[PATCH 00/38] arm64: Add support for FEAT_NMI
Jinjie Ruan
ruanjinjie at huawei.com
Mon Oct 26 23:39:39 PDT 2026
在 2026/9/14 18:20, Vladimir Murzin 写道:
> FEAT_NMI provides an architected mechanism for supporting non-maskable
> interrupts (NMIs) and less-masked interrupts (LMIs).
>
> Since we already support pseudo-NMIs via priority masking, introducing
> another flavour of NMI on top of the existing infrastructure could
> easily become messy, making the code harder to follow and reason
> about.
>
> To avoid that, this series first makes room for the new NMI "tenant"
> by restructuring the existing exception masking logic (patches 01/38 -
> 15/38)
>
> The main idea is to separate the logical view of exception state from
> its hardware representation. To achieve this, we introduce logical
> exception contexts that can be mapped onto the corresponding hardware
> state. This naturally consolidates the hardware-specific handling into
> a small number of places, while allowing the rest of the code to
> operate purely in terms of logical exception contexts.
>
> Since this restructuring is non-trivial and carries a risk of subtle
> behavioural changes, the series adds extensive debug checks to verify
> that the hardware state always matches the expected logical state.
>
> With this restructuring in place, wiring FEAT_NMI into the new
> framework becomes much more manageable (pathes 16/38 - 32/38). GIC
> support for NMI is build on top (pathes 33/38 - 38/38)
>
> This work would not have been possible without the contributions of
> Ada Couprie Diaz, Mark Brown, and Lorenzo Pieralisi - please credit
> them for everything that works well. Any remaining bugs or issues are
> entirely my own.
>
> Although I droped RFC tag, I'd still appreciate feedback on the
> overall approach.
>
> Most of the testing has been done on QEMU, Fast Model and pre-silicon
> environment, so the series definitely benefit from extensive testing
> on real hardware (without NMI, with pseudo-NMI, and with FEAT_NMI).
Hi Vladimir,
I used my LLM to generate some testcases and tested it
on QEMU 11.1.50 (arm64 virt, TCG) and all pass, no warnings:
1. Three modes: no NMI, pseudo-NMI and FEAT_NMI on GICv2/v3/v4/v5
2. CPU/GIC support mismatches: NMI falls back to a normal IRQ, or is
ignored.
3. NMI delivered while IRQs are off; broadcast, perf and hardlockup stress.
4. ALLINT masking, kprobe rejection of ALLINT instructions, hotplug,
suspend, ACPI/EFI runtime.
5. Panic stop via IPI_CPU_STOP_NMI;
6. ARM64_NMI=n and PSEUDO_NMI=n builds.
The testcase is avalible at:
https://github.com/ruanjinjie-eng/feat_nmi_tests
I will find a real hardware to test them later.
Tested-by: Jinjie Ruan <ruanjinjie at huawei.com>
>
> Changelog
> RFC v2 -> v1
>
> - Rebased on v7.3-rc3.
> - Dropped RFC tag, have not received objections, at the same time
> got support from Jinjie
> - Dropped prerequisite patches already present in the newer base
> - Added logic to reject probing/stepping over ALLINT
> - Moved addition of arm64_debug_exc_context() in separate patch
> - Reworked debug logic for validating direction of exception
> transition
> - Split support for NMI in GICv5 in 3 separate patches
> - Added review tags
>
> RFC v1 -> RFC v2
>
> - Rebased on v7.2-rc5.
> - Improved commit descriptions.
> - Split some patches into smaller ones.
> - Added a graceful fallback for IPI requests when FEAT_NMI is
> supported by the CPU but unsupported by the interrupt
> controller.
> - Split the GICv3 preparation from the FEAT_GICv3_NMI
> implementation.
> - Added NMI support to GICv5, primarily as an illustration of the
> implementation, although it also happens to work on Fast Model.
> - Added review tags only to unchanged patches. Review tags were
> intentionally dropped from modified patches to reflect those
> changes and encourage re-review.
>
> RFC v1:
> https://lore.kernel.org/linux-arm-kernel/20260709121333.23507-1-vladimir.murzin@arm.com/
>
> RFC v2:
> https://lore.kernel.org/linux-arm-kernel/20260727163453.7969-1-vladimir.murzin@arm.com/
>
> Thanks!
> Vladimir
>
> Ada Couprie Diaz (15):
> arm64: irqflags: Introduce arm64-specific irqflags type
> arm64: irqflags: save and use both DAIF and PMR
> arm64: interrupts: Add common exception state helpers
> arm64: entry: Introduce entry specific exception masking helpers
> arm64: entry: replace DAIF helpers with entry helpers
> arm64: interrupts: Introduce exception masking save/restore helpers
> arm64: interrupts: introduce a helper for GIC priority initialization
> arm64: replace local_daif helpers
> arm64: cpuidle: use new helpers to bypass interrupt priority masking
> arm64: remove daifflags.h
> arm64: gicv3: remove GIC_PRIO_PSR_I_SET
> arm64: ptrace: Add PSR_ALLINT_BIT
> arm64: cpufeature: Detect PE support for FEAT_NMI
> arm64: nmi: Manage masking for superpriority interrupts
> arm64: irq: Report FEAT_NMI masking local IRQs
>
> Lorenzo Pieralisi (2):
> irqchip/gic-v3: Rename nmi to pseudo_nmi
> irqchip/gic-v3: Implement FEAT_GICv3_NMI support
>
> Mark Brown (5):
> arm64: booting: Document boot requirements for FEAT_NMI
> arm64: sysreg: Add definitions for immediate versions of MSR ALLINT
> arm64: idreg: Add an override for FEAT_NMI
> arm64: nmi: Add handling of superpriority interrupts as NMIs
> arm64: nmi: Add Kconfig for NMI
>
> Vladimir Murzin (16):
> arm64: process: Lift check for exception state to generic
> infrastructure
> arm64: cpufeature: Remove system_has_prio_mask_debugging()
> arm64: irqflags: Switch to CONFIG_DEBUG_IRQFLAGS
> arm64: Kconfig: Remove CONFIG_ARM64_DEBUG_PRIORITY_MASKING
> efi/runtime-wrappers: Permit architectures to override IRQ flags
> checks
> arm64/efi: Implement override for IRQ flags checks
> arm64: probes: Reject stepping over ALLINT
> arm64: suspend: Always initialise PSTATE.ALLINT
> arm64/efi: Add ALLINT to IRQ flags checks
> arm64: kprobes: Disable NMIs
> arm64: smp: Abstract SGI and LPI operations
> arm64: smp: Fall back to IRQ when IPI NMI request fails
> arm64: smp: Add NMI support for LPI-backed IPIs
> genirq: Trust local irqchip when considering IRQ for NMI
> genirq: Do not call add_interrupt_randomness() in NMI context
> irqchip/gic-v5: Add NMI support
>
> Documentation/arch/arm64/booting.rst | 6 +
> arch/arm64/Kconfig | 29 +-
> arch/arm64/include/asm/assembler.h | 20 +-
> arch/arm64/include/asm/cpucaps.h | 2 +
> arch/arm64/include/asm/cpufeature.h | 14 +-
> arch/arm64/include/asm/cpuidle.h | 18 +-
> arch/arm64/include/asm/daifflags.h | 144 --------
> arch/arm64/include/asm/efi.h | 42 ++-
> arch/arm64/include/asm/entry-common.h | 8 +-
> arch/arm64/include/asm/insn.h | 1 +
> .../include/asm/interrupts/common_flags.h | 256 +++++++++++++
> arch/arm64/include/asm/interrupts/entry.h | 102 ++++++
> arch/arm64/include/asm/interrupts/masking.h | 166 +++++++++
> arch/arm64/include/asm/irqflags.h | 150 ++++----
> arch/arm64/include/asm/kvm_host.h | 1 -
> arch/arm64/include/asm/mmu_context.h | 1 -
> arch/arm64/include/asm/ptrace.h | 25 +-
> arch/arm64/include/asm/sysreg.h | 2 +
> arch/arm64/include/uapi/asm/ptrace.h | 1 +
> arch/arm64/kernel/acpi.c | 15 +-
> arch/arm64/kernel/cpufeature.c | 68 +++-
> arch/arm64/kernel/debug-monitors.c | 1 -
> arch/arm64/kernel/entry-common.c | 335 +++++++++++++-----
> arch/arm64/kernel/entry.S | 14 +-
> arch/arm64/kernel/hibernate.c | 14 +-
> arch/arm64/kernel/irq.c | 45 ++-
> arch/arm64/kernel/machine_kexec.c | 4 +-
> arch/arm64/kernel/pi/idreg-override.c | 1 +
> arch/arm64/kernel/probes/decode-insn.c | 11 +-
> arch/arm64/kernel/probes/kprobes.c | 24 +-
> arch/arm64/kernel/process.c | 24 +-
> arch/arm64/kernel/setup.c | 4 +-
> arch/arm64/kernel/signal.c | 1 -
> arch/arm64/kernel/smp.c | 216 +++++++----
> arch/arm64/kernel/suspend.c | 14 +-
> arch/arm64/kernel/traps.c | 1 -
> arch/arm64/kvm/hyp/nvhe/switch.c | 2 +-
> arch/arm64/kvm/hyp/vgic-v3-sr.c | 7 +-
> arch/arm64/kvm/hyp/vhe/switch.c | 14 +-
> arch/arm64/mm/fault.c | 1 -
> arch/arm64/mm/mmu.c | 7 +-
> arch/arm64/tools/cpucaps | 2 +
> drivers/firmware/efi/runtime-wrappers.c | 32 +-
> drivers/irqchip/irq-gic-v3.c | 132 ++++++-
> drivers/irqchip/irq-gic-v5.c | 244 ++++++++++++-
> include/linux/irq.h | 2 +-
> include/linux/irqchip/arm-gic-v3-prio.h | 8 -
> include/linux/irqchip/arm-gic-v3.h | 4 +
> kernel/irq/handle.c | 3 +-
> kernel/irq/manage.c | 5 -
> 50 files changed, 1661 insertions(+), 582 deletions(-)
> delete mode 100644 arch/arm64/include/asm/daifflags.h
> create mode 100644 arch/arm64/include/asm/interrupts/common_flags.h
> create mode 100644 arch/arm64/include/asm/interrupts/entry.h
> create mode 100644 arch/arm64/include/asm/interrupts/masking.h
>
--
Best regards,
Jinjie
More information about the linux-arm-kernel
mailing list