This patch addes the debugexit function to DM. If it's enabled
by DM cmdline (by add --debugexit), the guest could write a
32bit value to port 0xF4 to trigger guest shutdown.
Tracked-on: #1465
Signed-off-by: Yin Fengwei <fengwei.yin@intel.com>
Reviewed-by: Jason Chen CJ <jason.cj.chen@intel.com>
Acked-by: Yu Wang <yu1.wang@intel.com>
