xenmgr: Re-work rebootVM as shutdown & start

Replace the use of `xl reboot` by `xl shutdown` and `xl start` to
implement the vm reboot DBus command.  xl shutdown needs
on_reboot="destroy" in the xl.cfg file.  This allows us to remove the
xenmgr <-> xl signal synchronization.

Xl.shutdown & RpcAgent shutdowns both wait for the VM to shutdown,
except the `xl shutdown -c` hypercall version which seems to terminate
right quick.  The waitForState call is therefore not really implementing
a timeout out.

The corner case is if the VM has ACPI & no PV drivers, but is configured
not to react to the power button.  In that case we can't do much.  If
the VM then internally reboots, the xenmgr React code will reboot the VM
and the waitForState will eventually timeout.

writeXlConfig is removed as rebootVm -> restartVm -> _startVm
startVmInternal -> bootVm calls writeXlConfig.

Signed-off-by: Jason Andryuk <jandryuk@gmail.com>

Author: jandryuk

xenmgr/Vm/Actions.hs

@@ -1018,15 +1018,15 @@ applyVmBackendShift bkuuid = do
 
 
 -- Reboot a VM
-rebootVm :: Uuid -> Rpc ()
+rebootVm :: Uuid -> XM ()
 rebootVm uuid = do
     info $ "rebooting VM " ++ show uuid
-    -- Write XL configuration file
-    writeXlConfig =<< getVmConfig uuid True
-    --Let xl take care of bringing down the domain and updating our state
-    --When xenmgr sees the 'Rebooted' state, it fires off a startVm call,
-    --which performs all the normal guest boot tasks, while xl brings up the domain.
-    liftIO $ Xl.reboot uuid
+    debug $ "reboot issuing shutdown to " ++ show uuid
+    liftRpc $ shutdownVm uuid
+    debug $ "reboot done issuing shutdown to " ++ show uuid
+    done <- liftIO $ Xl.waitForState uuid Shutdown (Just 60)
+    debug $ "reboot waitForState returned " ++ show done
+    when done $ restartVm uuid
 
 shutdownVm :: Uuid -> Rpc ()
 shutdownVm uuid = do

xenmgr/XenMgr/Expose/VmObject.hs

@@ -104,7 +104,7 @@ implementationFor xm uuid = self where
   , comCitrixXenclientXenmgrVmSwitch             = switchVm uuid >> return ()
   , comCitrixXenclientXenmgrVmStart              = runXM xm (startVm uuid) >> return ()
   , comCitrixXenclientXenmgrVmStartInternal      = runXM xm (startVmInternal uuid False) >> return ()
-  , comCitrixXenclientXenmgrVmReboot             = rebootVm uuid
+  , comCitrixXenclientXenmgrVmReboot             = runXM xm (rebootVm uuid) >> return ()
   , comCitrixXenclientXenmgrVmShutdown           = runvm invokeShutdownVm
   , comCitrixXenclientXenmgrVmDestroy            = runvm invokeForceShutdownVm
   , comCitrixXenclientXenmgrVmSleep              = sleepVm uuid

xenmgr/XenMgr/PowerManagement.hs

@@ -283,7 +283,7 @@ resumeS3' uuid S3Pv = do
   void . liftIO $ Xl.resumeFromSleep uuid
   info $ "PM: Successfully resumed " ++ show uuid ++ " from S3"
 resumeS3' uuid S3Restart = do
-  liftRpc $ rebootVm uuid
+  a <- rebootVm uuid
   info $ "PM: Restarted " ++ show uuid ++ " after S3"
 
 resumeS3' uuid S3Snapshot =