8301050: Detect Xen Virtualization on Linux aarch64

Reviewed-by: dholmes, clanger

src/hotspot/cpu/aarch64/vm_version_aarch64.cpp

@@ -564,26 +564,40 @@ void VM_Version::initialize() {
   check_virtualizations();
 }
 
-void VM_Version::check_virtualizations() {
 #if defined(LINUX)
-  const char* info_file = "/sys/devices/virtual/dmi/id/product_name";
-  // check for various strings in the dmi data indicating virtualizations
+static bool check_info_file(const char* fpath,
+                            const char* virt1, VirtualizationType vt1,
+                            const char* virt2, VirtualizationType vt2) {
   char line[500];
-  FILE* fp = os::fopen(info_file, "r");
+  FILE* fp = os::fopen(fpath, "r");
   if (fp == nullptr) {
-    return;
+    return false;
   }
   while (fgets(line, sizeof(line), fp) != nullptr) {
-    if (strcasestr(line, "KVM") != 0) {
-      Abstract_VM_Version::_detected_virtualization = KVM;
-      break;
+    if (strcasestr(line, virt1) != 0) {
+      Abstract_VM_Version::_detected_virtualization = vt1;
+      fclose(fp);
+      return true;
     }
-    if (strcasestr(line, "VMware") != 0) {
-      Abstract_VM_Version::_detected_virtualization = VMWare;
-      break;
+    if (virt2 != NULL && strcasestr(line, virt2) != 0) {
+      Abstract_VM_Version::_detected_virtualization = vt2;
+      fclose(fp);
+      return true;
     }
   }
   fclose(fp);
+  return false;
+}
+#endif
+
+void VM_Version::check_virtualizations() {
+#if defined(LINUX)
+  const char* pname_file = "/sys/devices/virtual/dmi/id/product_name";
+  const char* tname_file = "/sys/hypervisor/type";
+  if (check_info_file(pname_file, "KVM", KVM, "VMWare", VMWare)) {
+    return;
+  }
+  check_info_file(tname_file, "Xen", XenHVM, NULL, NoDetectedVirtualization);
 #endif
 }
 

src/hotspot/share/runtime/abstract_vm_version.hpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1997, 2022, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1997, 2023, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -71,9 +71,10 @@ class Abstract_VM_Version: AllStatic {
   static int          _vm_build_number;
   static unsigned int _data_cache_line_flush_size;
 
+ public:
+
   static VirtualizationType _detected_virtualization;
 
- public:
   // Called as part of the runtime services initialization which is
   // called from the management module initialization (via init_globals())
   // after argument parsing and attaching of the main thread has