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=-5.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 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 05ABEC433B4 for ; Fri, 23 Apr 2021 17:58:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id CD85461458 for ; Fri, 23 Apr 2021 17:58:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S243449AbhDWR7S (ORCPT ); Fri, 23 Apr 2021 13:59:18 -0400 Received: from mga18.intel.com ([134.134.136.126]:3919 "EHLO mga18.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S243414AbhDWR7Q (ORCPT ); Fri, 23 Apr 2021 13:59:16 -0400 IronPort-SDR: NBlRA/JQ+kUDWCx3ljh4tEaz7WBu1MP/rB+pnv9hP23KSpax/4krUkAT+WpUKwcNt4NKQHmnPk 485k6Pk01+rA== X-IronPort-AV: E=McAfee;i="6200,9189,9963"; a="183588844" X-IronPort-AV: E=Sophos;i="5.82,246,1613462400"; d="scan'208";a="183588844" Received: from fmsmga002.fm.intel.com ([10.253.24.26]) by orsmga106.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 23 Apr 2021 10:58:37 -0700 IronPort-SDR: 1QueziNWla9gBTeipZoFde/DyjkitLQ9uxKZA9iB9OrcnFPty8Z46XsXyE2klSgpO773fMBbuF Vrt0+mWp4owA== X-IronPort-AV: E=Sophos;i="5.82,246,1613462400"; d="scan'208";a="456307503" Received: from aberdasc-mobl.amr.corp.intel.com (HELO skuppusw-mobl5.amr.corp.intel.com) ([10.254.2.101]) by fmsmga002-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 23 Apr 2021 10:58:36 -0700 Subject: Re: [PATCH v2 3/3] x86/acpi, x86/boot: Add multiprocessor wake-up support To: "Rafael J. Wysocki" Cc: Rafael J Wysocki , Thomas Gleixner , Ingo Molnar , "H . Peter Anvin" , Peter Zijlstra , Len Brown , Robert Moore , Erik Kaneda , ACPI Devel Maling List , Linux Kernel Mailing List , Sean Christopherson , Andi Kleen , the arch/x86 maintainers References: <20210422214708.716164-1-sathyanarayanan.kuppuswamy@linux.intel.com> <20210422214708.716164-4-sathyanarayanan.kuppuswamy@linux.intel.com> From: "Kuppuswamy, Sathyanarayanan" Message-ID: <789781a4-026b-f023-6192-5a0099fd88fd@linux.intel.com> Date: Fri, 23 Apr 2021 10:58:33 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 4/23/21 6:05 AM, Rafael J. Wysocki wrote: > Although I've looked at this patch already, I now realize that > according to the spec the mailbox is only suitable for the first AP > wakeup during system initialization. > > Shouldn't the original handler be restored then to handle subsequent wakeups? For TDX use case, since it does not support CPU hotplug/offline features, once the AP is turned on, it will never be off-lined and hence need not support subsequent wakeups. AFAIK, this MADT wake table is mainly defined for TDX use case. Please also check the TDX GHCI spec, sec 4.1. For each TD-guest, application processor, the mailbox can be used once for the wakeup command. After the guest-application processor takes the action according to the command, the intention is the mailbox will no longer be checked by the guest-application processor. Other guest processors can continue using the mailbox for the next command. -- Sathyanarayanan Kuppuswamy Linux Kernel Developer