Problem with usb device redirect with qemu-kvm under ubuntu 16.04.3

If you don't see any redirected usb devices in guest system, try to edit
sudo joe /etc/apparmor.d/abstractions/libvirt-qem

that it looks like
...
  # for usb access
  /dev/bus/usb/ rw,
  /etc/udev/udev.conf r,
  /sys/bus/ r,
  /sys/class/ r,
  /dev/bus/usb/*/[0-9]* rw,
  /run/udev/** rw,

...

Mount ecryptfs

# ecryptfs-recover-private .Private 

# mount -o remount,rw /path/to/.../.Private /tmp/ecryptfs.XXXXXXXX