From mboxrd@z Thu Jan 1 00:00:00 1970 Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751458AbeAEDWc (ORCPT + 1 other); Thu, 4 Jan 2018 22:22:32 -0500 Received: from mx1.redhat.com ([209.132.183.28]:33424 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751298AbeAEDWb (ORCPT ); Thu, 4 Jan 2018 22:22:31 -0500 Date: Fri, 5 Jan 2018 11:22:26 +0800 From: Baoquan He To: linux-kernel@vger.kernel.org Cc: mingo@redhat.com, tglx@linutronix.de, hpa@zytor.com, x86@kernel.org, douly.fnst@cn.fujitsu.com, rostedt@goodmis.org, jgross@suse.com, peterz@infradead.org, uobergfe@redhat.com, joro@8bytes.org Subject: [PATCH 1/3] x86/apic: Set up through LAPIC on boot CPU's LINT0 if ioapic is disabled to kexec/kdump kernel Message-ID: <20180105032226.GE7235@x1> References: <1515120933-27414-1-git-send-email-bhe@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1515120933-27414-1-git-send-email-bhe@redhat.com> User-Agent: Mutt/1.7.0 (2016-08-17) X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.25]); Fri, 05 Jan 2018 03:22:31 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Return-Path: Kdump kernel will become very slow if 'noapic' is specified in kernel command line. Normal kernel doesn't have this issue. This is because the legacy irq mode is disabled in crashed kernel before jump jump to kdump kernel since commit 522e66464467 ("x86/apic: Disable I/O APIC before shutdown of the local APIC") is merged. While in normal kernel, the legacy irq mode has been set in BIOS. So we need set the delivery mode AS ExtINT for LVT0 of boot CPU's LAPIC explicitly if IO-APIC is disabled, to set up through-local-APIC. Signed-off-by: Baoquan He --- arch/x86/kernel/apic/apic.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c index 880441f24146..7e613fb90630 100644 --- a/arch/x86/kernel/apic/apic.c +++ b/arch/x86/kernel/apic/apic.c @@ -1521,7 +1521,7 @@ void setup_local_APIC(void) * TODO: set up through-local-APIC from through-I/O-APIC? --macro */ value = apic_read(APIC_LVT0) & APIC_LVT_MASKED; - if (!cpu && (pic_mode || !value)) { + if (!cpu && (pic_mode || !value || skip_ioapic_setup)) { value = APIC_DM_EXTINT; apic_printk(APIC_VERBOSE, "enabled ExtINT on CPU#%d\n", cpu); } else { -- 2.5.5