x86/microcode/intel: Look into the patch cache first

The cache might contain a newer patch - look in there first.

A follow-on change will make sure newest patches are loaded into the
cache of microcode patches.
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Tom Lendacky <thomas.lendacky@amd.com>
Tested-by: Ashok Raj <ashok.raj@intel.com>
Cc: Arjan Van De Ven <arjan.van.de.ven@intel.com>
Link: https://lkml.kernel.org/r/20180228102846.13447-6-bp@alien8.de

arch/x86/kernel/cpu/microcode/intel.c

@@ -791,9 +791,9 @@ static int collect_cpu_info(int cpu_num, struct cpu_signature *csig)
 
 static enum ucode_state apply_microcode_intel(int cpu)
 {
-	struct microcode_intel *mc;
-	struct ucode_cpu_info *uci;
+	struct ucode_cpu_info *uci = ucode_cpu_info + cpu;
 	struct cpuinfo_x86 *c = &cpu_data(cpu);
+	struct microcode_intel *mc;
 	static int prev_rev;
 	u32 rev;
 
@@ -801,11 +801,10 @@ static enum ucode_state apply_microcode_intel(int cpu)
 	if (WARN_ON(raw_smp_processor_id() != cpu))
 		return UCODE_ERROR;
 
-	uci = ucode_cpu_info + cpu;
-	mc = uci->mc;
-	if (!mc) {
 	/* Look for a newer patch in our cache: */
 	mc = find_patch(uci);
+	if (!mc) {
+		mc = uci->mc;
 		if (!mc)
 			return UCODE_NFOUND;
 	}