hvm: add ACPI power button for HVM

This patch adds the ACPI fixed hardware power button for HVM.
It enables a graceful shutdown of a guest OS by direction of Dom0.
(if a proper action for the power button is set inside the guest)

usage:
  xm trigger <Domain> power

Signed-off-by: Kouya Shimura <kouya@jp.fujitsu.com>

tools/python/xen/xend/XendConstants.py

@@ -105,13 +105,15 @@ LAST_SHUTDOWN_REASON = 'xend/last_shutdown_reason'
 TRIGGER_NMI   = 0
 TRIGGER_RESET = 1
 TRIGGER_INIT  = 2
-TRIGGER_S3RESUME = 3
+TRIGGER_POWER = 3
+TRIGGER_S3RESUME = 4
 
 TRIGGER_TYPE = {
     "nmi"   : TRIGGER_NMI,
     "reset" : TRIGGER_RESET,
     "init"  : TRIGGER_INIT,
-    "s3resume": TRIGGER_S3RESUME
+    "s3resume": TRIGGER_S3RESUME,
+    "power": TRIGGER_POWER
 }
 
 #

tools/python/xen/xm/main.py

@@ -151,7 +151,7 @@ SUBCOMMAND_HELP = {
                      'Get/set credit scheduler parameters.'),
     'sysrq'       : ('<Domain> <letter>', 'Send a sysrq to a domain.'),
     'debug-keys'  : ('<Keys>', 'Send debug keys to Xen.'),
-    'trigger'     : ('<Domain> <nmi|reset|init|s3resume> [<VCPU>]',
+    'trigger'     : ('<Domain> <nmi|reset|init|s3resume|power> [<VCPU>]',
                      'Send a trigger to a domain.'),
     'vcpu-list'   : ('[Domain, ...]',
                      'List the VCPUs for all/some domains.'),