x86/microcode/intel: Do not issue microcode updates messages on each CPU

On large systems the microcode driver is very noisy, because it prints a
line for each CPU. The lines are redundant because usually all CPUs are
updated to the same microcode revision.

All other subsystems have been patched previously to not print a line
for each CPU. Only the microcode driver is left.

Only print an microcode revision update when something changed. This
results in typically only a single line being printed.

Signed-off-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tony Luck <tony.luck@intel.com>
Cc: elliott@hpe.com
Cc: hmh@hmh.eng.br
Link: http://lkml.kernel.org/r/20160609134141.5981-1-andi@firstfloor.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

1 files changed, 17 insertions, 7 deletions

diff --git a/arch/x86/kernel/cpu/microcode/intel.c b/arch/x86/kernel/cpu/microcode/intel.c
index 8962d6acee39..6515c802346a 100644
--- a/arch/x86/kernel/cpu/microcode/intel.c
+++ b/arch/x86/kernel/cpu/microcode/intel.c
@@ -843,6 +843,7 @@ void reload_ucode_intel(void)
 
 static int collect_cpu_info(int cpu_num, struct cpu_signature *csig)
 {
+        static struct cpu_signature prev;
         struct cpuinfo_x86 *c = &cpu_data(cpu_num);
         unsigned int val[2];
 
@@ -857,8 +858,13 @@ static int collect_cpu_info(int cpu_num, struct cpu_signature *csig)
         }
 
         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);
+
+        /* No extra locking on prev, races are harmless. */
+        if (csig->sig != prev.sig || csig->pf != prev.pf || csig->rev != prev.rev) {
+                pr_info("sig=0x%x, pf=0x%x, revision=0x%x\n",
+                        csig->sig, csig->pf, csig->rev);
+                prev = *csig;
+        }
 
         return 0;
 }
@@ -887,6 +893,7 @@ static int apply_microcode_intel(int cpu)
         struct ucode_cpu_info *uci;
         struct cpuinfo_x86 *c;
         unsigned int val[2];
+        static int prev_rev;
 
         /* We should bind the task to the CPU */
         if (WARN_ON(raw_smp_processor_id() != cpu))
@@ -921,11 +928,14 @@ static int apply_microcode_intel(int cpu)
                 return -1;
         }
 
-        pr_info("CPU%d updated to revision 0x%x, date = %04x-%02x-%02x\n",
-                cpu, val[1],
-                mc->hdr.date & 0xffff,
-                mc->hdr.date >> 24,
-                (mc->hdr.date >> 16) & 0xff);
+        if (val[1] != prev_rev) {
+                pr_info("updated to revision 0x%x, date = %04x-%02x-%02x\n",
+                        val[1],
+                        mc->hdr.date & 0xffff,
+                        mc->hdr.date >> 24,
+                        (mc->hdr.date >> 16) & 0xff);
+                prev_rev = val[1];
+        }
 
         c = &cpu_data(cpu);