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Fri, 10 Mar 2023 05:31:01 +0000 Received: from BN9PR11MB5276.namprd11.prod.outlook.com ([fe80::1aac:b695:f7c5:bcac]) by BN9PR11MB5276.namprd11.prod.outlook.com ([fe80::1aac:b695:f7c5:bcac%9]) with mapi id 15.20.6178.019; Fri, 10 Mar 2023 05:31:01 +0000 From: "Tian, Kevin" To: "Liu, Yi L" , "alex.williamson@redhat.com" , "jgg@nvidia.com" CC: "linux-s390@vger.kernel.org" , "Liu, Yi L" , "yi.y.sun@linux.intel.com" , "mjrosato@linux.ibm.com" , "kvm@vger.kernel.org" , "intel-gvt-dev@lists.freedesktop.org" , "joro@8bytes.org" , "cohuck@redhat.com" , "Hao, Xudong" , "peterx@redhat.com" , "Zhao, Yan Y" , "eric.auger@redhat.com" , "Xu, Terrence" , "nicolinc@nvidia.com" , "shameerali.kolothum.thodi@huawei.com" , "suravee.suthikulpanit@amd.com" , "intel-gfx@lists.freedesktop.org" , "chao.p.peng@linux.intel.com" , "lulu@redhat.com" , "robin.murphy@arm.com" , "jasowang@redhat.com" Subject: RE: [PATCH v6 12/24] vfio/pci: Allow passing zero-length fd array in VFIO_DEVICE_PCI_HOT_RESET Thread-Topic: [PATCH v6 12/24] vfio/pci: Allow passing zero-length fd array in VFIO_DEVICE_PCI_HOT_RESET Thread-Index: AQHZUcIISo3Z1SbL8EmJASujVt/DZK7zfnug Date: Fri, 10 Mar 2023 05:31:01 +0000 Message-ID: References: <20230308132903.465159-1-yi.l.liu@intel.com> <20230308132903.465159-13-yi.l.liu@intel.com> In-Reply-To: <20230308132903.465159-13-yi.l.liu@intel.com> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: authentication-results: dkim=none (message not signed) header.d=none;dmarc=none action=none header.from=intel.com; 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charset="us-ascii" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-AuthSource: BN9PR11MB5276.namprd11.prod.outlook.com X-MS-Exchange-CrossTenant-Network-Message-Id: c780a0b7-d994-4d88-fd2d-08db2128a290 X-MS-Exchange-CrossTenant-originalarrivaltime: 10 Mar 2023 05:31:01.2720 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: 46c98d88-e344-4ed4-8496-4ed7712e255d X-MS-Exchange-CrossTenant-mailboxtype: HOSTED X-MS-Exchange-CrossTenant-userprincipalname: im92GGfkBLp7xzFrq6lKj6tkjcpu6CoraYaHDd6qGxT5Vf2AMNkocOpu6yVWdrNV4oS+vg6Yq/s2Evq+XJpyOQ== X-MS-Exchange-Transport-CrossTenantHeadersStamped: IA1PR11MB7871 X-OriginatorOrg: intel.com Precedence: bulk List-ID: X-Mailing-List: linux-s390@vger.kernel.org > From: Yi Liu > Sent: Wednesday, March 8, 2023 9:29 PM >=20 > This is another method to issue PCI hot reset for the users that bounds > device to a positive iommufd value. In such case, iommufd is a proof of > device ownership. By passing a zero-length fd array, user indicates kerne= l > to do ownership check with the bound iommufd. All the opened devices > within > the affected dev_set should have been bound to the same iommufd. This is > simpler and faster as user does not need to pass a set of fds and kernel > no need to search the device within the given fds. >=20 > Suggested-by: Jason Gunthorpe > Signed-off-by: Yi Liu I think you also need a s-o-b from Jason since he wrote most of the code here. > +struct iommufd_ctx *vfio_iommufd_physical_ctx(struct vfio_device *vdev) > +{ > + /* Only serve for physical device */ > + if (!vdev->iommufd_device) > + return NULL; pointless comment > --- a/include/uapi/linux/vfio.h > +++ b/include/uapi/linux/vfio.h > @@ -682,6 +682,11 @@ struct vfio_pci_hot_reset_info { > * The ownership can be proved by: > * - An array of group fds > * - An array of device fds > + * - A zero-length array > + * > + * In the last case all affected devices which are opened by this user > + * must have been bound to a same iommufd_ctx. This approach is only > + * available for devices bound to positive iommufd. As we chatted before I still think the last sentence is pointless. If a dev= ice is bound to negative iommufd value (i.e. noiommu) it doesn't have a valid iommufd_ctx so won't meet "bound to a same iommufd_ctx".=20 From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 25B42C64EC4 for ; Fri, 10 Mar 2023 05:31:10 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 80F6410E954; Fri, 10 Mar 2023 05:31:09 +0000 (UTC) Received: from mga05.intel.com (mga05.intel.com [192.55.52.43]) by gabe.freedesktop.org (Postfix) with ESMTPS id B077110E954; Fri, 10 Mar 2023 05:31:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; 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charset="us-ascii" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-AuthSource: BN9PR11MB5276.namprd11.prod.outlook.com X-MS-Exchange-CrossTenant-Network-Message-Id: c780a0b7-d994-4d88-fd2d-08db2128a290 X-MS-Exchange-CrossTenant-originalarrivaltime: 10 Mar 2023 05:31:01.2720 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: 46c98d88-e344-4ed4-8496-4ed7712e255d X-MS-Exchange-CrossTenant-mailboxtype: HOSTED X-MS-Exchange-CrossTenant-userprincipalname: im92GGfkBLp7xzFrq6lKj6tkjcpu6CoraYaHDd6qGxT5Vf2AMNkocOpu6yVWdrNV4oS+vg6Yq/s2Evq+XJpyOQ== X-MS-Exchange-Transport-CrossTenantHeadersStamped: IA1PR11MB7871 X-OriginatorOrg: intel.com Subject: Re: [Intel-gfx] [PATCH v6 12/24] vfio/pci: Allow passing zero-length fd array in VFIO_DEVICE_PCI_HOT_RESET X-BeenThere: intel-gfx@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Intel graphics driver community testing & development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: "linux-s390@vger.kernel.org" , "Liu, Yi L" , "yi.y.sun@linux.intel.com" , "mjrosato@linux.ibm.com" , "kvm@vger.kernel.org" , "jasowang@redhat.com" , "robin.murphy@arm.com" , "joro@8bytes.org" , "cohuck@redhat.com" , "Hao, Xudong" , "peterx@redhat.com" , "eric.auger@redhat.com" , "Xu, Terrence" , "nicolinc@nvidia.com" , "shameerali.kolothum.thodi@huawei.com" , "suravee.suthikulpanit@amd.com" , "chao.p.peng@linux.intel.com" , "Zhao, Yan Y" , "lulu@redhat.com" , "intel-gvt-dev@lists.freedesktop.org" , "intel-gfx@lists.freedesktop.org" Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" > From: Yi Liu > Sent: Wednesday, March 8, 2023 9:29 PM >=20 > This is another method to issue PCI hot reset for the users that bounds > device to a positive iommufd value. In such case, iommufd is a proof of > device ownership. By passing a zero-length fd array, user indicates kerne= l > to do ownership check with the bound iommufd. All the opened devices > within > the affected dev_set should have been bound to the same iommufd. This is > simpler and faster as user does not need to pass a set of fds and kernel > no need to search the device within the given fds. >=20 > Suggested-by: Jason Gunthorpe > Signed-off-by: Yi Liu I think you also need a s-o-b from Jason since he wrote most of the code here. > +struct iommufd_ctx *vfio_iommufd_physical_ctx(struct vfio_device *vdev) > +{ > + /* Only serve for physical device */ > + if (!vdev->iommufd_device) > + return NULL; pointless comment > --- a/include/uapi/linux/vfio.h > +++ b/include/uapi/linux/vfio.h > @@ -682,6 +682,11 @@ struct vfio_pci_hot_reset_info { > * The ownership can be proved by: > * - An array of group fds > * - An array of device fds > + * - A zero-length array > + * > + * In the last case all affected devices which are opened by this user > + * must have been bound to a same iommufd_ctx. This approach is only > + * available for devices bound to positive iommufd. As we chatted before I still think the last sentence is pointless. If a dev= ice is bound to negative iommufd value (i.e. noiommu) it doesn't have a valid iommufd_ctx so won't meet "bound to a same iommufd_ctx".=20