linux-kernel - [PATCH v2 0/5] KVM nVHE Hypervisor stack unwinder

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Date:   Mon,  2 May 2022 12:12:00 -0700
From:   Kalesh Singh <kaleshsingh@...gle.com>
To:     unlisted-recipients:; (no To-header on input)
Cc:     mark.rutland@....com, broonie@...nel.org, will@...nel.org,
        maz@...nel.org, qperret@...gle.com, tabba@...gle.com,
        surenb@...gle.com, kernel-team@...roid.com,
        Kalesh Singh <kaleshsingh@...gle.com>,
        James Morse <james.morse@....com>,
        Alexandru Elisei <alexandru.elisei@....com>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        Catalin Marinas <catalin.marinas@....com>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Alexei Starovoitov <ast@...nel.org>,
        Peter Collingbourne <pcc@...gle.com>,
        "Madhavan T. Venkataraman" <madvenka@...ux.microsoft.com>,
        Andrew Jones <drjones@...hat.com>,
        Zenghui Yu <yuzenghui@...wei.com>,
        Keir Fraser <keirf@...gle.com>,
        Kefeng Wang <wangkefeng.wang@...wei.com>,
        linux-arm-kernel@...ts.infradead.org, kvmarm@...ts.cs.columbia.edu,
        linux-kernel@...r.kernel.org
Subject: [PATCH v2 0/5] KVM nVHE Hypervisor stack unwinder

Hi all,

This v2 of the nVHE hypervisor stack unwinder. The previous version was
posted at:
v1: https://lore.kernel.org/lkml/20220427184716.1949239-1-kaleshsingh@google.com/

The series is based on arm64 for-next/core and is also dependent on
kvm-arm64/hyp-stack-guard [1].

The main changes in this version is splitting some patches into more
incremental changes, per Mark Brown

The relevant parts of the previous cover letter are copied below for
convenience.

[1] https://git.kernel.org/pub/scm/linux/kernel/git/maz/arm-platforms.git/log/?h=kvm-arm64/hyp-stack-guard

Thanks,
Kalesh

-------

This new version of the unwinder splits the unwinding and dumping
of the stack between the hypervisor and host:
  - The hypervisor unwinds its stack and dumps the address entries
    into a page shared with the host.
  - The host then symnolizes and prints the hyp stacktrace from
    the shared page.

The new approach doesn't depend on CONFIG_NVHE_EL2_DEBUG,
and allows dumping hyp stacktraces in prodcution environments
(!CONFIG_NVHE_EL2_DEBUG).

arm64/kernel/stacktrace.c is compiled twice: stacktrace.o for the
host kernel and stacktrace.nvhe.o for the hypervisor. This allows
reusing most of the host unwinding logic in the nVHE hypervisor.


Kalesh Singh (5):
  KVM: arm64: Factor out common stack unwinding logic
  KVM: arm64: Compile stacktrace.nvhe.o
  KVM: arm64: Add hypervisor overflow stack
  KVM: arm64: Allocate shared stacktrace pages
  KVM: arm64: Unwind and dump nVHE hypervisor stacktrace

 arch/arm64/include/asm/kvm_asm.h    |   1 +
 arch/arm64/include/asm/stacktrace.h |  58 +++++++++--
 arch/arm64/kernel/stacktrace.c      | 151 +++++++++++++++++++++++-----
 arch/arm64/kvm/arm.c                |  34 +++++++
 arch/arm64/kvm/handle_exit.c        |   4 +
 arch/arm64/kvm/hyp/nvhe/Makefile    |   3 +-
 arch/arm64/kvm/hyp/nvhe/host.S      |   9 +-
 arch/arm64/kvm/hyp/nvhe/setup.c     |  11 ++
 arch/arm64/kvm/hyp/nvhe/switch.c    |   4 +
 9 files changed, 231 insertions(+), 44 deletions(-)

-- 
2.36.0.464.gb9c8b46e94-goog