Date: Mon, 6 May 2024 20:12:46 +0800
From: "Liao, Chang" <liaochang1@...wei.com>
To: Mark Rutland <mark.rutland@....com>
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Subject: Re: [PATCH v3 0/8] Rework the DAIF mask, unmask and track API



在 2024/5/4 1:10, Mark Rutland 写道:
> Hi,
> 
> On Mon, Apr 15, 2024 at 06:47:50AM +0000, Liao Chang wrote:
>> This patch series reworks the DAIF mask, unmask, and track API for the
>> upcoming FEAT_NMI extension added in Armv8.8.
>>
>> As platform and virtualization[1] supports for FEAT_NMI is emerging, and
>> Mark Brown's FEAT_NMI patch series[2] highlighted the need for clean up
>> the existing hacking style approach about DAIF management code before
>> adding NMI functionality, furthermore, we discover some subtle bugs
>> during 'perf' and 'ipi_backtrace' transition from PSEUDO_NMI to
>> FEAT_NMI, in summary, all of these emphasize the importance of rework.
>>
>> This series of reworking patches follows the suggestion from Mark
>> Rutland mentioned in Mark Brown's patchset. In summary, he think the
>> better way for DAIF manangement look likes as following:
>>
>> (a) Adding entry-specific helpers to manipulate abstract exception masks
>>     covering DAIF + PMR + ALLINT. Those need unmask-at-entry and
>>     mask-at-exit behaviour, and today only need to manage DAIF + PMR.
>>
>>     It should be possible to do this ahead of ALLINT / NMI support.
>>
>> (b) Adding new "logical exception mask" helpers that treat DAIF + PMR +
>>     ALLINT as separate elements. 
> 
> I've started looking at this in the series. There are some subtleties here, and
> I don't think the helpers in this series are quite right as-is. I will try to
> get back to you next week with a description of those; it'll take a short while
> to write that up correctly and clearly and I don't trust myself to rush that
> last thing on a Friday.
> 
> Thanks,
> Mark.

Hi，Mark

Thanks for your feedback.I apprecaite your interest in this patch series
and look forward to receiving additional comments from you and others in
the community.

I am pleased to inform you that the FEAT_NMI features has been successfully
merged into the upstream QEMU codebase at the "master" branch recently. This
allow for initial testing without requiring hardware support for FEAT_NMI.

To ensure minimal regressions introduced by this patch series, i have done
testing using perf top, hardlokup and ipi nmi for various configurations,
including (1) no NMI (2) use CONFIG_PSEUDO_NMI (3) use CONFIG_ARM64_NMI.

We encourage further discussion and feedback on the patch series. We are
particularly interested in hearing from developers who might have experience
with NMI handling or those using platforms with FEAT_NMI capabilities.

Thank you.

> 
>>
>> This patches cherry-pick a part of Mark Brown' FEAT_NMI series, in order
>> to pass compilation and basic testing, includes perf and ipi_backtrace.
>>
>> [1] https://lore.kernel.org/all/20240407081733.3231820-1-ruanjinjie@huawei.com/
>> [2] https://lore.kernel.org/linux-arm-kernel/Y4sH5qX5bK9xfEBp@lpieralisi/
>>
>> v3->v2:
>> 1. Squash two commits that address two minor issues into Mark Brown's
>>    origin patch for detecting FEAT_NMI.
>> 2. Add one patch resolves the kprobe reenter panic while testing
>>    FEAT_NMI on QEMU.
>>
>> v2->v1:
>> Add SoB tags following the origin author's SoBs.
>>
>> Liao Chang (5):
>>   arm64: daifflags: Add logical exception masks covering DAIF + PMR +
>>     ALLINT
>>   arm64: Unify exception masking at entry and exit of exception
>>   arm64: Deprecate old local_daif_{mask,save,restore}
>>   irqchip/gic-v3: Improve the maintainability of NMI masking in GIC
>>     driver
>>   arm64: kprobe: Keep NMI maskabled while kprobe is stepping xol
>>
>> Mark Brown (3):
>>   arm64/sysreg: Add definitions for immediate versions of MSR ALLINT
>>   arm64/cpufeature: Detect PE support for FEAT_NMI
>>   arm64/nmi: Add Kconfig for NMI
>>
>>  arch/arm64/Kconfig                   |  17 ++
>>  arch/arm64/include/asm/cpufeature.h  |   6 +
>>  arch/arm64/include/asm/daifflags.h   | 298 ++++++++++++++++++++++-----
>>  arch/arm64/include/asm/nmi.h         |  27 +++
>>  arch/arm64/include/asm/sysreg.h      |   2 +
>>  arch/arm64/include/uapi/asm/ptrace.h |   1 +
>>  arch/arm64/kernel/acpi.c             |  10 +-
>>  arch/arm64/kernel/cpufeature.c       |  58 +++++-
>>  arch/arm64/kernel/debug-monitors.c   |   7 +-
>>  arch/arm64/kernel/entry-common.c     |  96 +++++----
>>  arch/arm64/kernel/entry.S            |   2 -
>>  arch/arm64/kernel/hibernate.c        |   6 +-
>>  arch/arm64/kernel/irq.c              |   2 +-
>>  arch/arm64/kernel/machine_kexec.c    |   2 +-
>>  arch/arm64/kernel/probes/kprobes.c   |   4 +-
>>  arch/arm64/kernel/setup.c            |   2 +-
>>  arch/arm64/kernel/smp.c              |   6 +-
>>  arch/arm64/kernel/suspend.c          |   6 +-
>>  arch/arm64/kvm/hyp/vgic-v3-sr.c      |   6 +-
>>  arch/arm64/kvm/hyp/vhe/switch.c      |   4 +-
>>  arch/arm64/mm/mmu.c                  |   6 +-
>>  arch/arm64/tools/cpucaps             |   2 +
>>  drivers/irqchip/irq-gic-v3.c         |   6 +-
>>  23 files changed, 442 insertions(+), 134 deletions(-)
>>  create mode 100644 arch/arm64/include/asm/nmi.h
>>
>> -- 
>> 2.34.1
>>
>>
> 

-- 
BR
Liao, Chang

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