[PATCH] lib: sbi: sbi_pmu: Fix multiple start and stop operations of FW counters

[Anup Patel]

On Sat, Dec 13, 2025 at 4:12 PM James Raphael Tiovalen
<jamestiotio at gmail.com> wrote:
>
> Currently, OpenSBI returns SBI_ERR_ALREADY_STARTED when attempting to
> start a HW counter that is already started and SBI_ERR_ALREADY_STOPPED
> when attempting to stop a HW counter that is already stopped. However,
> this is not yet implemented for FW counters.
>
> Add the necessary checks to return the same error codes when attempting
> the same actions on FW counters.
>
> Signed-off-by: James Raphael Tiovalen <jamestiotio at gmail.com>
> ---
>  lib/sbi/sbi_pmu.c | 6 ++++++
>  1 file changed, 6 insertions(+)
>
> diff --git a/lib/sbi/sbi_pmu.c b/lib/sbi/sbi_pmu.c
> index e24e485d..0218c921 100644
> --- a/lib/sbi/sbi_pmu.c
> +++ b/lib/sbi/sbi_pmu.c
> @@ -468,6 +468,9 @@ static int pmu_ctr_start_fw(struct sbi_pmu_hart_state *phs,
>                                                  cidx - num_hw_ctrs,
>                                                  event_data);
>         } else {
> +               if (phs->fw_counters_started & BIT(cidx - num_hw_ctrs))
> +                       return SBI_EALREADY_STARTED;
> +

This check should also be done for platform firmware counters
hence it should be just before this if-else block.

>                 if (ival_update)
>                         phs->fw_counters_data[cidx - num_hw_ctrs] = ival;
>         }
> @@ -629,6 +632,9 @@ static int pmu_ctr_stop_fw(struct sbi_pmu_hart_state *phs,
>                         return ret;
>         }
>
> +       if (!(phs->fw_counters_started & BIT(cidx - num_hw_ctrs)))
> +                       return SBI_EALREADY_STOPPED;
> +

As comment as above, this check should be before the previous
if block.

>         phs->fw_counters_started &= ~BIT(cidx - num_hw_ctrs);
>
>         return 0;
> --
> 2.43.0
>
>
> --
> opensbi mailing list
> opensbi at lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/opensbi

I have taken care of the above comments at the time of
merging this patch.

Reviewed-by: Anup Patel <anup at brainfault.org>

Applied this patch to the riscv/opensbi repo.

Thanks,
Anup