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From:   Jing Zhang <jingzhangos@google.com>
Date:   Thu, 29 Jul 2021 13:07:45 -0700
Message-ID: <CAAdAUtge_wRL-Ri-TngototL5jixSfDyJm7nTaYBXJqXU0jfmw@mail.gmail.com>
Subject: Re: [PATCH 1/3] KVM: arm64: Record number of signal exits as a vCPU stat
To:     Oliver Upton <oupton@google.com>
Cc:     KVM ARM <kvmarm@lists.cs.columbia.edu>, KVM <kvm@vger.kernel.org>,
        linux-kernel@vger.kernel.org, Paolo Bonzini <pbonzini@redhat.com>,
        Marc Zyngier <maz@kernel.org>,
        James Morse <james.morse@arm.com>,
        Alexandru Elisei <alexandru.elisei@arm.com>,
        Suzuki K Poulose <suzuki.poulose@arm.com>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Will Deacon <will@kernel.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Peter Zijlstra <peterz@infradead.org>,
        Andy Lutomirski <luto@kernel.org>,
        linux-arm-kernel@lists.infradead.org,
        Peter Shier <pshier@google.com>,
        Shakeel Butt <shakeelb@google.com>,
        Guangyu Shi <guangyus@google.com>
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On Thu, Jul 29, 2021 at 12:56 PM Oliver Upton <oupton@google.com> wrote:
>
> Most other architectures that implement KVM record a statistic
> indicating the number of times a vCPU has exited due to a pending
> signal. Add support for that stat to arm64.
>
> Cc: Jing Zhang <jingzhangos@google.com>
> Signed-off-by: Oliver Upton <oupton@google.com>
> ---
>  arch/arm64/include/asm/kvm_host.h | 1 +
>  arch/arm64/kvm/arm.c              | 1 +
>  arch/arm64/kvm/guest.c            | 3 ++-
>  3 files changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
> index 41911585ae0c..70e129f2b574 100644
> --- a/arch/arm64/include/asm/kvm_host.h
> +++ b/arch/arm64/include/asm/kvm_host.h
> @@ -576,6 +576,7 @@ struct kvm_vcpu_stat {
>         u64 wfi_exit_stat;
>         u64 mmio_exit_user;
>         u64 mmio_exit_kernel;
> +       u64 signal_exits;
>         u64 exits;
>  };
>
> diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
> index e9a2b8f27792..60d0a546d7fd 100644
> --- a/arch/arm64/kvm/arm.c
> +++ b/arch/arm64/kvm/arm.c
> @@ -783,6 +783,7 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu)
>                 if (signal_pending(current)) {
>                         ret = -EINTR;
>                         run->exit_reason = KVM_EXIT_INTR;
> +                       ++vcpu->stat.signal_exits;
>                 }
>
>                 /*
> diff --git a/arch/arm64/kvm/guest.c b/arch/arm64/kvm/guest.c
> index 1dfb83578277..50fc16ad872f 100644
> --- a/arch/arm64/kvm/guest.c
> +++ b/arch/arm64/kvm/guest.c
> @@ -50,7 +50,8 @@ const struct _kvm_stats_desc kvm_vcpu_stats_desc[] = {
>         STATS_DESC_COUNTER(VCPU, wfi_exit_stat),
>         STATS_DESC_COUNTER(VCPU, mmio_exit_user),
>         STATS_DESC_COUNTER(VCPU, mmio_exit_kernel),
> -       STATS_DESC_COUNTER(VCPU, exits)
> +       STATS_DESC_COUNTER(VCPU, exits),
> +       STATS_DESC_COUNTER(VCPU, signal_exits),
How about put signal_exits before exits as the same order in
kvm_vcpu_stat just for readability?
>  };
>  static_assert(ARRAY_SIZE(kvm_vcpu_stats_desc) ==
>                 sizeof(struct kvm_vcpu_stat) / sizeof(u64));
> --
> 2.32.0.554.ge1b32706d8-goog
>
Reviewed-by: Jing Zhang <jingzhangos@google.com>

Thanks,
Jing