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=-2.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT autolearn=unavailable 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 DADAAC04E87 for ; Wed, 15 May 2019 12:54:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id ABE262082E for ; Wed, 15 May 2019 12:54:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727177AbfEOMyH (ORCPT ); Wed, 15 May 2019 08:54:07 -0400 Received: from mx2.suse.de ([195.135.220.15]:60302 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726677AbfEOMyG (ORCPT ); Wed, 15 May 2019 08:54:06 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 585B1AC8E; Wed, 15 May 2019 12:54:05 +0000 (UTC) Received: by ds.suse.cz (Postfix, from userid 10065) id B7B24DA866; Wed, 15 May 2019 14:55:05 +0200 (CEST) Date: Wed, 15 May 2019 14:55:05 +0200 From: David Sterba To: Eric Biggers Cc: linux-crypto@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: Can crypto API provide information about hw acceleration? Message-ID: <20190515125505.GP3138@suse.cz> Reply-To: dsterba@suse.cz Mail-Followup-To: dsterba@suse.cz, Eric Biggers , linux-crypto@vger.kernel.org, linux-kernel@vger.kernel.org References: <20190514163348.GM3138@twin.jikos.cz> <20190514213409.GA115510@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190514213409.GA115510@gmail.com> User-Agent: Mutt/1.5.23.1 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, May 14, 2019 at 02:34:10PM -0700, Eric Biggers wrote: > On Tue, May 14, 2019 at 06:33:48PM +0200, David Sterba wrote: > > Hi, > > > > Q: is there a way to query the crypto layer whether a given algorithm > > (digest, crypto) is accelerated by the driver? > > > > This information can be used to decide if eg. a checksum should can be > > calculated right away or offloaded to a thread. This is done in btrfs, > > (fs/btrfs/disk-io.c:check_async_write). > > > > At this moment it contains a static check for a cpu feature, and only > > for x86. I briefly searched the arch/ directory for implementations of > > crc32c that possibly use hw aid and there are several of them. Adding a > > static check a-la x86 for the other architectures (arm, ppc, mips, > > sparc, s390) is wrong, so I'm looking for a clean solution. > > > > The struct shash_alg definition of the algorithms does not say anything > > about the acceleration. The closest thing is the cra_priority, but I > > don't know if this is reliable information. The default implementations > > seem to have 100, and acceleated 200 or 300. > > > > This would be probably sufficient, but I'd like a confirmation from > > crypto people. > > > > There's only one default implementation of crc32c, not multiple, and it has > priority 100. All other crc32c implementations have priority > 100. So yes, > you can check the priority (which would require adding a function to > lib/libcrc32c.c to get it). Alternatively you could check whether the driver > name is "crc32c-generic" or not. Thanks, the driver name check seems to be ok for my needs. At mount time the struct crypto_shash is initialized and this provides the driver name, then a bit is set whether it's generic or not and later used to decide whether to offload.