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 DE8CDC433E0 for ; Thu, 14 May 2020 14:16:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B855E20671 for ; Thu, 14 May 2020 14:16:25 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=alien8.de header.i=@alien8.de header.b="B/sOjEXB" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726492AbgENOQZ (ORCPT ); Thu, 14 May 2020 10:16:25 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33338 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726050AbgENOQY (ORCPT ); Thu, 14 May 2020 10:16:24 -0400 Received: from mail.skyhub.de (mail.skyhub.de [IPv6:2a01:4f8:190:11c2::b:1457]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5D826C061A0C for ; Thu, 14 May 2020 07:16:24 -0700 (PDT) Received: from zn.tnic (p200300EC2F0BBD00DC45039F589BC722.dip0.t-ipconnect.de [IPv6:2003:ec:2f0b:bd00:dc45:39f:589b:c722]) (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 C712A1EC015C; Thu, 14 May 2020 16:16:20 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=alien8.de; s=dkim; t=1589465780; 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=j3imiznRcTcesSved9eAcuXC+pa5ngT+M54jGjyJhLM=; b=B/sOjEXBhpV8YUWlTypNzQpxGaJEb+QBrJu20oiBM46w2rubcez3+gujWhltnAg1yO1hJH 6ejjyRDTpkAijOAKrYplYMaETfO8SM7zo2tHNEsK4YAdaZE1PvsxDjeK7J7c/NKpDmn/X+ no9h/n9PzV0+H3MuI9UoTo6uqEcD+PA= Date: Thu, 14 May 2020 16:16:16 +0200 From: Borislav Petkov To: Andy Lutomirski Cc: Thomas Gleixner , LKML , X86 ML , "Paul E. McKenney" , Alexandre Chartre , Frederic Weisbecker , Paolo Bonzini , Sean Christopherson , Masami Hiramatsu , Petr Mladek , Steven Rostedt , Joel Fernandes , Boris Ostrovsky , Juergen Gross , Brian Gerst , Mathieu Desnoyers , Josh Poimboeuf , Will Deacon , "Peter Zijlstra (Intel)" Subject: Re: [patch V4 part 1 29/36] x86/mce: Send #MC singal from task work Message-ID: <20200514141616.GC9266@zn.tnic> References: <20200505131602.633487962@linutronix.de> <20200505134100.957390899@linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: 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 Thu, May 07, 2020 at 11:02:09AM -0700, Andy Lutomirski wrote: > IOW, if we want to recover from CPL0 #MC, we will need a different mechanism. Recovering from CPL0 #MC is mostly doomed to failure. Except this mcsafe crap with the exception handling: /* * Handle an MCE which has happened in kernel space but from * which the kernel can recover: ex_has_fault_handler() has * already verified that the rIP at which the error happened is * a rIP from which the kernel can recover (by jumping to * recovery code specified in _ASM_EXTABLE_FAULT()) and the * corresponding exception handler which would do that is the * proper one. */ if (m.kflags & MCE_IN_KERNEL_RECOV) { if (!fixup_exception(regs, X86_TRAP_MC, error_code, 0)) mce_panic("Failed kernel mode recovery", &m, msg); Other than that, we iz done. -- Regards/Gruss, Boris. https://people.kernel.org/tglx/notes-about-netiquette