From a42e2f4daaa9537eeea41f68eae1ef16265f4010 Mon Sep 17 00:00:00 2001
From: Stefan Reinauer <reinauer@chromium.org>
Date: Mon, 15 Oct 2012 13:18:06 -0700
Subject: [PATCH] Add spinlock to serialize Intel microcode updates

Updating microcode on several threads in a core at once
can be harmful. Hence add a spinlock to make sure that
does not happen.

Change-Id: I0c9526b6194202ae7ab5c66361fe04ce137372cc
Signed-off-by: Stefan Reinauer <reinauer@google.com>
Reviewed-on: http://review.coreboot.org/1778
Tested-by: build bot (Jenkins)
Reviewed-by: Ronald G. Minnich <rminnich@gmail.com>
---
 src/cpu/intel/microcode/microcode.c | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/src/cpu/intel/microcode/microcode.c b/src/cpu/intel/microcode/microcode.c
index a4471ca042..15d6513b33 100644
--- a/src/cpu/intel/microcode/microcode.c
+++ b/src/cpu/intel/microcode/microcode.c
@@ -28,12 +28,16 @@
 #include <cpu/x86/msr.h>
 #include <cpu/intel/microcode.h>
 
-#if CONFIG_CPU_MICROCODE_IN_CBFS
 #ifdef __PRE_RAM__
+#if CONFIG_CPU_MICROCODE_IN_CBFS
 #include <arch/cbfs.h>
+#endif
 #else
+#if CONFIG_CPU_MICROCODE_IN_CBFS
 #include <cbfs.h>
 #endif
+#include <smp/spinlock.h>
+DECLARE_SPIN_LOCK(microcode_lock)
 #endif
 
 struct microcode {
@@ -112,6 +116,9 @@ void intel_update_microcode(const void *microcode_updates)
 	printk(BIOS_DEBUG, "microcode: sig=0x%x pf=0x%x revision=0x%x\n",
 			sig, pf, rev);
 #endif
+#if !defined(__ROMCC__) && !defined(__PRE_RAM__)
+	spin_lock(&microcode_lock);
+#endif
 
 	m = microcode_updates;
 	for(c = microcode_updates; m->hdrver; m = (const struct microcode *)c) {
@@ -142,6 +149,10 @@ void intel_update_microcode(const void *microcode_updates)
 			c += 2048;
 		}
 	}
+
+#if !defined(__ROMCC__) && !defined(__PRE_RAM__)
+	spin_unlock(&microcode_lock);
+#endif
 }
 
 #if CONFIG_CPU_MICROCODE_IN_CBFS