Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751427AbdIMSFJ (ORCPT ); Wed, 13 Sep 2017 14:05:09 -0400 Received: from mail-dm3nam03on0134.outbound.protection.outlook.com ([104.47.41.134]:46905 "EHLO NAM03-DM3-obe.outbound.protection.outlook.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751106AbdIMSFH (ORCPT ); Wed, 13 Sep 2017 14:05:07 -0400 From: KY Srinivasan To: Ingo Molnar CC: Dan Carpenter , "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" Subject: RE: [PATCH 1/1] x86/hyper-V: Allocate the IDT entry early in boot Thread-Topic: [PATCH 1/1] x86/hyper-V: Allocate the IDT entry early in boot Thread-Index: AQHTKPio6J/WpSIIyE2MnS3jK+rNM6KsZL4AgABSZkCABdSJAIAAl9jw Date: Wed, 13 Sep 2017 18:05:04 +0000 Message-ID: References: <20170908231557.2419-1-kys@exchange.microsoft.com> <20170909105428.osqbcf4gnibobpse@mwanda> <20170913090056.nveesthowrsjytm6@gmail.com> In-Reply-To: <20170913090056.nveesthowrsjytm6@gmail.com> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: msip_labels: MSIP_Label_f42aa342-8706-4288-bd11-ebb85995028c_Enabled=True; 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x-forefront-prvs: 042957ACD7 x-forefront-antispam-report: SFV:NSPM;SFS:(10019020)(6009001)(346002)(376002)(39860400002)(47760400005)(189002)(377454003)(199003)(13464003)(54534003)(24454002)(2900100001)(229853002)(10090500001)(74316002)(305945005)(7736002)(105586002)(9686003)(53936002)(93886005)(101416001)(106356001)(99286003)(54906002)(55016002)(77096006)(6436002)(6506006)(33656002)(97736004)(66066001)(3660700001)(68736007)(3280700002)(2906002)(102836003)(6116002)(3846002)(8990500004)(53546010)(8936002)(14454004)(81166006)(81156014)(7416002)(189998001)(2950100002)(6916009)(316002)(7696004)(5660300001)(10290500003)(6246003)(50986999)(86612001)(22452003)(76176999)(86362001)(25786009)(478600001)(8676002)(110136004)(54356999)(4326008);DIR:OUT;SFP:1102;SCL:1;SRVR:CY4PR21MB0775;H:CY4PR21MB0471.namprd21.prod.outlook.com;FPR:;SPF:None;PTR:InfoNoRecords;MX:1;A:1;LANG:en; spamdiagnosticoutput: 1:99 spamdiagnosticmetadata: NSPM Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 X-OriginatorOrg: microsoft.com X-MS-Exchange-CrossTenant-originalarrivaltime: 13 Sep 2017 18:05:04.5803 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: 72f988bf-86f1-41af-91ab-2d7cd011db47 X-MS-Exchange-Transport-CrossTenantHeadersStamped: CY4PR21MB0775 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from quoted-printable to 8bit by nfs id v8DI5FGu019423 Content-Length: 1967 Lines: 58 > -----Original Message----- > From: Ingo Molnar [mailto:mingo.kernel.org@gmail.com] On Behalf Of Ingo > Molnar > Sent: Wednesday, September 13, 2017 2:01 AM > To: KY Srinivasan > Cc: Dan Carpenter ; 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 > Subject: Re: [PATCH 1/1] x86/hyper-V: Allocate the IDT entry early in boot > > > * KY Srinivasan wrote: > > > > > > > > -----Original Message----- > > > From: Dan Carpenter [mailto:dan.carpenter@oracle.com] > > > Sent: Saturday, September 9, 2017 4:04 AM > > > To: KY Srinivasan > > > Cc: 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; mingo@kernel.org > > > Subject: Re: [PATCH 1/1] x86/hyper-V: Allocate the IDT entry early in boot > > > > > > On Fri, Sep 08, 2017 at 04:15:57PM -0700, kys@exchange.microsoft.com > > > wrote: > > > > From: "K. Y. Srinivasan" > > > > > > > > Allocate the hypervisor callback IDT entry early in the boot sequence. > > > > > > > > > > I'm guessing this fixes a NULL dereference or something? The changelog > > > doesn't really say why we are doing this. > > > > The changelog does say what we are doing - allocating the IDT entry early in > the boot sequence. > > But the question was the 'why', not the 'what' - so Dan's question is > fully justified ... > > > The current code would allocate the entry as part of registering the handler > > when vmbus driver loaded and this caused a problem for the cleanup > Thomas had > > implemented. > > I've put this explanation into the changelog. You are right. Thanks, Ingo. K. Y > > Thanks, > > Ingo