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Wed, 22 Mar 2023 04:42:16 +0000 Received: from DS0PR11MB7529.namprd11.prod.outlook.com ([fe80::6f7:944a:aaad:301f]) by DS0PR11MB7529.namprd11.prod.outlook.com ([fe80::6f7:944a:aaad:301f%8]) with mapi id 15.20.6178.037; Wed, 22 Mar 2023 04:42:16 +0000 From: "Liu, Yi L" To: Alex Williamson , Jason Gunthorpe CC: "Tian, Kevin" , "kvm@vger.kernel.org" , "jasowang@redhat.com" , "Hao, Xudong" , "peterx@redhat.com" , "Xu, Terrence" , "chao.p.peng@linux.intel.com" , "linux-s390@vger.kernel.org" , "mjrosato@linux.ibm.com" , "lulu@redhat.com" , "joro@8bytes.org" , "nicolinc@nvidia.com" , "Zhao, Yan Y" , "intel-gfx@lists.freedesktop.org" , "eric.auger@redhat.com" , "intel-gvt-dev@lists.freedesktop.org" , "yi.y.sun@linux.intel.com" , "cohuck@redhat.com" , "shameerali.kolothum.thodi@huawei.com" , "suravee.suthikulpanit@amd.com" , "robin.murphy@arm.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: AQHZW095081R6kW/70aeRy5pC5KSt68ERp6AgAANFoCAAV3gAIAABT4AgAADFwCAABYxgIAAB4uAgABetDA= Date: Wed, 22 Mar 2023 04:42:16 +0000 Message-ID: References: <20230316182256.6659bbbd.alex.williamson@redhat.com> <20230317091557.196638a6.alex.williamson@redhat.com> <20230320165217.5b1019a4.alex.williamson@redhat.com> <20230321143122.632f7e63.alex.williamson@redhat.com> <20230321150112.1c482380.alex.williamson@redhat.com> <20230321164737.62b45132.alex.williamson@redhat.com> In-Reply-To: <20230321164737.62b45132.alex.williamson@redhat.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: DS0PR11MB7529.namprd11.prod.outlook.com X-MS-Exchange-CrossTenant-Network-Message-Id: 914f9816-1987-4881-17e0-08db2a8fd010 X-MS-Exchange-CrossTenant-originalarrivaltime: 22 Mar 2023 04:42:16.2139 (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: wPS8zAz6Y+rhRj76Ef8Dd62mD3J4Z1qGqhb5Tm0s/JOijV/+14ZB/Kh5ERL+EflzJLNSTKs5JUt63hKDsLI+sg== X-MS-Exchange-Transport-CrossTenantHeadersStamped: SA1PR11MB7061 X-OriginatorOrg: intel.com Precedence: bulk List-ID: X-Mailing-List: linux-s390@vger.kernel.org > From: Alex Williamson > Sent: Wednesday, March 22, 2023 6:48 AM >=20 > On Tue, 21 Mar 2023 19:20:37 -0300 > Jason Gunthorpe wrote: >=20 > > On Tue, Mar 21, 2023 at 03:01:12PM -0600, Alex Williamson wrote: > > > > > > Though it would be nice if qemu didn't need two implementations so = Yi > > > > I'd rather see a new info in this series as well and qemu can just > > > > consistently use dev_id and never bdf in iommufd mode. > > > > > > We also need to consider how libvirt determines if QEMU has the kerne= l > > > support it needs to pass file descriptors. It'd be a lot cleaner if > > > this aligned with the introduction of vfio cdevs. > > > > Yes, that would be much better if it was one package. > > > > But this is starting to grow and we have so many threads that need to > > progress blocked on this cdev enablement :( > > > > Could we go forward with the cdev main patches and kconfig it to > > experimental or something while the rest of the parts are completed > > and tested through qemu? ie move the vfio-pci reset enablment to after > > the cdev patches? >=20 > We need to be able to guarantee that there cannot be any significant > builds of the kernel with vfio cdev support if our intention is to stage > it for libvirt. We don't have a global EXPERIMENTAL config option any > more. Adding new code under BROKEN seems wrong. Fedora ships with > STAGING enabled. A sternly worded Kconfig entry is toothless. What is > the proposed mechanism to make this not look like a big uncompiled code > dump? Thanks, Just out of curious, is the BDF mapping gap only for cdev or it also exists in the traditional group path? IMHO, if it is only a gap for cdev, m= aybe we can use CONFIG_VFIO_DEVICE_CDEV to stage it. This kconfig is N by default. I think it won't change until one day the whole ecosystem is updated. Anyhow, I'll also see the complexity of adding a new _INFO ioctl. It should return a set of dev_id to user rather than the bdf info in the existing _IN= FO ioctl. Is it? Regards, Yi Liu