From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757222Ab3AYQKW (ORCPT ); Fri, 25 Jan 2013 11:10:22 -0500 Received: from mail-pa0-f45.google.com ([209.85.220.45]:47919 "EHLO mail-pa0-f45.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753392Ab3AYQKT (ORCPT ); Fri, 25 Jan 2013 11:10:19 -0500 Date: Fri, 25 Jan 2013 08:10:16 -0800 From: Greg KH To: Olaf Hering Cc: linux-kernel@vger.kernel.org, stable@kernel.org, KY Srinivasan Subject: Re: [PATCH] x86: Hyper-V: register clocksource only if its advertised Message-ID: <20130125161016.GA9906@kroah.com> References: <1359121036-16309-1-git-send-email-olaf@aepfle.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1359121036-16309-1-git-send-email-olaf@aepfle.de> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Jan 25, 2013 at 02:37:16PM +0100, Olaf Hering wrote: > 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 > Cc: stable@kernel.org > Cc: KY Srinivasan > Cc: Greg KH > --- > arch/x86/kernel/cpu/mshyperv.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) This needs to go through the x86 maintainers, not me, sorry. greg k-h