qemu_log_mask(GUEST_ERROR) is more appropriate:

  $ qemu -d help
  Log items (comma separated):
  guest_errors    log when the guest OS does something invalid (eg accessing a non-existent register)

Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Acked-by: Michael Walle <michael@walle.cc>
Message-Id: <20181029130034.26750-1-f4bug@amsat.org>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>