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=-11.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS autolearn=ham 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 C82E6C52D47 for ; Thu, 27 Feb 2020 14:16:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A6B9124691 for ; Thu, 27 Feb 2020 14:16:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2389448AbgB0OQM (ORCPT ); Thu, 27 Feb 2020 09:16:12 -0500 Received: from Galois.linutronix.de ([193.142.43.55]:34441 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2388997AbgB0OQD (ORCPT ); Thu, 27 Feb 2020 09:16:03 -0500 Received: from [5.158.153.53] (helo=tip-bot2.lab.linutronix.de) by Galois.linutronix.de with esmtpsa (TLS1.2:DHE_RSA_AES_256_CBC_SHA256:256) (Exim 4.80) (envelope-from ) id 1j7JxG-0005BW-9N; Thu, 27 Feb 2020 15:15:58 +0100 Received: from [127.0.1.1] (localhost [IPv6:::1]) by tip-bot2.lab.linutronix.de (Postfix) with ESMTP id ECFAF1C216F; Thu, 27 Feb 2020 15:15:57 +0100 (CET) Date: Thu, 27 Feb 2020 14:15:57 -0000 From: "tip-bot2 for Thomas Gleixner" Reply-to: linux-kernel@vger.kernel.org To: linux-tip-commits@vger.kernel.org Subject: [tip: x86/entry] x86/traps: Document do_spurious_interrupt_bug() Cc: Thomas Gleixner , Frederic Weisbecker , Alexandre Chartre , Andy Lutomirski , x86 , LKML In-Reply-To: <20200225220216.624165786@linutronix.de> References: <20200225220216.624165786@linutronix.de> MIME-Version: 1.0 Message-ID: <158281295772.28353.8582733776925406910.tip-bot2@tip-bot2> X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit X-Linutronix-Spam-Score: -1.0 X-Linutronix-Spam-Level: - X-Linutronix-Spam-Status: No , -1.0 points, 5.0 required, ALL_TRUSTED=-1,SHORTCIRCUIT=-0.0001 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The following commit has been merged into the x86/entry branch of tip: Commit-ID: d244d0e195bc12964bcf3b8eef45e715a7f203b0 Gitweb: https://git.kernel.org/tip/d244d0e195bc12964bcf3b8eef45e715a7f203b0 Author: Thomas Gleixner AuthorDate: Tue, 25 Feb 2020 22:36:41 +01:00 Committer: Thomas Gleixner CommitterDate: Thu, 27 Feb 2020 14:48:40 +01:00 x86/traps: Document do_spurious_interrupt_bug() Add a comment which explains why this empty handler for a reserved vector exists. Requested-by: Josh Poimboeuf Signed-off-by: Thomas Gleixner Reviewed-by: Frederic Weisbecker Reviewed-by: Alexandre Chartre Reviewed-by: Andy Lutomirski Link: https://lkml.kernel.org/r/20200225220216.624165786@linutronix.de --- arch/x86/kernel/traps.c | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+) diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c index 474b8cb..7ffb6f4 100644 --- a/arch/x86/kernel/traps.c +++ b/arch/x86/kernel/traps.c @@ -862,6 +862,25 @@ do_simd_coprocessor_error(struct pt_regs *regs, long error_code) dotraplinkage void do_spurious_interrupt_bug(struct pt_regs *regs, long error_code) { + /* + * This addresses a Pentium Pro Erratum: + * + * PROBLEM: If the APIC subsystem is configured in mixed mode with + * Virtual Wire mode implemented through the local APIC, an + * interrupt vector of 0Fh (Intel reserved encoding) may be + * generated by the local APIC (Int 15). This vector may be + * generated upon receipt of a spurious interrupt (an interrupt + * which is removed before the system receives the INTA sequence) + * instead of the programmed 8259 spurious interrupt vector. + * + * IMPLICATION: The spurious interrupt vector programmed in the + * 8259 is normally handled by an operating system's spurious + * interrupt handler. However, a vector of 0Fh is unknown to some + * operating systems, which would crash if this erratum occurred. + * + * In theory this could be limited to 32bit, but the handler is not + * hurting and who knows which other CPUs suffer from this. + */ } dotraplinkage void