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

Raghavendra Rao Ananta
2023-03-09T22:20:54Z

Hi Reiji,

On Thu, Mar 2, 2023 at 7:06 PM Reiji Watanabe <reijiw@google.com> wrote:
>
> Hi Raghu,
>
> On Tue, Feb 14, 2023 at 5:07 PM Raghavendra Rao Ananta
> <rananta@google.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@google.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
> >