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=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_GIT autolearn=unavailable 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 0A9A1C3A5AA for ; Wed, 4 Sep 2019 18:19:58 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id DAEF2208E4 for ; Wed, 4 Sep 2019 18:19:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1567621197; bh=pfHA4ghX1sdzBre+QSIFvxbGOXnT+CmSpcZh5msUerA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=mBOMobZLOy9PoPldtV/BRRnOzdrarR8JAhY1P3ZgPQQaopNMpmwDqoKo66JR9xpPq x03AHa9pbhyzxUpZbUepndGUSImxoqW7svdi/lTiQKN43xkvi64M09XiXb30Bk2WkH Tyc3bbhKf7U6pOFHst28mzn8RWjwnBSmbCKj4gII= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2389070AbfIDSIo (ORCPT ); Wed, 4 Sep 2019 14:08:44 -0400 Received: from mail.kernel.org ([198.145.29.99]:51722 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2389832AbfIDSIo (ORCPT ); Wed, 4 Sep 2019 14:08:44 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id C9ECE206B8; Wed, 4 Sep 2019 18:08:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1567620523; bh=pfHA4ghX1sdzBre+QSIFvxbGOXnT+CmSpcZh5msUerA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=AONVxaHq9vJc5YZCARfcJHeEGKpMQhhyhZar5pEiHf+vAblj+7N+sFogM2dtnT09O dp2C4afac5+a4+vXd7lorb0aYhBcAZXlQ3wR6S9vCB4pnnbBDQ2wIkwuE6ECOg5fmn XksfdwnptGCgpvE8c1xKuP0n0aNHW92nxxhDRb+A= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Thomas Gleixner , Bandan Das Subject: [PATCH 4.19 49/93] x86/apic: Do not initialize LDR and DFR for bigsmp Date: Wed, 4 Sep 2019 19:53:51 +0200 Message-Id: <20190904175307.302636845@linuxfoundation.org> X-Mailer: git-send-email 2.23.0 In-Reply-To: <20190904175302.845828956@linuxfoundation.org> References: <20190904175302.845828956@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Bandan Das commit bae3a8d3308ee69a7dbdf145911b18dfda8ade0d upstream. Legacy apic init uses bigsmp for smp systems with 8 and more CPUs. The bigsmp APIC implementation uses physical destination mode, but it nevertheless initializes LDR and DFR. The LDR even ends up incorrectly with multiple bit being set. This does not cause a functional problem because LDR and DFR are ignored when physical destination mode is active, but it triggered a problem on a 32-bit KVM guest which jumps into a kdump kernel. The multiple bits set unearthed a bug in the KVM APIC implementation. The code which creates the logical destination map for VCPUs ignores the disabled state of the APIC and ends up overwriting an existing valid entry and as a result, APIC calibration hangs in the guest during kdump initialization. Remove the bogus LDR/DFR initialization. This is not intended to work around the KVM APIC bug. The LDR/DFR ininitalization is wrong on its own. The issue goes back into the pre git history. The fixes tag is the commit in the bitkeeper import which introduced bigsmp support in 2003. git://git.kernel.org/pub/scm/linux/kernel/git/tglx/history.git Fixes: db7b9e9f26b8 ("[PATCH] Clustered APIC setup for >8 CPU systems") Suggested-by: Thomas Gleixner Signed-off-by: Bandan Das Signed-off-by: Thomas Gleixner Cc: stable@vger.kernel.org Link: https://lkml.kernel.org/r/20190826101513.5080-2-bsd@redhat.com Signed-off-by: Greg Kroah-Hartman --- arch/x86/kernel/apic/bigsmp_32.c | 24 ++---------------------- 1 file changed, 2 insertions(+), 22 deletions(-) --- a/arch/x86/kernel/apic/bigsmp_32.c +++ b/arch/x86/kernel/apic/bigsmp_32.c @@ -38,32 +38,12 @@ static int bigsmp_early_logical_apicid(i return early_per_cpu(x86_cpu_to_apicid, cpu); } -static inline unsigned long calculate_ldr(int cpu) -{ - unsigned long val, id; - - val = apic_read(APIC_LDR) & ~APIC_LDR_MASK; - id = per_cpu(x86_bios_cpu_apicid, cpu); - val |= SET_APIC_LOGICAL_ID(id); - - return val; -} - /* - * Set up the logical destination ID. - * - * Intel recommends to set DFR, LDR and TPR before enabling - * an APIC. See e.g. "AP-388 82489DX User's Manual" (Intel - * document number 292116). So here it goes... + * bigsmp enables physical destination mode + * and doesn't use LDR and DFR */ static void bigsmp_init_apic_ldr(void) { - unsigned long val; - int cpu = smp_processor_id(); - - apic_write(APIC_DFR, APIC_DFR_FLAT); - val = calculate_ldr(cpu); - apic_write(APIC_LDR, val); } static void bigsmp_setup_apic_routing(void)