On Thu, Jan 12, 2023 at 2:06 AM Andrew Jones <ajones@xxxxxxxxxxxxxxxx> wrote:
>
> On Thu, Dec 15, 2022 at 09:00:36AM -0800, Atish Patra wrote:
> > KVM module needs to know how many hardware counters and the counter
> > width that the platform supports. Otherwise, it will not be able to show
> > optimal value of virtual counters to the guest. The virtual hardware
> > counters also need to have the same width as the logical hardware
> > counters for simplicity. However, there shouldn't be mapping between
> > virtual hardware counters and logical hardware counters. As we don't
> > support hetergeneous harts or counters with different width as of now,
> > the implementation relies on the counter width of the first available
> > programmable counter.
> >
> > Signed-off-by: Atish Patra <atishp@xxxxxxxxxxxx>
> > ---
> > drivers/perf/riscv_pmu_sbi.c | 35 +++++++++++++++++++++++++++++++++-
> > include/linux/perf/riscv_pmu.h | 3 +++
> > 2 files changed, 37 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/perf/riscv_pmu_sbi.c b/drivers/perf/riscv_pmu_sbi.c
> > index 3852c18..65d4aa4 100644
> > --- a/drivers/perf/riscv_pmu_sbi.c
> > +++ b/drivers/perf/riscv_pmu_sbi.c
> > @@ -49,6 +49,9 @@ static const struct attribute_group *riscv_pmu_attr_groups[] = {
> > static union sbi_pmu_ctr_info *pmu_ctr_list;
> > static unsigned int riscv_pmu_irq;
> >
> > +/* Cache the available counters in a bitmask */
> > +unsigned long cmask;
>
> I presume this can be static since it's not getting added to the header.
> And don't we need this to be a long long for rv32? We should probably
> just use u64.
>
Yeah. u64 would be better. I will change it along with static. Thanks.
> > +
> > struct sbi_pmu_event_data {
> > union {
> > union {
> > @@ -264,6 +267,37 @@ static bool pmu_sbi_ctr_is_fw(int cidx)
> > return (info->type == SBI_PMU_CTR_TYPE_FW) ? true : false;
> > }
> >
> > +/*
> > + * Returns the counter width of a programmable counter and number of hardware
> > + * counters. As we don't support heterneous CPUs yet, it is okay to just
>
> heterogeneous
>
Fixed.
> > + * return the counter width of the first programmable counter.
> > + */
> > +int riscv_pmu_get_hpm_info(u32 *hw_ctr_width, u32 *num_hw_ctr)
> > +{
> > + int i;
> > + union sbi_pmu_ctr_info *info;
> > + u32 hpm_width = 0, hpm_count = 0;
> > +
> > + if (!cmask)
> > + return -EINVAL;
> > +
> > + for_each_set_bit(i, &cmask, RISCV_MAX_COUNTERS) {
> > + info = &pmu_ctr_list[i];
> > + if (!info)
> > + continue;
> > + if (!hpm_width && (info->csr != CSR_CYCLE) && (info->csr != CSR_INSTRET))
>
> nit: No need for () around the != expressions
>
Fixed.
> > + hpm_width = info->width;
> > + if (info->type == SBI_PMU_CTR_TYPE_HW)
> > + hpm_count++;
> > + }
> > +
> > + *hw_ctr_width = hpm_width;
> > + *num_hw_ctr = hpm_count;
> > +
> > + return 0;
> > +}
> > +EXPORT_SYMBOL(riscv_pmu_get_hpm_info);
>
> EXPORT_SYMBOL_GPL ?
>
Is that mandatory ? I have seen usage of both in arch/riscv and other
places though.
I am also not sure if any other non-GPL module should/need access to this.
> > +
> > static int pmu_sbi_ctr_get_idx(struct perf_event *event)
> > {
> > struct hw_perf_event *hwc = &event->hw;
> > @@ -798,7 +832,6 @@ static void riscv_pmu_destroy(struct riscv_pmu *pmu)
> > static int pmu_sbi_device_probe(struct platform_device *pdev)
> > {
> > struct riscv_pmu *pmu = NULL;
> > - unsigned long cmask = 0;
> > int ret = -ENODEV;
> > int num_counters;
> >
> > diff --git a/include/linux/perf/riscv_pmu.h b/include/linux/perf/riscv_pmu.h
> > index e17e86a..a1c3f77 100644
> > --- a/include/linux/perf/riscv_pmu.h
> > +++ b/include/linux/perf/riscv_pmu.h
> > @@ -73,6 +73,9 @@ void riscv_pmu_legacy_skip_init(void);
> > static inline void riscv_pmu_legacy_skip_init(void) {};
> > #endif
> > struct riscv_pmu *riscv_pmu_alloc(void);
> > +#ifdef CONFIG_RISCV_PMU_SBI
> > +int riscv_pmu_get_hpm_info(u32 *hw_ctr_width, u32 *num_hw_ctr);
> > +#endif
> >
> > #endif /* CONFIG_RISCV_PMU */
> >
> > --
> > 2.25.1
> >
>
> Thanks,
> drew
