On Fri, 31 Mar 2023 03:14:23 +0000 "Jiang, Yanting" <yanting.jiang@xxxxxxxxx> wrote: > > > > VFIO_DEVICE_PCI_HOT_RESET requires user to pass an array of group fds to > > prove that it owns all devices affected by resetting the calling device. This series > > introduces several extensions to allow the ownership check better aligned with > > iommufd and coming vfio device cdev support. > > > > First, resetting an unopened device is always safe given nobody is using it. So > > relax the check to allow such devices not covered by group fd array. [1] > > > > When iommufd is used we can simply verify that all affected devices are bound > > to a same iommufd then no need for the user to provide extra fd information. > > This is enabled by the user passing a zero-length fd array and moving forward > > this should be the preferred way for hot reset. [2] > > > > However the iommufd method has difficulty working with noiommu devices > > since those devices don't have a valid iommufd, unless the noiommu device is in > > a singleton dev_set hence no ownership check is required. [3] > > > > For noiommu backward compatibility a 3rd method is introduced by allowing the > > user to pass an array of device fds to prove ownership. [4] > > > > As suggested by Jason [5], we have this series to introduce the above stuffs to > > the vfio PCI hot reset. Per the dicussion in [6], this series also adds a new _INFO > > ioctl to get hot reset scope for given device. > > > Tested NIC passthrough on Intel platform. > Result looks good hence, > Tested by: Jiang, Yanting <yanting.jiang@xxxxxxxxx> I'm not aware of any userspace that exercises this reset ioctl in cdev mode. Is this regression testing only? Thanks, Alex
