x86/tsc: Drastically reduce the number of firmware bug warnings

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

diff --git a/arch/x86/kernel/tsc_sync.c b/arch/x86/kernel/tsc_sync.c
index 3bdb983fd11b15bb385e2aaa966d84499e3356b7..26ba0530a8a7aeb8ad169458a5c7c17c633fd1bd 100644 (file)
--- a/arch/x86/kernel/tsc_sync.c
+++ b/arch/x86/kernel/tsc_sync.c
@@ -177,10 +177,9 @@ bool tsc_store_and_check_tsc_adjust(bool bootcpu)
         * 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 bootcpu)
         * 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);
        }