sdei_watchdog: refresh 'last_timestamp' when enabling nmi_watchdog

commit 5bc048a102ef9c3748464cacce443a0f1d9bed5b openeuler.

The trigger period of secure time is set by firmware. We need to check
the time_stamp every time the secure time fires to make sure the
hardlockup detection is not executed too soon. We need to refresh
'last_timestamp' to the current time when we enable the nmi_watchdog.
Otherwise, false hardlockup may be detected when the secure timer fires
the first time.

Signed-off-by: huwentao <huwentao19@h-partners.com>

arch/arm64/kernel/watchdog_sdei.c

@@ -30,6 +30,8 @@ int watchdog_nmi_enable(unsigned int cpu)
 	if (!sdei_watchdog_registered)
 		return -EINVAL;
 
+	refresh_hld_last_timestamp();
+
 	ret = sdei_api_event_enable(sdei_watchdog_event_num);
 	if (ret) {
 		pr_err("Enable NMI Watchdog failed on cpu%d\n",

include/linux/nmi.h

@@ -208,6 +208,7 @@ u64 hw_nmi_get_sample_period(int watchdog_thresh);
 #if defined(CONFIG_HARDLOCKUP_CHECK_TIMESTAMP) && \
     defined(CONFIG_HARDLOCKUP_DETECTOR)
 void watchdog_update_hrtimer_threshold(u64 period);
+void refresh_hld_last_timestamp(void);
 #else
 static inline void watchdog_update_hrtimer_threshold(u64 period) { }
 #endif

kernel/watchdog_hld.c

@@ -89,6 +89,15 @@ static bool watchdog_check_timestamp(void)
 	__this_cpu_write(last_timestamp, now);
 	return true;
 }
+
+void refresh_hld_last_timestamp(void)
+{
+	ktime_t now;
+
+	now = ktime_get_mono_fast_ns();
+	__this_cpu_write(last_timestamp, now);
+
+}
 #else
 static inline bool watchdog_check_timestamp(void)
 {