8295844: jdk/test/whitebox/CPUInfoTest.java failed with "not all features are known: expected true, was false"

Reviewed-by: tschatzl, dnsimon

src/hotspot/cpu/x86/vm_version_x86.hpp

@@ -311,6 +311,11 @@ protected:
   static address   _cpuinfo_segv_addr; // address of instruction which causes SEGV
   static address   _cpuinfo_cont_addr; // address of instruction after the one which causes SEGV
 
+  /*
+   * Update following files when declaring new flags:
+   * test/lib-test/jdk/test/whitebox/CPUInfoTest.java
+   * src/jdk.internal.vm.ci/share/classes/jdk.vm.ci.amd64/src/jdk/vm/ci/amd64/AMD64.java
+   */
   enum Feature_Flag : uint64_t {
 #define CPU_FEATURE_FLAGS(decl) \
     decl(CX8,               "cx8",               0)  /*  next bits are from cpuid 1 (EDX) */ \

test/lib-test/jdk/test/whitebox/CPUInfoTest.java

@@ -64,7 +64,8 @@ public class CPUInfoTest {
                     "avx512_vnni",  "clflush",          "clflushopt",        "clwb",
                     "avx512_vbmi2", "avx512_vbmi",      "rdtscp",            "rdpid",
                     "hv",           "fsrm",             "avx512_bitalg",     "gfni",
-                    "f16c"
+                    "f16c",         "pku",              "ospke",             "cet_ibt",
+                    "cet_ss"
                     );
             // @formatter:on
             // Checkstyle: resume