From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932489AbaJVTer (ORCPT ); Wed, 22 Oct 2014 15:34:47 -0400 Received: from terminus.zytor.com ([198.137.202.10]:57783 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932253AbaJVTeo (ORCPT ); Wed, 22 Oct 2014 15:34:44 -0400 Date: Wed, 22 Oct 2014 12:34:20 -0700 From: tip-bot for Andy Lutomirski Message-ID: Cc: luto@amacapital.net, linux-kernel@vger.kernel.org, bsd@redhat.com, mingo@kernel.org, tglx@linutronix.de, hpa@zytor.com Reply-To: mingo@kernel.org, bsd@redhat.com, linux-kernel@vger.kernel.org, hpa@zytor.com, tglx@linutronix.de, luto@amacapital.net In-Reply-To: References: To: linux-tip-commits@vger.kernel.org Subject: [tip:x86/urgent] x86, apic: Handle a bad TSC more gracefully Git-Commit-ID: b47dcbdc5161d3d5756f430191e2840d9b855492 X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: b47dcbdc5161d3d5756f430191e2840d9b855492 Gitweb: http://git.kernel.org/tip/b47dcbdc5161d3d5756f430191e2840d9b855492 Author: Andy Lutomirski AuthorDate: Wed, 15 Oct 2014 10:12:07 -0700 Committer: Thomas Gleixner CommitDate: Wed, 22 Oct 2014 21:31:46 +0200 x86, apic: Handle a bad TSC more gracefully If the TSC is unusable or disabled, then this patch fixes: - Confusion while trying to clear old APIC interrupts. - Division by zero and incorrect programming of the TSC deadline timer. This fixes boot if the CPU has a TSC deadline timer but a missing or broken TSC. The failure to boot can be observed with qemu using -cpu qemu64,-tsc,+tsc-deadline This also happens to me in nested KVM for unknown reasons. With this patch, I can boot cleanly (although without a TSC). Signed-off-by: Andy Lutomirski Cc: Bandan Das Cc: stable@vger.kernel.org Link: http://lkml.kernel.org/r/e2fa274e498c33988efac0ba8b7e3120f7f92d78.1413393027.git.luto@amacapital.net Signed-off-by: Thomas Gleixner --- arch/x86/kernel/apic/apic.c | 4 ++-- arch/x86/kernel/tsc.c | 5 ++++- 2 files changed, 6 insertions(+), 3 deletions(-) diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c index 6776027..24b5894 100644 --- a/arch/x86/kernel/apic/apic.c +++ b/arch/x86/kernel/apic/apic.c @@ -1297,7 +1297,7 @@ void setup_local_APIC(void) unsigned int value, queued; int i, j, acked = 0; unsigned long long tsc = 0, ntsc; - long long max_loops = cpu_khz; + long long max_loops = cpu_khz ? cpu_khz : 1000000; if (cpu_has_tsc) rdtscll(tsc); @@ -1383,7 +1383,7 @@ void setup_local_APIC(void) break; } if (queued) { - if (cpu_has_tsc) { + if (cpu_has_tsc && cpu_khz) { rdtscll(ntsc); max_loops = (cpu_khz << 10) - (ntsc - tsc); } else diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c index b6025f9..b7e50bb 100644 --- a/arch/x86/kernel/tsc.c +++ b/arch/x86/kernel/tsc.c @@ -1166,14 +1166,17 @@ void __init tsc_init(void) x86_init.timers.tsc_pre_init(); - if (!cpu_has_tsc) + if (!cpu_has_tsc) { + setup_clear_cpu_cap(X86_FEATURE_TSC_DEADLINE_TIMER); return; + } tsc_khz = x86_platform.calibrate_tsc(); cpu_khz = tsc_khz; if (!tsc_khz) { mark_tsc_unstable("could not calculate TSC khz"); + setup_clear_cpu_cap(X86_FEATURE_TSC_DEADLINE_TIMER); return; }