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 C080EC432BE for ; Tue, 31 Aug 2021 22:44:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A58A860FF2 for ; Tue, 31 Aug 2021 22:44:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240331AbhHaWph (ORCPT ); Tue, 31 Aug 2021 18:45:37 -0400 Received: from mail-ej1-f44.google.com ([209.85.218.44]:38730 "EHLO mail-ej1-f44.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229602AbhHaWpg (ORCPT ); Tue, 31 Aug 2021 18:45:36 -0400 Received: by mail-ej1-f44.google.com with SMTP id n27so2331494eja.5 for ; Tue, 31 Aug 2021 15:44:39 -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=qSp4z9/S/GmJmZB+68ZXewALFEkWTtL9H0IgTSE7BNw=; b=GKhG0+1+VRIOLmQ0if/rasXZmAPpfj+m9/zhs1Y0fLaKhxpBwrQ8yXrAHhO0LFM0cH CuA8ll8aGHT04bf8hhrJZBgWn5iwyl9yMjoLfStx+4Df0+aTkYAAmVkQvGMvznlGObzU aTplA2mtp4wJCCjo4vo7PUF/of4EYbaYu7Ee9JOlZxF7MQB1yyBEKhGacW16qP0iuVAc wkT213Yo1JwM9M2AfxFGoE6RdfgxSuPFQb0s3qZMo0zDlD9ouDIaOV+HQ1Y72wTCCH4+ lbosHiWBwGJV1Z6wdyaPXhcSuddliLo6KYlnqK0sdtfufOJhvZKwzh97bF+INjX8IjVX VRmg== X-Gm-Message-State: AOAM533av+BZ+dH6wHQR9ZuWF5MtHsuk8Y6UBTFF60C5r1NipAfREik7 S4KNFJzo657SjfOhlX/QYeG/UB+BFUTxqJq1Csk= X-Google-Smtp-Source: ABdhPJyN8v48bt7PC2J0FDeKIZcBbMhlgZYHhrj2dOl2GEIDlo5sNdc+BMmTiXQvAxch/pBc3C8qtksti+9h5KCUjNU= X-Received: by 2002:a17:906:988a:: with SMTP id zc10mr34003082ejb.256.1630449879396; Tue, 31 Aug 2021 15:44:39 -0700 (PDT) MIME-Version: 1.0 References: <20210730145957.7927-1-chang.seok.bae@intel.com> <2020841.9MqWvG71rC@tjmaciei-mobl5> In-Reply-To: <2020841.9MqWvG71rC@tjmaciei-mobl5> From: Len Brown Date: Tue, 31 Aug 2021 18:44:28 -0400 Message-ID: Subject: Re: [PATCH v9 12/26] x86/fpu/xstate: Use feature disable (XFD) to protect dynamic user state To: Thiago Macieira Cc: Dave Hansen , Borislav Petkov , "Chang S. Bae" , Andy Lutomirski , Thomas Gleixner , Ingo Molnar , X86 ML , "Brown, Len" , "Liu, Jing2" , "Ravi V. Shankar" , Linux Kernel Mailing List Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Aug 31, 2021 at 6:39 PM Thiago Macieira wrote: > > On Tuesday, 31 August 2021 15:15:55 PDT Len Brown wrote: > > Indeed, I believe that there is universal agreement that a synchronous > > return code > > from a system call is a far superior programming model than decoding > > the location of a failure in a system call. (no, the IP isn't random -- it > > is always the 1st instruction in that thread to touch a TMM register). > > That instruction is actually likely going to be a memory load, probably an > LDTILECFG. There is no fault on LDTILECONFIG, it will occur on the load tile data. But yes, still a memory load (with a TMM destination) Len Brown, Intel Open Source Technology Center