> From: Matthew Rosato <mjrosato@xxxxxxxxxxxxx> > Sent: Wednesday, February 1, 2023 4:07 AM > > - device->kvm = kvm; > + /* > + * Get the KVM pointer currently associated with the group, if there > + * is one, and obtain a reference now that will be held until the > + * open_count reaches 0. Save the pointer in the device for use by > + * drivers. > + */ > + spin_lock_irqsave(&group->kvm_ref_lock, flags); > + if (group->kvm && vfio_kvm_get_kvm_safe(device, group->kvm)) > + device->kvm = group->kvm; > + spin_unlock_irqrestore(&group->kvm_ref_lock, flags); > + No group reference in vfio_main.c. btw Yi, looks the deadlock issue also exists in your cdev work. kvm_vfio_release() holds kvm lock and then try to acquire device->device_set->lock in vfio_device_file_set_kvm(). vfio_device_ioctl_bind_iommufd() holds device->device_set->lock and then call vfio_device_open() which finally hit kvm lock acquisition in driver's open_device routine (e.g. vfio-ap). A similar fix is required in your series. Thanks Kevin
