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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 3A67CC47258 for ; Tue, 23 Jan 2024 10:26:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Message-ID:Subject:CC:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=zCCqP1Tc8Mi8E/mxB5p5kl+HH4jIogMvVe3VAny5yLM=; b=LZTNh53zojsFqO AUVn2ULVlHp5bU8q0D6LfeLNKrHGGUfa5aW4yVpUL6w6iSyiGIwwOG52/vKV2YD673iHz/MvNnOE3 YdzSFx/yGEakiJ22kVnUIqKV1F7oxJskzx/Mo8rv6R9X7gxfnATGES8TyV26VlRW7jcPtBDIiVsCA Uto2av785RCNXLWSsLTa8UN2MCzKMC/sEjPz7wqxMN2Q9Faba/pLMyLanXqXzy+uZD09hDSkE0mTA 1gHvEGKPW3DFAAOg/xxuf7nyOcdxxX7loGjPO4PHH2qRg9D/DNwm+W5Jwpq/BEVUQtg4MgK6MnVyW pOG0uC56wDEEUSJZGpbQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.96 #2 (Red Hat Linux)) id 1rSDyy-00FvET-1D; Tue, 23 Jan 2024 10:26:16 +0000 Received: from frasgout.his.huawei.com ([185.176.79.56]) by bombadil.infradead.org with esmtps (Exim 4.96 #2 (Red Hat Linux)) id 1rSDyu-00FvCw-30; Tue, 23 Jan 2024 10:26:15 +0000 Received: from mail.maildlp.com (unknown [172.18.186.216]) by frasgout.his.huawei.com (SkyGuard) with ESMTP id 4TK37w3nrBz6JB35; Tue, 23 Jan 2024 18:23:08 +0800 (CST) Received: from lhrpeml500005.china.huawei.com (unknown [7.191.163.240]) by mail.maildlp.com (Postfix) with ESMTPS id 56FC3140A86; Tue, 23 Jan 2024 18:26:05 +0800 (CST) Received: from localhost (10.202.227.76) by lhrpeml500005.china.huawei.com (7.191.163.240) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.35; Tue, 23 Jan 2024 10:26:04 +0000 Date: Tue, 23 Jan 2024 10:26:03 +0000 From: Jonathan Cameron To: "Russell King (Oracle)" CC: , , , , , , , , , , , , , , Salil Mehta , Jean-Philippe Brucker , , , James Morse Subject: Re: [PATCH RFC v3 17/21] ACPI: add support to register CPUs based on the _STA enabled bit Message-ID: <20240123102603.00004244@Huawei.com> In-Reply-To: <20240102145320.000062f9@Huawei.com> References: <20240102145320.000062f9@Huawei.com> Organization: Huawei Technologies Research and Development (UK) Ltd. X-Mailer: Claws Mail 4.1.0 (GTK 3.24.33; x86_64-w64-mingw32) MIME-Version: 1.0 X-Originating-IP: [10.202.227.76] X-ClientProxiedBy: lhrpeml500002.china.huawei.com (7.191.160.78) To lhrpeml500005.china.huawei.com (7.191.163.240) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240123_022613_254842_DF3732AA X-CRM114-Status: GOOD ( 27.71 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Tue, 2 Jan 2024 14:53:20 +0000 Jonathan Cameron wrote: > On Mon, 18 Dec 2023 13:03:32 +0000 > "Russell King (Oracle)" wrote: > > > On Wed, Dec 13, 2023 at 12:50:38PM +0000, Russell King wrote: > > > From: James Morse > > > > > > acpi_processor_get_info() registers all present CPUs. Registering a > > > CPU is what creates the sysfs entries and triggers the udev > > > notifications. > > > > > > arm64 virtual machines that support 'virtual cpu hotplug' use the > > > enabled bit to indicate whether the CPU can be brought online, as > > > the existing ACPI tables require all hardware to be described and > > > present. > > > > > > If firmware describes a CPU as present, but disabled, skip the > > > registration. Such CPUs are present, but can't be brought online for > > > whatever reason. (e.g. firmware/hypervisor policy). > > > > > > Once firmware sets the enabled bit, the CPU can be registered and > > > brought online by user-space. Online CPUs, or CPUs that are missing > > > an _STA method must always be registered. > > > > ... > > > > > @@ -526,6 +552,9 @@ static void acpi_processor_post_eject(struct acpi_device *device) > > > acpi_processor_make_not_present(device); > > > return; > > > } > > > + > > > + if (cpu_present(pr->id) && !(sta & ACPI_STA_DEVICE_ENABLED)) > > > + arch_unregister_cpu(pr->id); > > > > This change isn't described in the commit log, but seems to be the cause > > of the build error identified by the kernel build bot that is fixed > > later in this series. I'm wondering whether this should be in a > > different patch, maybe "ACPI: Check _STA present bit before making CPUs > > not present" ? > > Would seem a bit odd to call arch_unregister_cpu() way before the code > is added to call the matching arch_registers_cpu() > > Mind you this eject doesn't just apply to those CPUs that are registered > later I think, but instead to all. So we run into the spec hole that > there is no way to identify initially 'enabled' CPUs that might be disabled > later. > > > > > Or maybe my brain isn't working properly (due to being Covid positive.) > > Any thoughts, Jonathan? > > I'll go with a resounding 'not sure' on where this change belongs. > I blame my non existent start of the year hangover. > Hope you have recovered! Looking again, I think you were right, move it to that earlier patch. J > > Jonathan > > > _______________________________________________ > linux-arm-kernel mailing list > linux-arm-kernel@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel