2 files changed, 20 insertions, 5 deletions

diff --git a/arch/x86/kernel/microcode_core.c b/arch/x86/kernel/microcode_core.c
index 82fb2809ce32..c4b5b24e0217 100644
--- a/arch/x86/kernel/microcode_core.c
+++ b/arch/x86/kernel/microcode_core.c
@@ -272,13 +272,18 @@ static struct attribute_group mc_attr_group = {
         .name = "microcode",
 };
 
-static void microcode_fini_cpu(int cpu)
+static void __microcode_fini_cpu(int cpu)
 {
         struct ucode_cpu_info *uci = ucode_cpu_info + cpu;
 
-        mutex_lock(&microcode_mutex);
         microcode_ops->microcode_fini_cpu(cpu);
         uci->valid = 0;
+}
+
+static void microcode_fini_cpu(int cpu)
+{
+        mutex_lock(&microcode_mutex);
+        __microcode_fini_cpu(cpu);
         mutex_unlock(&microcode_mutex);
 }
 
@@ -306,12 +311,16 @@ static int microcode_resume_cpu(int cpu)
          * to this cpu (a bit of paranoia):
          */
         if (microcode_ops->collect_cpu_info(cpu, &nsig)) {
-                microcode_fini_cpu(cpu);
+                __microcode_fini_cpu(cpu);
+                printk(KERN_ERR "failed to collect_cpu_info for resuming cpu #%d\n",
+                                cpu);
                 return -1;
         }
 
-        if (memcmp(&nsig, &uci->cpu_sig, sizeof(nsig))) {
-                microcode_fini_cpu(cpu);
+        if ((nsig.sig != uci->cpu_sig.sig) || (nsig.pf != uci->cpu_sig.pf)) {
+                __microcode_fini_cpu(cpu);
+                printk(KERN_ERR "cached ucode doesn't match the resuming cpu #%d\n",
+                                cpu);
                 /* Should we look for a new ucode here? */
                 return 1;
         }
diff --git a/arch/x86/kernel/microcode_intel.c b/arch/x86/kernel/microcode_intel.c
index 622dc4a21784..a8e62792d171 100644
--- a/arch/x86/kernel/microcode_intel.c
+++ b/arch/x86/kernel/microcode_intel.c
@@ -155,6 +155,7 @@ static DEFINE_SPINLOCK(microcode_update_lock);
 static int collect_cpu_info(int cpu_num, struct cpu_signature *csig)
 {
         struct cpuinfo_x86 *c = &cpu_data(cpu_num);
+        unsigned long flags;
         unsigned int val[2];
 
         memset(csig, 0, sizeof(*csig));
@@ -174,11 +175,16 @@ static int collect_cpu_info(int cpu_num, struct cpu_signature *csig)
                 csig->pf = 1 << ((val[1] >> 18) & 7);
         }
 
+        /* serialize access to the physical write to MSR 0x79 */
+        spin_lock_irqsave(&microcode_update_lock, flags);
+
         wrmsr(MSR_IA32_UCODE_REV, 0, 0);
         /* see notes above for revision 1.07.  Apparent chip bug */
         sync_core();
         /* get the current revision from MSR 0x8B */
         rdmsr(MSR_IA32_UCODE_REV, val[0], csig->rev);
+        spin_unlock_irqrestore(&microcode_update_lock, flags);
+
         pr_debug("microcode: collect_cpu_info : sig=0x%x, pf=0x%x, rev=0x%x\n",
                         csig->sig, csig->pf, csig->rev);