x86, intel: Output microcode revision in /proc/cpuinfo

I got a request to make it easier to determine the microcode
update level on Intel CPUs. This patch adds a new "microcode"
field to /proc/cpuinfo.

The microcode level is also outputed on fatal machine checks
together with the other CPUID model information.

I removed the respective code from the microcode update driver,
it just reads the field from cpu_data. Also when the microcode
is updated it fills in the new values too.

I had to add a memory barrier to native_cpuid to prevent it
being optimized away when the result is not used.

This turns out to clean up further code which already got this
information manually. This is done in followon patches.

Signed-off-by: Andi Kleen <ak@linux.intel.com>
Acked-by: H. Peter Anvin <hpa@zytor.com>
Link: http://lkml.kernel.org/r/1318466795-7393-1-git-send-email-andi@firstfloor.org
Signed-off-by: Ingo Molnar <mingo@elte.hu>

5 files changed, 26 insertions, 12 deletions

diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index 0d1171c97729..b650435ffb53 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -111,6 +111,7 @@ struct cpuinfo_x86 {
         /* Index into per_cpu list: */
         u16                     cpu_index;
 #endif
+        u32                     microcode;
 } __attribute__((__aligned__(SMP_CACHE_BYTES)));
 
 #define X86_VENDOR_INTEL        0
@@ -179,7 +180,8 @@ static inline void native_cpuid(unsigned int *eax, unsigned int *ebx,
               "=b" (*ebx),
               "=c" (*ecx),
               "=d" (*edx)
-            : "0" (*eax), "2" (*ecx));
+            : "0" (*eax), "2" (*ecx)
+            : "memory");
 }
 
 static inline void load_cr3(pgd_t *pgdir)
diff --git a/arch/x86/kernel/cpu/intel.c b/arch/x86/kernel/cpu/intel.c
index ed6086eedf1d..26627a3a7148 100644
--- a/arch/x86/kernel/cpu/intel.c
+++ b/arch/x86/kernel/cpu/intel.c
@@ -47,6 +47,15 @@ static void __cpuinit early_init_intel(struct cpuinfo_x86 *c)
                 (c->x86 == 0x6 && c->x86_model >= 0x0e))
                 set_cpu_cap(c, X86_FEATURE_CONSTANT_TSC);
 
+        if (c->x86 >= 6 && !cpu_has(c, X86_FEATURE_IA64)) {
+                unsigned lower_word;
+
+                wrmsr(MSR_IA32_UCODE_REV, 0, 0);
+                /* Required by the SDM */
+                sync_core();
+                rdmsr(MSR_IA32_UCODE_REV, lower_word, c->microcode);
+        }
+
         /*
          * Atom erratum AAE44/AAF40/AAG38/AAH41:
          *
diff --git a/arch/x86/kernel/cpu/mcheck/mce.c b/arch/x86/kernel/cpu/mcheck/mce.c
index 08363b042122..8af6fa473233 100644
--- a/arch/x86/kernel/cpu/mcheck/mce.c
+++ b/arch/x86/kernel/cpu/mcheck/mce.c
@@ -217,8 +217,13 @@ static void print_mce(struct mce *m)
                 pr_cont("MISC %llx ", m->misc);
 
         pr_cont("\n");
-        pr_emerg(HW_ERR "PROCESSOR %u:%x TIME %llu SOCKET %u APIC %x\n",
-                m->cpuvendor, m->cpuid, m->time, m->socketid, m->apicid);
+        /*
+         * Note this output is parsed by external tools and old fields
+         * should not be changed.
+         */
+        pr_emerg(HW_ERR "PROCESSOR %u:%x TIME %llu SOCKET %u APIC %x microcode %u\n",
+                m->cpuvendor, m->cpuid, m->time, m->socketid, m->apicid,
+                cpu_data(m->extcpu).microcode);
 
         /*
          * Print out human-readable details about the MCE error,
diff --git a/arch/x86/kernel/cpu/proc.c b/arch/x86/kernel/cpu/proc.c
index 62ac8cb6ba27..6254fdae3e77 100644
--- a/arch/x86/kernel/cpu/proc.c
+++ b/arch/x86/kernel/cpu/proc.c
@@ -85,6 +85,8 @@ static int show_cpuinfo(struct seq_file *m, void *v)
                 seq_printf(m, "stepping\t: %d\n", c->x86_mask);
         else
                 seq_printf(m, "stepping\t: unknown\n");
+        if (c->microcode)
+                seq_printf(m, "microcode\t: %u\n", c->microcode);
 
         if (cpu_has(c, X86_FEATURE_TSC)) {
                 unsigned int freq = cpufreq_quick_get(cpu);
diff --git a/arch/x86/kernel/microcode_intel.c b/arch/x86/kernel/microcode_intel.c
index 1a1b606d3e92..3ca42d0e43a2 100644
--- a/arch/x86/kernel/microcode_intel.c
+++ b/arch/x86/kernel/microcode_intel.c
@@ -161,12 +161,7 @@ static int collect_cpu_info(int cpu_num, struct cpu_signature *csig)
                 csig->pf = 1 << ((val[1] >> 18) & 7);
         }
 
-        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);
-
+        csig->rev = c->microcode;
         pr_info("CPU%d sig=0x%x, pf=0x%x, revision=0x%x\n",
                 cpu_num, csig->sig, csig->pf, csig->rev);
 
@@ -299,9 +294,9 @@ static int apply_microcode(int cpu)
         struct microcode_intel *mc_intel;
         struct ucode_cpu_info *uci;
         unsigned int val[2];
-        int cpu_num;
+        int cpu_num = raw_smp_processor_id();
+        struct cpuinfo_x86 *c = &cpu_data(cpu_num);
 
-        cpu_num = raw_smp_processor_id();
         uci = ucode_cpu_info + cpu;
         mc_intel = uci->mc;
 
@@ -317,7 +312,7 @@ static int apply_microcode(int cpu)
               (unsigned long) mc_intel->bits >> 16 >> 16);
         wrmsr(MSR_IA32_UCODE_REV, 0, 0);
 
-        /* see notes above for revision 1.07.  Apparent chip bug */
+        /* As documented in the SDM: Do a CPUID 1 here */
         sync_core();
 
         /* get the current revision from MSR 0x8B */
@@ -335,6 +330,7 @@ static int apply_microcode(int cpu)
                 (mc_intel->hdr.date >> 16) & 0xff);
 
         uci->cpu_sig.rev = val[1];
+        c->microcode = val[1];
 
         return 0;
 }