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=-4.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 5F0BCC46484 for ; Thu, 4 Jul 2019 16:35:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3F932218C3 for ; Thu, 4 Jul 2019 16:35:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727729AbfGDQfj (ORCPT ); Thu, 4 Jul 2019 12:35:39 -0400 Received: from Galois.linutronix.de ([193.142.43.55]:59611 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727200AbfGDQd7 (ORCPT ); Thu, 4 Jul 2019 12:33:59 -0400 Received: from localhost ([127.0.0.1] helo=nanos.tec.linutronix.de) by Galois.linutronix.de with esmtp (Exim 4.80) (envelope-from ) id 1hj4gH-0005eh-UD; Thu, 04 Jul 2019 18:33:58 +0200 Message-Id: <20190704155608.544562614@linutronix.de> User-Agent: quilt/0.65 Date: Thu, 04 Jul 2019 17:51:48 +0200 From: Thomas Gleixner To: LKML Cc: x86@kernel.org, Nadav Amit , Ricardo Neri , Stephane Eranian , Feng Tang Subject: [patch V2 03/25] x86/apic: Soft disable APIC before initializing it References: <20190704155145.617706117@linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org If the APIC was already enabled on entry of setup_local_APIC() then disabling it soft via the SPIV register makes a lot of sense. That masks all LVT entries and brings it into a well defined state. Otherwise previously enabled LVTs which are not touched in the setup function stay unmasked and might surprise the just booting kernel. Signed-off-by: Thomas Gleixner --- arch/x86/kernel/apic/apic.c | 8 ++++++++ 1 file changed, 8 insertions(+) --- a/arch/x86/kernel/apic/apic.c +++ b/arch/x86/kernel/apic/apic.c @@ -1493,6 +1493,14 @@ static void setup_local_APIC(void) return; } + /* + * If this comes from kexec/kcrash the APIC might be enabled in + * SPIV. Soft disable it before doing further initialization. + */ + value = apic_read(APIC_SPIV); + value &= ~APIC_SPIV_APIC_ENABLED; + apic_write(APIC_SPIV, value); + #ifdef CONFIG_X86_32 /* Pound the ESR really hard over the head with a big hammer - mbligh */ if (lapic_is_integrated() && apic->disable_esr) {