linux-kernel - Re: [REPOST PATCH 07/16] selftests: KVM: aarch64: Add PMU cycle counter helpers

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Message-ID: <CAJHc60w7gwUJ_rh6B3F_9SD_uxEDMRLFyahowGpCi54-84y3Hg@mail.gmail.com>
Date:   Thu, 9 Mar 2023 14:19:07 -0800
From:   Raghavendra Rao Ananta <rananta@...gle.com>
To:     Reiji Watanabe <reijiw@...gle.com>
Cc:     Oliver Upton <oupton@...gle.com>, Marc Zyngier <maz@...nel.org>,
        Ricardo Koller <ricarkol@...gle.com>,
        James Morse <james.morse@....com>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Jing Zhang <jingzhangos@...gle.com>,
        Colton Lewis <coltonlewis@...gle.com>,
        linux-arm-kernel@...ts.infradead.org, kvmarm@...ts.linux.dev,
        linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Subject: Re: [REPOST PATCH 07/16] selftests: KVM: aarch64: Add PMU cycle
 counter helpers

Hi Reiji,

On Thu, Mar 2, 2023 at 7:06 PM Reiji Watanabe <reijiw@...gle.com> wrote:
>
> Hi Raghu,
>
> On Tue, Feb 14, 2023 at 5:07 PM Raghavendra Rao Ananta
> <rananta@...gle.com> wrote:
> >
> > Add basic helpers for the test to access the cycle counter
> > registers. The helpers will be used in the upcoming patches
> > to run the tests related to cycle counter.
> >
> > No functional change intended.
> >
> > Signed-off-by: Raghavendra Rao Ananta <rananta@...gle.com>
> > ---
> >  .../testing/selftests/kvm/aarch64/vpmu_test.c | 40 +++++++++++++++++++
> >  1 file changed, 40 insertions(+)
> >
> > diff --git a/tools/testing/selftests/kvm/aarch64/vpmu_test.c b/tools/testing/selftests/kvm/aarch64/vpmu_test.c
> > index d72c3c9b9c39f..15aebc7d7dc94 100644
> > --- a/tools/testing/selftests/kvm/aarch64/vpmu_test.c
> > +++ b/tools/testing/selftests/kvm/aarch64/vpmu_test.c
> > @@ -147,6 +147,46 @@ static inline void disable_counter(int idx)
> >         isb();
> >  }
> >
> > +static inline uint64_t read_cycle_counter(void)
> > +{
> > +       return read_sysreg(pmccntr_el0);
> > +}
> > +
> > +static inline void reset_cycle_counter(void)
> > +{
> > +       uint64_t v = read_sysreg(pmcr_el0);
> > +
> > +       write_sysreg(ARMV8_PMU_PMCR_C | v, pmcr_el0);
> > +       isb();
> > +}
> > +
> > +static inline void enable_cycle_counter(void)
> > +{
> > +       uint64_t v = read_sysreg(pmcntenset_el0);
> > +
> > +       write_sysreg(ARMV8_PMU_CNTENSET_C | v, pmcntenset_el0);
> > +       isb();
> > +}
>
> You might want to use enable_counter() and disable_counter()
> from enable_cycle_counter() and disable_cycle_counter() respectively?
>
Yes, that should work. I'll do that.

Thank you.
Raghavendra

> Thank you,
> Reiji
>
> > +
> > +static inline void disable_cycle_counter(void)
> > +{
> > +       uint64_t v = read_sysreg(pmcntenset_el0);
> > +
> > +       write_sysreg(ARMV8_PMU_CNTENSET_C | v, pmcntenclr_el0);
> > +       isb();
> > +}
> > +
> > +static inline void write_pmccfiltr(unsigned long val)
> > +{
> > +       write_sysreg(val, pmccfiltr_el0);
> > +       isb();
> > +}
> > +
> > +static inline uint64_t read_pmccfiltr(void)
> > +{
> > +       return read_sysreg(pmccfiltr_el0);
> > +}
> > +
> >  static inline uint64_t get_pmcr_n(void)
> >  {
> >         return FIELD_GET(ARMV8_PMU_PMCR_N, read_sysreg(pmcr_el0));
> > --
> > 2.39.1.581.gbfd45094c4-goog
> >