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 69000C433EF for ; Fri, 24 Jun 2022 18:58:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231545AbiFXS6e (ORCPT ); Fri, 24 Jun 2022 14:58:34 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55362 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231690AbiFXS6b (ORCPT ); Fri, 24 Jun 2022 14:58:31 -0400 Received: from mga04.intel.com (mga04.intel.com [192.55.52.120]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9F7AB2656; Fri, 24 Jun 2022 11:57:57 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1656097084; x=1687633084; h=message-id:date:mime-version:subject:to:cc:references: from:in-reply-to:content-transfer-encoding; bh=XBbME1oeuKj97S6OdL7ubRRQgcB84W95SpJxy8wliwc=; b=TiStzioEB/eB1+jGTOshxx1N55DM0wOO8Bkv3eu3bRJ/PNGTkUS/5DGh MXIk0bHAJ5bDQ518qpZDx/V6FRoEQ0K6E4TzNvX1PY8TPoEK4dXP7kmiH 6HXNgft+uow3V8y/FOakM/FQOA5uz4jjhyxGBsWau7gBOEzEuetuacFJh tT/kuGsoLGqmfXnnDPUtrvdFNMRp+tWt8FGhe66AGOIsgXtE4Yb7OQPnZ IyNFxt00aUexBSgIlJEeuNjPvl0yANJWuvJfvqAH2QJzfYUye9Sf8eNgJ Lq4zOORcmWJTwxrlHkN2+xLeFOukrBbq2Cri3AARccKNuZl1CqHFji4aM w==; X-IronPort-AV: E=McAfee;i="6400,9594,10388"; a="279830715" X-IronPort-AV: E=Sophos;i="5.92,220,1650956400"; d="scan'208";a="279830715" Received: from fmsmga001.fm.intel.com ([10.253.24.23]) by fmsmga104.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 24 Jun 2022 11:57:57 -0700 X-IronPort-AV: E=Sophos;i="5.92,220,1650956400"; d="scan'208";a="731431403" Received: from mdedeogl-mobl.amr.corp.intel.com (HELO [10.209.126.186]) ([10.209.126.186]) by fmsmga001-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 24 Jun 2022 11:57:55 -0700 Message-ID: <43a67bfe-9707-33e0-2574-1e6eca6aa24b@intel.com> Date: Fri, 24 Jun 2022 11:57:20 -0700 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.9.1 Subject: Re: [PATCH v5 02/22] cc_platform: Add new attribute to prevent ACPI CPU hotplug Content-Language: en-US To: Kai Huang , linux-kernel@vger.kernel.org, kvm@vger.kernel.org Cc: linux-acpi@vger.kernel.org, seanjc@google.com, pbonzini@redhat.com, len.brown@intel.com, tony.luck@intel.com, rafael.j.wysocki@intel.com, reinette.chatre@intel.com, dan.j.williams@intel.com, peterz@infradead.org, ak@linux.intel.com, kirill.shutemov@linux.intel.com, sathyanarayanan.kuppuswamy@linux.intel.com, isaku.yamahata@intel.com, thomas.lendacky@amd.com, Tianyu.Lan@microsoft.com, rdunlap@infradead.org, Jason@zx2c4.com, juri.lelli@redhat.com, mark.rutland@arm.com, frederic@kernel.org, yuehaibing@huawei.com, dongli.zhang@oracle.com References: From: Dave Hansen In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On 6/22/22 04:15, Kai Huang wrote: > Platforms with confidential computing technology may not support ACPI > CPU hotplug when such technology is enabled by the BIOS. Examples > include Intel platforms which support Intel Trust Domain Extensions > (TDX). > > If the kernel ever receives ACPI CPU hotplug event, it is likely a BIOS > bug. For ACPI CPU hot-add, the kernel should speak out this is a BIOS > bug and reject the new CPU. For hot-removal, for simplicity just assume > the kernel cannot continue to work normally, and BUG(). So, the kernel is now declaring ACPI CPU hotplug and TDX to be incompatible and even BUG()'ing if we see them together. Has anyone told the firmware guys about this? Is this in a spec somewhere? When the kernel goes boom, are the firmware folks going to cry "Kernel bug!!"? This doesn't seem like something the kernel should be doing unilaterally.