xdp hw hints for redirect #9242
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In the BPF token example, the fsopen() syscall is called as privileged user. This is unneeded because fsopen() can be called also as unprivileged user from the user namespace. As the `fs_fd` file descriptor which was sent back and forth is still the same, keep it open instead of cloning and closing it twice via SCM_RIGHTS. cfr. systemd/systemd#36134 Signed-off-by: Matteo Croce <[email protected]> Signed-off-by: Andrii Nakryiko <[email protected]> Link: https://lore.kernel.org/bpf/[email protected]
Introduce the `xdp_rx_meta` structure to serve as a container for XDP RX
hardware hints within XDP packet buffers. Initially, this structure will
accommodate `rx_hash` and `rx_vlan` metadata. (The `rx_timestamp` hint will
get stored in `skb_shared_info`).
A key design aspect is making this metadata accessible both during BPF
program execution (via `struct xdp_buff`) and later if an `struct
xdp_frame` is materialized (e.g., for XDP_REDIRECT).
To achieve this:
- The `struct xdp_frame` embeds an `xdp_rx_meta` field directly for
storage.
- The `struct xdp_buff` includes an `xdp_rx_meta` pointer. This pointer
is initialized (in `xdp_prepare_buff`) to point to the memory location
within the packet buffer's headroom where the `xdp_frame`'s embedded
`rx_meta` field would reside.
This setup allows BPF kfuncs, operating on `xdp_buff`, to populate the
metadata in the precise location where it will be found if an `xdp_frame`
is subsequently created.
The availability of this metadata storage area within the buffer is
indicated by the `XDP_FLAGS_META_AREA` flag in `xdp_buff->flags` (and
propagated to `xdp_frame->flags`). This flag is only set if sufficient
headroom (at least `XDP_MIN_HEADROOM`, currently 192 bytes) is present.
Specific hints like `XDP_FLAGS_META_RX_HASH` and `XDP_FLAGS_META_RX_VLAN`
will then denote which types of metadata have been populated into the
`xdp_rx_meta` structure.
This patch is a step for enabling the preservation and use of XDP RX
hints across operations like XDP_REDIRECT.
Signed-off-by: Lorenzo Bianconi <[email protected]>
Signed-off-by: Jesper Dangaard Brouer <[email protected]>
Patchset increased xdp_buff with a pointer 8 bytes, and the bpf/test_run struct xdp_page_head have two xdp_buff's. Thus adjust test with 16 bytes. Signed-off-by: Jesper Dangaard Brouer <[email protected]>
Introduce the following kfuncs to store hw metadata provided by the NIC into the xdp_buff struct: - rx-hash: bpf_xdp_store_rx_hash - rx-vlan: bpf_xdp_store_rx_vlan - rx-hw-ts: bpf_xdp_store_rx_ts Signed-off-by: Lorenzo Bianconi <[email protected]> Signed-off-by: Jesper Dangaard Brouer <[email protected]>
Update the following hw metadata provided by the NIC building the skb from a xdp_frame. - rx hash - rx vlan - rx hw-ts Signed-off-by: Lorenzo Bianconi <[email protected]>
Report xdp_rx_meta info if available in xdp_buff struct in xdp_metadata_ops callbacks for veth driver Signed-off-by: Lorenzo Bianconi <[email protected]>
Introduce bpf selftests for the XDP rx_meta store kfuncs. Signed-off-by: Lorenzo Bianconi <[email protected]>
Update the documentation[1] based on the changes in this patchset. [1] https://docs.kernel.org/networking/xdp-rx-metadata.html Signed-off-by: Jesper Dangaard Brouer <[email protected]>
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