From mboxrd@z Thu Jan 1 00:00:00 1970 From: Juergen Gross Subject: Re: Debug-Registers in HVM domain destroyed Date: Thu, 20 Feb 2014 08:44:51 +0100 Message-ID: <5305B273.9000803@ts.fujitsu.com> References: <52FDE2ED.4030008@ts.fujitsu.com> <52FE00C8020000780011C649@nat28.tlf.novell.com> <52FE09A2.4000909@ts.fujitsu.com> <52FE21E4020000780011C6F5@nat28.tlf.novell.com> <53035689.4000602@ts.fujitsu.com> <53036688020000780011D4B5@nat28.tlf.novell.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; Format="flowed" Content-Transfer-Encoding: 7bit Return-path: Received: from mail6.bemta4.messagelabs.com ([85.158.143.247]) by lists.xen.org with esmtp (Exim 4.72) (envelope-from ) id 1WGOJR-00014x-Og for xen-devel@lists.xenproject.org; Thu, 20 Feb 2014 07:44:53 +0000 In-Reply-To: <53036688020000780011D4B5@nat28.tlf.novell.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Jan Beulich Cc: xen-devel List-Id: xen-devel@lists.xenproject.org On 18.02.2014 13:56, Jan Beulich wrote: >>>> On 18.02.14 at 13:48, Juergen Gross wrote: >> On 14.02.2014 14:02, Jan Beulich wrote: >>>>>> On 14.02.14 at 13:18, Juergen Gross wrote: >>>> Is this the case when the guest itself uses single stepping? Initially the >>>> debug trap shouldn't cause a VMEXIT, I think. >>> >>> That looks like a bug, indeed - it's missing from the initially set >>> exception_bitmap. Could you check whether adding this in >>> construct_vmcs() addresses that part of the issue? (A proper fix >>> would likely include further adjustments to the setting of this flag, >>> e.g. clearing it alongside clearing the DR intercept.) But then >>> again all of this already depends on cpu_has_monitor_trap_flag - >>> if that's set on your system, maybe you could try suppressing its >>> detection (by removing CPU_BASED_MONITOR_TRAP_FLAG from >>> the optional feature set in vmx_init_vmcs_config())? >> >> I've currently a test running with the attached patch (the bug was hit about >> once every 3 hours, test is running now for about 4 hours without problem). >> Test machine is running with Xen 4.2.3 hypervisor from SLES11 SP3. > > Which, if it continues running fine, would confirm the theory. > I'd like to defer to the VMX folks though for putting together a > proper fix then - I'd likely overlook some corner case. Okay, theory confirmed. Unless you want to do it, I'll start another thread with the info found so far and include Jun Nakajima and Eddie Dong. Juergen -- Juergen Gross Principal Developer Operating Systems PBG PDG ES&S SWE OS6 Telephone: +49 (0) 89 62060 2932 Fujitsu e-mail: juergen.gross@ts.fujitsu.com Mies-van-der-Rohe-Str. 8 Internet: ts.fujitsu.com D-80807 Muenchen Company details: ts.fujitsu.com/imprint.html