From: "mike.travis@hpe.com" <mike.travis@hpe.com>
Subject: x86/tsc: Drastically reduce the number of firmware bug warnings
Git-commit: 41e7864ab5ce4ec36e89a9f55d8d9dfe19b0392c
Patch-mainline: v4.15-rc1
References: bsc#1082579
Acked-by: Jiri Bohac <jbohac@suse.cz>

Prior to the TSC ADJUST MSR being available, the method to set TSC's in
sync with each other naturally caused a small skew between cpu threads.
This was NOT a firmware bug at the time so introducing a whole avalanche
of alarming warning messages might cause unnecessary concern and customer
complaints. (Example: >3000 msgs in a 32 socket Skylake system.)

Simply report the warning condition, if possible do the necessary fixes,
and move on.

Signed-off-by: Mike Travis <mike.travis@hpe.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Dimitri Sivanich <dimitri.sivanich@hpe.com>
Reviewed-by: Russ Anderson <russ.anderson@hpe.com>
Reviewed-by: Peter Zijlstra <peterz@infradead.org>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Andrew Banman <andrew.banman@hpe.com>
Cc: Bin Gao <bin.gao@linux.intel.com>
Link: https://lkml.kernel.org/r/20171012163202.175062400@stormcage.americas.sgi.com

---
 arch/x86/kernel/tsc_sync.c |    9 +++------
 1 file changed, 3 insertions(+), 6 deletions(-)

--- a/arch/x86/kernel/tsc_sync.c
+++ b/arch/x86/kernel/tsc_sync.c
@@ -183,10 +183,9 @@ bool tsc_store_and_check_tsc_adjust(bool
 	 * Compare the boot value and complain if it differs in the
 	 * package.
 	 */
-	if (bootval != ref->bootval) {
-		pr_warn(FW_BUG "TSC ADJUST differs: Reference CPU%u: %lld CPU%u: %lld\n",
-			refcpu, ref->bootval, cpu, bootval);
-	}
+	if (bootval != ref->bootval)
+		printk_once(FW_BUG "TSC ADJUST differs within socket(s), fixing all errors\n");
+
 	/*
 	 * The TSC_ADJUST values in a package must be the same. If the boot
 	 * value on this newly upcoming CPU differs from the adjustment
@@ -194,8 +193,6 @@ bool tsc_store_and_check_tsc_adjust(bool
 	 * adjusted value.
 	 */
 	if (bootval != ref->adjusted) {
-		pr_warn("TSC ADJUST synchronize: Reference CPU%u: %lld CPU%u: %lld\n",
-			refcpu, ref->adjusted, cpu, bootval);
 		cur->adjusted = ref->adjusted;
 		wrmsrl(MSR_IA32_TSC_ADJUST, ref->adjusted);
 	}