From: Jakub Sitnicki <jakub@cloudflare•com>
To: Jesper Dangaard Brouer <hawk@kernel•org>
Cc: bpf@vger•kernel.org, netdev@vger•kernel.org,
Jakub Kicinski <kuba@kernel•org>,
lorenzo@kernel•org, Alexei Starovoitov <ast@kernel•org>,
Daniel Borkmann <borkmann@iogearbox•net>,
Eric Dumazet <eric.dumazet@gmail•com>,
"David S. Miller" <davem@davemloft•net>,
Paolo Abeni <pabeni@redhat•com>,
sdf@fomichev•me, kernel-team@cloudflare•com,
arthur@arthurfabre•com
Subject: Re: [PATCH bpf-next V2 1/7] net: xdp: Add xdp_rx_meta structure
Date: Thu, 17 Jul 2025 11:19:59 +0200 [thread overview]
Message-ID: <87v7nrdvi8.fsf@cloudflare.com> (raw)
In-Reply-To: <175146829944.1421237.13943404585579626611.stgit@firesoul> (Jesper Dangaard Brouer's message of "Wed, 02 Jul 2025 16:58:19 +0200")
On Wed, Jul 02, 2025 at 04:58 PM +02, Jesper Dangaard Brouer wrote:
> From: Lorenzo Bianconi <lorenzo@kernel•org>
>
> 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 <lorenzo@kernel•org>
> Signed-off-by: Jesper Dangaard Brouer <hawk@kernel•org>
> ---
> include/net/xdp.h | 57 +++++++++++++++++++++++++++++++++++------------
> net/core/xdp.c | 1 +
> net/xdp/xsk_buff_pool.c | 4 ++-
> 3 files changed, 47 insertions(+), 15 deletions(-)
>
> diff --git a/include/net/xdp.h b/include/net/xdp.h
> index b40f1f96cb11..f52742a25212 100644
> --- a/include/net/xdp.h
> +++ b/include/net/xdp.h
> @@ -71,11 +71,31 @@ struct xdp_txq_info {
> struct net_device *dev;
> };
>
> +struct xdp_rx_meta {
> + struct xdp_rx_meta_hash {
> + u32 val;
> + u32 type; /* enum xdp_rss_hash_type */
> + } hash;
> + struct xdp_rx_meta_vlan {
> + __be16 proto;
> + u16 tci;
> + } vlan;
> +};
> +
> +/* Storage area for HW RX metadata only available with reasonable headroom
> + * available. Less than XDP_PACKET_HEADROOM due to Intel drivers.
> + */
> +#define XDP_MIN_HEADROOM 192
> +
> enum xdp_buff_flags {
> XDP_FLAGS_HAS_FRAGS = BIT(0), /* non-linear xdp buff */
> XDP_FLAGS_FRAGS_PF_MEMALLOC = BIT(1), /* xdp paged memory is under
> * pressure
> */
> + XDP_FLAGS_META_AREA = BIT(2), /* storage area available */
Idea: Perhaps this could be called *HW*_META_AREA to differentiate from
the existing custom metadata area:
https://docs.kernel.org/networking/xdp-rx-metadata.html#af-xdp
> + XDP_FLAGS_META_RX_HASH = BIT(3), /* hw rx hash */
> + XDP_FLAGS_META_RX_VLAN = BIT(4), /* hw rx vlan */
> + XDP_FLAGS_META_RX_TS = BIT(5), /* hw rx timestamp */
> };
>
[...]
next prev parent reply other threads:[~2025-07-17 9:20 UTC|newest]
Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-07-02 14:58 [PATCH bpf-next V2 0/7] xdp: Allow BPF to set RX hints for XDP_REDIRECTed packets Jesper Dangaard Brouer
2025-07-02 14:58 ` [PATCH bpf-next V2 1/7] net: xdp: Add xdp_rx_meta structure Jesper Dangaard Brouer
2025-07-17 9:19 ` Jakub Sitnicki [this message]
2025-07-17 14:40 ` Jesper Dangaard Brouer
2025-07-18 10:33 ` Jakub Sitnicki
2025-07-02 14:58 ` [PATCH bpf-next V2 2/7] selftests/bpf: Adjust test for maximum packet size in xdp_do_redirect Jesper Dangaard Brouer
2025-07-02 14:58 ` [PATCH bpf-next V2 3/7] net: xdp: Add kfuncs to store hw metadata in xdp_buff Jesper Dangaard Brouer
2025-07-03 11:41 ` Jesper Dangaard Brouer
2025-07-03 12:26 ` Lorenzo Bianconi
2025-07-02 14:58 ` [PATCH bpf-next V2 4/7] net: xdp: Set skb hw metadata from xdp_frame Jesper Dangaard Brouer
2025-07-02 14:58 ` [PATCH bpf-next V2 5/7] net: veth: Read xdp metadata from rx_meta struct if available Jesper Dangaard Brouer
2025-07-17 12:11 ` Jakub Sitnicki
2025-07-02 14:58 ` [PATCH bpf-next V2 6/7] bpf: selftests: Add rx_meta store kfuncs selftest Jesper Dangaard Brouer
2025-07-23 9:24 ` Bouska, Zdenek
2025-07-02 14:58 ` [PATCH bpf-next V2 7/7] net: xdp: update documentation for xdp-rx-metadata.rst Jesper Dangaard Brouer
2025-07-02 16:05 ` [PATCH bpf-next V2 0/7] xdp: Allow BPF to set RX hints for XDP_REDIRECTed packets Stanislav Fomichev
2025-07-03 11:17 ` Jesper Dangaard Brouer
2025-07-07 14:40 ` Stanislav Fomichev
2025-07-09 9:31 ` Lorenzo Bianconi
2025-07-11 16:04 ` Stanislav Fomichev
2025-07-16 11:17 ` Lorenzo Bianconi
2025-07-16 21:20 ` Jakub Kicinski
2025-07-17 13:08 ` Jesper Dangaard Brouer
2025-07-18 1:25 ` Jakub Kicinski
2025-07-18 10:56 ` Jesper Dangaard Brouer
2025-07-22 1:13 ` Jakub Kicinski
2025-07-28 10:53 ` Lorenzo Bianconi
2025-07-28 16:29 ` Jakub Kicinski
2025-07-29 11:15 ` Jesper Dangaard Brouer
2025-07-29 19:47 ` Martin KaFai Lau
2025-07-31 16:27 ` Jesper Dangaard Brouer
2025-08-01 20:38 ` Jakub Kicinski
2025-08-04 13:18 ` Jesper Dangaard Brouer
2025-08-06 0:28 ` Jakub Kicinski
2025-08-07 18:26 ` Jesper Dangaard Brouer
2025-08-06 1:24 ` Martin KaFai Lau
2025-08-07 19:07 ` Jesper Dangaard Brouer
2025-08-13 2:59 ` Martin KaFai Lau
2025-07-31 21:18 ` Lorenzo Bianconi
2025-08-01 20:40 ` Jakub Kicinski
2025-08-05 13:18 ` Lorenzo Bianconi
2025-08-05 23:54 ` Jakub Kicinski
2025-07-18 9:55 ` Lorenzo Bianconi
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