> From: Liu, Yi L <yi.l.liu@xxxxxxxxx> > Sent: Tuesday, January 17, 2023 9:50 PM > > Allow the vfio_device file to be in a state where the device FD is > opened but the device cannot be used by userspace (i.e. its .open_device() > hasn't been called). This inbetween state is not used when the device > FD is spawned from the group FD, however when we create the device FD > directly by opening a cdev it will be opened in the blocked state. > > In the blocked state, currently only the bind operation is allowed, > other device accesses are not allowed. Completing bind will allow user > to further access the device. > > This is implemented by adding a flag in struct vfio_device_file to mark > the blocked state and using a simple smp_load_acquire() to obtain the > flag value and serialize all the device setup with the thread accessing > this device. > > Due to this scheme it is not possible to unbind the FD, once it is bound, > it remains bound until the FD is closed. > My question to the last version was not answered... Can you elaborate why it is impossible to unbind? Is it more an implementation choice or conceptual restriction?
