gpa2hva: add INVAVLID_HPA return value check

For return value of local_gpa2hpa, either INVALID_HPA or NULL
means the EPT walking failure. Current code only take care of
NULL return and leave INVALID_HPA as correct case.

In some cases (if guest page table is filled with invalid memory
address), it could crash ACRN from guest.

Add INVALID_HPA return check as well.
Also add @pre assumptions for some gpa2hpa usages.

Tracked-On: #4730
Signed-off-by: Yin Fengwei <fengwei.yin@intel.com>

hypervisor/arch/x86/configs/vacpi.c

@@ -113,6 +113,7 @@ static struct acpi_table_info acpi_table_template[CONFIG_MAX_VM_NUM] = {
 /**
  * @pre vm != NULL
  * @pre vm->vm_id < CONFIG_MAX_VM_NUM
+ * @pre (vm->min_mem_addr <= ACPI_XSDT_ADDR) && (ACPI_XSDT_ADDR < vm->max_mem_addr)
  */
 void build_vacpi(struct acrn_vm *vm)
 {