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=-0.8 required=3.0 tests=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 895B2C3A59F for ; Mon, 26 Aug 2019 10:15:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5D2D62186A for ; Mon, 26 Aug 2019 10:15:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730788AbfHZKPu (ORCPT ); Mon, 26 Aug 2019 06:15:50 -0400 Received: from mx1.redhat.com ([209.132.183.28]:56480 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726669AbfHZKPt (ORCPT ); Mon, 26 Aug 2019 06:15:49 -0400 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id C84B530832C8; Mon, 26 Aug 2019 10:15:49 +0000 (UTC) Received: from gigantic.usersys.redhat.com (helium.bos.redhat.com [10.18.17.132]) by smtp.corp.redhat.com (Postfix) with ESMTP id 3304A608C1; Mon, 26 Aug 2019 10:15:49 +0000 (UTC) From: Bandan Das To: Thomas Gleixner , Ingo Molnar , Borislav Petkov Cc: x86@kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v2 0/2] x86/apic: reset LDR in clear_local_APIC Date: Mon, 26 Aug 2019 06:15:11 -0400 Message-Id: <20190826101513.5080-1-bsd@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.44]); Mon, 26 Aug 2019 10:15:49 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org v2: 1/2: clear out the bogus initialization in bigsmp_init_apic_ldr 2/2: reword commit message as suggested by Thomas v1 posted at https://lkml.org/lkml/2019/8/14/1 On a 32 bit RHEL6 guest with greater than 8 cpus, the kdump kernel hangs when calibrating apic. This happens because when apic initializes bigsmp, it also initializes LDR even though it probably wouldn't be used. When booting into kdump, KVM apic incorrectly reads the stale LDR values from the guest while building the logical destination map even for inactive vcpus. While KVM apic can be fixed to ignore apics that haven't been enabled, a simple guest only change can be to just clear out the LDR. Bandan Das (2): x86/apic: Do not initialize LDR and DFR for bigsmp x86/apic: include the LDR when clearing out apic registers arch/x86/kernel/apic/apic.c | 4 ++++ arch/x86/kernel/apic/bigsmp_32.c | 24 ++---------------------- 2 files changed, 6 insertions(+), 22 deletions(-) -- 2.20.1