linux-kernel - [PATCH 4.15 116/168] x86/microcode/intel: Look into the patch cache first

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Message-Id: <20180410212805.443922815@linuxfoundation.org>
Date:   Wed, 11 Apr 2018 00:24:18 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Borislav Petkov <bp@...e.de>,
        Thomas Gleixner <tglx@...utronix.de>,
        Tom Lendacky <thomas.lendacky@....com>,
        Ashok Raj <ashok.raj@...el.com>,
        Arjan Van De Ven <arjan.van.de.ven@...el.com>
Subject: [PATCH 4.15 116/168] x86/microcode/intel: Look into the patch cache first

4.15-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Borislav Petkov <bp@...e.de>

commit d8c3b52c00a05036e0a6b315b4b17921a7b67997 upstream.

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@...e.de>
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Tested-by: Tom Lendacky <thomas.lendacky@....com>
Tested-by: Ashok Raj <ashok.raj@...el.com>
Cc: Arjan Van De Ven <arjan.van.de.ven@...el.com>
Link: https://lkml.kernel.org/r/20180228102846.13447-6-bp@alien8.de
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 arch/x86/kernel/cpu/microcode/intel.c |   11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

--- a/arch/x86/kernel/cpu/microcode/intel.c
+++ b/arch/x86/kernel/cpu/microcode/intel.c
@@ -791,9 +791,9 @@ static int collect_cpu_info(int cpu_num,
 
 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_
 	if (WARN_ON(raw_smp_processor_id() != cpu))
 		return UCODE_ERROR;
 
-	uci = ucode_cpu_info + cpu;
-	mc = uci->mc;
+	/* Look for a newer patch in our cache: */
+	mc = find_patch(uci);
 	if (!mc) {
-		/* Look for a newer patch in our cache: */
-		mc = find_patch(uci);
+		mc = uci->mc;
 		if (!mc)
 			return UCODE_NFOUND;
 	}