMPLETE = CHECKSUM_COMPLETE,
+};
+
struct xdp_metadata_ops {
int (*xmo_rx_timestamp)(const struct xdp_md *ctx, u64 *timestamp);
int (*xmo_rx_hash)(const struct xdp_md *ctx, u32 *hash,
enum xdp_rss_hash_type *rss_type);
int (*xmo_rx_vlan_tag)(const struct xdp_md *ctx, __be16 *vlan_proto,
u16 *vlan_tci);
+ int (*xmo_rx_checksum)(const struct xdp_md *ctx,
+ enum xdp_checksum *ip_summed,
+ u32 *cksum_meta);
};

#ifdef CONFIG_NET
diff --git a/include/uapi/linux/netdev.h b/include/uapi/linux/netdev.h
index e0b579a1df4f2126acec6c44c299e97bbbefe640..d20da430cfd57bc26b5ea2f406c27b48d8a81693 100644
--- a/include/uapi/linux/netdev.h
+++ b/include/uapi/linux/netdev.h
@@ -47,11 +47,14 @@ enum netdev_xdp_act {
* hash via bpf_xdp_metadata_rx_hash().
* @NETDEV_XDP_RX_METADATA_VLAN_TAG: Device is capable of exposing receive
* packet VLAN tag via bpf_xdp_metadata_rx_vlan_tag().
+ * @NETDEV_XDP_RX_METADATA_CHECKSUM: Device is capable of exposing receive
+ * checksum result via bpf_xdp_metadata_rx_checksum().
*/
enum netdev_xdp_rx_metadata {
NETDEV_XDP_RX_METADATA_TIMESTAMP = 1,
NETDEV_XDP_RX_METADATA_HASH = 2,
NETDEV_XDP_RX_METADATA_VLAN_TAG = 4,
+ NETDEV_XDP_RX_METADATA_CHECKSUM = 8,
};

/**
diff --git a/net/core/xdp.c b/net/core/xdp.c
index fee6d080ee85fc2d278bfdddfd1365633058ec06..7d1e08d8ab4151ab42c91203def2afafc66d3149 100644
--- a/net/core/xdp.c
+++ b/net/core/xdp.c
@@ -961,6 +961,34 @@ __bpf_kfunc int bpf_xdp_metadata_rx_vlan_tag(const struct xdp_md *ctx,
return -EOPNOTSUPP;
}

+/**
+ * bpf_xdp_metadata_rx_checksum - Read XDP frame RX checksum.
+ * @ctx: XDP context pointer.
+ * @ip_summed: Return value pointer indicating checksum result.
+ * @cksum_meta: Return value pointer indicating checksum result metadata.
+ *
+ * In case of success, ``ip_summed`` is set to the RX checksum result. Possible
+ * values are:
+ * ``XDP_CHECKSUM_NONE``
+ * ``XDP_CHECKSUM_UNNECESSARY``
+ * ``XDP_CHECKSUM_COMPLETE``
+ *
+ * In case of success, ``cksum_meta`` contains the hw computed checksum value
+ * for ``XDP_CHECKSUM_COMPLETE`` or the ``csum_level`` for
+ * ``XDP_CHECKSUM_UNNECESSARY``. It is set to 0 for ``XDP_CHECKSUM_NONE``
+ *
+ * Return:
+ * * Returns 0 on success or ``-errno`` on error.
+ * * ``-EOPNOTSUPP`` : means device driver does not implement kfunc
+ * * ``-ENODATA`` : means no RX-checksum available for this frame
+ */
+__bpf_kfunc int bpf_xdp_metadata_rx_checksum(const struct xdp_md *ctx,
+ enum xdp_checksum *ip_summed,
+ u32 *cksum_meta)
+{
+ return -EOPNOTSUPP;
+}
+
__bpf_kfunc_end_defs();

BTF_KFUNCS_START(xdp_metadata_kfunc_ids)
diff --git a/tools/include/uapi/linux/netdev.h b/tools/include/uapi/linux/netdev.h
index e0b579a1df4f2126acec6c44c299e97bbbefe640..d20da430cfd57bc26b5ea2f406c27b48d8a81693 100644
--- a/tools/include/uapi/linux/netdev.h
+++ b/tools/include/uapi/linux/netdev.h
@@ -47,11 +47,14 @@ enum netdev_xdp_act {
* hash via bpf_xdp_metadata_rx_hash().
* @NETDEV_XDP_RX_METADATA_VLAN_TAG: Device is capable of exposing receive
* packet VLAN tag via bpf_xdp_metadata_rx_vlan_tag().
+ * @NETDEV_XDP_RX_METADATA_CHECKSUM: Device is capable of exposing receive
+ * checksum result via bpf_xdp_metadata_rx_checksum().
*/
enum netdev_xdp_rx_metadata {
NETDEV_XDP_RX_METADATA_TIMESTAMP = 1,
NETDEV_XDP_RX_METADATA_HASH = 2,
NETDEV_XDP_RX_METADATA_VLAN_TAG = 4,
+ NETDEV_XDP_RX_METADATA_CHECKSUM = 8,
};

/**

--
2.53.0