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Tsirkin" Subject: Re: [PATCH V2] Add a new PIIX option to control PCI hot unplugging of devices on non-root buses Thread-Topic: [PATCH V2] Add a new PIIX option to control PCI hot unplugging of devices on non-root buses Thread-Index: AQHWHUYvMyDNYIpa20C9378Nh0w8t6iOszWAgAAA+QCAAANNgIAABV8AgABEbYCAAEbYAIAASz+AgAAMEQCAAAuhAIAAAIgA Date: Wed, 29 Apr 2020 06:54:52 +0000 Message-ID: References: <1588069012-211196-1-git-send-email-ani.sinha@nutanix.com> <20200428120426-mutt-send-email-mst@kernel.org> <67e481a5-de04-4e01-b9ec-70932194d69f@Spark> <20200428121837-mutt-send-email-mst@kernel.org> <20200428164428-mutt-send-email-mst@kernel.org> <20200429011228-mutt-send-email-mst@kernel.org> <544B4749-9A1C-44BB-BD89-C37A7E8D86F4@nutanix.com> <20200429025200-mutt-send-email-mst@kernel.org> In-Reply-To: <20200429025200-mutt-send-email-mst@kernel.org> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: authentication-results: redhat.com; dkim=none (message not signed) header.d=none;redhat.com; dmarc=none action=none header.from=nutanix.com; x-originating-ip: [192.146.154.3] x-ms-publictraffictype: Email x-ms-office365-filtering-correlation-id: f72b933f-726b-4063-1e4b-08d7ec0a380f x-ms-traffictypediagnostic: MN2PR02MB5904: x-microsoft-antispam-prvs: x-proofpoint-crosstenant: true x-ms-oob-tlc-oobclassifiers: OLM:8273; x-forefront-prvs: 03883BD916 x-forefront-antispam-report: CIP:255.255.255.255; CTRY:; LANG:en; SCL:1; SRV:; IPV:NLI; SFV:NSPM; H:MN2PR02MB5742.namprd02.prod.outlook.com; PTR:; CAT:NONE; SFTY:; SFS:(366004)(136003)(346002)(396003)(376002)(39850400004)(86362001)(71200400001)(44832011)(5660300002)(36756003)(478600001)(2616005)(2906002)(7416002)(33656002)(8676002)(6916009)(316002)(64756008)(186003)(4326008)(26005)(6486002)(6512007)(91956017)(66556008)(6506007)(66946007)(66476007)(53546011)(54906003)(8936002)(66446008)(76116006); DIR:OUT; SFP:1102; x-ms-exchange-senderadcheck: 1 x-microsoft-antispam: BCL:0; x-microsoft-antispam-message-info: F6+tCJX8KpWjoApbtCfWG61fMZxbUFx5HfSWExEsurSMq8UaT50aNLV2a3DRP+mnbVe3U0M3MutHwNNFnwgngZQA18Ha7662FHGu5J2872PQIJUxcG3rH/bzveP5Jh53Tdq/N/gO1JL0zjttdP7aJ99GwxS7qKSrszr9t20OcZjzss7EadiJrwLaSq3W8iEKs2oLpDK+0fxTdS0Xf+ktRu8ixCaQt7omypmKUU3mf0k0RlyjU1IJT7bDpGIyDJQ4JWt7OgDRzSvSC+85jVxs67EWgEccZgkdgxPXq+RloVyy/L85A7MZLbQ5RpCA0KH0ZYAwRWS6clG8p2ZMCT+0nkjzXcN/7OhTuaiid2l07ZeZMV7F250VsGBqZF/zb5NiW16jLRIjvgG/uze73ATG2n5mxUpY29tgGNwv51SLtuU1A0Gf6StHdPUMPABvLu4o x-ms-exchange-antispam-messagedata: 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 x-ms-exchange-transport-forked: True Content-Type: text/plain; charset="iso-8859-1" Content-ID: Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-OriginatorOrg: nutanix.com X-MS-Exchange-CrossTenant-Network-Message-Id: f72b933f-726b-4063-1e4b-08d7ec0a380f X-MS-Exchange-CrossTenant-originalarrivaltime: 29 Apr 2020 06:54:52.9458 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: bb047546-786f-4de1-bd75-24e5b6f79043 X-MS-Exchange-CrossTenant-mailboxtype: HOSTED X-MS-Exchange-CrossTenant-userprincipalname: 9sXzP36JbQ6Y1ygFZ1uPXHtI3oDKdHGQyo0MoQnQB4nGk5K8HcxiUQwNpg65S1vO7oT8khM5ysi8DW4V+3b5zw== X-MS-Exchange-Transport-CrossTenantHeadersStamped: MN2PR02MB5904 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.138, 18.0.676 definitions=2020-04-29_02:2020-04-28, 2020-04-29 signatures=0 X-Proofpoint-Spam-Reason: safe Received-SPF: pass client-ip=148.163.151.68; envelope-from=ani.sinha@nutanix.com; helo=mx0a-002c1b01.pphosted.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/04/29 02:00:18 X-ACL-Warn: Detected OS = Linux 3.x [generic] X-Received-From: 148.163.151.68 X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Eduardo Habkost , "qemu-devel@nongnu.org" , Aleksandar Markovic , Paolo Bonzini , Ani Sinha , Igor Mammedov , =?iso-8859-1?Q?Philippe_Mathieu-Daud=E9?= , Aurelien Jarno , Richard Henderson Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" > On Apr 29, 2020, at 12:22 PM, Michael S. Tsirkin wrote: >=20 > On Wed, Apr 29, 2020 at 06:11:20AM +0000, Ani Sinha wrote: >>=20 >>=20 >>> On Apr 29, 2020, at 10:58 AM, Michael S. Tsirkin wrote= : >>>=20 >>> o if there's a need to disable >>> just one of these, commit log needs to do a better job documenting the >>> usecase. >>=20 >> The use case is simple. With this feature admins will be able to do what= they were forced to do from Windows driver level but now at the bus level.= Hence,=20 >> (a) They need not have access to the guest VM to change or update window= s driver registry settings. They can enable the same setting from admin man= agement console without any access to VM. >> (b) It is more robust. No need to mess with driver settings. Incorrect s= ettings can brick guest OS. Also no guest specific knowhow required. >> (c) It is more scalable since a single cluster wide setting can be used = for all VM power ons and the management plane can take care of the rest aut= omatically. No need to access individual VMs to enforce this. >> (d) I am told that the driver level solution does not persist across a r= eboot.=20 >>=20 >> Ani >=20 > Looks like disabling both plug and unplug would also address these needs. No the driver level solution does not prevent hot plugging of devices but b= locks just hot unplugging. The solution I am proposing tries to do the same= but from the bus/hypervisor level. > --=20 > MST >=20