linux-kernel - Re: [PATCH v5 00/17] KVM nVHE Hypervisor stack unwinder

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Date:   Fri, 22 Jul 2022 11:48:31 +0100
From:   Oliver Upton <oliver.upton@...ux.dev>
To:     Kalesh Singh <kaleshsingh@...gle.com>
Cc:     maz@...nel.org, mark.rutland@....com, broonie@...nel.org,
        madvenka@...ux.microsoft.com, tabba@...gle.com, will@...nel.org,
        qperret@...gle.com, james.morse@....com, alexandru.elisei@....com,
        suzuki.poulose@....com, catalin.marinas@....com,
        andreyknvl@...il.com, vincenzo.frascino@....com,
        mhiramat@...nel.org, ast@...nel.org, drjones@...hat.com,
        wangkefeng.wang@...wei.com, elver@...gle.com, keirf@...gle.com,
        yuzenghui@...wei.com, ardb@...nel.org,
        linux-arm-kernel@...ts.infradead.org, kvmarm@...ts.cs.columbia.edu,
        linux-kernel@...r.kernel.org, android-mm@...gle.com,
        kernel-team@...roid.com
Subject: Re: [PATCH v5 00/17] KVM nVHE Hypervisor stack unwinder

Hi Kalesh,

On Wed, Jul 20, 2022 at 10:57:11PM -0700, Kalesh Singh wrote:

[...]

> Kalesh Singh (17):
>   arm64: stacktrace: Add shared header for common stack unwinding code
>   arm64: stacktrace: Factor out on_accessible_stack_common()
>   arm64: stacktrace: Factor out unwind_next_common()
>   arm64: stacktrace: Handle frame pointer from different address spaces
>   arm64: stacktrace: Factor out common unwind()
>   arm64: stacktrace: Add description of stacktrace/common.h
>   KVM: arm64: On stack overflow switch to hyp overflow_stack
>   KVM: arm64: Add PROTECTED_NVHE_STACKTRACE Kconfig
>   KVM: arm64: Allocate shared pKVM hyp stacktrace buffers
>   KVM: arm64: Stub implementation of pKVM HYP stack unwinder
>   KVM: arm64: Stub implementation of non-protected nVHE HYP stack
>     unwinder
>   KVM: arm64: Save protected-nVHE (pKVM) hyp stacktrace
>   KVM: arm64: Prepare non-protected nVHE hypervisor stacktrace
>   KVM: arm64: Implement protected nVHE hyp stack unwinder
>   KVM: arm64: Implement non-protected nVHE hyp stack unwinder
>   KVM: arm64: Introduce pkvm_dump_backtrace()
>   KVM: arm64: Introduce hyp_dump_backtrace()

Adding a general comment on the organization of the series. I think for
the next spin it'd be good to organize the entire non-pKVM
implementation first, followed by the pKVM implementation. Otherwise,
reviewers need to jump around the series a lot in order to page in the
appropriate context.

I had mentioned this about the last two patches earlier, but after
grokking the stack I see the comment applies to the entire KVM portion
of the series.

--
Thanks,
Oliver