[PATCH 11/15] xdp: Add checksum level hint

[Larysa Zaremba]

Implement functionality that enables drivers to expose to XDP code,
whether checksums was checked and on what level.

Signed-off-by: Larysa Zaremba <larysa.zaremba@xxxxxxxxx>
---
 Documentation/networking/xdp-rx-metadata.rst |  3 +++
 include/linux/netdevice.h                    |  1 +
 include/net/xdp.h                            |  2 ++
 kernel/bpf/offload.c                         |  2 ++
 net/core/xdp.c                               | 12 ++++++++++++
 5 files changed, 20 insertions(+)

diff --git a/Documentation/networking/xdp-rx-metadata.rst b/Documentation/networking/xdp-rx-metadata.rst
index 73a78029c596..f74f0e283097 100644
--- a/Documentation/networking/xdp-rx-metadata.rst
+++ b/Documentation/networking/xdp-rx-metadata.rst
@@ -29,6 +29,9 @@ metadata is supported, this set will grow:
 .. kernel-doc:: net/core/xdp.c
    :identifiers: bpf_xdp_metadata_rx_stag
 
+.. kernel-doc:: net/core/xdp.c
+   :identifiers: bpf_xdp_metadata_rx_csum_lvl
+
 An XDP program can use these kfuncs to read the metadata into stack
 variables for its own consumption. Or, to pass the metadata on to other
 consumers, an XDP program can store it into the metadata area carried
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index fdae37fe11f5..ddade3a15366 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -1657,6 +1657,7 @@ struct xdp_metadata_ops {
 			       enum xdp_rss_hash_type *rss_type);
 	int	(*xmo_rx_ctag)(const struct xdp_md *ctx, u16 *vlan_tag);
 	int	(*xmo_rx_stag)(const struct xdp_md *ctx, u16 *vlan_tag);
+	int	(*xmo_rx_csum_lvl)(const struct xdp_md *ctx, u8 *csum_level);
 };
 
 /**
diff --git a/include/net/xdp.h b/include/net/xdp.h
index 2db7439fc60f..0fbd25616241 100644
--- a/include/net/xdp.h
+++ b/include/net/xdp.h
@@ -393,6 +393,8 @@ void xdp_attachment_setup(struct xdp_attachment_info *info,
 			   bpf_xdp_metadata_rx_ctag) \
 	XDP_METADATA_KFUNC(XDP_METADATA_KFUNC_RX_STAG, \
 			   bpf_xdp_metadata_rx_stag) \
+	XDP_METADATA_KFUNC(XDP_METADATA_KFUNC_RX_CSUM_LVL, \
+			   bpf_xdp_metadata_rx_csum_lvl) \
 
 enum {
 #define XDP_METADATA_KFUNC(name, _) name,
diff --git a/kernel/bpf/offload.c b/kernel/bpf/offload.c
index 2c6b6e82cfac..8bd54fb4ac63 100644
--- a/kernel/bpf/offload.c
+++ b/kernel/bpf/offload.c
@@ -852,6 +852,8 @@ void *bpf_dev_bound_resolve_kfunc(struct bpf_prog *prog, u32 func_id)
 		p = ops->xmo_rx_ctag;
 	else if (func_id == bpf_xdp_metadata_kfunc_id(XDP_METADATA_KFUNC_RX_STAG))
 		p = ops->xmo_rx_stag;
+	else if (func_id == bpf_xdp_metadata_kfunc_id(XDP_METADATA_KFUNC_RX_CSUM_LVL))
+		p = ops->xmo_rx_csum_lvl;
 out:
 	up_read(&bpf_devs_lock);
 
diff --git a/net/core/xdp.c b/net/core/xdp.c
index eff21501609f..7dd45fd62983 100644
--- a/net/core/xdp.c
+++ b/net/core/xdp.c
@@ -762,6 +762,18 @@ __bpf_kfunc int bpf_xdp_metadata_rx_stag(const struct xdp_md *ctx, u16 *vlan_tag
 	return -EOPNOTSUPP;
 }
 
+/**
+ * bpf_xdp_metadata_rx_csum_lvl - Get depth at which HW has checked the checksum.
+ * @ctx: XDP context pointer.
+ * @csum_level: Return value pointer.
+ *
+ * Returns 0 on success (HW has checked the checksum) or ``-errno`` on error.
+ */
+__bpf_kfunc int bpf_xdp_metadata_rx_csum_lvl(const struct xdp_md *ctx, u8 *csum_level)
+{
+	return -EOPNOTSUPP;
+}
+
 __diag_pop();
 
 BTF_SET8_START(xdp_metadata_kfunc_ids)
-- 
2.35.3