hvm, x86: Allow virtual timer mode to be specified.

In HVM config file:
timer_mode=0 # Default: virtual time is delayed when timer ticks are
             # missed dur to preemption
timer_mode=1 # Virtual time always equals wall time, even while missed
             # ticks are pending

From: Haitao Shan <haitao.shan@intel.com>
Signed-off-by: Keir Fraser <keir@xensource.com>

tools/python/xen/xend/XendConfig.py

@@ -127,7 +127,7 @@ XENAPI_PLATFORM_CFG = [ 'acpi', 'apic', 'boot', 'device_model', 'display',
                         'fda', 'fdb', 'keymap', 'isa', 'localtime', 'monitor', 
                         'nographic', 'pae', 'rtc_timeoffset', 'serial', 'sdl',
                         'soundhw','stdvga', 'usb', 'usbdevice', 'vnc',
-                        'vncconsole', 'vncdisplay', 'vnclisten',
+                        'vncconsole', 'vncdisplay', 'vnclisten', 'timer_mode',
                         'vncpasswd', 'vncunused', 'xauthority', 'pci', 'vhpt']
 
 # Xen API console 'other_config' keys.

tools/python/xen/xend/XendConstants.py

@@ -46,6 +46,7 @@ HVM_PARAM_BUFIOREQ_PFN = 6
 HVM_PARAM_NVRAM_FD     = 7
 HVM_PARAM_VHPT_SIZE    = 8
 HVM_PARAM_BUFPIOREQ_PFN = 9
+HVM_PARAM_TIMER_MODE   = 10
 
 restart_modes = [
     "restart",

tools/python/xen/xend/XendDomainInfo.py

@@ -1596,6 +1596,11 @@ class XendDomainInfo:
 
         self._recreateDom()
 
+        # Set timer configration of domain
+        if hvm:
+            xc.hvm_set_param(self.domid, HVM_PARAM_TIMER_MODE,
+                long(self.info["platform"].get("timer_mode")))
+
         # Set maximum number of vcpus in domain
         xc.domain_max_vcpus(self.domid, int(self.info['VCPUs_max']))
 

tools/python/xen/xm/create.py

@@ -194,6 +194,11 @@ gopts.var('pae', val='PAE',
           fn=set_int, default=1,
           use="Disable or enable PAE of HVM domain.")
 
+gopts.var('timer_mode', val='TIMER_MODE',
+          fn=set_int, default=0,
+          use="""Timer mode (0=delay virtual time when ticks are missed;
+          1=virtual time is always wallclock time.""")
+
 gopts.var('acpi', val='ACPI',
           fn=set_int, default=1,
           use="Disable or enable ACPI of HVM domain.")
@@ -724,7 +729,7 @@ def configure_vifs(config_devs, vals):
 def configure_hvm(config_image, vals):
     """Create the config for HVM devices.
     """
-    args = [ 'device_model', 'pae', 'vcpus', 'boot', 'fda', 'fdb',
+    args = [ 'device_model', 'pae', 'vcpus', 'boot', 'fda', 'fdb', 'timer_mode',
              'localtime', 'serial', 'stdvga', 'isa', 'nographic', 'soundhw',
              'vnc', 'vncdisplay', 'vncunused', 'vncconsole', 'vnclisten',
              'sdl', 'display', 'xauthority', 'rtc_timeoffset', 'monitor',

tools/python/xen/xm/xenapi_create.py

@@ -818,7 +818,7 @@ class sxp2xml:
 
 
     def extract_platform(self, image, document):
-        platform_keys = ['acpi', 'apic', 'pae', 'vhpt']
+        platform_keys = ['acpi', 'apic', 'pae', 'vhpt', 'timer_mode']
 
         def extract_platform_key(key):
             platform = document.createElement("platform")