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From: Lorenzo Bianconi <lorenzo@kernel.org>
To: "Toke Høiland-Jørgensen" <toke@redhat.com>
Cc: Jakub Kicinski <kuba@kernel.org>,
	Alexei Starovoitov <alexei.starovoitov@gmail.com>,
	Lorenz Bauer <lmb@cloudflare.com>, bpf <bpf@vger.kernel.org>,
	Networking <netdev@vger.kernel.org>,
	Lorenzo Bianconi <lorenzo.bianconi@redhat.com>,
	"David S . Miller" <davem@davemloft.net>,
	Alexei Starovoitov <ast@kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>,
	shayagr@amazon.com, John Fastabend <john.fastabend@gmail.com>,
	David Ahern <dsahern@kernel.org>,
	Jesper Dangaard Brouer <brouer@redhat.com>,
	Eelco Chaudron <echaudro@redhat.com>,
	Jason Wang <jasowang@redhat.com>,
	Alexander Duyck <alexander.duyck@gmail.com>,
	Saeed Mahameed <saeed@kernel.org>,
	Maciej Fijalkowski <maciej.fijalkowski@intel.com>,
	"Karlsson, Magnus" <magnus.karlsson@intel.com>,
	tirthendu.sarkar@intel.com
Subject: Re: [PATCH v14 bpf-next 00/18] mvneta: introduce XDP multi-buffer support
Date: Fri, 1 Oct 2021 11:03:58 +0200	[thread overview]
Message-ID: <YVbO/kit/mjWTrv6@lore-desk> (raw)
In-Reply-To: <87mtnvi0bc.fsf@toke.dk>

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> Jakub Kicinski <kuba@kernel.org> writes:
> 
> > On Wed, 29 Sep 2021 11:54:46 -0700 Alexei Starovoitov wrote:
> >> I'm missing something. Why do we need a separate flush() helper?
> >> Can't we do:
> >> char buf[64], *p;
> >> p = xdp_mb_pointer(ctx, flags, off, len, buf);
> >> read/write p[]
> >> if (p == buf)
> >>     xdp_store_bytes(ctx, off, buf, len, flags);
> >
> > Sure we can. That's what I meant by "leave the checking to the program".
> > It's bike shedding at this point.
> 
> Yeah, let's discuss the details once we have a patch :)
> 
> -Toke
> 

Hi,

I implemented the xdp_mb_pointer/xdp_mb_pointer_flush logic here (according to
current discussion):
https://github.com/LorenzoBianconi/bpf-next/commit/a5c61c0fa6cb05bab8caebd96aca5fbbd9510867

For the moment I have only defined two utility routines and I have not exported
them in ebpf helpers since I need to check what are missing bits in the verifier
code (but afaik this would be orthogonal with respect to the "helper code"):
- bpf_xdp_pointer --> xdp_mb_pointer
- bpf_xdp_copy_buf --> xdp_mb_pointer_flush

In order to test them I have defined two new ebpf helpers (they use
bpf_xdp_pointer/bpf_xdp_copy_buf internally):
- bpf_xdp_load_bytes
- bpf_xdp_store_bytes

In order to test bpf_xdp_load_bytes/bpf_xdp_store_bytes +
bpf_xdp_pointer/bpf_xdp_copy_buf I added some selftests here:
https://github.com/LorenzoBianconi/bpf-next/commit/5661a491a890c00db744f2884b7ee3a6d0319384

Can you please check if the code above is aligned to current requirements or if
it is missing something?
If this code it is fine, I guess we have two option here:
- integrate the commits above in xdp multi-buff series (posting v15) and work on
  the verfier code in parallel (if xdp_mb_pointer helper is not required from day0)
- integrate verfier changes in xdp multi-buff series, drop bpf_xdp_load_bytes
  helper (probably we will still need bpf_xdp_store_bytes) and introduce
  bpf_xdp_pointer as new ebpf helper.

I am fine both ways. If we decide for the second option I would need some
guidance on verifier changes since I am not so familiar with that code.

Regards,
Lorenzo

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  reply	other threads:[~2021-10-01  9:04 UTC|newest]

Thread overview: 58+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-10 16:14 [PATCH v14 bpf-next 00/18] mvneta: introduce XDP multi-buffer support Lorenzo Bianconi
2021-09-10 16:14 ` [PATCH v14 bpf-next 01/18] net: skbuff: add size metadata to skb_shared_info for xdp Lorenzo Bianconi
2021-09-10 16:18   ` Jesper Dangaard Brouer
2021-09-10 16:14 ` [PATCH v14 bpf-next 02/18] xdp: introduce flags field in xdp_buff/xdp_frame Lorenzo Bianconi
2021-09-10 16:19   ` Jesper Dangaard Brouer
2021-09-10 16:14 ` [PATCH v14 bpf-next 03/18] net: mvneta: update mb bit before passing the xdp buffer to eBPF layer Lorenzo Bianconi
2021-09-20  8:25   ` Shay Agroskin
2021-09-20  8:37     ` Lorenzo Bianconi
2021-09-20  8:45       ` Shay Agroskin
2021-09-20  9:00         ` Lorenzo Bianconi
2021-09-10 16:14 ` [PATCH v14 bpf-next 04/18] net: mvneta: simplify mvneta_swbm_add_rx_fragment management Lorenzo Bianconi
2021-09-10 16:14 ` [PATCH v14 bpf-next 05/18] net: xdp: add xdp_update_skb_shared_info utility routine Lorenzo Bianconi
2021-09-10 16:14 ` [PATCH v14 bpf-next 06/18] net: marvell: rely on " Lorenzo Bianconi
2021-09-10 16:14 ` [PATCH v14 bpf-next 07/18] xdp: add multi-buff support to xdp_return_{buff/frame} Lorenzo Bianconi
2021-09-10 16:14 ` [PATCH v14 bpf-next 08/18] net: mvneta: add multi buffer support to XDP_TX Lorenzo Bianconi
2021-09-10 16:14 ` [PATCH v14 bpf-next 09/18] net: mvneta: enable jumbo frames for XDP Lorenzo Bianconi
2021-09-10 16:14 ` [PATCH v14 bpf-next 10/18] bpf: add multi-buff support to the bpf_xdp_adjust_tail() API Lorenzo Bianconi
2021-09-16 16:55   ` Jakub Kicinski
2021-09-17 10:02     ` Lorenzo Bianconi
2021-09-17 13:03       ` Jakub Kicinski
2021-09-10 16:14 ` [PATCH v14 bpf-next 11/18] bpf: introduce bpf_xdp_get_buff_len helper Lorenzo Bianconi
2021-09-10 16:14 ` [PATCH v14 bpf-next 12/18] bpf: add multi-buffer support to xdp copy helpers Lorenzo Bianconi
2021-09-10 16:14 ` [PATCH v14 bpf-next 13/18] bpf: move user_size out of bpf_test_init Lorenzo Bianconi
2021-09-10 16:14 ` [PATCH v14 bpf-next 14/18] bpf: introduce multibuff support to bpf_prog_test_run_xdp() Lorenzo Bianconi
2021-09-10 16:14 ` [PATCH v14 bpf-next 15/18] bpf: test_run: add xdp_shared_info pointer in bpf_test_finish signature Lorenzo Bianconi
2021-09-10 16:14 ` [PATCH v14 bpf-next 16/18] bpf: update xdp_adjust_tail selftest to include multi-buffer Lorenzo Bianconi
2021-09-10 16:14 ` [PATCH v14 bpf-next 17/18] net: xdp: introduce bpf_xdp_adjust_data helper Lorenzo Bianconi
2021-09-10 16:14 ` [PATCH v14 bpf-next 18/18] bpf: add bpf_xdp_adjust_data selftest Lorenzo Bianconi
2021-09-16 16:55 ` [PATCH v14 bpf-next 00/18] mvneta: introduce XDP multi-buffer support Jakub Kicinski
2021-09-17 14:51   ` Lorenzo Bianconi
2021-09-17 18:33     ` Jakub Kicinski
2021-09-17 18:43       ` Alexei Starovoitov
2021-09-17 19:00         ` Jakub Kicinski
2021-09-17 19:10           ` Alexei Starovoitov
2021-09-17 22:07             ` John Fastabend
2021-09-18 11:53               ` Toke Høiland-Jørgensen
2021-09-20 18:02                 ` Jakub Kicinski
2021-09-20 21:01                   ` Toke Høiland-Jørgensen
2021-09-20 21:25                     ` Jakub Kicinski
2021-09-20 22:44                       ` Toke Høiland-Jørgensen
2021-09-21 10:03                         ` Eelco Chaudron
2021-09-28 11:48                           ` Magnus Karlsson
2021-09-29 10:36                         ` Lorenz Bauer
2021-09-29 12:25                           ` Toke Høiland-Jørgensen
2021-09-29 12:32                             ` Lorenz Bauer
2021-09-29 17:48                             ` Jakub Kicinski
2021-09-29 17:46                           ` Jakub Kicinski
2021-09-29 10:41   ` Lorenz Bauer
2021-09-29 12:10     ` Toke Høiland-Jørgensen
2021-09-29 12:38       ` Lorenz Bauer
2021-09-29 18:54         ` Alexei Starovoitov
2021-09-29 19:22           ` Jakub Kicinski
2021-09-29 20:39             ` Toke Høiland-Jørgensen
2021-10-01  9:03               ` Lorenzo Bianconi [this message]
2021-10-01 18:35                 ` Jakub Kicinski
2021-10-06  9:32                   ` Lorenzo Bianconi
2021-10-06 10:08                     ` Eelco Chaudron
2021-10-06 12:15                       ` Lorenzo Bianconi

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