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 6B1C6C433ED for ; Mon, 10 May 2021 17:24:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 37F0961264 for ; Mon, 10 May 2021 17:24:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231670AbhEJRZ6 (ORCPT ); Mon, 10 May 2021 13:25:58 -0400 Received: from mail-oo1-f49.google.com ([209.85.161.49]:42809 "EHLO mail-oo1-f49.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232812AbhEJRZz (ORCPT ); Mon, 10 May 2021 13:25:55 -0400 Received: by mail-oo1-f49.google.com with SMTP id w6-20020a4a9d060000b02901f9175244e7so3623255ooj.9; Mon, 10 May 2021 10:24:49 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=9SXuLvWg3KjN+JqmbvmLSLywnYwrjuAJqCkQskXCj0c=; b=aR/9/s78mR5UrX+gr0APivX7j3pL1Yg4d20QWgnXxLge7UpwhKXOHBgPpYJUerhbXP nsDi8ugvHIHftDAzkztdg+ybgqxH40asdbNPZsQOeyw5uba+kZUJVGEHo625bQrhyF7A PseN6L9FxA9ou7G+z9DNDCHiXplUKcmK89LIu81nm2GcxgYze/xwTucB9WyaVy6TX/0k VTHpsRCq2NLpW6zLYW7Duny4NqmiYI3OFWLoddfAMOigAWx/IrzdmqzvytNIQBaZNdr+ fjLuNFNHRGFqC6W2ddz0b0LLrp/OA71gXSrvQ53trwH5PmUD4j37IBji2GxVpJpWydCd rO+w== X-Gm-Message-State: AOAM532P5QhTWjMaPzN74AjsfDuRLiFDP5b7BRShUQ2F98lalIu8d5Md scLZz2duDBHkuogX6yRAD0taNliBn5Z8m+lZxNc= X-Google-Smtp-Source: ABdhPJzwswJbWq9pBS/asjw2XXIwyKlMuYXJI2Y1gk1Yxte0zCZydzcU2dUf5kBLVvZdwuYdtU6sWEV1HxZ0wSIlbUc= X-Received: by 2002:a4a:ab83:: with SMTP id m3mr6209836oon.2.1620667489272; Mon, 10 May 2021 10:24:49 -0700 (PDT) MIME-Version: 1.0 References: <20210426023941.729334-1-sathyanarayanan.kuppuswamy@linux.intel.com> <20210426023941.729334-4-sathyanarayanan.kuppuswamy@linux.intel.com> <97e14cdc-ea98-18b8-0c89-db52440a7716@linux.intel.com> <4fa40e7a-bcb2-db0f-8dc5-28728b14377d@linux.intel.com> <20210510172237.GU4032392@tassilo.jf.intel.com> In-Reply-To: <20210510172237.GU4032392@tassilo.jf.intel.com> From: "Rafael J. Wysocki" Date: Mon, 10 May 2021 19:24:38 +0200 Message-ID: Subject: Re: [PATCH v3 3/3] x86/acpi, x86/boot: Add multiprocessor wake-up support To: Andi Kleen Cc: "Kuppuswamy, Sathyanarayanan" , "Rafael J. Wysocki" , Rafael J Wysocki , Thomas Gleixner , Ingo Molnar , "H . Peter Anvin" , Peter Zijlstra , Len Brown , Robert Moore , Erik Kaneda , ACPI Devel Maling List , "open list:ACPI COMPONENT ARCHITECTURE (ACPICA)" , Linux Kernel Mailing List , "the arch/x86 maintainers" , Sean Christopherson Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-acpi@vger.kernel.org On Mon, May 10, 2021 at 7:22 PM Andi Kleen wrote: > > On Mon, May 10, 2021 at 10:10:24AM -0700, Kuppuswamy, Sathyanarayanan wrote: > > > > > > On 5/10/21 9:55 AM, Rafael J. Wysocki wrote: > > > I'm not sure how my comment regarding the fact that for a given CPU > > > this function is only usable once has been addressed. > > > > > > While it may not be a practical concern in the use case that you are > > > after (TDX), this is a generic mechanism and it needs to cover other > > > possible usage scenarios. > > > > For the same CPU, if we try to use mailbox again, firmware will not > > respond to it. So the command will timeout and return error. > > Right because the firmware code doesn't run anymore. > > The only possibility would be for Linux to put back some code that spins > and waits again, but that would be quite pointless and wasteful. The wakeup function can return an error when it is called for the second time on the same CPU. From mboxrd@z Thu Jan 1 00:00:00 1970 Content-Type: multipart/mixed; boundary="===============0809185804614166360==" MIME-Version: 1.0 From: Rafael J. Wysocki Subject: [Devel] Re: [PATCH v3 3/3] x86/acpi, x86/boot: Add multiprocessor wake-up support Date: Mon, 10 May 2021 19:24:38 +0200 Message-ID: In-Reply-To: 20210510172237.GU4032392@tassilo.jf.intel.com List-ID: To: devel@acpica.org --===============0809185804614166360== Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable On Mon, May 10, 2021 at 7:22 PM Andi Kleen wrote: > > On Mon, May 10, 2021 at 10:10:24AM -0700, Kuppuswamy, Sathyanarayanan wro= te: > > > > > > On 5/10/21 9:55 AM, Rafael J. Wysocki wrote: > > > I'm not sure how my comment regarding the fact that for a given CPU > > > this function is only usable once has been addressed. > > > > > > While it may not be a practical concern in the use case that you are > > > after (TDX), this is a generic mechanism and it needs to cover other > > > possible usage scenarios. > > > > For the same CPU, if we try to use mailbox again, firmware will not > > respond to it. So the command will timeout and return error. > > Right because the firmware code doesn't run anymore. > > The only possibility would be for Linux to put back some code that spins > and waits again, but that would be quite pointless and wasteful. The wakeup function can return an error when it is called for the second time on the same CPU. --===============0809185804614166360==--