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[209.132.180.67]) by mx.google.com with ESMTP id u190si1428112pgc.432.2018.01.25.02.55.05; Thu, 25 Jan 2018 02:55:18 -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; 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 Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751562AbeAYKyb (ORCPT + 99 others); Thu, 25 Jan 2018 05:54:31 -0500 Received: from Galois.linutronix.de ([146.0.238.70]:34740 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751173AbeAYKy3 (ORCPT ); Thu, 25 Jan 2018 05:54:29 -0500 Received: from hsi-kbw-5-158-153-52.hsi19.kabel-badenwuerttemberg.de ([5.158.153.52] helo=nanos) by Galois.linutronix.de with esmtpsa (TLS1.2:DHE_RSA_AES_256_CBC_SHA256:256) (Exim 4.80) (envelope-from ) id 1eef87-0000YY-To; Thu, 25 Jan 2018 11:51:40 +0100 Date: Thu, 25 Jan 2018 11:54:20 +0100 (CET) From: Thomas Gleixner To: David Woodhouse cc: arjan@linux.intel.com, karahmed@amazon.de, x86@kernel.org, linux-kernel@vger.kernel.org, tim.c.chen@linux.intel.com, bp@alien8.de, peterz@infradead.org, pbonzini@redhat.com, ak@linux.intel.com, torvalds@linux-foundation.org, gregkh@linux-foundation.org, dave.hansen@intel.com, gnomes@lxorguk.ukuu.org.uk, ashok.raj@intel.com, mingo@kernel.org Subject: Re: [PATCH v4 6/7] x86/cpufeature: Blacklist SPEC_CTRL on early Spectre v2 microcodes In-Reply-To: <1516876994.30244.51.camel@infradead.org> Message-ID: References: <1516872189-16577-1-git-send-email-dwmw@amazon.co.uk> <1516872189-16577-7-git-send-email-dwmw@amazon.co.uk> <1516876994.30244.51.camel@infradead.org> User-Agent: Alpine 2.20 (DEB 67 2015-01-07) MIME-Version: 1.0 Content-Type: multipart/mixed; BOUNDARY="8323329-1455264887-1516877661=:2020" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This message is in MIME format. The first part should be readable text, while the remaining parts are likely unreadable without MIME-aware tools. --8323329-1455264887-1516877661=:2020 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT On Thu, 25 Jan 2018, David Woodhouse wrote: > On Thu, 2018-01-25 at 09:23 +0000, David Woodhouse wrote: > > > > +/* > > + * Early microcode releases for the Spectre v2 mitigation were broken. > > + * Information taken from; > > + * • https://newsroom.intel.com/wp-content/uploads/sites/11/2018/01/microcode-update-guidance.pdf > > Oh look, Intel have released a *third* version of that document > already, and they've bumped the bad Kabylake versions to 0x84, although > they're *still* missing out the KBL 906EA SKU which was updated to 0x80 > in the public 20180108 microcode release. I'll bump them all in my tree > to 0x84. > > Thomas, want another copy in email now, or were we waiting for another > round of these before you merge them anyway? Looking at this mess makes me even less convinced that a blacklist is a good idea. We have already at least 3 different variants of blacklists. So I rather see a whitelist approach which says: if (ucode_version < known_good(family, model)) return; I know it would require that Intel releases a set of known good ucodes at some point in the future, but that's a reasonable request. I rather take a few patches which add the cutoff for family/model (and NO, I don't want to add stepping into the mix at all) than having this blacklist mess which keeps changing every other day. Thanks, tglx --8323329-1455264887-1516877661=:2020--