1 files changed, 103 insertions, 0 deletions
diff --git a/arch/x86/kernel/cpu/topology.c b/arch/x86/kernel/cpu/topology.c
new file mode 100644
index 000000000..71ca064e3
--- /dev/null
+++ b/arch/x86/kernel/cpu/topology.c
@@ -0,0 +1,103 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Check for extended topology enumeration cpuid leaf 0xb and if it
+ * exists, use it for populating initial_apicid and cpu topology
+ * detection.
+ */
+
+#include <linux/cpu.h>
+#include <asm/apic.h>
+#include <asm/pat.h>
+#include <asm/processor.h>
+
+/* leaf 0xb SMT level */
+#define SMT_LEVEL	0
+
+/* leaf 0xb sub-leaf types */
+#define INVALID_TYPE	0
+#define SMT_TYPE	1
+#define CORE_TYPE	2
+
+#define LEAFB_SUBTYPE(ecx)		(((ecx) >> 8) & 0xff)
+#define BITS_SHIFT_NEXT_LEVEL(eax)	((eax) & 0x1f)
+#define LEVEL_MAX_SIBLINGS(ebx)		((ebx) & 0xffff)
+
+int detect_extended_topology_early(struct cpuinfo_x86 *c)
+{
+#ifdef CONFIG_SMP
+	unsigned int eax, ebx, ecx, edx;
+
+	if (c->cpuid_level < 0xb)
+		return -1;
+
+	cpuid_count(0xb, SMT_LEVEL, &eax, &ebx, &ecx, &edx);
+
+	/*
+	 * check if the cpuid leaf 0xb is actually implemented.
+	 */
+	if (ebx == 0 || (LEAFB_SUBTYPE(ecx) != SMT_TYPE))
+		return -1;
+
+	set_cpu_cap(c, X86_FEATURE_XTOPOLOGY);
+
+	/*
+	 * initial apic id, which also represents 32-bit extended x2apic id.
+	 */
+	c->initial_apicid = edx;
+	smp_num_siblings = LEVEL_MAX_SIBLINGS(ebx);
+#endif
+	return 0;
+}
+
+/*
+ * Check for extended topology enumeration cpuid leaf 0xb and if it
+ * exists, use it for populating initial_apicid and cpu topology
+ * detection.
+ */
+int detect_extended_topology(struct cpuinfo_x86 *c)
+{
+#ifdef CONFIG_SMP
+	unsigned int eax, ebx, ecx, edx, sub_index;
+	unsigned int ht_mask_width, core_plus_mask_width;
+	unsigned int core_select_mask, core_level_siblings;
+
+	if (detect_extended_topology_early(c) < 0)
+		return -1;
+
+	/*
+	 * Populate HT related information from sub-leaf level 0.
+	 */
+	cpuid_count(0xb, SMT_LEVEL, &eax, &ebx, &ecx, &edx);
+	core_level_siblings = smp_num_siblings = LEVEL_MAX_SIBLINGS(ebx);
+	core_plus_mask_width = ht_mask_width = BITS_SHIFT_NEXT_LEVEL(eax);
+
+	sub_index = 1;
+	do {
+		cpuid_count(0xb, sub_index, &eax, &ebx, &ecx, &edx);
+
+		/*
+		 * Check for the Core type in the implemented sub leaves.
+		 */
+		if (LEAFB_SUBTYPE(ecx) == CORE_TYPE) {
+			core_level_siblings = LEVEL_MAX_SIBLINGS(ebx);
+			core_plus_mask_width = BITS_SHIFT_NEXT_LEVEL(eax);
+			break;
+		}
+
+		sub_index++;
+	} while (LEAFB_SUBTYPE(ecx) != INVALID_TYPE);
+
+	core_select_mask = (~(-1 << core_plus_mask_width)) >> ht_mask_width;
+
+	c->cpu_core_id = apic->phys_pkg_id(c->initial_apicid, ht_mask_width)
+						 & core_select_mask;
+	c->phys_proc_id = apic->phys_pkg_id(c->initial_apicid, core_plus_mask_width);
+	/*
+	 * Reinit the apicid, now that we have extended initial_apicid.
+	 */
+	c->apicid = apic->phys_pkg_id(c->initial_apicid, 0);
+
+	c->x86_max_cores = (core_level_siblings / smp_num_siblings);
+#endif
+	return 0;
+}