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Subject[RFC PATCH v2 14/14] x86/watchdog: Add a shim hardlockup detector
Date
The generic hardlockup detector is based on perf. It also provides a set
of weak stubs that CPU architectures can override. Add a shim hardlockup
detector for x86 that selects between perf and hpet implementations.

Specifically, this shim implementation is needed for the HPET-based
hardlockup detector; it can also be used for future implementations.

Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ashok Raj <ashok.raj@intel.com>
Cc: Andi Kleen <andi.kleen@intel.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Clemens Ladisch <clemens@ladisch.de>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Philippe Ombredanne <pombredanne@nexb.com>
Cc: Kate Stewart <kstewart@linuxfoundation.org>
Cc: "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>
Cc: Mimi Zohar <zohar@linux.ibm.com>
Cc: Jan Kiszka <jan.kiszka@siemens.com>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: Nayna Jain <nayna@linux.ibm.com>
Cc: "Ravi V. Shankar" <ravi.v.shankar@intel.com>
Cc: x86@kernel.org
Suggested-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Ricardo Neri <ricardo.neri-calderon@linux.intel.com>
---
arch/x86/Kconfig.debug | 4 ++
arch/x86/kernel/Makefile | 1 +
arch/x86/kernel/watchdog_hld.c | 78 ++++++++++++++++++++++++++++++++++
3 files changed, 83 insertions(+)
create mode 100644 arch/x86/kernel/watchdog_hld.c

diff --git a/arch/x86/Kconfig.debug b/arch/x86/Kconfig.debug
index 3a2845a29e8a..5e5f4d2330af 100644
--- a/arch/x86/Kconfig.debug
+++ b/arch/x86/Kconfig.debug
@@ -169,10 +169,14 @@ config IOMMU_LEAK
config HAVE_MMIOTRACE_SUPPORT
def_bool y

+config X86_HARDLOCKUP_DETECTOR
+ bool
+
config X86_HARDLOCKUP_DETECTOR_HPET
bool "Use HPET Timer for Hard Lockup Detection"
select SOFTLOCKUP_DETECTOR
select HARDLOCKUP_DETECTOR
+ select X86_HARDLOCKUP_DETECTOR
depends on HPET_TIMER && HPET && X86_64
help
Say y to enable a hardlockup detector that is driven by an High-
diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile
index 9d610e8a9224..5372453fe2a7 100644
--- a/arch/x86/kernel/Makefile
+++ b/arch/x86/kernel/Makefile
@@ -106,6 +106,7 @@ obj-$(CONFIG_VM86) += vm86_32.o
obj-$(CONFIG_EARLY_PRINTK) += early_printk.o

obj-$(CONFIG_HPET_TIMER) += hpet.o
+obj-$(CONFIG_X86_HARDLOCKUP_DETECTOR) += watchdog_hld.o
obj-$(CONFIG_X86_HARDLOCKUP_DETECTOR_HPET) += watchdog_hld_hpet.o
obj-$(CONFIG_APB_TIMER) += apb_timer.o

diff --git a/arch/x86/kernel/watchdog_hld.c b/arch/x86/kernel/watchdog_hld.c
new file mode 100644
index 000000000000..a2f6190dbce0
--- /dev/null
+++ b/arch/x86/kernel/watchdog_hld.c
@@ -0,0 +1,78 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * A shim hardlockup detector. It simply overrides the weak stubs of the
+ * generic implementation.
+ *
+ * Copyright (C) Intel Corporation 2019
+ */
+
+#include <linux/nmi.h>
+#include <asm/hpet.h>
+
+enum x86_hardlockup_detector {
+ X86_HARDLOCKUP_DETECTOR_PERF,
+ X86_HARDLOCKUP_DETECTOR_HPET,
+};
+
+static enum __read_mostly x86_hardlockup_detector detector_type;
+
+int watchdog_nmi_enable(unsigned int cpu)
+{
+ if (detector_type == X86_HARDLOCKUP_DETECTOR_PERF) {
+ hardlockup_detector_perf_enable();
+ return 0;
+ }
+
+ if (detector_type == X86_HARDLOCKUP_DETECTOR_HPET) {
+ hardlockup_detector_hpet_enable();
+ return 0;
+ }
+
+ return -ENODEV;
+}
+
+void watchdog_nmi_disable(unsigned int cpu)
+{
+ if (detector_type == X86_HARDLOCKUP_DETECTOR_PERF) {
+ hardlockup_detector_perf_disable();
+ return;
+ }
+
+ if (detector_type == X86_HARDLOCKUP_DETECTOR_HPET) {
+ hardlockup_detector_hpet_disable();
+ return;
+ }
+}
+
+int __init watchdog_nmi_probe(void)
+{
+ int ret;
+
+ /*
+ * Try first with the HPET hardlockup detector. It will only
+ * succeed if selected at build time and the nmi_watchdog
+ * command-line parameter is configured. This ensure that the
+ * perf-based detector is used by default, if selected at
+ * build time.
+ */
+ ret = hardlockup_detector_hpet_init();
+ if (!ret) {
+ detector_type = X86_HARDLOCKUP_DETECTOR_HPET;
+ return ret;
+ }
+
+ ret = hardlockup_detector_perf_init();
+ if (!ret) {
+ detector_type = X86_HARDLOCKUP_DETECTOR_PERF;
+ return ret;
+ }
+
+ return ret;
+}
+
+void watchdog_nmi_stop(void)
+{
+ /* Only the HPET lockup detector defines a stop function. */
+ if (detector_type == X86_HARDLOCKUP_DETECTOR_HPET)
+ hardlockup_detector_hpet_enable();
+}
--
2.17.1
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