!210 x86/tsc: use topology_max_packages() in tsc watchdog check

Merge Pull Request from: @juntianlinux 
 
[Description]​
Temporary fix for #I5U037

Occasionally TSC clocksource is wrongly judged as unstable watchdog like 'jiffies', HPET on some platforms like Skylake 4S. 

For normal cases, we can use nr_online_nodes <= 4 as a quick workaround for this issue. However, there are many cases that 'nr_online_nodes' could have issue. Intel is still working on a formal fix, the patch in this PR is a more general fix but still have open under discussion.

Generally, there are some corner cases, but we can use this for a temporary fix to this issue. In next step, we need to update this fix after upstream merging the final solution.

 
 
Link:https://gitee.com/openeuler/kernel/pulls/210 
Reviewed-by: Jiao Fenfang <jiaofenfang@uniontech.com> 
Reviewed-by: Chen Wei <chenwei@xfusion.com> 
Reviewed-by: Xibo.Wang <wangxb12@chinatelecom.cn> 
Signed-off-by: Xie XiuQi <xiexiuqi@huawei.com> 

arch/x86/kernel/tsc.c

@@ -1129,8 +1129,7 @@ static struct clocksource clocksource_tsc_early = {
 	.rating			= 299,
 	.read			= read_tsc,
 	.mask			= CLOCKSOURCE_MASK(64),
-	.flags			= CLOCK_SOURCE_IS_CONTINUOUS |
-				  CLOCK_SOURCE_MUST_VERIFY,
+	.flags			= CLOCK_SOURCE_IS_CONTINUOUS,
 	.vdso_clock_mode	= VDSO_CLOCKMODE_TSC,
 	.enable			= tsc_cs_enable,
 	.resume			= tsc_resume,
@@ -1178,12 +1177,6 @@ void mark_tsc_unstable(char *reason)
 
 EXPORT_SYMBOL_GPL(mark_tsc_unstable);
 
-static void __init tsc_disable_clocksource_watchdog(void)
-{
-	clocksource_tsc_early.flags &= ~CLOCK_SOURCE_MUST_VERIFY;
-	clocksource_tsc.flags &= ~CLOCK_SOURCE_MUST_VERIFY;
-}
-
 static void __init check_system_tsc_reliable(void)
 {
 #if defined(CONFIG_MGEODEGX1) || defined(CONFIG_MGEODE_LX) || defined(CONFIG_X86_GENERIC)
@@ -1200,23 +1193,6 @@ static void __init check_system_tsc_reliable(void)
 #endif
 	if (boot_cpu_has(X86_FEATURE_TSC_RELIABLE))
 		tsc_clocksource_reliable = 1;
-
-	/*
-	 * Disable the clocksource watchdog when the system has:
-	 *  - TSC running at constant frequency
-	 *  - TSC which does not stop in C-States
-	 *  - the TSC_ADJUST register which allows to detect even minimal
-	 *    modifications
-	 *  - not more than two sockets. As the number of sockets cannot be
-	 *    evaluated at the early boot stage where this has to be
-	 *    invoked, check the number of online memory nodes as a
-	 *    fallback solution which is an reasonable estimate.
-	 */
-	if (boot_cpu_has(X86_FEATURE_CONSTANT_TSC) &&
-	    boot_cpu_has(X86_FEATURE_NONSTOP_TSC) &&
-	    boot_cpu_has(X86_FEATURE_TSC_ADJUST) &&
-	    nr_online_nodes <= 2)
-		tsc_disable_clocksource_watchdog();
 }
 
 /*
@@ -1411,6 +1387,20 @@ static int __init init_tsc_clocksource(void)
 	if (boot_cpu_has(X86_FEATURE_NONSTOP_TSC_S3))
 		clocksource_tsc.flags |= CLOCK_SOURCE_SUSPEND_NONSTOP;
 
+	/*
+	 * Disable the clocksource watchdog when the system has:
+	 *  - TSC running at constant frequency
+	 *  - TSC which does not stop in C-States
+	 *  - the TSC_ADJUST register which allows to detect even minimal
+	 *    modifications
+	 *  - not more than four sockets.
+	 */
+	if (boot_cpu_has(X86_FEATURE_CONSTANT_TSC) &&
+	    boot_cpu_has(X86_FEATURE_NONSTOP_TSC) &&
+	    boot_cpu_has(X86_FEATURE_TSC_ADJUST) &&
+	    topology_max_packages() <= 4)
+		clocksource_tsc.flags &= ~CLOCK_SOURCE_MUST_VERIFY;
+
 	/*
 	 * When TSC frequency is known (retrieved via MSR or CPUID), we skip
 	 * the refined calibration and directly register it as a clocksource.
@@ -1545,7 +1535,7 @@ void __init tsc_init(void)
 	}
 
 	if (tsc_clocksource_reliable || no_tsc_watchdog)
-		tsc_disable_clocksource_watchdog();
+		clocksource_tsc.flags &= ~CLOCK_SOURCE_MUST_VERIFY;
 
 	clocksource_register_khz(&clocksource_tsc_early, tsc_khz);
 	detect_art();