1 files changed, 45 insertions, 0 deletions
diff --git a/src/cpu/intel/common/hyperthreading.c b/src/cpu/intel/common/hyperthreading.c
new file mode 100644
index 0000000000..4caf49e5b6
--- /dev/null
+++ b/src/cpu/intel/common/hyperthreading.c
@@ -0,0 +1,45 @@
+/*
+ * This file is part of the coreboot project.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <cpu/x86/lapic.h>
+#include <cpu/intel/common/common.h>
+#include <arch/cpu.h>
+
+/*
+ * Return true if running thread does not have the smallest lapic ID
+ * within a CPU core.
+ */
+bool intel_ht_sibling(void)
+{
+	struct cpuid_result result;
+	unsigned int core_ids, apic_ids, threads;
+
+	/* Is Hyper-Threading supported */
+	if (!(cpuid_edx(1) & CPUID_FEAURE_HTT))
+		return false;
+
+	apic_ids = 1;
+	if (cpuid_eax(0) >= 1)
+		apic_ids = (cpuid_ebx(1) >> 16) & 0xff;
+	if (apic_ids == 0)
+		apic_ids = 1;
+
+	core_ids = 1;
+	if (cpuid_eax(0) >= 4) {
+		result = cpuid_ext(4, 0);
+		core_ids += (result.eax >> 26) & 0x3f;
+	}
+
+	threads = (apic_ids / core_ids);
+	return !!(lapicid() & (threads - 1));
+}