[PATCH 3/5] x86/kernel: Drastically reduce the number of firmware bug warnings

[mike.travis]

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@xxxxxxx>
Reviewed-by: Dimitri Sivanich <dimitri.sivanich@xxxxxxx>
Reviewed-by: Russ Anderson <russ.anderson@xxxxxxx>
Reviewed-by: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
---
v2: Patches merged against 4.14.0-rc4
---
 arch/x86/kernel/tsc_sync.c |    9 +++------
 1 file changed, 3 insertions(+), 6 deletions(-)

--- linux.orig/arch/x86/kernel/tsc_sync.c
+++ linux/arch/x86/kernel/tsc_sync.c
@@ -177,10 +177,9 @@ 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
@@ -188,8 +187,6 @@ 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);
 	}

--