> From: Jason Gunthorpe <jgg@xxxxxxxxxx> > Sent: Tuesday, February 28, 2023 3:21 AM > > On Mon, Feb 27, 2023 at 03:11:16AM -0800, 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. Then refactors the vfio to be > > able to handle iommufd binding. This refactor includes the mechanism of > > blocking device access before iommufd bind, making the device_open > exclusive. > > between the group path and the cdev path. Eventually, adds the cdev > support > > for vfio device, and makes group infrastructure optional as it is not needed > > when vfio device cdev is compiled. > > > > This is also a prerequisite for iommu nesting for vfio device[2]. > > > > The complete code can be found in below branch, simple test done with > the > > legacy group path and the cdev path. Draft QEMU branch can be found > at[3] > > > > https://github.com/yiliu1765/iommufd/tree/vfio_device_cdev_v5 > > (config CONFIG_IOMMUFD=y CONFIG_VFIO_DEVICE_CDEV=y) > > > > base-commit: 63777bd2daa3625da6eada88bd9081f047664dad > > This needs to be rebased onto a clean v6.3-rc1 when it comes out Yes, I'll send rebase and send one more version when v6.3-rc1 comes. Here just try to be near to the vfio code in Alex's next branch. Regards, Yi Liu
