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 E7ABFC25B08 for ; Wed, 17 Aug 2022 12:11:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239494AbiHQMLO (ORCPT ); Wed, 17 Aug 2022 08:11:14 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57856 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239375AbiHQMLI (ORCPT ); Wed, 17 Aug 2022 08:11:08 -0400 Received: from mail.skyhub.de (mail.skyhub.de [5.9.137.197]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6D6C0883EA for ; Wed, 17 Aug 2022 05:11:01 -0700 (PDT) Received: from zn.tnic (p200300ea971b98b0329c23fffea6a903.dip0.t-ipconnect.de [IPv6:2003:ea:971b:98b0:329c: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 CAC791EC04E4; Wed, 17 Aug 2022 14:10:55 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=alien8.de; s=dkim; t=1660738255; 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=S3cBS4v+Qikhrp7lNpliwl8WSYfYa+IrcHrTLvuTVTA=; b=lJo43ZW6+6qDlyMH1nICaHqZ6i2x6IMB0oQGq00t0matO3FaWY6b+jl7g0rfSKu4jDYwbG 3q5l268bn5Hz0md1OuoxNol4iscPiBaZ+cFSB2WemTiahDuTIq1+G1ibUwKUuZPDuju7eH kx+8jcoRnFKAh0dOGq6Nq01NAYvcS2M= Date: Wed, 17 Aug 2022 14:10:51 +0200 From: Borislav Petkov To: Ashok Raj Cc: Ingo Molnar , Thomas Gleixner , Tony Luck , Dave Hansen , LKML Mailing List , X86-kernel , Andy Lutomirski , Tom Lendacky , Jacon Jun Pan Subject: Re: [PATCH v3 3/5] x86/microcode: Avoid any chance of MCE's during microcode update Message-ID: References: <20220817051127.3323755-1-ashok.raj@intel.com> <20220817051127.3323755-4-ashok.raj@intel.com> 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 Wed, Aug 17, 2022 at 11:57:37AM +0000, Ashok Raj wrote: > You have this reversed. if you get an MCE and MCIP=1 -> shutdown Yeah yeah. > When MCE's happen during the update they are always fatal errors. How did you decide that? Because all CPUs are executing the loop and thus no user process? > What we do here by setting MCIP=1, we promote to a more severe shutdown. It probably should say somewhere that a shutdown is possible. Because if the shutdown really happens, you get a black screen and no info as to why... > Ideally I would rather let the fallout happen since its observable vs a > blind shutdown is what we are promoting to. What fallout do you mean exactly? > Shutdown, shutdown.. There is only 1 MCE no matter how many CPUs you have. Because all CPUs are executing the loop? Or how do you decide this? > Exception is the Local MCE which is recoverable, but only to user space. > > If you get an error in the atomic we are polling, its a fatal error since > SW can't recover and we shutdown. Aha, I think you mean that: the MCE is fatal because if it happens on any CPU, it will be in kernel mode. > Overthinking :-).. If there is concensus, if Boris feels comfortable > enough, i would drop this patch. This is what we're doing right now - thinking about the consensus. And Boris will feel comfortable once we've arrived at a sensible decision. :-) -- Regards/Gruss, Boris. https://people.kernel.org/tglx/notes-about-netiquette