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=-14.0 required=3.0 tests=BAYES_00,INCLUDES_CR_TRAILER, MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 CE738C433E0 for ; Wed, 17 Feb 2021 14:39:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9C36564E2E for ; Wed, 17 Feb 2021 14:39:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233453AbhBQOj3 (ORCPT ); Wed, 17 Feb 2021 09:39:29 -0500 Received: from mail.kernel.org ([198.145.29.99]:45806 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233044AbhBQOjY (ORCPT ); Wed, 17 Feb 2021 09:39:24 -0500 Received: from disco-boy.misterjones.org (disco-boy.misterjones.org [51.254.78.96]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 3F82A64DFF; Wed, 17 Feb 2021 14:38:44 +0000 (UTC) Received: from 78.163-31-62.static.virginmediabusiness.co.uk ([62.31.163.78] helo=why.misterjones.org) by disco-boy.misterjones.org with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.94) (envelope-from ) id 1lCNyR-00Ec2r-CW; Wed, 17 Feb 2021 14:38:42 +0000 Date: Wed, 17 Feb 2021 14:38:27 +0000 Message-ID: <87h7mapxng.wl-maz@kernel.org> From: Marc Zyngier To: Mark Rutland Cc: Hector Martin , linux-arm-kernel@lists.infradead.org, Rob Herring , Arnd Bergmann , Olof Johansson , Krzysztof Kozlowski , Mark Kettenis , Tony Lindgren , Mohamed Mediouni , Stan Skowronek , Alexander Graf , Will Deacon , Linus Walleij , devicetree@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2 09/25] arm64: entry: Map the FIQ vector to IRQ on NEEDS_FIQ platforms In-Reply-To: <20210217114923.GB5556@C02TD0UTHF1T.local> References: <20210215121713.57687-1-marcan@marcan.st> <20210215121713.57687-10-marcan@marcan.st> <20210217114923.GB5556@C02TD0UTHF1T.local> User-Agent: Wanderlust/2.15.9 (Almost Unreal) SEMI-EPG/1.14.7 (Harue) FLIM-LB/1.14.9 (=?UTF-8?B?R29qxY0=?=) APEL-LB/10.8 EasyPG/1.0.0 Emacs/27.1 (x86_64-pc-linux-gnu) MULE/6.0 (HANACHIRUSATO) MIME-Version: 1.0 (generated by SEMI-EPG 1.14.7 - "Harue") Content-Type: text/plain; charset=US-ASCII X-SA-Exim-Connect-IP: 62.31.163.78 X-SA-Exim-Rcpt-To: mark.rutland@arm.com, marcan@marcan.st, linux-arm-kernel@lists.infradead.org, robh@kernel.org, arnd@kernel.org, olof@lixom.net, krzk@kernel.org, mark.kettenis@xs4all.nl, tony@atomide.com, mohamed.mediouni@caramail.com, stan@corellium.com, graf@amazon.com, will@kernel.org, linus.walleij@linaro.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 17 Feb 2021 11:49:23 +0000, Mark Rutland wrote: > > Hi Hector, > > On Mon, Feb 15, 2021 at 09:16:57PM +0900, Hector Martin wrote: > > From: Marc Zyngier > > > > By default, FIQ exceptions trigger a panic. On platforms that need to > > deliver interrupts via FIQ, this gets redirected via an alternative to > > instead handle FIQ the same way as IRQ. It is up to the irqchip handler > > to discriminate between the two. > > > > Signed-off-by: Marc Zyngier > > Signed-off-by: Hector Martin > > Since the use of FIQ is a platform integration detail rather than a CPU > implementation detail (and e.g. can differ across bare-metal and VM), > I'd prefer to always have separate registered handlers for IRQ/FIQ (also > avoiding the need for patching). That way we can explicitly opt-in to > FIQ when required, and avoid edge-cases where an unexpected FIQ could > livelock an unaware IRQ handler. > > Marc and I had a quick play with that, and I have a series of patches > I've pushed to: > > https://git.kernel.org/pub/scm/linux/kernel/git/mark/linux.git/log/?h=arm64/fiq > git://git.kernel.org/pub/scm/linux/kernel/git/mark/linux.git arm64/fiq > > ... which I'll post out shortly. FWIW, I've just posted a more complete version of the first patch in this series[1], which you may want to use directly (though I plan to take it as a fix for 5.12). Thanks, M. [1] https://lore.kernel.org/r/20210217142800.2547737-1-maz@kernel.org -- Without deviation from the norm, progress is not possible.