stdlib: AbstractCore calls ArmV8KvmCPU class for aarch64

This change calls the stdlib's correct ArmKvmCPU class (ArmKvmCPU or
ArmV8KVMCPU) depending upon the host machine's architecture when
using KVM cores with ARM ISA.

Change-Id: I2ba8070825503659cd93da15da8507528d7f12ad
Signed-off-by: Kaustav Goswami <kggoswami@ucdavis.edu>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/60329
Maintainer: Bobby Bruce <bbruce@ucdavis.edu>
Tested-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: Bobby Bruce <bbruce@ucdavis.edu>

src/python/gem5/components/processors/abstract_core.py

@@ -27,6 +27,7 @@
 from abc import ABCMeta, abstractmethod
 from typing import Optional
 import importlib
+import platform
 
 from .cpu_types import CPUTypes
 from ...isas import ISA
@@ -34,7 +35,6 @@ from ...utils.requires import requires
 
 from m5.objects import BaseMMU, Port, SubSystem
 
-
 class AbstractCore(SubSystem):
     __metaclass__ = ABCMeta
 
@@ -158,8 +158,18 @@ class AbstractCore(SubSystem):
         else:
             module_str = f"m5.objects.{_isa_string_map[isa]}CPU"
 
-        cpu_class_str = f"{_isa_string_map[isa]}"\
-                        f"{_cpu_types_string_map[cpu_type]}"
+        # GEM5 compiles two versions of KVM for ARM depending upon the host CPU
+        # : ArmKvmCPU and ArmV8KvmCPU for 32 bit (Armv7l) and 64 bit (Armv8)
+        # respectively.
+
+        if isa.name == "ARM" and \
+                cpu_type == CPUTypes.KVM and \
+                platform.architecture()[0] == "64bit":
+            cpu_class_str = f"{_isa_string_map[isa]}V8"\
+                            f"{_cpu_types_string_map[cpu_type]}"
+        else:
+            cpu_class_str = f"{_isa_string_map[isa]}"\
+                            f"{_cpu_types_string_map[cpu_type]}"
 
         try:
             to_return_cls = getattr(importlib.import_module(module_str),