hv: implement NEED_SHUTDOWN_VM request to idle thread

For pre-launched VMs and SOS, VM shutdown should not be executed in the
current VM context.

- implement NEED_SHUTDOWN_VM request so that the BSP of the target VM can shut
  down the guest in idle thread.
- implement shutdown_vm_from_idle() to shut down target VM.

Tracked-On: #2700
Signed-off-by: Zide Chen <zide.chen@intel.com>
Signed-off-by: Sainath Grandhi <sainath.grandhi@intel.com>
Acked-by: Eddie Dong <eddie.dong@intel.com>

hypervisor/common/hv_main.c

@@ -5,6 +5,7 @@
  */
 
 #include <vm.h>
+#include <vm_reset.h>
 #include <vmcs.h>
 #include <vmexit.h>
 #include <irq.h>
@@ -88,6 +89,8 @@ void default_idle(__unused struct sched_object *obj)
 			schedule();
 		} else if (need_offline(pcpu_id) != 0) {
 			cpu_dead();
+		} else if (need_shutdown_vm(pcpu_id)) {
+			shutdown_vm_from_idle(pcpu_id);
 		} else {
 			CPU_IRQ_ENABLE();
 			cpu_do_idle();