linux-crypto.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: "Toke Høiland-Jørgensen" <toke@toke.dk>
To: "Jason A. Donenfeld" <Jason@zx2c4.com>,
	Pascal Van Leeuwen <pvanleeuwen@verimatrix.com>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>,
	Linux Crypto Mailing List <linux-crypto@vger.kernel.org>,
	linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
	Herbert Xu <herbert@gondor.apana.org.au>,
	David Miller <davem@davemloft.net>,
	Greg KH <gregkh@linuxfoundation.org>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Samuel Neves <sneves@dei.uc.pt>,
	Dan Carpenter <dan.carpenter@oracle.com>,
	Arnd Bergmann <arnd@arndb.de>, Eric Biggers <ebiggers@google.com>,
	Andy Lutomirski <luto@kernel.org>, Will Deacon <will@kernel.org>,
	Marc Zyngier <maz@kernel.org>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Willy Tarreau <w@1wt.eu>, Netdev <netdev@vger.kernel.org>,
	Dave Taht <dave.taht@gmail.com>
Subject: Re: chapoly acceleration hardware [Was: Re: [RFC PATCH 00/18] crypto: wireguard using the existing crypto API]
Date: Thu, 26 Sep 2019 13:38:36 +0200	[thread overview]
Message-ID: <8736gj2soz.fsf@toke.dk> (raw)
In-Reply-To: <CAHmME9r5m7D-oMU6Lv_ZhEyWmrNscMr5HokzdK0wg2Ayzzbeow@mail.gmail.com>

"Jason A. Donenfeld" <Jason@zx2c4.com> writes:

> [CC +willy, toke, dave, netdev]
>
> Hi Pascal
>
> On Thu, Sep 26, 2019 at 12:19 PM Pascal Van Leeuwen
> <pvanleeuwen@verimatrix.com> wrote:
>> Actually, that assumption is factually wrong. I don't know if anything
>> is *publicly* available, but I can assure you the silicon is running in
>> labs already. And something will be publicly available early next year
>> at the latest. Which could nicely coincide with having Wireguard support
>> in the kernel (which I would also like to see happen BTW) ...
>>
>> Not "at some point". It will. Very soon. Maybe not in consumer or server
>> CPUs, but definitely in the embedded (networking) space.
>> And it *will* be much faster than the embedded CPU next to it, so it will
>> be worth using it for something like bulk packet encryption.
>
> Super! I was wondering if you could speak a bit more about the
> interface. My biggest questions surround latency. Will it be
> synchronous or asynchronous? If the latter, why? What will its
> latencies be? How deep will its buffers be? The reason I ask is that a
> lot of crypto acceleration hardware of the past has been fast and
> having very deep buffers, but at great expense of latency. In the
> networking context, keeping latency low is pretty important. Already
> WireGuard is multi-threaded which isn't super great all the time for
> latency (improvements are a work in progress). If you're involved with
> the design of the hardware, perhaps this is something you can help
> ensure winds up working well? For example, AES-NI is straightforward
> and good, but Intel can do that because they are the CPU. It sounds
> like your silicon will be adjacent. How do you envision this working
> in a low latency environment?

Being asynchronous doesn't *necessarily* have to hurt latency; you just
need the right queue back-pressure.


We already have multiple queues in the stack. With an async crypto
engine we would go from something like:

stack -> [qdisc] -> wg if -> [wireguard buffer] -> netdev driver ->
device -> [device buffer] -> wire

to

stack -> [qdisc] -> wg if -> [wireguard buffer] -> crypto stack ->
crypto device -> [crypto device buffer] -> wg post-crypto -> netdev
driver -> device -> [device buffer] -> wire

(where everything in [] is a packet queue).

The wireguard buffer is the source of the latency you're alluding to
above (the comment about multi-threaded behaviour), so we probably need
to fix that anyway. For the device buffer we have BQL to keep it at a
minimum. So that leaves the buffering in the crypto offload device. If
we add something like BQL to the crypto offload drivers, we could
conceivably avoid having that add a significant amount of latency. In
fact, doing so may benefit other users of crypto offloads as well, no?
Presumably ipsec has this same issue?


Caveat: I am fairly ignorant about the inner workings of the crypto
subsystem, so please excuse any inaccuracies in the above; the diagrams
are solely for illustrative purposes... :)

-Toke

  reply	other threads:[~2019-09-26 11:48 UTC|newest]

Thread overview: 66+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-09-25 16:12 [RFC PATCH 00/18] crypto: wireguard using the existing crypto API Ard Biesheuvel
2019-09-25 16:12 ` [RFC PATCH 01/18] crypto: shash - add plumbing for operating on scatterlists Ard Biesheuvel
2019-09-25 16:12 ` [RFC PATCH 02/18] crypto: x86/poly1305 - implement .update_from_sg method Ard Biesheuvel
2019-09-25 16:12 ` [RFC PATCH 03/18] crypto: arm/poly1305 - incorporate OpenSSL/CRYPTOGAMS NEON implementation Ard Biesheuvel
2019-09-25 16:12 ` [RFC PATCH 04/18] crypto: arm64/poly1305 " Ard Biesheuvel
2019-09-25 16:12 ` [RFC PATCH 05/18] crypto: chacha - move existing library code into lib/crypto Ard Biesheuvel
2019-09-25 16:12 ` [RFC PATCH 06/18] crypto: rfc7539 - switch to shash for Poly1305 Ard Biesheuvel
2019-09-25 16:12 ` [RFC PATCH 07/18] crypto: rfc7539 - use zero reqsize for sync instantiations without alignmask Ard Biesheuvel
2019-09-25 16:12 ` [RFC PATCH 08/18] crypto: testmgr - add a chacha20poly1305 test case Ard Biesheuvel
2019-09-25 16:12 ` [RFC PATCH 09/18] crypto: poly1305 - move core algorithm into lib/crypto Ard Biesheuvel
2019-09-25 16:12 ` [RFC PATCH 10/18] crypto: poly1305 - add init/update/final library routines Ard Biesheuvel
2019-09-25 16:12 ` [RFC PATCH 11/18] int128: move __uint128_t compiler test to Kconfig Ard Biesheuvel
2019-09-25 21:01   ` Linus Torvalds
2019-09-25 21:19     ` Ard Biesheuvel
2019-09-25 16:12 ` [RFC PATCH 12/18] crypto: BLAKE2s - generic C library implementation and selftest Ard Biesheuvel
2019-09-25 16:12 ` [RFC PATCH 13/18] crypto: Curve25519 - generic C library implementations " Ard Biesheuvel
2019-09-25 16:12 ` [RFC PATCH 14/18] crypto: chacha20poly1305 - import construction and selftest from Zinc Ard Biesheuvel
2019-09-25 16:12 ` [RFC PATCH 15/18] net: WireGuard secure network tunnel Ard Biesheuvel
2019-09-25 16:12 ` [RFC PATCH 16/18] netlink: use new strict length types in policy for 5.2 Ard Biesheuvel
2019-09-25 16:12 ` [RFC PATCH 17/18] wg switch to lib/crypto algos Ard Biesheuvel
2019-09-25 16:12 ` [RFC PATCH 18/18] net: wireguard - switch to crypto API for packet encryption Ard Biesheuvel
2019-09-25 22:15   ` Linus Torvalds
2019-09-25 22:22     ` Linus Torvalds
2019-09-26  9:40     ` Pascal Van Leeuwen
2019-09-26 16:35       ` Linus Torvalds
2019-09-27  0:15         ` Pascal Van Leeuwen
2019-09-27  1:30           ` Linus Torvalds
2019-09-27  2:54             ` Linus Torvalds
2019-09-27  3:53               ` Herbert Xu
2019-09-27  4:37                 ` Andy Lutomirski
2019-09-27  4:59                   ` Herbert Xu
2019-09-27  4:01               ` Herbert Xu
2019-09-27  4:13                 ` Linus Torvalds
2019-09-27 10:44               ` Pascal Van Leeuwen
2019-09-27 11:08                 ` Pascal Van Leeuwen
2019-09-27  4:36             ` Andy Lutomirski
2019-09-27  9:58             ` Pascal Van Leeuwen
2019-09-27 10:11               ` Herbert Xu
2019-09-27 16:23               ` Linus Torvalds
2019-09-30 11:14                 ` France didn't want GSM encryption Marc Gonzalez
2019-09-30 21:37                   ` Linus Torvalds
2019-09-30 20:44                 ` [RFC PATCH 18/18] net: wireguard - switch to crypto API for packet encryption Pascal Van Leeuwen
2019-09-27  2:06           ` Linus Torvalds
2019-09-27 10:11             ` Pascal Van Leeuwen
2019-09-26 11:06     ` Ard Biesheuvel
2019-09-26 12:34       ` Ard Biesheuvel
2019-09-26  8:59 ` [RFC PATCH 00/18] crypto: wireguard using the existing crypto API Jason A. Donenfeld
2019-09-26 10:19   ` Pascal Van Leeuwen
2019-09-26 10:59     ` Jason A. Donenfeld
2019-09-26 11:06     ` chapoly acceleration hardware [Was: Re: [RFC PATCH 00/18] crypto: wireguard using the existing crypto API] Jason A. Donenfeld
2019-09-26 11:38       ` Toke Høiland-Jørgensen [this message]
2019-09-26 13:52       ` Pascal Van Leeuwen
2019-09-26 23:13         ` Dave Taht
2019-09-27 12:18           ` Pascal Van Leeuwen
2019-09-26 22:47       ` Jakub Kicinski
2019-09-26 12:07   ` [RFC PATCH 00/18] crypto: wireguard using the existing crypto API Ard Biesheuvel
2019-09-26 13:06     ` Pascal Van Leeuwen
2019-09-26 13:15       ` Ard Biesheuvel
2019-09-26 14:03         ` Pascal Van Leeuwen
2019-09-26 14:52           ` Ard Biesheuvel
2019-09-26 15:04             ` Pascal Van Leeuwen
2019-09-26 20:47     ` Jason A. Donenfeld
2019-09-26 21:22       ` Andrew Lunn
2019-09-26 21:36       ` Andy Lutomirski
2019-09-27  7:20         ` Jason A. Donenfeld
2019-10-01  8:56           ` Ard Biesheuvel

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=8736gj2soz.fsf@toke.dk \
    --to=toke@toke.dk \
    --cc=Jason@zx2c4.com \
    --cc=ard.biesheuvel@linaro.org \
    --cc=arnd@arndb.de \
    --cc=catalin.marinas@arm.com \
    --cc=dan.carpenter@oracle.com \
    --cc=dave.taht@gmail.com \
    --cc=davem@davemloft.net \
    --cc=ebiggers@google.com \
    --cc=gregkh@linuxfoundation.org \
    --cc=herbert@gondor.apana.org.au \
    --cc=linux-arm-kernel@lists.infradead.org \
    --cc=linux-crypto@vger.kernel.org \
    --cc=luto@kernel.org \
    --cc=maz@kernel.org \
    --cc=netdev@vger.kernel.org \
    --cc=pvanleeuwen@verimatrix.com \
    --cc=sneves@dei.uc.pt \
    --cc=torvalds@linux-foundation.org \
    --cc=w@1wt.eu \
    --cc=will@kernel.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).