[PATCH] x86/microcode/intel: Quieten down microcode updates on large systems

From: Andi Kleen
Date: Thu Jun 09 2016 - 16:56:25 EST


From: Andi Kleen <ak@xxxxxxxxxxxxxxx>

On large systems the microcode driver is very noisy, because it prints
a line for each CPU. The lines are redundant because 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.

v2: Change message to "One or more CPUs"
Signed-off-by: Andi Kleen <ak@xxxxxxxxxxxxxxx>
---
arch/x86/kernel/cpu/microcode/intel.c | 25 ++++++++++++++++++-------
1 file changed, 18 insertions(+), 7 deletions(-)

diff --git a/arch/x86/kernel/cpu/microcode/intel.c b/arch/x86/kernel/cpu/microcode/intel.c
index cbb3cf0..54f5f6c 100644
--- a/arch/x86/kernel/cpu/microcode/intel.c
+++ b/arch/x86/kernel/cpu/microcode/intel.c
@@ -794,6 +794,7 @@ 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];

@@ -808,8 +809,14 @@ 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("One or more CPUs sig=0x%x, pf=0x%x, revision=0x%x\n",
+ csig->sig, csig->pf, csig->rev);
+ prev = *csig;
+ }

return 0;
}
@@ -838,6 +845,7 @@ 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))
@@ -872,11 +880,14 @@ 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("One or more CPUs 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);

--
2.8.3