From: Ricardo Neri <ricardo.neri-calderon@linux.intel.com>
To: Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@kernel.org>, Borislav Petkov <bp@suse.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>, Ashok Raj <ashok.raj@intel.com>,
Andi Kleen <ak@linux.intel.com>, Tony Luck <tony.luck@intel.com>,
Nicholas Piggin <npiggin@gmail.com>,
"Peter Zijlstra (Intel)" <peterz@infradead.org>,
Andrew Morton <akpm@linux-foundation.org>,
Stephane Eranian <eranian@google.com>,
Suravee Suthikulpanit <Suravee.Suthikulpanit@amd.com>,
"Ravi V. Shankar" <ravi.v.shankar@intel.com>,
Ricardo Neri <ricardo.neri@intel.com>,
x86@kernel.org, linux-kernel@vger.kernel.org,
Ricardo Neri <ricardo.neri-calderon@linux.intel.com>,
Andi Kleen <andi.kleen@intel.com>
Subject: [RFC PATCH v5 13/16] watchdog/hardlockup/hpet: Only enable the HPET watchdog via a boot parameter
Date: Tue, 4 May 2021 12:05:23 -0700 [thread overview]
Message-ID: <20210504190526.22347-14-ricardo.neri-calderon@linux.intel.com> (raw)
In-Reply-To: <20210504190526.22347-1-ricardo.neri-calderon@linux.intel.com>
Keep the HPET-based hardlockup detector disabled unless explicitly enabled
via a command-line argument. If such parameter is not given, the
initialization of the hpet-based hardlockup detector fails and the NMI
watchdog will fall back to use the perf-based implementation.
Implement the command-line parsing using an early_param, as
__setup("nmi_watchdog=") only parses generic options.
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: Stephane Eranian <eranian@google.com>
Cc: "Ravi V. Shankar" <ravi.v.shankar@intel.com>
Cc: x86@kernel.org
Signed-off-by: Ricardo Neri <ricardo.neri-calderon@linux.intel.com>
--
Changes since v4:
* None
Changes since v3:
* None
Changes since v2:
* Do not imply that using nmi_watchdog=hpet means the detector is
enabled. Instead, print a warning in such case.
Changes since v1:
* Added documentation to the function handing the nmi_watchdog
kernel command-line argument.
---
.../admin-guide/kernel-parameters.txt | 8 ++++++-
arch/x86/kernel/watchdog_hld_hpet.c | 22 +++++++++++++++++++
2 files changed, 29 insertions(+), 1 deletion(-)
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 74db44ce4d9a..eafa38867270 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -3136,7 +3136,7 @@
Format: [state][,regs][,debounce][,die]
nmi_watchdog= [KNL,BUGS=X86] Debugging features for SMP kernels
- Format: [panic,][nopanic,][num]
+ Format: [panic,][nopanic,][num,][hpet]
Valid num: 0 or 1
0 - turn hardlockup detector in nmi_watchdog off
1 - turn hardlockup detector in nmi_watchdog on
@@ -3147,6 +3147,12 @@
please see 'nowatchdog'.
This is useful when you use a panic=... timeout and
need the box quickly up again.
+ When hpet is specified, the NMI watchdog will be driven
+ by an HPET timer, if available in the system. Otherwise,
+ it falls back to the default implementation (perf or
+ architecture-specific). Specifying hpet has no effect
+ if the NMI watchdog is not enabled (either at build time
+ or via the command line).
These settings can be accessed at runtime via
the nmi_watchdog and hardlockup_panic sysctls.
diff --git a/arch/x86/kernel/watchdog_hld_hpet.c b/arch/x86/kernel/watchdog_hld_hpet.c
index cd5f59b7c01b..3fd2405b31fa 100644
--- a/arch/x86/kernel/watchdog_hld_hpet.c
+++ b/arch/x86/kernel/watchdog_hld_hpet.c
@@ -548,6 +548,28 @@ void hardlockup_detector_hpet_stop(void)
disable_timer(hld_data);
}
+/**
+ * hardlockup_detector_hpet_setup() - Parse command-line parameters
+ * @str: A string containing the kernel command line
+ *
+ * Parse the nmi_watchdog parameter from the kernel command line. If
+ * selected by the user, use this implementation to detect hardlockups.
+ */
+static int __init hardlockup_detector_hpet_setup(char *str)
+{
+ if (!str)
+ return -EINVAL;
+
+ if (parse_option_str(str, "hpet"))
+ hardlockup_use_hpet = true;
+
+ if (!nmi_watchdog_user_enabled && hardlockup_use_hpet)
+ pr_err("Selecting HPET NMI watchdog has no effect with NMI watchdog disabled\n");
+
+ return 0;
+}
+early_param("nmi_watchdog", hardlockup_detector_hpet_setup);
+
/**
* hardlockup_detector_hpet_init() - Initialize the hardlockup detector
*
--
2.17.1
next prev parent reply other threads:[~2021-05-04 19:08 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-04 19:05 [RFC PATCH v5 00/16] x86: Implement an HPET-based hardlockup detector Ricardo Neri
2021-05-04 19:05 ` [RFC PATCH v5 01/16] x86/hpet: Expose hpet_writel() in header Ricardo Neri
2021-05-04 19:05 ` [RFC PATCH v5 02/16] x86/hpet: Add helper function hpet_set_comparator_periodic() Ricardo Neri
2021-05-04 19:05 ` [RFC PATCH v5 03/16] x86/hpet: Reserve an HPET channel for the hardlockup detector Ricardo Neri
2021-05-04 19:05 ` [RFC PATCH v5 04/16] watchdog/hardlockup: Define a generic function to detect hardlockups Ricardo Neri
2021-05-04 19:05 ` [RFC PATCH v5 05/16] watchdog/hardlockup: Decouple the hardlockup detector from perf Ricardo Neri
2021-05-04 19:05 ` [RFC PATCH v5 06/16] x86/nmi: Add an NMI_WATCHDOG NMI handler category Ricardo Neri
2021-05-04 19:05 ` [RFC PATCH v5 07/16] x86/watchdog/hardlockup: Add an HPET-based hardlockup detector Ricardo Neri
2021-05-04 20:53 ` Thomas Gleixner
2021-05-04 19:05 ` [RFC PATCH v5 08/16] x86/watchdog/hardlockup/hpet: Introduce a target_cpumask Ricardo Neri
2021-05-04 19:05 ` [RFC PATCH v5 09/16] watchdog/hardlockup/hpet: Group packages receiving IPIs when needed Ricardo Neri
2021-05-04 19:05 ` [RFC PATCH v5 10/16] watchdog/hardlockup/hpet: Adjust timer expiration on the number of monitored groups Ricardo Neri
2021-05-04 19:05 ` [RFC PATCH v5 11/16] x86/watchdog/hardlockup/hpet: Determine if HPET timer caused NMI Ricardo Neri
2021-05-04 19:05 ` [RFC PATCH v5 12/16] watchdog/hardlockup: Use parse_option_str() to handle "nmi_watchdog" Ricardo Neri
2021-05-04 19:05 ` Ricardo Neri [this message]
2021-05-04 19:05 ` [RFC PATCH v5 14/16] x86/watchdog: Add a shim hardlockup detector Ricardo Neri
2021-05-04 19:05 ` [RFC PATCH v5 15/16] watchdog: Expose lockup_detector_reconfigure() Ricardo Neri
2021-05-04 19:05 ` [RFC PATCH v5 16/16] x86/tsc: Switch to perf-based hardlockup detector if TSC become unstable Ricardo Neri
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