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[209.132.180.67]) by mx.google.com with ESMTP id r79si14225575pfb.126.2018.03.07.10.25.35; Wed, 07 Mar 2018 10:25:49 -0800 (PST) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; dkim=pass header.i=@linaro.org header.s=google header.b=jI00VsbE; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=linaro.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754672AbeCGSYP (ORCPT + 99 others); Wed, 7 Mar 2018 13:24:15 -0500 Received: from mail-io0-f195.google.com ([209.85.223.195]:35590 "EHLO mail-io0-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932759AbeCGSYL (ORCPT ); Wed, 7 Mar 2018 13:24:11 -0500 Received: by mail-io0-f195.google.com with SMTP id 30so4091311iog.2 for ; Wed, 07 Mar 2018 10:24:10 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=mime-version:in-reply-to:references:from:date:message-id:subject:to :cc; bh=0UGdShqpV/9RCb3lzGxqVE4DvhpFaxTfo211it5EX2A=; b=jI00VsbEtWLtvFCkszQf0v4IwazVlIsJvdyQBjngshpLMz76zN91IKd6+yMcXjfLT8 b93gIEHzLuoMhH/mjTdoLcgB4b5aZvOgYGDIt2A6JDPbqD6TwYqL1t9a5/lPd6qG8aiS uVzxxNoD2l2BynvffbwEqPBm08emDm7yDH55g= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:in-reply-to:references:from:date :message-id:subject:to:cc; bh=0UGdShqpV/9RCb3lzGxqVE4DvhpFaxTfo211it5EX2A=; b=ibwh6ARIuNAbhTbTDju+feTYNenN3+BExkGLp396zgNdu68rKJPTLDrjWSy2FbEVgr 9+uCtZtTyUv2h1QQxG22F4EZ9peUAzuWSJmxPHRKZU0Kn7FI5BbNEfETiBBJDLnmgS8N SFvHLpccWd9nDZaeMpjATJd4CNDMmJgd6t1dPAjYqF43AJuurn0vhBTa2npj9wZl44J1 zdYxgyLkmQInD7JINhKgLWLQ08FjLRtP7X1l1q2ULT/eAPyoBfwf2E78FbsbBYZFzsMQ qvuR10wIhoYpjwAPzspJ1cSuKXppRWjhpWIHlk+oxhsWNV+niQieFWBEvPphP+8B5dHi he9g== X-Gm-Message-State: AElRT7EwB8auv2S15jHu5/D0pvU2CWlxRo+Uvert6y0cYqqPgTgqXhHk 23YbdRwBQ5CBQWyWml028EJFe4s2755zbDY9wH9WHQ== X-Received: by 10.107.213.72 with SMTP id x8mr23501021ioc.60.1520447050278; Wed, 07 Mar 2018 10:24:10 -0800 (PST) MIME-Version: 1.0 Received: by 10.107.138.209 with HTTP; Wed, 7 Mar 2018 10:24:09 -0800 (PST) In-Reply-To: <20180302165415.GB8704@kroah.com> References: <1519790211-16582-1-git-send-email-alex.shi@linaro.org> <20180301152450.GA4061@kroah.com> <5cf40379-9098-da02-a471-8abd7d8f0be8@linaro.org> <20180302165415.GB8704@kroah.com> From: Ard Biesheuvel Date: Wed, 7 Mar 2018 18:24:09 +0000 Message-ID: Subject: Re: [PATCH 0/29] arm meltdown fix backporting review for lts 4.9 To: Greg KH Cc: Alex Shi , Marc Zyngier , Will Deacon , Catalin Marinas , stable@vger.kernel.org, linux-arm-kernel , Linux Kernel Mailing List Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2 March 2018 at 16:54, Greg KH wrote: > On Fri, Mar 02, 2018 at 05:14:50PM +0800, Alex Shi wrote: >> >> >> On 03/01/2018 11:24 PM, Greg KH wrote: >> > On Wed, Feb 28, 2018 at 11:56:22AM +0800, Alex Shi wrote: >> >> Hi All, >> >> >> >> This backport patchset fixed the meltdown issue, it's original branch: >> >> https://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git/log/?h=kpti >> >> A few dependency or fixingpatches are also picked up, if they are necessary >> >> and no functional changes. >> >> >> >> The patchset also on repository: >> >> git://git.linaro.org/kernel/linux-linaro-stable.git lts-4.9-spectrevv2 >> >> >> >> No bug found yet from kernelci.org and lkft testing. >> > >> > No bugs is good, but does it actually fix the meltdown problem? What >> > did you test it on? >> >> Oh, I have no A73/A75 cpu, so I can not reproduce meltdown bug. > > Then why should I trust this backport at all? > > Please test on the hardware that is affected, otherwise you do not know > if your patches do anything or not. > I don't think it is feasible to test these backports by confirming that they make the fundamental issue go away. We simply don't have the code to reproduce all the variants, and we have to rely on the information provided by ARM Ltd. regarding which cores are affected and which aren't. What we can do (and what I did for the v4.14 backport) is ensure that the mitigations take effect when they are expected to, i.e., confirm that the trampoline vector table and page tables are being used (which can be done using the exploit code for variant 3a btw), and to check that the branch predictor maintenance code is called as expected. For variant 1, we just have to have faith ... Note that I haven't done so for *this* backport, and I currently don't have any time to spend on this.