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=-2.4 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 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 6A733C43331 for ; Fri, 6 Sep 2019 17:17:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3CF1A208C3 for ; Fri, 6 Sep 2019 17:17:25 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=alien8.de header.i=@alien8.de header.b="Sq1EshMb" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2406011AbfIFRRY (ORCPT ); Fri, 6 Sep 2019 13:17:24 -0400 Received: from mail.skyhub.de ([5.9.137.197]:35874 "EHLO mail.skyhub.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1733278AbfIFRRX (ORCPT ); Fri, 6 Sep 2019 13:17:23 -0400 Received: from zn.tnic (p200300EC2F0B9E00A12ADCB2AAAA451F.dip0.t-ipconnect.de [IPv6:2003:ec:2f0b:9e00:a12a:dcb2:aaaa:451f]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.skyhub.de (SuperMail on ZX Spectrum 128k) with ESMTPSA id 07C531EC094F; Fri, 6 Sep 2019 19:17:22 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=alien8.de; s=dkim; t=1567790242; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:in-reply-to:in-reply-to: references:references; bh=DrItdgOwfueRiUWCUUuY7oRWF0Gci3i+6hFy85DBwzA=; b=Sq1EshMbCOXHbkKUAcE9HSUjqyLIuuEALX45VjE7MGs3qQ2P+ze6xON+60wK/hAJ0DD4rd msj/qiZfkMs/biLhpYBp0eV/RVgBZb1t1KKDUUMcOrk0QrUAEk8imGAIzz6oTqYT3H/+yb 2UVgFwQw2LR20KzNdO4XGfJGj8AbnFM= Date: Fri, 6 Sep 2019 19:17:20 +0200 From: Borislav Petkov To: Johannes Erdfelt Cc: Thomas Gleixner , "Raj, Ashok" , Boris Ostrovsky , Mihai Carabas , "H. Peter Anvin" , Ingo Molnar , Jon Grimm , kanth.ghatraju@oracle.com, konrad.wilk@oracle.com, patrick.colp@oracle.com, Tom Lendacky , x86-ml , linux-kernel@vger.kernel.org Subject: Re: [PATCH] x86/microcode: Add an option to reload microcode even if revision is unchanged Message-ID: <20190906171720.GM19008@zn.tnic> References: <20190905072029.GB19246@zn.tnic> <20190905194044.GA3663@otc-nc-03> <20190905222706.GA4422@otc-nc-03> <20190906144039.GA29569@sventech.com> <20190906151617.GE19008@zn.tnic> <20190906154618.GB29569@sventech.com> <20190906161735.GH19008@zn.tnic> <20190906165207.GC29569@sventech.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20190906165207.GC29569@sventech.com> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Sep 06, 2019 at 09:52:07AM -0700, Johannes Erdfelt wrote: > That doesn't mean that late loading isn't still useful. If it weren't useful, it would've been gone a long time ago. No one is arguing whether it is useful or not. > Just as I can't know for sure that every future microcode update will be > safely late loadable, you can't know for sure that every future microcode > update won't be safely late loadable. Well, you know what can happen so good luck, I guess. > We do use other techniques as well particularly when it's not time > sensitive. So you reboot or not? Do you do reboot-similar techniques where you can potentially do early microcode loading too? > It very much makes it right because it's still a tool that can be used > safely in the right cases. Just because it can't be used 100% of the time > (even if it is close to that in practice) doesn't make it magically unsafe > either. As I said, good luck with that. It's not like you haven't been warned about what can happen. -- Regards/Gruss, Boris. https://people.kernel.org/tglx/notes-about-netiquette