Re: [PATCH 14/19] target/ppc/pmu_book3s_helper.c: add generic timeout helpers

[David Gibson]

On Mon, Aug 09, 2021 at 10:10:52AM -0300, Daniel Henrique Barboza wrote:
> Before adding counter negative condition support for the other 5
> counters, create generic helpers that retrieves the elapsed timeout to
> counter negative based on the event being sampled.
> 
> Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>
> ---
>  target/ppc/pmu_book3s_helper.c | 41 +++++++++++++++++++++++++++++-----
>  1 file changed, 35 insertions(+), 6 deletions(-)
> 
> diff --git a/target/ppc/pmu_book3s_helper.c b/target/ppc/pmu_book3s_helper.c
> index e7af273cb6..7126e9b3d5 100644
> --- a/target/ppc/pmu_book3s_helper.c
> +++ b/target/ppc/pmu_book3s_helper.c
> @@ -111,23 +111,52 @@ static void update_PMCs(CPUPPCState *env, uint64_t 
> icount_delta)
>      update_PMC_PM_CYC(env, SPR_POWER_PMC6, icount_delta);
>  }
>  
> +static int64_t get_INST_CMPL_timeout(CPUPPCState *env, int sprn)
> +{
> +    int64_t remaining_insns;
> +
> +    if (env->spr[sprn] == 0) {

Why do you need to special case the PMC being 0?

> +        return icount_to_ns(COUNTER_NEGATIVE_VAL);
> +    }
> +
> +    if (env->spr[sprn] >= COUNTER_NEGATIVE_VAL) {
> +        return 0;
> +    }
> +
> +    remaining_insns = COUNTER_NEGATIVE_VAL - env->spr[sprn];
> +    return icount_to_ns(remaining_insns);
> +}
> +
> +static int64_t get_CYC_timeout(CPUPPCState *env, int sprn)
> +{
> +    int64_t remaining_cyc;
> +
> +    if (env->spr[sprn] == 0) {
> +        return icount_to_ns(COUNTER_NEGATIVE_VAL);

Why is icount involved in the CYC timeout logic?  AFAICT it wasn't
before this change.

> +    }
> +
> +    if (env->spr[sprn] >= COUNTER_NEGATIVE_VAL) {
> +        return 0;
> +    }
> +
> +    remaining_cyc = COUNTER_NEGATIVE_VAL - env->spr[sprn];
> +    return muldiv64(remaining_cyc, NANOSECONDS_PER_SECOND, PPC_CPU_FREQ);
> +}
> +
>  static void set_PMU_excp_timer(CPUPPCState *env)
>  {
> -    uint64_t timeout, now, remaining_val;
> +    uint64_t timeout, now;
>  
>      if (!(env->spr[SPR_POWER_MMCR0] & MMCR0_PMC1CE)) {
>          return;
>      }
>  
> -    remaining_val = COUNTER_NEGATIVE_VAL - env->spr[SPR_POWER_PMC1];
> -
>      switch (get_PMC_event(env, SPR_POWER_PMC1)) {
>      case 0x2:
> -        timeout = icount_to_ns(remaining_val);
> +        timeout = get_INST_CMPL_timeout(env, SPR_POWER_PMC1);
>          break;
>      case 0x1e:
> -        timeout = muldiv64(remaining_val, NANOSECONDS_PER_SECOND,
> -                           PPC_CPU_FREQ);
> +        timeout = get_CYC_timeout(env, SPR_POWER_PMC1);
>          break;
>      default:
>          return;

-- 
David Gibson                    | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au  | minimalist, thank you.  NOT _the_ _other_
                                | _way_ _around_!
http://www.ozlabs.org/~dgibson

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