> 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-by: Yanting Jiang <yanting.jiang@xxxxxxxxx> Thanks, Yanting
