x86/microcode: Ensure that module is only loaded on supported Intel CPUs

Exit early when there's no support for a particular CPU family.

Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Andreas Herrmann <andreas.herrmann3@amd.com>
Cc: Kay Sievers <kay.sievers@vrfy.org>
Cc: Dave Jones <davej@redhat.com>
Cc: tigran@aivazian.fsnet.co.uk
Cc: Borislav Petkov <borislav.petkov@amd.com>
Link: http://lkml.kernel.org/r/4F8BDB58.6070007@linux.vnet.ibm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

arch/x86/kernel/microcode_intel.c

@@ -147,12 +147,6 @@ static int collect_cpu_info(int cpu_num, struct cpu_signature *csig)
 
 	memset(csig, 0, sizeof(*csig));
 
-	if (c->x86_vendor != X86_VENDOR_INTEL || c->x86 < 6 ||
-	    cpu_has(c, X86_FEATURE_IA64)) {
-		pr_err("CPU%d not a capable Intel processor\n", cpu_num);
-		return -1;
-	}
-
 	csig->sig = cpuid_eax(0x00000001);
 
 	if ((c->x86_model >= 5) || (c->x86 > 6)) {
@@ -463,6 +457,14 @@ static struct microcode_ops microcode_intel_ops = {
 
 struct microcode_ops * __init init_intel_microcode(void)
 {
+	struct cpuinfo_x86 *c = &cpu_data(0);
+
+	if (c->x86_vendor != X86_VENDOR_INTEL || c->x86 < 6 ||
+	    cpu_has(c, X86_FEATURE_IA64)) {
+		pr_err("Intel CPU family 0x%x not supported\n", c->x86);
+		return NULL;
+	}
+
 	return &microcode_intel_ops;
 }