Messages in this thread Patch in this message | | | From | Ricardo Neri <> | Subject | [PATCH v6 21/29] x86/nmi: Add an NMI_WATCHDOG NMI handler category | Date | Thu, 5 May 2022 17:00:00 -0700 |
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Add a NMI_WATCHDOG as a new category of NMI handler. This new category is to be used with the HPET-based hardlockup detector. This detector does not have a direct way of checking if the HPET timer is the source of the NMI. Instead, it indirectly estimates it using the time-stamp counter.
Therefore, we may have false-positives in case another NMI occurs within the estimated time window. For this reason, we want the handler of the detector to be called after all the NMI_LOCAL handlers. A simple way of achieving this with a new NMI handler category.
Cc: Andi Kleen <ak@linux.intel.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: "Ravi V. Shankar" <ravi.v.shankar@intel.com> Cc: Stephane Eranian <eranian@google.com> Cc: iommu@lists.linux-foundation.org Cc: linuxppc-dev@lists.ozlabs.org Cc: x86@kernel.org Reviewed-by: Tony Luck <tony.luck@intel.com> Signed-off-by: Ricardo Neri <ricardo.neri-calderon@linux.intel.com> --- Changes since v5: * Updated to call instrumentation_end() as per f051f6979550 ("x86/nmi: Protect NMI entry against instrumentation")
Changes since v4: * None
Changes since v3: * None
Changes since v2: * Introduced this patch.
Changes since v1: * N/A --- arch/x86/include/asm/nmi.h | 1 + arch/x86/kernel/nmi.c | 10 ++++++++++ 2 files changed, 11 insertions(+)
diff --git a/arch/x86/include/asm/nmi.h b/arch/x86/include/asm/nmi.h index 1cb9c17a4cb4..4a0d5b562c91 100644 --- a/arch/x86/include/asm/nmi.h +++ b/arch/x86/include/asm/nmi.h @@ -28,6 +28,7 @@ enum { NMI_UNKNOWN, NMI_SERR, NMI_IO_CHECK, + NMI_WATCHDOG, NMI_MAX }; diff --git a/arch/x86/kernel/nmi.c b/arch/x86/kernel/nmi.c index e73f7df362f5..fde387e0812a 100644 --- a/arch/x86/kernel/nmi.c +++ b/arch/x86/kernel/nmi.c @@ -61,6 +61,10 @@ static struct nmi_desc nmi_desc[NMI_MAX] = .lock = __RAW_SPIN_LOCK_UNLOCKED(&nmi_desc[3].lock), .head = LIST_HEAD_INIT(nmi_desc[3].head), }, + { + .lock = __RAW_SPIN_LOCK_UNLOCKED(&nmi_desc[4].lock), + .head = LIST_HEAD_INIT(nmi_desc[4].head), + }, }; @@ -168,6 +172,8 @@ int __register_nmi_handler(unsigned int type, struct nmiaction *action) */ WARN_ON_ONCE(type == NMI_SERR && !list_empty(&desc->head)); WARN_ON_ONCE(type == NMI_IO_CHECK && !list_empty(&desc->head)); + WARN_ON_ONCE(type == NMI_WATCHDOG && !list_empty(&desc->head)); + /* * some handlers need to be executed first otherwise a fake @@ -379,6 +385,10 @@ static noinstr void default_do_nmi(struct pt_regs *regs) } raw_spin_unlock(&nmi_reason_lock); + handled = nmi_handle(NMI_WATCHDOG, regs); + if (handled == NMI_HANDLED) + goto out; + /* * Only one NMI can be latched at a time. To handle * this we may process multiple nmi handlers at once to -- 2.17.1
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