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=-11.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING, SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham 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 81983C433B4 for ; Mon, 12 Apr 2021 13:12:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 554836134F for ; Mon, 12 Apr 2021 13:12:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S241897AbhDLNMY (ORCPT ); Mon, 12 Apr 2021 09:12:24 -0400 Received: from mail.kernel.org ([198.145.29.99]:36842 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S241722AbhDLNMV (ORCPT ); Mon, 12 Apr 2021 09:12:21 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 49B446128A; Mon, 12 Apr 2021 13:12:01 +0000 (UTC) From: Catalin Marinas To: linux-crypto@vger.kernel.org, Ard Biesheuvel Cc: Will Deacon , Catalin Marinas , Sebastian Andrzej Siewior , Dave Martin , Peter Zijlstra , Eric Biggers , Ingo Molnar , Mark Brown , Herbert Xu , Thomas Gleixner , linux-arm-kernel@lists.infradead.org, Andy Lutomirski Subject: Re: (subset) [PATCH v2 0/9] running kernel mode SIMD with softirqs disabled Date: Mon, 12 Apr 2021 14:11:13 +0100 Message-Id: <161822613829.4133.7312323262518323547.b4-ty@arm.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20210302090118.30666-1-ardb@kernel.org> References: <20210302090118.30666-1-ardb@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-crypto@vger.kernel.org On Tue, 2 Mar 2021 10:01:09 +0100, Ard Biesheuvel wrote: > [ TL;DR for the non-ARM folks on CC: disabling softirq processing when using > SIMD in kernel mode could reduce complexity and improve performance, but we > need to decide whether we can do this, and how much softirq processing > latency we can tolerate. If we can find a satisfactory solution for this, > we might do the same for x86 and 32-bit ARM as well. > > However, based on preliminary off-list discussions with peterz and luto, it > seems that for x86, there is a preference for using per-CPU buffers to > preserve/restore the task context's kernel mode SIMD state when the task is > interrupted to perform kernel mode SIMD in softirq context. On arm64, we > actually had this arrangement before, and removed it because it made > reasoning about preserving/restoring userland SVE state (32 SIMD registers > of up to 2 kbit in size) rather complex. ] > > [...] Applied to arm64 (for-next/neon-softirqs-disabled), thanks! [1/9] arm64: assembler: remove conditional NEON yield macros https://git.kernel.org/arm64/c/27248fe1abb2 [2/9] arm64: assembler: introduce wxN aliases for wN registers https://git.kernel.org/arm64/c/4c4dcd3541f8 [3/9] arm64: fpsimd: run kernel mode NEON with softirqs disabled https://git.kernel.org/arm64/c/13150149aa6d -- Catalin