1 files changed, 8 insertions, 29 deletions

diff --git a/arch/x86/kernel/tsc_sync.c b/arch/x86/kernel/tsc_sync.c
index d0db011051a5..7842371bc9e4 100644
--- a/arch/x86/kernel/tsc_sync.c
+++ b/arch/x86/kernel/tsc_sync.c
@@ -71,13 +71,8 @@ static void tsc_sanitize_first_cpu(struct tsc_adjust *cur, s64 bootval,
 	 * non zero. We don't do that on non boot cpus because physical
 	 * hotplug should have set the ADJUST register to a value > 0 so
 	 * the TSC is in sync with the already running cpus.
-	 *
-	 * But we always force positive ADJUST values. Otherwise the TSC
-	 * deadline timer creates an interrupt storm. We also have to
-	 * prevent values > 0x7FFFFFFF as those wreckage the timer as well.
 	 */
-	if ((bootcpu && bootval != 0) || (!bootcpu && bootval < 0) ||
-	    (bootval > 0x7FFFFFFF)) {
+	if (bootcpu && bootval != 0) {
 		pr_warn(FW_BUG "TSC ADJUST: CPU%u: %lld force to 0\n", cpu,
 			bootval);
 		wrmsrl(MSR_IA32_TSC_ADJUST, 0);
@@ -286,13 +281,6 @@ void check_tsc_sync_source(int cpu)
 	if (unsynchronized_tsc())
 		return;
 
-	if (tsc_clocksource_reliable) {
-		if (cpu == (nr_cpu_ids-1) || system_state != SYSTEM_BOOTING)
-			pr_info(
-			"Skipped synchronization checks as TSC is reliable.\n");
-		return;
-	}
-
 	/*
 	 * Set the maximum number of test runs to
 	 *  1 if the CPU does not provide the TSC_ADJUST MSR
@@ -380,14 +368,19 @@ void check_tsc_sync_target(void)
 	int cpus = 2;
 
 	/* Also aborts if there is no TSC. */
-	if (unsynchronized_tsc() || tsc_clocksource_reliable)
+	if (unsynchronized_tsc())
 		return;
 
 	/*
 	 * Store, verify and sanitize the TSC adjust register. If
 	 * successful skip the test.
+	 *
+	 * The test is also skipped when the TSC is marked reliable. This
+	 * is true for SoCs which have no fallback clocksource. On these
+	 * SoCs the TSC is frequency synchronized, but still the TSC ADJUST
+	 * register might have been wreckaged by the BIOS..
 	 */
-	if (tsc_store_and_check_tsc_adjust(false)) {
+	if (tsc_store_and_check_tsc_adjust(false) || tsc_clocksource_reliable) {
 		atomic_inc(&skip_test);
 		return;
 	}
@@ -453,20 +446,6 @@ retry:
 	 */
 	cur->adjusted += cur_max_warp;
 
-	/*
-	 * TSC deadline timer stops working or creates an interrupt storm
-	 * with adjust values < 0 and > x07ffffff.
-	 *
-	 * To allow adjust values > 0x7FFFFFFF we need to disable the
-	 * deadline timer and use the local APIC timer, but that requires
-	 * more intrusive changes and we do not have any useful information
-	 * from Intel about the underlying HW wreckage yet.
-	 */
-	if (cur->adjusted < 0)
-		cur->adjusted = 0;
-	if (cur->adjusted > 0x7FFFFFFF)
-		cur->adjusted = 0x7FFFFFFF;
-
 	pr_warn("TSC ADJUST compensate: CPU%u observed %lld warp. Adjust: %lld\n",
 		cpu, cur_max_warp, cur->adjusted);