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=-0.7 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED 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 BEF18C432C0 for ; Thu, 21 Nov 2019 22:24:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 902A5206D7 for ; Thu, 21 Nov 2019 22:24:26 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=amacapital-net.20150623.gappssmtp.com header.i=@amacapital-net.20150623.gappssmtp.com header.b="y+Cx4cCN" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726905AbfKUWYZ (ORCPT ); Thu, 21 Nov 2019 17:24:25 -0500 Received: from mail-pj1-f66.google.com ([209.85.216.66]:44258 "EHLO mail-pj1-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726329AbfKUWYZ (ORCPT ); Thu, 21 Nov 2019 17:24:25 -0500 Received: by mail-pj1-f66.google.com with SMTP id w8so2135766pjh.11 for ; Thu, 21 Nov 2019 14:24:24 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amacapital-net.20150623.gappssmtp.com; s=20150623; h=content-transfer-encoding:from:mime-version:subject:date:message-id :references:cc:in-reply-to:to; bh=nuY8UNpMRJXSxqxTXzTq8RcrjbUCVRts4xYxAh2Zw8M=; b=y+Cx4cCNn5xgO0nDXLC0BI4Of9z8MkQpUSru1gRF5QsGlWCznI2XRsSZUDHP6b3RWY 4Ry1i2kE7J9ARo4w0HcYOZGlCj9ZbzYAoUgMyVO+d9RaiW7GfHe5WdNZpiZi2MWs072N j5Pl/NrtgmPWvSAA1nbmcLMyOMMvorF1VuGFWY3p2fdyWndyDBPX7jkq3FxcbNzV9V77 EdAUTLtm+Bm4HTCii3QsypMNNFyuIk0Pt72M4CXBI1vQLuJWLgmUscWdfUgsdkaH4sac AMPTL9uRtmHZCGOt8VJOw2HQb28q3lmotM9TsbQoTXnZlPWO2251HSfoveoEYtSAU7ju P3pw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:content-transfer-encoding:from:mime-version :subject:date:message-id:references:cc:in-reply-to:to; bh=nuY8UNpMRJXSxqxTXzTq8RcrjbUCVRts4xYxAh2Zw8M=; b=X6pn8tMOx3LXcJVsWoGgtsqtVYz4lb5rURKnGl/o9Qo85kxfZI8ppqYYJgFmyWdnlx OMvh9u+sjLH+Z+/3LWS5jGSLUu5ohhKvIcRRD9ODNdowWLF30VIxZ7XKiLGu97tVzwIq CT99Sb7mCW0cFy11+ix3EcK2D/Hpc470xf4uVAwp4Qk4KPqIoht8BmfXYXE3SqF/NNsW UceA1cfVCq2kJQ1CHq02HA7YwXJX7H9XdHPVZzVsjShnmPitx1Lr3XNfIg3pHeV7/ARe 2BSPyfzsBzHUBfvybjeuslRcgzPJS+EscypSS/RIDrIttYHzDbsqYSq8s7fWd4q0guow ATkA== X-Gm-Message-State: APjAAAXUCirqXfsjU8pckbD9hz2OTPo+Uk2VfF3s3LaQiwXpjmWTDc9O Ukcil/H3vayxgo/urS7BAl6vMg== X-Google-Smtp-Source: APXvYqy2Hs5OjH6w1+8YypLA88ewT6R7RiKsDsJdWInAwkbXpI0p+kpgFFuv3caPYxkia4Gs2IarKA== X-Received: by 2002:a17:90a:23c4:: with SMTP id g62mr14626631pje.121.1574375064089; Thu, 21 Nov 2019 14:24:24 -0800 (PST) Received: from ?IPv6:2601:646:c200:1ef2:e8cb:8497:2a8d:1ec8? ([2601:646:c200:1ef2:e8cb:8497:2a8d:1ec8]) by smtp.gmail.com with ESMTPSA id 83sm3506601pfv.157.2019.11.21.14.24.22 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 21 Nov 2019 14:24:22 -0800 (PST) Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable From: Andy Lutomirski Mime-Version: 1.0 (1.0) Subject: Re: [PATCH v10 6/6] x86/split_lock: Enable split lock detection by kernel parameter Date: Thu, 21 Nov 2019 14:24:21 -0800 Message-Id: <159DB397-87E2-435D-9F33-067FF9296ADC@amacapital.net> References: <20191121215126.GA9075@agluck-desk2.amr.corp.intel.com> Cc: Peter Zijlstra , Ingo Molnar , Fenghua Yu , Thomas Gleixner , Ingo Molnar , Borislav Petkov , H Peter Anvin , Ashok Raj , Ravi V Shankar , linux-kernel , x86 In-Reply-To: <20191121215126.GA9075@agluck-desk2.amr.corp.intel.com> To: "Luck, Tony" X-Mailer: iPhone Mail (17A878) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > On Nov 21, 2019, at 1:51 PM, Luck, Tony wrote: >=20 > =EF=BB=BFOn Thu, Nov 21, 2019 at 02:15:22PM +0100, Peter Zijlstra wrote: >> Also, just to remind everyone why we really want this. Split lock is a >> potent, unprivileged, DoS vector. >=20 > So how much do we "really want this"? >=20 > It's been 543 days since the first version of this patch was > posted. We've made exactly zero progress. >=20 > Current cut down patch series is the foundation to move one > small step towards getting this done. >=20 > Almost all of what's in this set will be required in whatever > final solution we want to end up with. Out of this: Why don=E2=80=99t we beat it into shape and apply it, hidden behind BROKEN. T= hen we can work on the rest of the patches and have a way to test them. It would be really, really nice if we could pass this feature through to a V= M. Can we?=