From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751139AbdAQUAR (ORCPT ); Tue, 17 Jan 2017 15:00:17 -0500 Received: from Galois.linutronix.de ([146.0.238.70]:46271 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750922AbdAQUAP (ORCPT ); Tue, 17 Jan 2017 15:00:15 -0500 Date: Tue, 17 Jan 2017 20:59:14 +0100 (CET) From: Thomas Gleixner To: Borislav Petkov cc: X86 ML , LKML Subject: Re: [PATCH 01/13] x86/microcode/intel: Drop stashed AP patch pointer optimization In-Reply-To: <20170117173734.14251-2-bp@alien8.de> Message-ID: References: <20170117173734.14251-1-bp@alien8.de> <20170117173734.14251-2-bp@alien8.de> User-Agent: Alpine 2.20 (DEB 67 2015-01-07) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 17 Jan 2017, Borislav Petkov wrote: > From: Borislav Petkov > > This was meant to save us the scanning of the microcode containter in > the initrd since the first AP had already done that but it can also hurt > us: > > Imagine a single hyperthreaded CPU (Intel(R) Atom(TM) CPU N270 for > example) which updates the microcode on the BSP but since the microcode > engine is shared between the two threads, the update on CPU1 doesn't > happen because it has already happened on CPU0 and we don't find a newer > microcode revision. > > Which doesn't set the intel_ucode_patch pointer and at initrd > jettisoning time and we don't save the microcode patch for later > application. > > Now, when we suspend to RAM, the loaded microcode gets cleared so we > need to reload but there's no patch saved in the cache. > > Removing this optimization fixes this issue and all is fine and dandy. > > Signed-off-by: Borislav Petkov So this one needs to go into x86/urgent Reviewed-by: Thomas Gleixner