> From: Liu, Yi L <yi.l.liu@xxxxxxxxx> > Sent: Tuesday, February 21, 2023 11:48 AM > > This allows user to directly open a vfio device w/o using the legacy > container/group interface, as a prerequisite for supporting new iommu > features like nested translation. > > The device fd opened in this manner doesn't have the capability to access > the device as the fops open() doesn't open the device until the successful > BIND_IOMMUFD which be added in next patch. > > With this patch, devices registered to vfio core have both group and device > interface created. > > - group interface : /dev/vfio/$groupID > - device interface: /dev/vfio/devices/vfioX (X is the minor number and > is unique across devices) > > Given a vfio device the user can identify the matching vfioX by checking > the sysfs path of the device. Take PCI device (0000:6a:01.0) for example, > /sys/bus/pci/devices/0000\:6a\:01.0/vfio-dev/vfio0/dev contains the > major:minor of the matching vfioX. > > Userspace then opens the /dev/vfio/devices/vfioX and checks with fstat > that the major:minor matches. > > The vfio_device cdev logic in this patch: > *) __vfio_register_dev() path ends up doing cdev_device_add() for each > vfio_device; > *) vfio_unregister_group_dev() path does cdev_device_del(); > > Signed-off-by: Yi Liu <yi.l.liu@xxxxxxxxx> Reviewed-by: Kevin Tian <kevin.tian@xxxxxxxxx>
