1 files changed, 55 insertions, 0 deletions
diff --git a/arch/x86/kernel/cpu/match.c b/arch/x86/kernel/cpu/match.c
new file mode 100644
index 000000000..751e59057
--- /dev/null
+++ b/arch/x86/kernel/cpu/match.c
@@ -0,0 +1,55 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <asm/cpu_device_id.h>
+#include <asm/cpufeature.h>
+#include <linux/cpu.h>
+#include <linux/export.h>
+#include <linux/slab.h>
+
+/**
+ * x86_match_cpu - match current CPU again an array of x86_cpu_ids
+ * @match: Pointer to array of x86_cpu_ids. Last entry terminated with
+ *         {}.
+ *
+ * Return the entry if the current CPU matches the entries in the
+ * passed x86_cpu_id match table. Otherwise NULL.  The match table
+ * contains vendor (X86_VENDOR_*), family, model and feature bits or
+ * respective wildcard entries.
+ *
+ * A typical table entry would be to match a specific CPU
+ * { X86_VENDOR_INTEL, 6, 0x12 }
+ * or to match a specific CPU feature
+ * { X86_FEATURE_MATCH(X86_FEATURE_FOOBAR) }
+ *
+ * Fields can be wildcarded with %X86_VENDOR_ANY, %X86_FAMILY_ANY,
+ * %X86_MODEL_ANY, %X86_FEATURE_ANY or 0 (except for vendor)
+ *
+ * Arrays used to match for this should also be declared using
+ * MODULE_DEVICE_TABLE(x86cpu, ...)
+ *
+ * This always matches against the boot cpu, assuming models and features are
+ * consistent over all CPUs.
+ */
+const struct x86_cpu_id *x86_match_cpu(const struct x86_cpu_id *match)
+{
+	const struct x86_cpu_id *m;
+	struct cpuinfo_x86 *c = &boot_cpu_data;
+
+	for (m = match;
+	     m->vendor | m->family | m->model | m->steppings | m->feature;
+	     m++) {
+		if (m->vendor != X86_VENDOR_ANY && c->x86_vendor != m->vendor)
+			continue;
+		if (m->family != X86_FAMILY_ANY && c->x86 != m->family)
+			continue;
+		if (m->model != X86_MODEL_ANY && c->x86_model != m->model)
+			continue;
+		if (m->steppings != X86_STEPPING_ANY &&
+		    !(BIT(c->x86_stepping) & m->steppings))
+			continue;
+		if (m->feature != X86_FEATURE_ANY && !cpu_has(c, m->feature))
+			continue;
+		return m;
+	}
+	return NULL;
+}
+EXPORT_SYMBOL(x86_match_cpu);