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 C4903C54EBD for ; Mon, 9 Jan 2023 10:28:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229890AbjAIK2o (ORCPT ); Mon, 9 Jan 2023 05:28:44 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48538 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235213AbjAIK21 (ORCPT ); Mon, 9 Jan 2023 05:28:27 -0500 Received: from mail-wm1-x329.google.com (mail-wm1-x329.google.com [IPv6:2a00:1450:4864:20::329]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 853381A0; Mon, 9 Jan 2023 02:28:26 -0800 (PST) Received: by mail-wm1-x329.google.com with SMTP id ja17so5899632wmb.3; Mon, 09 Jan 2023 02:28:26 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:sender:from:to:cc:subject:date:message-id :reply-to; bh=BEhA0ngAfEFL1HJCgzpGpDyeaM2Lphh/z9kK4dnHP7E=; b=PC77vZC8SH1jVuTyvKejeVCBeYiSmIaSBH+od2qXT+oTfp7mJ8T4esklJl+LO4UOq9 FqrV/NmbT7m/mD8sQHPG3xuRdxwxsW6++tTsyLiXC+ZN3Emk+eWZDjyBaXk6xEWltO7M 5PUTUQq5xj/NK6djO+vCJo8YdIY+/UutNostML71eye4hFygNBvX5q5iUfWNtb3PaiyG siPkvpT5n2nlNWYJInsqBW2mYIHmUl46ZUjeZBFRX8oA9qnw32qQh6RLSQlI6Sr7kc4s rNh0Gmpxl396kTo3K25+Ft1sU5OQNz5aVuLjaW2AoKhW2RwbmRwlcuwzCPHsCtO5IiAU Nq5A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:sender:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=BEhA0ngAfEFL1HJCgzpGpDyeaM2Lphh/z9kK4dnHP7E=; b=wVAGQoIW/h71hnz/u7v14EOOh8EUdEkJ6V7w72OUB3xSRWZ8lIfvpvHIsDbeX/Rfsy Y7r8SkpyrAW9BekPKErLQebvNcdBDWvy/z1heGaL5awtXfsWmC5IeCO3bhqGUv6nwdks byb3XdknTEhdRDYrJmDevA7/OpY5qRpixGrK5a3TV71WJ0uoypBd+Ecg8bjI7H3D2mpw 8KaDDr9LCcseeTJEng1iXa3516TF6KKVYVU1H72o/mAdtlHyf+MNyqWkE9R9K0JIowRB 8lFFHx/QMEzrTvjs+BGH58uPitiwuBkfpOdjsLSmqqcBJUtViORayNw9p27srajMf2OU XRUA== X-Gm-Message-State: AFqh2kr5Tq40vDj5MdZ6t3gw2HZaTgYt5uF2froBDtbztn5hrm/RU1gD O8RSNTnl//CkkiEfPvPgrMc= X-Google-Smtp-Source: AMrXdXtqX16sE+ajBjQhiLCE6WXu/5ampSI6HvxUNMjvp9KQRjeS9q9bqKmDIDhXPy7JHiM9pQ1hrw== X-Received: by 2002:a05:600c:4f11:b0:3d9:ee01:ae5b with SMTP id l17-20020a05600c4f1100b003d9ee01ae5bmr2798840wmq.12.1673260105081; Mon, 09 Jan 2023 02:28:25 -0800 (PST) Received: from gmail.com (1F2EF719.nat.pool.telekom.hu. [31.46.247.25]) by smtp.gmail.com with ESMTPSA id n14-20020a05600c3b8e00b003b49bd61b19sm17237133wms.15.2023.01.09.02.28.23 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 09 Jan 2023 02:28:24 -0800 (PST) Sender: Ingo Molnar Date: Mon, 9 Jan 2023 11:28:19 +0100 From: Ingo Molnar To: Randy Dunlap Cc: linux-kernel@vger.kernel.org, Thomas Gleixner , Borislav Petkov , Ingo Molnar , Dave Hansen , x86@kernel.org, Jonathan Corbet , linux-doc@vger.kernel.org Subject: Re: [PATCH] x86/retbleed: add "stuff" mode admin documentation Message-ID: References: <20230108213700.5703-1-rdunlap@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230108213700.5703-1-rdunlap@infradead.org> Precedence: bulk List-ID: X-Mailing-List: linux-doc@vger.kernel.org * Randy Dunlap wrote: > Add admin documentation for "retbleed=stuff", based on commit > description and source code. > > Fixes: d82a0345cf21 ("x86/retbleed: Add call depth tracking mitigation") > Signed-off-by: Randy Dunlap > Cc: Thomas Gleixner > Cc: Borislav Petkov > Cc: Ingo Molnar > Cc: Dave Hansen > Cc: x86@kernel.org > Cc: Jonathan Corbet > Cc: linux-doc@vger.kernel.org > --- > Documentation/admin-guide/kernel-parameters.txt | 8 ++++++++ > 1 file changed, 8 insertions(+) > > diff -- a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt > --- a/Documentation/admin-guide/kernel-parameters.txt > +++ b/Documentation/admin-guide/kernel-parameters.txt > @@ -5364,6 +5364,14 @@ > when STIBP is not available. This is > the alternative for systems which do not > have STIBP. > + stuff - Enables "stuffing" mode mitigation, > + which uses return thunking and call depth > + tracking. Only if effect if > + CONFIG_CALL_DEPTH_TRACKING is set and > + Spectre V2 mitigation mode is > + "retpoline". > + IBRS is fully secure mitigation but is > + more costly (slower) than stuffing. Typo: s/only if effect if /only in effect if Other than that: Acked-by: Ingo Molnar Thanks, Ingo