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From: Stephane Eranian via iommu <iommu@lists.linux-foundation.org>
To: Ricardo Neri <ricardo.neri-calderon@linux.intel.com>
Cc: "Ravi V. Shankar" <ravi.v.shankar@intel.com>,
	x86 <x86@kernel.org>, Ashok Raj <ashok.raj@intel.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Randy Dunlap <rdunlap@infradead.org>,
	LKML <linux-kernel@vger.kernel.org>,
	Ricardo Neri <ricardo.neri@intel.com>,
	iommu@lists.linux-foundation.org,
	Andi Kleen <andi.kleen@intel.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Borislav Petkov <bp@suse.de>, Ingo Molnar <mingo@kernel.org>
Subject: Re: [RFC PATCH v4 17/21] x86/tsc: Switch to perf-based hardlockup detector if TSC become unstable
Date: Thu, 6 Jun 2019 17:35:51 -0700
Message-ID: <CABPqkBQP=JxpiQE7SVuJO3xPWvsFbAPj916RTYUgaMBDG1OdaQ@mail.gmail.com> (raw)
In-Reply-To: <1558660583-28561-18-git-send-email-ricardo.neri-calderon@linux.intel.com>

Hi Ricardo,
Thanks for your contribution here. It is very important to move the
watchdog out of the PMU wherever possible.

On Thu, May 23, 2019 at 6:17 PM Ricardo Neri
<ricardo.neri-calderon@linux.intel.com> wrote:
>
> The HPET-based hardlockup detector relies on the TSC to determine if an
> observed NMI interrupt was originated by HPET timer. Hence, this detector
> can no longer be used with an unstable TSC.
>
> In such case, permanently stop the HPET-based hardlockup detector and
> start the perf-based detector.
>
> Signed-off-by: Ricardo Neri <ricardo.neri-calderon@linux.intel.com>
> ---
>  arch/x86/include/asm/hpet.h    | 2 ++
>  arch/x86/kernel/tsc.c          | 2 ++
>  arch/x86/kernel/watchdog_hld.c | 7 +++++++
>  3 files changed, 11 insertions(+)
>
> diff --git a/arch/x86/include/asm/hpet.h b/arch/x86/include/asm/hpet.h
> index fd99f2390714..a82cbe17479d 100644
> --- a/arch/x86/include/asm/hpet.h
> +++ b/arch/x86/include/asm/hpet.h
> @@ -128,6 +128,7 @@ extern int hardlockup_detector_hpet_init(void);
>  extern void hardlockup_detector_hpet_stop(void);
>  extern void hardlockup_detector_hpet_enable(unsigned int cpu);
>  extern void hardlockup_detector_hpet_disable(unsigned int cpu);
> +extern void hardlockup_detector_switch_to_perf(void);
>  #else
>  static inline struct hpet_hld_data *hpet_hardlockup_detector_assign_timer(void)
>  { return NULL; }
> @@ -136,6 +137,7 @@ static inline int hardlockup_detector_hpet_init(void)
>  static inline void hardlockup_detector_hpet_stop(void) {}
>  static inline void hardlockup_detector_hpet_enable(unsigned int cpu) {}
>  static inline void hardlockup_detector_hpet_disable(unsigned int cpu) {}
> +static void harrdlockup_detector_switch_to_perf(void) {}
>  #endif /* CONFIG_X86_HARDLOCKUP_DETECTOR_HPET */
>
This does not compile for me when CONFIG_X86_HARDLOCKUP_DETECTOR_HPET
is not enabled.
because:
   1- you have a typo on the function name
    2- you are missing the inline keyword


>  #else /* CONFIG_HPET_TIMER */
> diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c
> index 59b57605e66c..b2210728ce3d 100644
> --- a/arch/x86/kernel/tsc.c
> +++ b/arch/x86/kernel/tsc.c
> @@ -1158,6 +1158,8 @@ void mark_tsc_unstable(char *reason)
>
>         clocksource_mark_unstable(&clocksource_tsc_early);
>         clocksource_mark_unstable(&clocksource_tsc);
> +
> +       hardlockup_detector_switch_to_perf();
>  }
>
>  EXPORT_SYMBOL_GPL(mark_tsc_unstable);
> diff --git a/arch/x86/kernel/watchdog_hld.c b/arch/x86/kernel/watchdog_hld.c
> index c2512d4c79c5..c8547c227a41 100644
> --- a/arch/x86/kernel/watchdog_hld.c
> +++ b/arch/x86/kernel/watchdog_hld.c
> @@ -76,3 +76,10 @@ void watchdog_nmi_stop(void)
>         if (detector_type == X86_HARDLOCKUP_DETECTOR_HPET)
>                 hardlockup_detector_hpet_stop();
>  }
> +
> +void hardlockup_detector_switch_to_perf(void)
> +{
> +       detector_type = X86_HARDLOCKUP_DETECTOR_PERF;
> +       hardlockup_detector_hpet_stop();
> +       hardlockup_start_all();
> +}
> --
> 2.17.1
>
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  reply index

Thread overview: 54+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-05-24  1:16 [RFC PATCH v4 00/21] Implement an HPET-based hardlockup detector Ricardo Neri
2019-05-24  1:16 ` [RFC PATCH v4 01/21] x86/msi: Add definition for NMI delivery mode Ricardo Neri
2019-05-24  1:16 ` [RFC PATCH v4 02/21] x86/hpet: Expose hpet_writel() in header Ricardo Neri
2019-05-24  1:16 ` [RFC PATCH v4 03/21] x86/hpet: Calculate ticks-per-second in a separate function Ricardo Neri
2019-06-14 15:54   ` Thomas Gleixner
2019-06-14 15:59     ` Thomas Gleixner
2019-06-18 22:48     ` Ricardo Neri
2019-06-18 23:13       ` Thomas Gleixner
2019-05-24  1:16 ` [RFC PATCH v4 04/21] x86/hpet: Add hpet_set_comparator() for periodic and one-shot modes Ricardo Neri
2019-06-14 18:17   ` Thomas Gleixner
2019-06-18 22:48     ` Ricardo Neri
2019-05-24  1:16 ` [RFC PATCH v4 05/21] x86/hpet: Reserve timer for the HPET hardlockup detector Ricardo Neri
2019-06-11 19:54   ` Thomas Gleixner
2019-06-14  1:14     ` Ricardo Neri
2019-06-14 16:10       ` Thomas Gleixner
2019-06-18 22:48         ` Ricardo Neri
2019-05-24  1:16 ` [RFC PATCH v4 06/21] x86/hpet: Configure the timer used by the " Ricardo Neri
2019-05-24  1:16 ` [RFC PATCH v4 07/21] watchdog/hardlockup: Define a generic function to detect hardlockups Ricardo Neri
2019-05-24  1:16 ` [RFC PATCH v4 08/21] watchdog/hardlockup: Decouple the hardlockup detector from perf Ricardo Neri
2019-05-24  1:16 ` [RFC PATCH v4 09/21] x86/nmi: Add a NMI_WATCHDOG NMI handler category Ricardo Neri
2019-05-24  1:16 ` [RFC PATCH v4 10/21] watchdog/hardlockup: Add function to enable NMI watchdog on all allowed CPUs at once Ricardo Neri
2019-05-24  1:16 ` [RFC PATCH v4 11/21] x86/watchdog/hardlockup: Add an HPET-based hardlockup detector Ricardo Neri
2019-05-24  1:16 ` [RFC PATCH v4 12/21] watchdog/hardlockup/hpet: Adjust timer expiration on the number of monitored CPUs Ricardo Neri
2019-06-11 20:11   ` Thomas Gleixner
2019-06-18 22:46     ` Ricardo Neri
2019-05-24  1:16 ` [RFC PATCH v4 13/21] x86/watchdog/hardlockup/hpet: Determine if HPET timer caused NMI Ricardo Neri
2019-05-24  1:16 ` [RFC PATCH v4 14/21] watchdog/hardlockup: Use parse_option_str() to handle "nmi_watchdog" Ricardo Neri
2019-05-24  1:16 ` [RFC PATCH v4 15/21] watchdog/hardlockup/hpet: Only enable the HPET watchdog via a boot parameter Ricardo Neri
2019-05-24  1:16 ` [RFC PATCH v4 16/21] x86/watchdog: Add a shim hardlockup detector Ricardo Neri
2019-05-24  1:16 ` [RFC PATCH v4 17/21] x86/tsc: Switch to perf-based hardlockup detector if TSC become unstable Ricardo Neri
2019-06-07  0:35   ` Stephane Eranian via iommu [this message]
2019-06-07 14:14     ` Ricardo Neri
2019-05-24  1:16 ` [RFC PATCH v4 18/21] x86/apic: Add a parameter for the APIC delivery mode Ricardo Neri
2019-06-16  9:55   ` Thomas Gleixner
2019-06-18 22:47     ` Ricardo Neri
2019-06-18 23:15       ` Thomas Gleixner
2019-05-24  1:16 ` [RFC PATCH v4 19/21] iommu/vt-d: Rework prepare_irte() to support per-irq " Ricardo Neri
2019-05-24  1:16 ` [RFC PATCH v4 20/21] iommu/vt-d: hpet: Reserve an interrupt remampping table entry for watchdog Ricardo Neri
2019-06-16 18:42   ` Thomas Gleixner
2019-06-16 19:21   ` Thomas Gleixner
2019-06-17  8:25     ` Thomas Gleixner
2019-06-17 21:38       ` Stephane Eranian via iommu
2019-06-17 23:08         ` Thomas Gleixner
2019-06-19 15:43           ` Jacob Pan
2019-06-21 15:33             ` Thomas Gleixner
2019-06-21 17:31               ` Jacob Pan
2019-06-21 18:39                 ` Jacob Pan
2019-06-21 20:05                   ` Thomas Gleixner
2019-06-21 23:55                     ` Ricardo Neri
2019-06-22  7:21                       ` Thomas Gleixner
2019-06-18 22:45       ` Ricardo Neri
2019-05-24  1:16 ` [RFC PATCH v4 21/21] x86/watchdog/hardlockup/hpet: Support interrupt remapping Ricardo Neri
2019-06-16  8:44   ` Thomas Gleixner
2019-06-16  8:53     ` Thomas Gleixner

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