From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9DCDDC433DF for ; Thu, 20 Aug 2020 07:01:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8306C20738 for ; Thu, 20 Aug 2020 07:01:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726325AbgHTHBq (ORCPT ); Thu, 20 Aug 2020 03:01:46 -0400 Received: from helcar.hmeau.com ([216.24.177.18]:48904 "EHLO fornost.hmeau.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725819AbgHTHBq (ORCPT ); Thu, 20 Aug 2020 03:01:46 -0400 Received: from gwarestrin.arnor.me.apana.org.au ([192.168.0.7]) by fornost.hmeau.com with smtp (Exim 4.92 #5 (Debian)) id 1k8eZy-0005rQ-Nc; Thu, 20 Aug 2020 17:01:43 +1000 Received: by gwarestrin.arnor.me.apana.org.au (sSMTP sendmail emulation); Thu, 20 Aug 2020 17:01:42 +1000 Date: Thu, 20 Aug 2020 17:01:42 +1000 From: Herbert Xu To: Ard Biesheuvel Cc: Ben Greear , Linux Crypto Mailing List , Eric Biggers Subject: Re: [PATCH 0/5] crypto: Implement cmac based on cbc skcipher Message-ID: <20200820070142.GA21343@gondor.apana.org.au> References: <20200818135128.GA25652@gondor.apana.org.au> <2aad9569-877e-4398-88ef-e40d9bbf7656@candelatech.com> <20200818140532.GA25807@gondor.apana.org.au> <20200818221550.GA27421@gondor.apana.org.au> <20200818222719.GA27622@gondor.apana.org.au> <20200818223359.GA27712@gondor.apana.org.au> <8b248ef3-d4c7-43fd-6ae4-1c3381597579@candelatech.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-crypto-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-crypto@vger.kernel.org On Thu, Aug 20, 2020 at 08:58:15AM +0200, Ard Biesheuvel wrote: > > But if we look at the actual issue at hand, we might also look into > amortizing the FPU preserve/restore over multiple invocations of a > cipher. I proposed a patch a while ago that makes cipher an internal > crypto API abstraction, and we could easily add pre/post hooks that > preserve/restore the FPU in this case, in which case we would not need > any changes at higher levels. I think any use of SIMD crypto_cipher on bulk data is just wrong. Because the performance degradation when SIMD cannot be used is too great for this to make sense. So optimising the FPU overhead is attacking the wrong problem. Cheers, -- Email: Herbert Xu Home Page: http://gondor.apana.org.au/~herbert/ PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt