On Tue, Jul 18, 2023 at 06:55:25AM -0700, Yi Liu wrote: > Existing VFIO provides group-centric user APIs for userspace. Userspace > opens the /dev/vfio/$group_id first before getting device fd and hence > getting access to device. This is not the desired model for iommufd. Per > the conclusion of community discussion[1], iommufd provides device-centric > kAPIs and requires its consumer (like VFIO) to be device-centric user > APIs. Such user APIs are used to associate device with iommufd and also > the I/O address spaces managed by the iommufd. > > This series first introduces a per device file structure to be prepared > for further enhancement and refactors the kvm-vfio code to be prepared > for accepting device file from userspace. After this, adds a mechanism for > blocking device access before iommufd bind. Then refactors the vfio to be > able to handle cdev paths (e.g. iommufd binding, no-iommufd, [de]attach ioas). > This refactor includes making the device_open exclusive between the group > and the cdev path, only allow single device open in cdev path; vfio-iommufd > code is also refactored to support cdev. e.g. split the vfio_iommufd_bind() > into two steps. Eventually, adds the cdev support for vfio device and the > new ioctls, then makes group infrastructure optional as it is not needed > when vfio device cdev is compiled. > > This series is based on some preparation works done to vfio emulated devices[2] > and vfio pci hot reset enhancements[3]. Per discussion[4], this series does not > support cdev for physical devices that do not have IOMMU. Such devices only > have group-centric user APIs. > > This series is a prerequisite for iommu nesting for vfio device[5] [6]. > > The complete code can be found in below branch, simple tests done to the > legacy group path and the cdev path. QEMU changes are in upstreaming[7] > and the complete code can be found at[8] > > https://github.com/yiliu1765/iommufd/tree/vfio_device_cdev_v15 > (config CONFIG_IOMMUFD=y CONFIG_VFIO_DEVICE_CDEV=y) Alex, if you are still good with this lets make this into a shared branch, do you want to do it or would you like a PR from me? Thanks, Jason
