svm: adopt "JDK-8365673: Incorrect number of cores are reported on Ryzen CPU"

Author: zapster

substratevm/src/com.oracle.svm.core/src/com/oracle/svm/core/amd64/AMD64LibCHelper.java

@@ -43,7 +43,7 @@
  *  - substratevm/src/com.oracle.svm.native.libchelper/include/amd64hotspotcpuinfo.h
  *  - substratevm/src/com.oracle.svm.native.libchelper/src/cpuid.c
  */
-@BasedOnJDKFile("https://github.com/openjdk/jdk/blob/jdk-25+23/src/hotspot/cpu/x86/vm_version_x86.hpp#L41-L348")
+@BasedOnJDKFile("https://github.com/openjdk/jdk/blob/jdk-26+13/src/hotspot/cpu/x86/vm_version_x86.hpp#L43-L351")
 @CLibrary(value = "libchelper", requireStatic = true)
 public class AMD64LibCHelper {
     @Platforms(Platform.AMD64.class)

substratevm/src/com.oracle.svm.native.libchelper/include/amd64hotspotcpuinfo.h

@@ -188,8 +188,8 @@ typedef union {
 typedef union {
   uint32_t value;
   struct {
-    uint32_t cores_per_cpu : 8,
-                           : 24;
+    uint32_t threads_per_cpu : 8,
+                             : 24;
   } bits;
 } ExtCpuid8Ecx;
 

substratevm/src/com.oracle.svm.native.libchelper/src/cpuid.c

@@ -211,7 +211,10 @@ static uint32_t cores_per_cpu(CpuidInfo *_cpuid_info) {
   }
   else if (is_amd_family(_cpuid_info))
   {
-    result = (_cpuid_info->ext_cpuid8_ecx.bits.cores_per_cpu + 1);
+    result = _cpuid_info->ext_cpuid8_ecx.bits.threads_per_cpu + 1;
+    if (cpu_family(_cpuid_info) >= 0x17) { // Zen or later
+      result /= _cpuid_info->ext_cpuid1E_ebx.bits.threads_per_core + 1;
+    }
   }
   else if (is_zx(_cpuid_info))
   {