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 9DED4C34026 for ; Tue, 18 Feb 2020 20:09:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6687B22B48 for ; Tue, 18 Feb 2020 20:09:04 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=alien8.de header.i=@alien8.de header.b="FyTZYuiD" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728265AbgBRUJD (ORCPT ); Tue, 18 Feb 2020 15:09:03 -0500 Received: from mail.skyhub.de ([5.9.137.197]:56696 "EHLO mail.skyhub.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726729AbgBRUJB (ORCPT ); Tue, 18 Feb 2020 15:09:01 -0500 Received: from zn.tnic (p200300EC2F0C1F00DCB96C3517B36067.dip0.t-ipconnect.de [IPv6:2003:ec:2f0c:1f00:dcb9:6c35:17b3:6067]) (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 B54D41EC0C1A; Tue, 18 Feb 2020 21:08:59 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=alien8.de; s=dkim; t=1582056539; 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=jmx0+z5jUn1UpZBqLi7uGXjByEV5/Ttc9P/ABLwrAZM=; b=FyTZYuiDS+cpITcqPx08jBvNoaFPPFytcGfkneBv1JenackcGRNG4pz9x0VbXJc0lsPVU2 zRZzcgf9XMiZ2F8jtGhV8XwpWUhCBWAl/a5XF5JgG1T96yEZKVR6ELdlwHW12A3VF+wTNc iCKVlddjRiyTnZkxeqZd3x/46DXUJqQ= Date: Tue, 18 Feb 2020 21:09:00 +0100 From: Borislav Petkov To: Peter Zijlstra Cc: "Luck, Tony" , Steven Rostedt , Andy Lutomirski , x86-ml , lkml Subject: Re: [RFC] #MC mess Message-ID: <20200218200900.GS14449@zn.tnic> References: <20200218173150.GK14449@zn.tnic> <3908561D78D1C84285E8C5FCA982C28F7F57B937@ORSMSX115.amr.corp.intel.com> <20200218200200.GE11457@worktop.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20200218200200.GE11457@worktop.programming.kicks-ass.net> 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 Tue, Feb 18, 2020 at 09:02:00PM +0100, Peter Zijlstra wrote: > Then please rewrite the #MC entry code to deal with nested exceptions > unmasking the MCE, very similr to NMI. > > The moment you allow tracing, jump_labels or anything else you can > expect #PF, #BP and probably #DB while inside #MC, those will then IRET > and re-enable the #MC. Yeah, I'd like to keep it simple and reenable all the crap we disabled only on exit from the handler. Dunno if we care about losing tracing samples when an MCE happened... > The current situation is completely and utterly buggered. Lovely. ;-( -- Regards/Gruss, Boris. https://people.kernel.org/tglx/notes-about-netiquette