watchdog: add nmi_watchdog support for arm64 based on SDEI

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

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

Add nmi_watchdog support for arm64 based on SDEI.
Signed-off-by: NXiongfeng Wang <wangxiongfeng2@huawei.com>
Reviewed-by: NKefeng Wang <wangkefeng.wang@huawei.com>
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>

arch/arm64/kernel/Makefile

@@ -59,6 +59,7 @@ arm64-obj-$(CONFIG_CRASH_DUMP)		+= crash_dump.o
 arm64-obj-$(CONFIG_CRASH_CORE)		+= crash_core.o
 arm64-obj-$(CONFIG_ARM_SDE_INTERFACE)	+= sdei.o
 arm64-obj-$(CONFIG_ARM64_SSBD)		+= ssbd.o
+arm64-obj-$(CONFIG_SDEI_WATCHDOG) 	+= watchdog_sdei.o
 
 obj-y					+= $(arm64-obj-y) vdso/ probes/
 obj-m					+= $(arm64-obj-m)

arch/arm64/kernel/watchdog_sdei.c

+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Detect hard lockups on a system
+ *
+ * Note: Most of this code is borrowed heavily from the perf hardlockup
+ * detector, so thanks to Don for the initial implementation.
+ */
+
+#define pr_fmt(fmt) "SDEI NMI watchdog: " fmt
+
+#include <asm/irq_regs.h>
+#include <asm/kvm_hyp.h>
+#include <asm/smp_plat.h>
+#include <asm/sdei.h>
+#include <asm/virt.h>
+#include <linux/arm_sdei.h>
+#include <linux/nmi.h>
+
+/* We use the arch virt timer as SDEI NMI watchdog timer */
+#define SDEI_NMI_WATCHDOG_HWIRQ		27
+#define SDEI_TIMER_INTERVAL		3
+
+static int sdei_watchdog_event_num;
+static bool disable_sdei_nmi_watchdog;
+
+static void start_arch_virt_timer(int seconds)
+{
+	int timer_freq = arch_timer_get_rate();
+
+	write_sysreg_el0(1, cntv_ctl);
+	write_sysreg_el0(timer_freq * seconds, cntv_tval);
+}
+
+static void stop_arch_virt_timer(void)
+{
+	write_sysreg_el0(0, cntv_ctl);
+}
+
+int watchdog_nmi_enable(unsigned int cpu)
+{
+	int ret;
+
+	ret = sdei_api_event_enable(sdei_watchdog_event_num);
+	if (ret) {
+		pr_err("Enable NMI Watchdog failed on cpu%d\n",
+				smp_processor_id());
+		return ret;
+	}
+
+	start_arch_virt_timer(SDEI_TIMER_INTERVAL);
+
+	return 0;
+}
+
+void watchdog_nmi_disable(unsigned int cpu)
+{
+	int ret;
+
+	ret = sdei_api_event_disable(sdei_watchdog_event_num);
+	if (ret)
+		pr_err("Disable NMI Watchdog failed on cpu%d\n",
+				smp_processor_id());
+
+	stop_arch_virt_timer();
+}
+
+static int sdei_watchdog_callback(u32 event,
+		struct pt_regs *regs, void *arg)
+{
+	/* reprogram the arch virt timer */
+	start_arch_virt_timer(SDEI_TIMER_INTERVAL);
+	watchdog_hardlockup_check(regs);
+
+	return 0;
+}
+
+static void sdei_nmi_watchdog_bind(void *data)
+{
+	int ret;
+
+	ret = sdei_api_event_interrupt_bind(SDEI_NMI_WATCHDOG_HWIRQ);
+	if (ret < 0)
+		pr_err("SDEI bind failed on cpu%d, return %d\n",
+				smp_processor_id(), ret);
+}
+
+/* Before BIOS implements SDEI platform event, the host OS will use arch
+ * virt timer as SDEI watchdog timer, so the guest os will failed to start
+ * because it can not use arch virt timer. We provide a mechanism to disable
+ * SDEI NMI watchdog in the host.
+ */
+static int __init disable_sdei_nmi_watchdog_setup(char *str)
+{
+	disable_sdei_nmi_watchdog = true;
+	return 1;
+}
+__setup("disable_sdei_nmi_watchdog", disable_sdei_nmi_watchdog_setup);
+
+int __init watchdog_nmi_probe(void)
+{
+	int ret;
+
+	if (disable_sdei_nmi_watchdog)
+		return -EINVAL;
+
+	/*
+	 * When hyp mode is not available and kernel is not in hyp mode, the system
+	 * will use arch virt timer, which will conflict with SDEI NMI Watchdog.
+	 * Refer to 'arch_timer_select_ppi'.
+	 */
+	if (!is_kernel_in_hyp_mode() && !is_hyp_mode_available()) {
+		pr_err("Disable SDEI NMI Watchdog because the system will use virt timer\n");
+		return -EINVAL;
+	}
+
+	sdei_watchdog_event_num = sdei_api_event_interrupt_bind(SDEI_NMI_WATCHDOG_HWIRQ);
+	if (sdei_watchdog_event_num < 0) {
+		pr_err("bind interrupt failed !\n");
+		return sdei_watchdog_event_num;
+	}
+
+	on_each_cpu(sdei_nmi_watchdog_bind, NULL, true);
+
+	ret = sdei_event_register(sdei_watchdog_event_num,
+					sdei_watchdog_callback, NULL);
+	if (ret) {
+		pr_err("SDEI Watchdog register callback failed\n");
+		return ret;
+	}
+
+	pr_info("SDEI Watchdog registered successfully\n");
+
+	return 0;
+}

lib/Kconfig.debug

@@ -836,6 +836,12 @@ config HARDLOCKUP_DETECTOR_PERF
 	bool
 	select SOFTLOCKUP_DETECTOR
 
+config SDEI_WATCHDOG
+	bool "SDEI NMI Watchdog support"
+	depends on ARM_SDE_INTERFACE
+	select HAVE_HARDLOCKUP_DETECTOR_ARCH
+	select HARDLOCKUP_CHECK_TIMESTAMP
+
 #
 # Enables a timestamp based low pass filter to compensate for perf based
 # hard lockup detection which runs too fast due to turbo modes.