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=-4.0 required=3.0 tests=BAYES_00,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS 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 65BFDC432BE for ; Fri, 23 Jul 2021 08:14:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 50DF960E8E for ; Fri, 23 Jul 2021 08:14:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234358AbhGWHdl (ORCPT ); Fri, 23 Jul 2021 03:33:41 -0400 Received: from mail.kernel.org ([198.145.29.99]:54100 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229907AbhGWHdj (ORCPT ); Fri, 23 Jul 2021 03:33:39 -0400 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 451BC60F02; Fri, 23 Jul 2021 08:14:13 +0000 (UTC) Received: from sofa.misterjones.org ([185.219.108.64] helo=why.misterjones.org) by disco-boy.misterjones.org with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.94.2) (envelope-from ) id 1m6qJv-000RV6-A8; Fri, 23 Jul 2021 09:14:11 +0100 Date: Fri, 23 Jul 2021 09:14:10 +0100 Message-ID: <8735s530rx.wl-maz@kernel.org> From: Marc Zyngier To: Andy Shevchenko Cc: Bjorn Helgaas , Thomas Gleixner , LKML , Alex Williamson , "Raj, Ashok" , Bjorn Helgaas , "linux-pci@vger.kernel.org" , "David S. Miller" , Kevin Tian , Ingo Molnar , "x86@kernel.org" Subject: Re: [patch 4/8] PCI/MSI: Enforce MSI[X] entry updates to be visible In-Reply-To: References: <20210721192650.499597025@linutronix.de> <20210722214843.GA350177@bjorn-Precision-5520> 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: 185.219.108.64 X-SA-Exim-Rcpt-To: andy.shevchenko@gmail.com, helgaas@kernel.org, tglx@linutronix.de, linux-kernel@vger.kernel.org, alex.williamson@redhat.com, ashok.raj@intel.com, bhelgaas@google.com, linux-pci@vger.kernel.org, davem@davemloft.net, kevin.tian@intel.com, mingo@kernel.org, x86@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 Thu, 22 Jul 2021 22:54:48 +0100, Andy Shevchenko wrote: > > [1 ] > On Friday, July 23, 2021, Bjorn Helgaas wrote: > > > On Wed, Jul 21, 2021 at 09:11:30PM +0200, Thomas Gleixner wrote: > > > Nothing enforces the posted writes to be visible when the function > > > returns. Flush them even if the flush might be redundant when the entry > > is > > > masked already as the unmask will flush as well. This is either setup or > > a > > > rare affinity change event so the extra flush is not the end of the > > world. > > > > > > While this is more a theoretical issue especially the X86 MSI affinity > > > stter mechanism relies on the assumption that the update has reached the > > > > stter? > > > Setter I suppose My bet is on 'steer', given that this is about affinity management. M. -- Without deviation from the norm, progress is not possible.