From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753343Ab3A3AYp (ORCPT ); Tue, 29 Jan 2013 19:24:45 -0500 Received: from p3plsmtps2ded01.prod.phx3.secureserver.net ([208.109.80.58]:33401 "EHLO p3plsmtps2ded01.prod.phx3.secureserver.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753272Ab3A3AYk (ORCPT ); Tue, 29 Jan 2013 19:24:40 -0500 x-originating-ip: 72.167.245.219 From: "K. Y. Srinivasan" To: x86@kernel.org, gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org, devel@linuxdriverproject.org, olaf@aepfle.de, apw@canonical.com, jasowang@redhat.com, tglx@linutronix.de, hpa@zytor.com, JBeulich@suse.com, bp@alien8.de Cc: Olaf Hering <"[mailto:olaf@aepfle.de]"@linuxonhyperv.com>, "K. Y. Srinivasan" , stable@kernel.org Subject: [PATCH 1/3] x86: Hyper-V: register clocksource only if its advertised Date: Tue, 29 Jan 2013 16:51:46 -0800 Message-Id: <1359507108-26091-1-git-send-email-kys@microsoft.com> X-Mailer: git-send-email 1.7.4.1 In-Reply-To: <1359507077-26050-1-git-send-email-kys@microsoft.com> References: <1359507077-26050-1-git-send-email-kys@microsoft.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Olaf Hering <[mailto:olaf@aepfle.de]> Enable hyperv_clocksource only if its advertised as a feature. XenServer 6 returns the signature which is checked in ms_hyperv_platform(), but it does not offer all features. Currently the clocksource is enabled unconditionally in ms_hyperv_init_platform(), and the result is a hanging guest. Hyper-V spec Bit 1 indicates the availability of Partition Reference Counter. Register the clocksource only if this bit is set. The guest in question prints this in dmesg: [ 0.000000] Hypervisor detected: Microsoft HyperV [ 0.000000] HyperV: features 0x70, hints 0x0 This bug can be reproduced easily be setting 'viridian=1' in a HVM domU .cfg file. A workaround without this patch is to boot the HVM guest with 'clocksource=jiffies'. Signed-off-by: Olaf Hering Signed-off-by: K. Y. Srinivasan Cc: stable@kernel.org Cc: Greg KH --- arch/x86/kernel/cpu/mshyperv.c | 3 ++- 1 files changed, 2 insertions(+), 1 deletions(-) diff --git a/arch/x86/kernel/cpu/mshyperv.c b/arch/x86/kernel/cpu/mshyperv.c index 0a630dd..646d192 100644 --- a/arch/x86/kernel/cpu/mshyperv.c +++ b/arch/x86/kernel/cpu/mshyperv.c @@ -68,7 +68,8 @@ static void __init ms_hyperv_init_platform(void) printk(KERN_INFO "HyperV: features 0x%x, hints 0x%x\n", ms_hyperv.features, ms_hyperv.hints); - clocksource_register_hz(&hyperv_cs, NSEC_PER_SEC/100); + if (ms_hyperv.features & HV_X64_MSR_TIME_REF_COUNT_AVAILABLE) + clocksource_register_hz(&hyperv_cs, NSEC_PER_SEC/100); } const __refconst struct hypervisor_x86 x86_hyper_ms_hyperv = { -- 1.7.4.1