linux-kernel - [tip:x86/microcode] x86/microcode/intel: Do not issue microcode updates messages on each CPU

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Date:	Tue, 14 Jun 2016 04:25:22 -0700
From:	tip-bot for Andi Kleen <tipbot@...or.com>
To:	linux-tip-commits@...r.kernel.org
Cc:	hpa@...or.com, brgerst@...il.com, bp@...en8.de,
	torvalds@...ux-foundation.org, tony.luck@...el.com,
	mingo@...nel.org, peterz@...radead.org,
	linux-kernel@...r.kernel.org, ak@...ux.intel.com,
	dvlasenk@...hat.com, bp@...e.de, tglx@...utronix.de,
	luto@...capital.net
Subject: [tip:x86/microcode] x86/microcode/intel: Do not issue microcode
 updates messages on each CPU

Commit-ID:  354542d034ab2a849a284edcc661e76b753a57dc
Gitweb:     http://git.kernel.org/tip/354542d034ab2a849a284edcc661e76b753a57dc
Author:     Andi Kleen <ak@...ux.intel.com>
AuthorDate: Thu, 9 Jun 2016 06:41:41 -0700
Committer:  Ingo Molnar <mingo@...nel.org>
CommitDate: Tue, 14 Jun 2016 10:51:43 +0200

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@...ux.intel.com>
Signed-off-by: Borislav Petkov <bp@...e.de>
Cc: Andy Lutomirski <luto@...capital.net>
Cc: Borislav Petkov <bp@...en8.de>
Cc: Brian Gerst <brgerst@...il.com>
Cc: Denys Vlasenko <dvlasenk@...hat.com>
Cc: H. Peter Anvin <hpa@...or.com>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Tony Luck <tony.luck@...el.com>
Cc: elliott@....com
Cc: hmh@....eng.br
Link: http://lkml.kernel.org/r/20160609134141.5981-1-andi@firstfloor.org
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
 arch/x86/kernel/cpu/microcode/intel.c | 24 +++++++++++++++++-------
 1 file changed, 17 insertions(+), 7 deletions(-)

diff --git a/arch/x86/kernel/cpu/microcode/intel.c b/arch/x86/kernel/cpu/microcode/intel.c
index 8962d6a..6515c80 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);