On Thu, Oct 30, 2025 at 5:19 PM Pasha Tatashin <[email protected]> wrote: > On Thu, Oct 30, 2025 at 7:10 PM David Matlack <[email protected]> wrote: > > On 2025-10-27 01:44 PM, Jacob Pan wrote: > > > On Fri, 17 Oct 2025 17:06:58 -0700 Vipin Sharma <[email protected]> > > > wrote: > > > > + guard(mutex)(&device->dev_set->lock); > > > > + return vfio_device_cdev_opened(device); > > > > > > IIUC, vfio_device_cdev_opened(device) will only return true after > > > vfio_df_ioctl_bind_iommufd(). Where it does: > > > device->cdev_opened = true; > > > > > > Does this imply that devices not bound to an iommufd cannot be > > > preserved? > > > > Event if being bound to an iommufd is required, it seems wrong to check > > it in can_preserve(), as the device can just be unbound from the iommufd > > before preserve(). > > > > I think can_preserve() just needs to check if this is a VFIO cdev file, > > i.e. vfio_device_from_file() returns non-NULL. > > +1, can_preserve() must be fast, as it might be called on every single > FD that is being preserved, to check if type is correct. > So, simply check if "struct file" is cdev via ops check perhaps via > and thats it. It should be a very simple operation
Small correction, vfio_device_from_file() checks if file->fops are &vfio_device_fops. But device files acquired via group FDs use the same ops. So I think we actually need to check "device && !device->group" here to identify VFIO cdev files, and then check device->ops == &vfio_pci_ops to make sure this is a vfio-pci device.
