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/include/arch/x86/per_cpu.h

@@ -18,6 +18,7 @@
 #include <gdt.h>
 #include <schedule.h>
 #include <security.h>
+#include <vm_config.h>
 
 struct per_cpu_region {
 	/* vmxon_region MUST be 4KB-aligned */
@@ -52,6 +53,7 @@ struct per_cpu_region {
 #ifdef PROFILING_ON
 	struct profiling_info_wrapper profiling_info;
 #endif
+	uint16_t shutdown_vm_id;
 } __aligned(PAGE_SIZE); /* per_cpu_region size aligned with PAGE_SIZE */
 
 extern struct per_cpu_region per_cpu_data[CONFIG_MAX_PCPU_NUM];