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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+AgAAI5YA= Date: Wed, 29 Apr 2020 05:59:59 +0000 Message-ID: <5AD9B19D-EACA-4111-BB5B-78F8378AE93D@nutanix.com> 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> In-Reply-To: <20200429011228-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: aa3bdc85-7e93-4fa9-e1fb-08d7ec028d39 x-ms-traffictypediagnostic: MN2PR02MB6365: x-microsoft-antispam-prvs: x-proofpoint-crosstenant: true x-ms-oob-tlc-oobclassifiers: OLM:466; x-forefront-prvs: 03883BD916 x-ms-exchange-senderadcheck: 1 x-microsoft-antispam: BCL:0; x-microsoft-antispam-message-info: 1T77ZrywZq0jidUEUf1fr2LgFIruBnvnbJFAPbGMU5nvqUKFKRO2mcmpPijYFAo+iU7oaoixm9ITA0HBpghj3CZOnCppFlf6O4iXZxTUiybQ5mNudzRsn9vr0hO02RHo8mcB4KqlAKNAazxbFqW3wV03GZ9DGlXxVIA1wdT+NmRG8iKpAY82x+9GB4/alH1/gzgazgCElzu2RUtG0duGKxQLUfkNa7YY9T30ylFgkTWGYhb69Ea6x3bJCCQYMwxhbTc1Af0ohAkRaQVGJ78bvEXE8VmehcAZ6TU515z0lv1Hp8x/8GDVsaDFsgfv1r1EVFEmRZq/Lk6MAoDiMeKImyMYf7jsmufSn3MreceUbbKGcO7ihKc6NzQVJpFydWJV6XKKedQL31/BnSHv8IJtpJP05H70rQSof9db2HFX5Nk8/1e/tdlc8a+aSX5Ohjo4 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:(39840400004)(396003)(376002)(136003)(366004)(346002)(76116006)(8936002)(91956017)(66946007)(5660300002)(36756003)(6916009)(2906002)(478600001)(8676002)(33656002)(86362001)(6512007)(6486002)(7416002)(4326008)(71200400001)(186003)(26005)(53546011)(6506007)(44832011)(66446008)(316002)(64756008)(54906003)(2616005)(66556008)(66476007); DIR:OUT; SFP:1102; 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: aa3bdc85-7e93-4fa9-e1fb-08d7ec028d39 X-MS-Exchange-CrossTenant-originalarrivaltime: 29 Apr 2020 05:59:59.8835 (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: YR+vrX8OpoYIEVaTr+JXcAYiRrggud7do2o/n8y869OX462o6TRQw0+NZpbyofANNriBRWvPngHbT0i25C3/aA== X-MS-Exchange-Transport-CrossTenantHeadersStamped: MN2PR02MB6365 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.138, 18.0.676 definitions=2020-04-29_01:2020-04-28, 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 10:58 AM, Michael S. Tsirkin wrote: >=20 > For example, how about hot-plugging a bridge which doesn't > support hotplug itself? So now for every device we want to hot plug, we will add a new bridge? Soun= ds not a scalable and elegant idea. > Would that happen to make windows > do what you want, for both PCI and PCIE? We don't support > hotplugging bridges with devices behind them ATM, but > that sounds like a useful option. >=20 >=20 > Also, pcie root ports recently gained ability to disable hotplug, see > commit 530a0963184e57e71a5b538e9161f115df533e96 > Author: Julia Suvorova > Date: Wed Feb 26 18:46:07 2020 +0100 >=20 > pcie_root_port: Add hotplug disabling option >=20 > adding this to pci and pcie bridges sounds very reasonable. This patch uses PCIE native hot plug capability to turn on or turn off per = slot hot plug option. This does not enable hot unplugging while allowing de= vices to be hot plugged on a PCIE port. Besides, PCI-PCI bridges already ha= ve an option to disable hot plug capability for all the slots of that bridg= e. My patch follows that approach.