linux-kernel - Re: [PATCH 1/3] KVM: arm64: Record number of signal exits as a vCPU stat

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Message-ID: <CAOQ_QshrXJx42AS4Efu3gSZj1fnGgJ9FMFCydtdZ9h3Zj8cy=A@mail.gmail.com>
Date:   Thu, 29 Jul 2021 13:23:52 -0700
From:   Oliver Upton <oupton@...gle.com>
To:     Jing Zhang <jingzhangos@...gle.com>
Cc:     KVM ARM <kvmarm@...ts.cs.columbia.edu>, KVM <kvm@...r.kernel.org>,
        linux-kernel@...r.kernel.org, Paolo Bonzini <pbonzini@...hat.com>,
        Marc Zyngier <maz@...nel.org>,
        James Morse <james.morse@....com>,
        Alexandru Elisei <Alexandru.Elisei@....com>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Peter Zijlstra <peterz@...radead.org>,
        Andy Lutomirski <luto@...nel.org>,
        linux-arm-kernel@...ts.infradead.org,
        Peter Shier <pshier@...gle.com>,
        Shakeel Butt <shakeelb@...gle.com>,
        Guangyu Shi <guangyus@...gle.com>
Subject: Re: [PATCH 1/3] KVM: arm64: Record number of signal exits as a vCPU stat

On Thu, Jul 29, 2021 at 1:07 PM Jing Zhang <jingzhangos@...gle.com> wrote:
>
> On Thu, Jul 29, 2021 at 12:56 PM Oliver Upton <oupton@...gle.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@...gle.com>
> > Signed-off-by: Oliver Upton <oupton@...gle.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?

Definitely.

> >  };
> >  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@...gle.com>

Thanks Jing!