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From: Martin KaFai Lau <martin.lau@linux.dev>
To: Stanislav Fomichev <sdf@google.com>
Cc: ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org,
	song@kernel.org, yhs@fb.com, john.fastabend@gmail.com,
	kpsingh@kernel.org, haoluo@google.com, jolsa@kernel.org,
	David Ahern <dsahern@gmail.com>, Jakub Kicinski <kuba@kernel.org>,
	Willem de Bruijn <willemb@google.com>,
	Jesper Dangaard Brouer <brouer@redhat.com>,
	Anatoly Burakov <anatoly.burakov@intel.com>,
	Alexander Lobakin <alexandr.lobakin@intel.com>,
	Magnus Karlsson <magnus.karlsson@gmail.com>,
	Maryam Tahhan <mtahhan@redhat.com>,
	xdp-hints@xdp-project.net, netdev@vger.kernel.org,
	bpf@vger.kernel.org
Subject: [xdp-hints] Re: [PATCH bpf-next v4 05/15] bpf: XDP metadata RX kfuncs
Date: Tue, 13 Dec 2022 17:53:58 -0800	[thread overview]
Message-ID: <74e48fc9-8f5d-4183-9f39-c4587c74a74e@linux.dev> (raw)
In-Reply-To: <20221213023605.737383-6-sdf@google.com>

On 12/12/22 6:35 PM, Stanislav Fomichev wrote:
> diff --git a/include/linux/bpf.h b/include/linux/bpf.h
> index ca22e8b8bd82..de6279725f41 100644
> --- a/include/linux/bpf.h
> +++ b/include/linux/bpf.h
> @@ -2477,6 +2477,8 @@ void bpf_offload_dev_netdev_unregister(struct bpf_offload_dev *offdev,
>   				       struct net_device *netdev);
>   bool bpf_offload_dev_match(struct bpf_prog *prog, struct net_device *netdev);
>   
> +void *bpf_dev_bound_resolve_kfunc(struct bpf_prog *prog, u32 func_id);
> +

This probably requires an inline version for !CONFIG_NET.

> diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
> index d434a994ee04..c3e501e3e39c 100644
> --- a/kernel/bpf/core.c
> +++ b/kernel/bpf/core.c
> @@ -2097,6 +2097,13 @@ bool bpf_prog_map_compatible(struct bpf_map *map,
>   	if (fp->kprobe_override)
>   		return false;
>   
> +	/* When tail-calling from a non-dev-bound program to a dev-bound one,
> +	 * XDP metadata helpers should be disabled. Until it's implemented,
> +	 * prohibit adding dev-bound programs to tail-call maps.
> +	 */
> +	if (bpf_prog_is_dev_bound(fp->aux))
> +		return false;
> +
>   	spin_lock(&map->owner.lock);
>   	if (!map->owner.type) {
>   		/* There's no owner yet where we could check for
> diff --git a/kernel/bpf/offload.c b/kernel/bpf/offload.c
> index f714c941f8ea..3b6c9023f24d 100644
> --- a/kernel/bpf/offload.c
> +++ b/kernel/bpf/offload.c
> @@ -757,6 +757,29 @@ void bpf_dev_bound_netdev_unregister(struct net_device *dev)
>   	up_write(&bpf_devs_lock);
>   }
>   
> +void *bpf_dev_bound_resolve_kfunc(struct bpf_prog *prog, u32 func_id)
> +{
> +	const struct xdp_metadata_ops *ops;
> +	void *p = NULL;
> +
> +	down_read(&bpf_devs_lock);
> +	if (!prog->aux->offload || !prog->aux->offload->netdev)

This happens when netdev is unregistered in the middle of bpf_prog_load and the 
bpf_offload_dev_match() will eventually fail during dev_xdp_attach()? A comment 
will be useful.

> +		goto out;
> +
> +	ops = prog->aux->offload->netdev->xdp_metadata_ops;
> +	if (!ops)
> +		goto out;
> +
> +	if (func_id == xdp_metadata_kfunc_id(XDP_METADATA_KFUNC_RX_TIMESTAMP))
> +		p = ops->xmo_rx_timestamp;
> +	else if (func_id == xdp_metadata_kfunc_id(XDP_METADATA_KFUNC_RX_HASH))
> +		p = ops->xmo_rx_hash;
> +out:
> +	up_read(&bpf_devs_lock);
> +
> +	return p;
> +}
> +
>   static int __init bpf_offload_init(void)
>   {
>   	int err;
> diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
> index 203d8cfeda70..e61fe0472b9b 100644
> --- a/kernel/bpf/verifier.c
> +++ b/kernel/bpf/verifier.c
> @@ -15479,12 +15479,35 @@ static int fixup_kfunc_call(struct bpf_verifier_env *env, struct bpf_insn *insn,
>   			    struct bpf_insn *insn_buf, int insn_idx, int *cnt)
>   {
>   	const struct bpf_kfunc_desc *desc;
> +	void *xdp_kfunc;
>   
>   	if (!insn->imm) {
>   		verbose(env, "invalid kernel function call not eliminated in verifier pass\n");
>   		return -EINVAL;
>   	}
>   
> +	*cnt = 0;
> +
> +	if (xdp_is_metadata_kfunc_id(insn->imm)) {
> +		if (!bpf_prog_is_dev_bound(env->prog->aux)) {

The "xdp_is_metadata_kfunc_id() && (!bpf_prog_is_dev_bound() || 
bpf_prog_is_offloaded())" test should have been done much earlier in 
add_kfunc_call(). Then the later stage of the verifier does not have to keep 
worrying about it like here.

nit. may be rename xdp_is_metadata_kfunc_id() to bpf_dev_bound_kfunc_id() and 
hide the "!bpf_prog_is_dev_bound() || bpf_prog_is_offloaded()" test into 
bpf_dev_bound_kfunc_check(&env->log, env->prog).

The change in fixup_kfunc_call could then become:

	if (bpf_dev_bound_kfunc_id(insn->imm)) {
		xdp_kfunc = bpf_dev_bound_resolve_kfunc(env->prog, insn->imm);
		/* ... */
	}

> +			verbose(env, "metadata kfuncs require device-bound program\n");
> +			return -EINVAL;
> +		}
> +
> +		if (bpf_prog_is_offloaded(env->prog->aux)) {
> +			verbose(env, "metadata kfuncs can't be offloaded\n");
> +			return -EINVAL;
> +		}
> +
> +		xdp_kfunc = bpf_dev_bound_resolve_kfunc(env->prog, insn->imm);
> +		if (xdp_kfunc) {
> +			insn->imm = BPF_CALL_IMM(xdp_kfunc);
> +			return 0;
> +		}
> +
> +		/* fallback to default kfunc when not supported by netdev */
> +	}
> +



  parent reply	other threads:[~2022-12-14  1:54 UTC|newest]

Thread overview: 41+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-12-13  2:35 [xdp-hints] [PATCH bpf-next v4 00/15] xdp: hints via kfuncs Stanislav Fomichev
2022-12-13  2:35 ` [xdp-hints] [PATCH bpf-next v4 01/15] bpf: Document XDP RX metadata Stanislav Fomichev
2022-12-13 16:37   ` [xdp-hints] " David Vernet
2022-12-13 20:42     ` Stanislav Fomichev
2022-12-14 10:34       ` Toke Høiland-Jørgensen
2022-12-14 18:42         ` Stanislav Fomichev
2022-12-14 23:46           ` Toke Høiland-Jørgensen
2022-12-15  3:48             ` Stanislav Fomichev
2022-12-15 14:04               ` Toke Høiland-Jørgensen
2022-12-14 23:46   ` Toke Høiland-Jørgensen
2022-12-17  4:20   ` kernel test robot
2022-12-13  2:35 ` [xdp-hints] [PATCH bpf-next v4 02/15] bpf: Rename bpf_{prog,map}_is_dev_bound to is_offloaded Stanislav Fomichev
2022-12-13  2:35 ` [xdp-hints] [PATCH bpf-next v4 03/15] bpf: Introduce device-bound XDP programs Stanislav Fomichev
2022-12-13 23:25   ` [xdp-hints] " Martin KaFai Lau
2022-12-14 18:42     ` Stanislav Fomichev
2022-12-13  2:35 ` [xdp-hints] [PATCH bpf-next v4 04/15] selftests/bpf: Update expected test_offload.py messages Stanislav Fomichev
2022-12-13  2:35 ` [xdp-hints] [PATCH bpf-next v4 05/15] bpf: XDP metadata RX kfuncs Stanislav Fomichev
2022-12-13 17:00   ` [xdp-hints] " David Vernet
2022-12-13 20:42     ` Stanislav Fomichev
2022-12-13 21:45       ` David Vernet
2022-12-14  1:53   ` Martin KaFai Lau [this message]
2022-12-14 18:43     ` Stanislav Fomichev
2022-12-14 10:54   ` Toke Høiland-Jørgensen
2022-12-14 18:43     ` Stanislav Fomichev
2022-12-13  2:35 ` [xdp-hints] [PATCH bpf-next v4 07/15] veth: Introduce veth_xdp_buff wrapper for xdp_buff Stanislav Fomichev
2022-12-13  2:35 ` [xdp-hints] [PATCH bpf-next v4 08/15] veth: Support RX XDP metadata Stanislav Fomichev
2022-12-13 15:55   ` [xdp-hints] " Jesper Dangaard Brouer
2022-12-13 20:42     ` Stanislav Fomichev
2022-12-14  9:48       ` Jesper Dangaard Brouer
2022-12-14 10:47         ` Toke Høiland-Jørgensen
2022-12-14 18:09           ` Martin KaFai Lau
2022-12-14 18:44             ` Stanislav Fomichev
2022-12-13  2:35 ` [xdp-hints] [PATCH bpf-next v4 09/15] selftests/bpf: Verify xdp_metadata xdp->af_xdp path Stanislav Fomichev
2022-12-13  2:36 ` [xdp-hints] [PATCH bpf-next v4 10/15] net/mlx4_en: Introduce wrapper for xdp_buff Stanislav Fomichev
2022-12-13  8:56   ` [xdp-hints] " Tariq Toukan
2022-12-13  2:36 ` [xdp-hints] [PATCH bpf-next v4 11/15] net/mlx4_en: Support RX XDP metadata Stanislav Fomichev
2022-12-13  8:56   ` [xdp-hints] " Tariq Toukan
2022-12-13  2:36 ` [xdp-hints] [PATCH bpf-next v4 12/15] xsk: Add cb area to struct xdp_buff_xsk Stanislav Fomichev
2022-12-13  2:36 ` [xdp-hints] [PATCH bpf-next v4 13/15] net/mlx5e: Introduce wrapper for xdp_buff Stanislav Fomichev
2022-12-13  2:36 ` [xdp-hints] [PATCH bpf-next v4 14/15] net/mlx5e: Support RX XDP metadata Stanislav Fomichev
2022-12-13  2:36 ` [xdp-hints] [PATCH bpf-next v4 15/15] selftests/bpf: Simple program to dump XDP RX metadata Stanislav Fomichev

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