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=-5.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS 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 185B7C433E6 for ; Wed, 17 Mar 2021 10:14:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B864464F26 for ; Wed, 17 Mar 2021 10:14:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229710AbhCQKNk (ORCPT ); Wed, 17 Mar 2021 06:13:40 -0400 Received: from casper.infradead.org ([90.155.50.34]:57108 "EHLO casper.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229686AbhCQKNi (ORCPT ); Wed, 17 Mar 2021 06:13:38 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=ldg8P+ntHqhW13UFSCgwfQWUuj8y81ZkwHhfEwqZwlg=; b=KoqbwD6jrkk+2HGJvS+4wSDpbv 974mecgUwOBbcvj0ogNZ0lXo6sRy0WTSl7wIMMo2/1q0mnDsjG7hT4vl9S6U7/yBfolgRTVU/BC/v Le1BIEjmOcDIikwNREiHbnlv6lNXkNZwrMfCMu9cLcgaM2f2iDKdHyvrTUGxndB2+A9R/yAg3nMQC 0lqCSjICMctUioZxKQ0lvFOtlTLYP2/tcXE/zfNzYZS+P/0w1SCPDhQn6PxMNLvchgeQPAIiaeGyJ XpRqyD9wzyO3zFip+smRmOzVM2Gh4xOxlG1JOiGHkYUIv5pbTp3EknPIPegtfuO3ZgVAuXJROp9Mn VKrzn1hA==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.94 #2 (Red Hat Linux)) id 1lMTAs-001MYH-9x; Wed, 17 Mar 2021 10:13:11 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 3AE4E3006E0; Wed, 17 Mar 2021 11:13:09 +0100 (CET) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 23AE82C3C233E; Wed, 17 Mar 2021 11:13:09 +0100 (CET) Date: Wed, 17 Mar 2021 11:13:09 +0100 From: Peter Zijlstra To: Ingo Molnar Cc: Kim Phillips , Jiri Olsa , Borislav Petkov , Tom Lendacky , x86@kernel.org, lkml , Alexander Shishkin , Arnaldo Carvalho de Melo , Stanislav Kozina , Michael Petlan , Pierre Amadio , onatalen@redhat.com, darcari@redhat.com, "Rafael J. Wysocki" Subject: Re: unknown NMI on AMD Rome Message-ID: References: <36397980-f897-147f-df55-f37805d869c9@amd.com> <20210317084829.GA474581@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210317084829.GA474581@gmail.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Mar 17, 2021 at 09:48:29AM +0100, Ingo Molnar wrote: > > https://developer.amd.com/wp-content/resources/56323-PUB_0.78.pdf > > So: > > > 1215 IBS (Instruction Based Sampling) Counter Valid Value > May be Incorrect After Exit From Core C6 (CC6) State > > Description > > If a core's IBS feature is enabled and configured to generate an interrupt, including NMI (Non-Maskable > Interrupt), and the IBS counter overflows during the entry into the Core C6 (CC6) state, the interrupt may be > issued, but an invalid value of the valid bit may be restored when the core exits CC6. > Potential Effect on System > > The operating system may receive interrupts due to an IBS counter event, including NMI, and not observe an > valid IBS register. Console messages indicating "NMI received for unknown reason" have been observed on > Linux systems. > > Suggested Workaround: None > Fix Planned: No fix planned Should be simple enough to disable CC6 while IBS is in use. Kim, can you please make that happen?