From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756470Ab3AYN67 (ORCPT ); Fri, 25 Jan 2013 08:58:59 -0500 Received: from mo-p00-ob.rzone.de ([81.169.146.160]:25880 "EHLO mo-p00-ob.rzone.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753359Ab3AYN65 (ORCPT ); Fri, 25 Jan 2013 08:58:57 -0500 X-RZG-AUTH: :P2EQZWCpfu+qG7CngxMFH1J+zrwiavkK6tmQaLfmztM8TOFGji0LFus= X-RZG-CLASS-ID: mo00 Date: Fri, 25 Jan 2013 14:58:35 +0100 From: Olaf Hering To: Jan Beulich Cc: KY Srinivasan , "bp@alien8.de" , "apw@canonical.com" , "x86@kernel.org" , "tglx@linutronix.de" , "devel@linuxdriverproject.org" , "gregkh@linuxfoundation.org" , "jasowang@redhat.com" , "linux-kernel@vger.kernel.org" , "hpa@zytor.com" Subject: Re: [PATCH RESEND 1/1] X86: Handle Hyper-V vmbus interrupts as special hypervisor interrupts Message-ID: <20130125135834.GA18361@aepfle.de> References: <1358990259-22551-1-git-send-email-kys@microsoft.com> <5101035D02000078000B8FFD@nat28.tlf.novell.com> <27092660926e4d3f80394697cc0dc858@SN2PR03MB061.namprd03.prod.outlook.com> <51016C3202000078000B943E@nat28.tlf.novell.com> <20130124185943.GA19194@aepfle.de> <510243B802000078000B9735@nat28.tlf.novell.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <510243B802000078000B9735@nat28.tlf.novell.com> User-Agent: Mutt/1.5.21.rev5632 (2013-01-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Jan 25, Jan Beulich wrote: > >>> On 24.01.13 at 19:59, Olaf Hering wrote: > > On Thu, Jan 24, KY Srinivasan wrote: > > > > > >> > Question is - considering you stated that this is supported > >> > starting in Win8, doesn't Hyper-V itself announce that > >> > capability in some explicit way? > >> > >> Thanks Jan. Unfortunately I don't think tis interrupt delivery model > >> is specified via a "feature" bit (I will check with the Windows guys). > >> Perhaps, we can have a Hyper-V specific compilation switch to address > >> the Xen emulation issue. > > > > Would that really help if both pvops XEN_PVHVM and HYPERV are enabled in > > the config? I assume at this point the access to the DMI data is not yet > > possible. > > As just said in another reply - with XEN_PVHVM, there's no problem, > since Xen gets checked for first. There's only a problem when > !XEN_PVHVM, because in that case Hyper-V will be probed for. > And the problem can only get bigger when on top of that the > out-of-tree PV drivers are intended to be used. Yes, xen_cpuid_base() recognizes Xen as hypervisor even with 'viridian=1' in the .cfg file. I think if there is no feature bit for this, the DMI can be used because its appearently available before the host is checked: ... [ 0.000000] NX (Execute Disable) protection: active [ 0.000000] DMI 2.4 present. [ 0.000000] DMI: Xen HVM domU, BIOS 4.1.3_06-0.7.1 12/05/2012 [ 0.000000] Hypervisor detected: Microsoft HyperV [ 0.000000] HyperV: features 0x70, hints 0x0 [ 0.000000] e820 update range: 0000000000000000 - 0000000000010000 (usable) ==> (reserved) ... Olaf