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Message-Id: <20210504190526.22347-15-ricardo.neri-calderon@linux.intel.com>
Date: Tue, 4 May 2021 12:05:24 -0700
From: Ricardo Neri <ricardo.neri-calderon@...ux.intel.com>
To: Thomas Gleixner <tglx@...utronix.de>,
Ingo Molnar <mingo@...nel.org>, Borislav Petkov <bp@...e.de>
Cc: "H. Peter Anvin" <hpa@...or.com>, Ashok Raj <ashok.raj@...el.com>,
Andi Kleen <ak@...ux.intel.com>,
Tony Luck <tony.luck@...el.com>,
Nicholas Piggin <npiggin@...il.com>,
"Peter Zijlstra (Intel)" <peterz@...radead.org>,
Andrew Morton <akpm@...ux-foundation.org>,
Stephane Eranian <eranian@...gle.com>,
Suravee Suthikulpanit <Suravee.Suthikulpanit@....com>,
"Ravi V. Shankar" <ravi.v.shankar@...el.com>,
Ricardo Neri <ricardo.neri@...el.com>, x86@...nel.org,
linux-kernel@...r.kernel.org,
Ricardo Neri <ricardo.neri-calderon@...ux.intel.com>,
Andi Kleen <andi.kleen@...el.com>
Subject: [RFC PATCH v5 14/16] x86/watchdog: Add a shim hardlockup detector
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@...or.com>
Cc: Ashok Raj <ashok.raj@...el.com>
Cc: Andi Kleen <andi.kleen@...el.com>
Cc: Tony Luck <tony.luck@...el.com>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Stephane Eranian <eranian@...gle.com>
Cc: "Ravi V. Shankar" <ravi.v.shankar@...el.com>
Cc: x86@...nel.org
Suggested-by: Nicholas Piggin <npiggin@...il.com>
Signed-off-by: Ricardo Neri <ricardo.neri-calderon@...ux.intel.com>
---
Changes since v4:
* Use a switch to enable and disable the various available detectors.
(Andi)
Changes since v3:
* Fixed style in multi-line comment. (Randy Dunlap)
Changes since v2:
* Pass cpu number as argument to hardlockup_detector_[enable|disable].
(Thomas Gleixner)
Changes since v1:
* Introduced this patch: Added an x86-specific shim hardlockup
detector. (Nicholas Piggin)
---
arch/x86/Kconfig.debug | 4 ++
arch/x86/kernel/Makefile | 1 +
arch/x86/kernel/watchdog_hld.c | 80 ++++++++++++++++++++++++++++++++++
3 files changed, 85 insertions(+)
create mode 100644 arch/x86/kernel/watchdog_hld.c
diff --git a/arch/x86/Kconfig.debug b/arch/x86/Kconfig.debug
index 0731da557a6d..4cdac3f80e80 100644
--- a/arch/x86/Kconfig.debug
+++ b/arch/x86/Kconfig.debug
@@ -117,9 +117,13 @@ config IOMMU_LEAK
config HAVE_MMIOTRACE_SUPPORT
def_bool y
+config X86_HARDLOCKUP_DETECTOR
+ bool
+
config X86_HARDLOCKUP_DETECTOR_HPET
bool "HPET Timer for Hard Lockup Detection"
select HARDLOCKUP_DETECTOR_CORE
+ select X86_HARDLOCKUP_DETECTOR
depends on HARDLOCKUP_DETECTOR && HPET_TIMER && HPET && (X86_64 || X86_32)
help
The hardlockup detector is driven by one counter of the Performance
diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile
index 5d1a90b23577..3303f10b3d0a 100644
--- a/arch/x86/kernel/Makefile
+++ b/arch/x86/kernel/Makefile
@@ -115,6 +115,7 @@ 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_AMD_NB) += amd_nb.o
diff --git a/arch/x86/kernel/watchdog_hld.c b/arch/x86/kernel/watchdog_hld.c
new file mode 100644
index 000000000000..8947a7644421
--- /dev/null
+++ b/arch/x86/kernel/watchdog_hld.c
@@ -0,0 +1,80 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * A shim hardlockup detector. It overrides the weak stubs of the generic
+ * implementation to select between the perf- or the hpet-based implementation.
+ *
+ * Copyright (C) Intel Corporation 2021
+ */
+
+#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)
+{
+ int ret = 0;
+
+ switch (detector_type) {
+ case X86_HARDLOCKUP_DETECTOR_PERF:
+ hardlockup_detector_perf_enable();
+ break;
+ case X86_HARDLOCKUP_DETECTOR_HPET:
+ hardlockup_detector_hpet_enable(cpu);
+ break;
+ default:
+ ret = -ENODEV;
+ }
+
+ return ret;
+}
+
+void watchdog_nmi_disable(unsigned int cpu)
+{
+ switch (detector_type) {
+ case X86_HARDLOCKUP_DETECTOR_PERF:
+ hardlockup_detector_perf_disable();
+ break;
+ case X86_HARDLOCKUP_DETECTOR_HPET:
+ hardlockup_detector_hpet_disable(cpu);
+ break;
+ }
+}
+
+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_stop();
+}
--
2.17.1
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