sdei_watchdog: set secure timer period base on 'watchdog_thresh'

hulk inclusion
category: feature
bugzilla: 48046
CVE: NA

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

The period of the secure timer is set to 3s by BIOS. That means the
secure timer interrupt will trigger every 3 seconds. To further decrease
the NMI watchdog's effect on performance, this patch set the period of
the secure timer base on 'watchdog_thresh'. This variable is initiallized
to 10s. We can also set the period at runtime by modifying
'/proc/sys/kernel/watchdog_thresh'
Signed-off-by: NXiongfeng Wang <wangxiongfeng2@huawei.com>
Reviewed-by: NHanjun Guo <guohanjun@huawei.com>
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>
Signed-off-by: NXiongfeng Wang <wangxiongfeng2@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>

arch/arm64/kernel/watchdog_sdei.c

@@ -30,7 +30,11 @@ int watchdog_nmi_enable(unsigned int cpu)
 	if (!sdei_watchdog_registered)
 		return -EINVAL;
 
+#ifdef CONFIG_HARDLOCKUP_CHECK_TIMESTAMP
 	refresh_hld_last_timestamp();
+#endif
+
+	sdei_api_set_secure_timer_period(watchdog_thresh);
 
 	ret = sdei_api_event_enable(sdei_watchdog_event_num);
 	if (ret) {
@@ -104,6 +108,17 @@ int __init watchdog_nmi_probe(void)
 		return sdei_watchdog_event_num;
 	}
 
+	/*
+	 * After we introduced 'sdei_api_set_secure_timer_period', we disselect
+	 * 'CONFIG_HARDLOCKUP_CHECK_TIMESTAMP'. So we need to make sure that
+	 * firmware can set the period of the secure timer and the timer
+	 * interrupt doesn't trigger too soon.
+	 */
+	if (sdei_api_set_secure_timer_period(watchdog_thresh)) {
+		pr_err("Firmware doesn't support setting the secure timer period, please update your BIOS !\n");
+		return -EINVAL;
+	}
+
 	on_each_cpu(sdei_nmi_watchdog_bind, NULL, true);
 
 	ret = sdei_event_register(sdei_watchdog_event_num,

drivers/firmware/arm_sdei.c

@@ -203,6 +203,12 @@ int sdei_api_clear_eoi(int hwirq)
 			NULL);
 }
 
+int sdei_api_set_secure_timer_period(int sec)
+{
+	return invoke_sdei_fn(SDEI_1_0_FN_SET_SECURE_TIMER_PERIOD, sec, 0, 0, 0,
+			0, NULL);
+}
+
 static int sdei_api_event_get_info(u32 event, u32 info, u64 *result)
 {
 	return invoke_sdei_fn(SDEI_1_0_FN_SDEI_EVENT_GET_INFO, event, info, 0,

include/linux/arm_sdei.h

@@ -40,6 +40,7 @@ int sdei_api_event_interrupt_bind(int hwirq);
 int sdei_api_event_disable(u32 event_num);
 int sdei_api_event_enable(u32 event_num);
 int sdei_api_clear_eoi(int hwirq);
+int sdei_api_set_secure_timer_period(int sec);
 
 /* GHES register/unregister helpers */
 int sdei_register_ghes(struct ghes *ghes, sdei_event_callback *normal_cb,

include/uapi/linux/arm_sdei.h

@@ -25,6 +25,7 @@
 #define SDEI_1_0_FN_SDEI_PRIVATE_RESET			SDEI_1_0_FN(0x11)
 #define SDEI_1_0_FN_SDEI_SHARED_RESET			SDEI_1_0_FN(0x12)
 #define SDEI_1_0_FN_SDEI_CLEAR_EOI			SDEI_1_0_FN(0x18)
+#define SDEI_1_0_FN_SET_SECURE_TIMER_PERIOD		SDEI_1_0_FN(0x19)
 
 #define SDEI_VERSION_MAJOR_SHIFT			48
 #define SDEI_VERSION_MAJOR_MASK				0x7fff

lib/Kconfig.debug

@@ -968,7 +968,6 @@ config SDEI_WATCHDOG
 	bool "SDEI NMI Watchdog support"
 	depends on ARM_SDE_INTERFACE
 	select HAVE_HARDLOCKUP_DETECTOR_ARCH
-	select HARDLOCKUP_CHECK_TIMESTAMP
 	select HARDLOCKUP_DETECTOR
 
 #