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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 12E29C433F5 for ; Fri, 27 May 2022 10:58:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1351097AbiE0K6c (ORCPT ); Fri, 27 May 2022 06:58:32 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57548 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1350706AbiE0K63 (ORCPT ); Fri, 27 May 2022 06:58:29 -0400 Received: from mail.skyhub.de (mail.skyhub.de [IPv6:2a01:4f8:190:11c2::b:1457]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CB1561271AD for ; Fri, 27 May 2022 03:58:27 -0700 (PDT) Received: from zn.tnic (p200300ea97465727329c23fffea6a903.dip0.t-ipconnect.de [IPv6:2003:ea:9746:5727:329c:23ff:fea6:a903]) (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 C30A31EC064E; Fri, 27 May 2022 12:58:21 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=alien8.de; s=dkim; t=1653649101; 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=qz4XrAcGGPsXYTIjWabEhNGNxbXciy2M07T6g7TPC7g=; b=i6+zzAkp4x2ZjS/trI7lM10v7YizyV220MfBnr/gKNkRXWPHCnIZoydApIqbQklQOQEb/+ B1b1KhoVwcDZBEu0rysOQNEhrLGSisjRMTJOVLUhBA8yDDAnH1wMWdv4moYSt1A8dYpT6X qERv21abMTGxeyqqM4N30kK/ZkjjQpU= Date: Fri, 27 May 2022 12:58:18 +0200 From: Borislav Petkov To: Ingo Molnar Cc: X86 ML , LKML , Peter Zijlstra , Andrew Cooper Subject: Re: [RFC PATCH 2/3] x86/microcode: Default-disable late loading Message-ID: References: <20220524185324.28395-1-bp@alien8.de> <20220524185324.28395-3-bp@alien8.de> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, May 27, 2022 at 12:37:24PM +0200, Ingo Molnar wrote: > Might make sense to outline here valid circumstances under which late > loading is used? Such as some weird kernel package that doesn't have the > latest firmware included in the initrd? Well, considering how we do correctness first, functionality later, I'd really really like to not do late loading at all. I wasn't aware of this sequence Cooper gave me on IRC but consider what happens where one thread is doing the microcode uploading and the other gets an NMI! Our "precious" dance we have right now is not protected against that scenario so *actually*, if we have to do the right thing, we should not do late loading at all and zap it. > Because it's hard (for me) to see any valid circumstance under which late > loading should be supported at all TBH: new kernels where this patch is > active would come with a modern package. > > Ie. we should consider removing late loading altogether. Yap, exactly. Late loading is actually broken as it is right now, IMNSVHO. Thx. -- Regards/Gruss, Boris. https://people.kernel.org/tglx/notes-about-netiquette