From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751449Ab1AEPKg (ORCPT ); Wed, 5 Jan 2011 10:10:36 -0500 Received: from queueout04-winn.ispmail.ntl.com ([81.103.221.58]:5558 "EHLO queueout04-winn.ispmail.ntl.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751231Ab1AEPKf (ORCPT ); Wed, 5 Jan 2011 10:10:35 -0500 X-Greylist: delayed 835 seconds by postgrey-1.27 at vger.kernel.org; Wed, 05 Jan 2011 10:10:35 EST From: Ian Campbell To: Sheng Yang Cc: Jeremy Fitzhardinge , Konrad Rzeszutek Wilk , "H. Peter Anvin" , Ingo Molnar , linux-kernel@vger.kernel.org In-Reply-To: <201101051547.12107.sheng@linux.intel.com> References: <1292912329-12451-1-git-send-email-sheng@linux.intel.com> <1292912329-12451-2-git-send-email-sheng@linux.intel.com> <201101051547.12107.sheng@linux.intel.com> Content-Type: text/plain; charset="UTF-8" Date: Wed, 05 Jan 2011 14:56:28 +0000 Message-ID: <1294239388.3831.3516.camel@zakaz.uk.xensource.com> Mime-Version: 1.0 X-Mailer: Evolution 2.30.3 Content-Transfer-Encoding: 7bit X-SA-Exim-Connect-IP: 62.200.22.2 X-SA-Exim-Mail-From: ijc@hellion.org.uk Subject: Re: [PATCH 2/2 v2] xen: HVM X2APIC support X-SA-Exim-Version: 4.2.1 (built Wed, 25 Jun 2008 17:14:11 +0000) X-SA-Exim-Scanned: Yes (on hopkins.hellion.org.uk) X-Cloudmark-Analysis: v=1.1 cv=JvdXmxIgLJv2/GthKqHpGJEEHukvLcvELVXUanXFreg= c=1 sm=0 a=z0RUBZs6AVsA:10 a=IkcTkHD0fZMA:10 a=EqSVyYDxCmx5PoDwFIsA:9 a=qJ0bFeMbzbMGuu1AVugA:7 a=P7rXIyUuUSQbflqvmqnNICf3BD4A:4 a=QEXdDO2ut3YA:10 a=HpAAvcLHHh0Zw7uRqdWCyQ==:117 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > > @@ -1384,6 +1365,17 @@ static bool __init xen_hvm_platform(void) > > return true; > > } > > > > +bool xen_hvm_need_lapic(void) > > +{ > > + if (xen_pv_domain()) > > + return false; > > + if (xen_hvm_domain() && xen_feature(XENFEAT_hvm_pirqs) && > > + xen_have_vector_callback) > > + return false; > > + return (xen_cpuid_base() != 0); > > +} > > +EXPORT_SYMBOL_GPL(xen_hvm_need_lapic); > > + Since xen_hvm_domain() is always true if xen_cpuid_base() != 0, isn't this more obviously written as: if (!xen_hvm_domain()) return false; if (xen_feature(XENFEAT_hvm_pirqs) && xen_have_vector_callback) return false; return true; ? Also, checking for the XenVMMXenVMM signature alone seems like a very broad test for checking the availability of a specific feature, is there nothing more specific which we could/should be testing? Ian. -- Ian Campbell Current Noise: Taint - Mass Appeal Sadness What's a cult? It just means not enough people to make a minority. -- Robert Altman