[xdp-hints] [PATCH bpf-next v2 12/20] xdp: Add checksum level hint

[Larysa Zaremba <larysa.zaremba@intel.com>]

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@intel.com>
---
 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                               | 21 ++++++++++++++++++++
 5 files changed, 29 insertions(+)

diff --git a/Documentation/networking/xdp-rx-metadata.rst b/Documentation/networking/xdp-rx-metadata.rst
index ea6dd79a21d3..4ec6ddfd2a52 100644
--- a/Documentation/networking/xdp-rx-metadata.rst
+++ b/Documentation/networking/xdp-rx-metadata.rst
@@ -26,6 +26,9 @@ metadata is supported, this set will grow:
 .. kernel-doc:: net/core/xdp.c
    :identifiers: bpf_xdp_metadata_rx_vlan_tag
 
+.. 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 4fa4380e6d89..569563687172 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -1660,6 +1660,7 @@ struct xdp_metadata_ops {
 			       enum xdp_rss_hash_type *rss_type);
 	int	(*xmo_rx_vlan_tag)(const struct xdp_md *ctx, u16 *vlan_tag,
 				   __be16 *vlan_proto);
+	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 89c58f56ffc6..61ed38fa79d1 100644
--- a/include/net/xdp.h
+++ b/include/net/xdp.h
@@ -391,6 +391,8 @@ void xdp_attachment_setup(struct xdp_attachment_info *info,
 			   bpf_xdp_metadata_rx_hash) \
 	XDP_METADATA_KFUNC(XDP_METADATA_KFUNC_RX_VLAN_TAG, \
 			   bpf_xdp_metadata_rx_vlan_tag) \
+	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 986e7becfd42..a133fb775f49 100644
--- a/kernel/bpf/offload.c
+++ b/kernel/bpf/offload.c
@@ -850,6 +850,8 @@ void *bpf_dev_bound_resolve_kfunc(struct bpf_prog *prog, u32 func_id)
 		p = ops->xmo_rx_hash;
 	else if (func_id == bpf_xdp_metadata_kfunc_id(XDP_METADATA_KFUNC_RX_VLAN_TAG))
 		p = ops->xmo_rx_vlan_tag;
+	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 f6262c90e45f..c666d3e0a26c 100644
--- a/net/core/xdp.c
+++ b/net/core/xdp.c
@@ -758,6 +758,27 @@ __bpf_kfunc int bpf_xdp_metadata_rx_vlan_tag(const struct xdp_md *ctx, u16 *vlan
 	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.
+ *
+ * In case of success, csum_level contains depth of the last verified checksum.
+ * If only the outermost checksum was verified, csum_level is 0, if both
+ * encapsulation and inner transport checksums were verified, csum_level is 1,
+ * and so on.
+ * For more details, refer to csum_level field in sk_buff.
+ *
+ * Return:
+ * * Returns 0 on success or ``-errno`` on error.
+ * * ``-EOPNOTSUPP`` : device driver doesn't implement kfunc
+ * * ``-ENODATA``    : Checksum was not validated
+ */
+__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)
-- 
2.41.0