sdei_watchdog: refresh 'last_timestamp' when enabling nmi_watchdog

euler inclusion
category: feature
Bugzilla: 5515
CVE: N/A

----------------------------------------

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: NXiongfeng Wang <wangxiongfeng2@huawei.com>
Reviewed-by: NHanjun Guo <guohanjun@huawei.com>
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>

arch/arm64/kernel/watchdog_sdei.c

@@ -26,6 +26,8 @@ int watchdog_nmi_enable(unsigned int cpu)
 {
 	int ret;
 
+	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

@@ -204,6 +204,7 @@ 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

@@ -87,6 +87,15 @@ 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)
 {