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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8053CC4332F for ; Fri, 10 Nov 2023 18:08:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1344496AbjKJSIY (ORCPT ); Fri, 10 Nov 2023 13:08:24 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33032 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1345484AbjKJSGd (ORCPT ); Fri, 10 Nov 2023 13:06:33 -0500 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6F3AF7D92 for ; Thu, 9 Nov 2023 23:02:17 -0800 (PST) Received: by smtp.kernel.org (Postfix) with ESMTPSA id BF575C433C8; Fri, 10 Nov 2023 04:34:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1699590899; bh=luMWNgUgOzDCukfqCzpzbeoC/xYIuvR4tlh8y8BriOI=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=Kkmb1yV3cX8ZqC2Ugs56PrhNzF27vOjUHj7Zi9Am2rWheYaIW6PoIBxdQXrExYQ6d /M+jhxGhYDtOneLSN0nlDZyHowUbNauRO+fyhNafAl1Y0X7jzGFlyJ+klNa7Lnat+y 49Yxbwrr+8p5wcA6XhOK34zy5ZlTMKxY4d7CSJYRNS14I1K2tao9RwYjCPJilMg4Fl TMDeMHKmxFrCqUeQbLDaIJMxJecWs33mXwwUJ6mX2FdYgr8bPk0PBecmLBjtz8C+Pt CUpVSOZvKNwscrCaq03QH8fQk86sPy/9dHwK9zdoOj2sp1EaZiVN3g3RVC/Z5zqJZe TM6yuwOERH10w== Date: Thu, 9 Nov 2023 20:34:57 -0800 From: Eric Biggers To: Jerry Shih Cc: Paul Walmsley , palmer@dabbelt.com, Albert Ou , herbert@gondor.apana.org.au, davem@davemloft.net, andy.chiu@sifive.com, greentime.hu@sifive.com, conor.dooley@microchip.com, guoren@kernel.org, bjorn@rivosinc.com, heiko@sntech.de, ardb@kernel.org, phoebe.chen@sifive.com, hongrong.hsu@sifive.com, linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, linux-crypto@vger.kernel.org Subject: Re: [PATCH 06/12] RISC-V: crypto: add accelerated AES-CBC/CTR/ECB/XTS implementations Message-ID: <20231110043457.GA6572@sol.localdomain> References: <20231025183644.8735-1-jerry.shih@sifive.com> <20231025183644.8735-7-jerry.shih@sifive.com> <20231102051639.GF1498@sol.localdomain> <39126F19-8FEB-4E18-B61D-4494B59C43A1@sifive.com> <20231109071623.GB1245@sol.localdomain> <659DE1CF-4F42-4935-9DFD-E127269CEC54@sifive.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <659DE1CF-4F42-4935-9DFD-E127269CEC54@sifive.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Nov 10, 2023 at 11:58:02AM +0800, Jerry Shih wrote: > On Nov 9, 2023, at 15:16, Eric Biggers wrote: > > On Tue, Nov 07, 2023 at 04:53:13PM +0800, Jerry Shih wrote: > >> On Nov 2, 2023, at 13:16, Eric Biggers wrote: > >>> On Thu, Oct 26, 2023 at 02:36:38AM +0800, Jerry Shih wrote: > >>>> +static int ecb_encrypt(struct skcipher_request *req) > >>>> +{ > >>> > >>> There's no fallback for !crypto_simd_usable() here. I really like it this way. > >>> However, for it to work (for skciphers and aeads), RISC-V needs to allow the > >>> vector registers to be used in softirq context. Is that already the case? > >> > >> The kernel-mode-vector could be enabled in softirq, but we don't have nesting > >> vector contexts. Will we have the case that kernel needs to jump to softirq for > >> encryptions during the regular crypto function? If yes, we need to have fallbacks > >> for all algorithms. > > > > Are you asking what happens if a softirq is taken while the CPU is between > > kernel_vector_begin() and kernel_vector_end()? I think that needs to be > > prevented by making kernel_vector_begin() and kernel_vector_end() disable and > > re-enable softirqs, like what kernel_neon_begin() and kernel_neon_end() do on > > arm64. Refer to commit 13150149aa6ded which implemented that behavior on arm64. > > > > - Eric > > The current kernel-mode-vector implementation, it only calls `preempt_disable()` during > vector context. So, we will hit nesting vector context issue from softirq which also use > kernel-vector. > https://lore.kernel.org/all/20230721112855.1006-1-andy.chiu@sifive.com/ > > Maybe we could use the `simd_register_aeads_compat()` wrapping as x86 platform > first in a simpler way first. The "crypto SIMD helpers" (simd_register_*() in crypto/simd.c) are quite complex and have some disadvantages such as marking the resulting algorithms as "asynchronous". I expect that a much better approach would be to align RISC-V with arm64 by disabling softirqs while the kernel vector unit is in use. - Eric