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 6A45EC04FF3 for ; Mon, 24 May 2021 18:21:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 40F7E6140B for ; Mon, 24 May 2021 18:21:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233783AbhEXSWq (ORCPT ); Mon, 24 May 2021 14:22:46 -0400 Received: from mail-ed1-f54.google.com ([209.85.208.54]:42984 "EHLO mail-ed1-f54.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233104AbhEXSWp (ORCPT ); Mon, 24 May 2021 14:22:45 -0400 Received: by mail-ed1-f54.google.com with SMTP id i13so33076194edb.9 for ; Mon, 24 May 2021 11:21:16 -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=QTRAn6sKnTpFLjexpEsWGr3qh3gJ0MoVGcpa7DMK578=; b=I4D8Gsfnj4uJECQ9i5XFtDvT7/xCeOhehqik0+/T+0I8V+9a0vvpxZ8K/Zy7z2phDx JJ6H4XgPQ5rTXrOcxhtIExL5LFtzyjZReUBZl/NGG1mD8Qq82PwfwMI/+11Oj4A+JCvJ VSWXrd8Qwn8DWoLlzTzR3zpY8lI+2a5QlpWZKxCitI+yE/ZbCIHMMrE2L6r5vd3HRevY fmvQIZnxQdipr9opIEIhsWjOFRxrA3BZEUKv5djua32YVa3KxX+dqjBBY4l76atnwt1E suhEplnIKXTkcqOhz2stq3x/p7h30FUz5IsuwmtdnmL91WHGnpW9oKdpn3xyiYUdmF3N XUug== X-Gm-Message-State: AOAM533GGSirB4CzKwxPsI8P5AQAgyAYOn99v4v5Sd8hvU2ZpYuYKsQ8 E74lDAThWe8Yd1UvslwgNJntacEK9Sa/JQ9Io6M= X-Google-Smtp-Source: ABdhPJw6vU4G3l2YTagz5gO4ugX7pzLV5Gtn3cUx+8qVU48cI3vngX63ipQU5FtBGPv1MOo7BIOPXM8KWajyCChKAwg= X-Received: by 2002:a05:6402:5a:: with SMTP id f26mr27248413edu.306.1621880476224; Mon, 24 May 2021 11:21:16 -0700 (PDT) MIME-Version: 1.0 References: <20210523193259.26200-1-chang.seok.bae@intel.com> <20210523193259.26200-22-chang.seok.bae@intel.com> <8c8d91ae-5a3b-9523-725d-134840102df7@kernel.org> <5a645958-10ab-46e7-9650-e5746a8d2276@www.fastmail.com> In-Reply-To: <5a645958-10ab-46e7-9650-e5746a8d2276@www.fastmail.com> From: Len Brown Date: Mon, 24 May 2021 14:21:05 -0400 Message-ID: Subject: Re: [PATCH v5 21/28] x86/fpu/amx: Initialize child's AMX state To: Andy Lutomirski Cc: "Bae, Chang Seok" , Borislav Petkov , Thomas Gleixner , Ingo Molnar , "the arch/x86 maintainers" , "Brown, Len" , Dave Hansen , "Liu, Jing2" , "Shankar, Ravi V" , Linux Kernel Mailing List Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, May 24, 2021 at 2:14 PM Andy Lutomirski wrote: > What does VOLATILE mean in this context? Volatile means caller-saved. Volatile registers can not be used for globals, static, or for parameter passing. ie. By the time the callee is running, they must be assumed to be invalid. This means that any routine, including the target of a system call, such as fork/clone, can't assume that any data exists in these registers. -- Len Brown, Intel Open Source Technology Center