Re: [PATCH v3 08/10] target/ppc: optimize p7 exception handling routines

["Nicholas Piggin" <npiggin@gmail.com>]

On Fri Sep 13, 2024 at 2:13 PM AEST, Harsh Prateek Bora wrote:
> Like p8 and p9, simplifying p7 exception handling rotuines to avoid
> un-necessary multiple indirect accesses to env->pending_interrupts and
> env->spr[SPR_LPCR].

Reviewed-by: Nicholas Piggin <npiggin@gmail.com>

>
> Signed-off-by: Harsh Prateek Bora <harshpb@linux.ibm.com>
> ---
>  target/ppc/excp_helper.c | 46 ++++++++++++++++++++++------------------
>  1 file changed, 25 insertions(+), 21 deletions(-)
>
> diff --git a/target/ppc/excp_helper.c b/target/ppc/excp_helper.c
> index c0828aac88..d0e0f609a0 100644
> --- a/target/ppc/excp_helper.c
> +++ b/target/ppc/excp_helper.c
> @@ -1683,51 +1683,54 @@ void ppc_cpu_do_interrupt(CPUState *cs)
>       PPC_INTERRUPT_PIT | PPC_INTERRUPT_DOORBELL | PPC_INTERRUPT_HDOORBELL | \
>       PPC_INTERRUPT_THERM | PPC_INTERRUPT_EBB)
>  
> -static int p7_interrupt_powersave(CPUPPCState *env)
> +static int p7_interrupt_powersave(uint32_t pending_interrupts,
> +                                  target_ulong lpcr)
>  {
> -    if ((env->pending_interrupts & PPC_INTERRUPT_EXT) &&
> -        (env->spr[SPR_LPCR] & LPCR_P7_PECE0)) {
> +    if ((pending_interrupts & PPC_INTERRUPT_EXT) &&
> +        (lpcr & LPCR_P7_PECE0)) {
>          return PPC_INTERRUPT_EXT;
>      }
> -    if ((env->pending_interrupts & PPC_INTERRUPT_DECR) &&
> -        (env->spr[SPR_LPCR] & LPCR_P7_PECE1)) {
> +    if ((pending_interrupts & PPC_INTERRUPT_DECR) &&
> +        (lpcr & LPCR_P7_PECE1)) {
>          return PPC_INTERRUPT_DECR;
>      }
> -    if ((env->pending_interrupts & PPC_INTERRUPT_MCK) &&
> -        (env->spr[SPR_LPCR] & LPCR_P7_PECE2)) {
> +    if ((pending_interrupts & PPC_INTERRUPT_MCK) &&
> +        (lpcr & LPCR_P7_PECE2)) {
>          return PPC_INTERRUPT_MCK;
>      }
> -    if ((env->pending_interrupts & PPC_INTERRUPT_HMI) &&
> -        (env->spr[SPR_LPCR] & LPCR_P7_PECE2)) {
> +    if ((pending_interrupts & PPC_INTERRUPT_HMI) &&
> +        (lpcr & LPCR_P7_PECE2)) {
>          return PPC_INTERRUPT_HMI;
>      }
> -    if (env->pending_interrupts & PPC_INTERRUPT_RESET) {
> +    if (pending_interrupts & PPC_INTERRUPT_RESET) {
>          return PPC_INTERRUPT_RESET;
>      }
>      return 0;
>  }
>  
> -static int p7_next_unmasked_interrupt(CPUPPCState *env)
> +static int p7_next_unmasked_interrupt(CPUPPCState *env,
> +                                      uint32_t pending_interrupts,
> +                                      target_ulong lpcr)
>  {
>      CPUState *cs = env_cpu(env);
>  
>      /* Ignore MSR[EE] when coming out of some power management states */
>      bool msr_ee = FIELD_EX64(env->msr, MSR, EE) || env->resume_as_sreset;
>  
> -    assert((env->pending_interrupts & P7_UNUSED_INTERRUPTS) == 0);
> +    assert((pending_interrupts & P7_UNUSED_INTERRUPTS) == 0);
>  
>      if (cs->halted) {
>          /* LPCR[PECE] controls which interrupts can exit power-saving mode */
> -        return p7_interrupt_powersave(env);
> +        return p7_interrupt_powersave(pending_interrupts, lpcr);
>      }
>  
>      /* Machine check exception */
> -    if (env->pending_interrupts & PPC_INTERRUPT_MCK) {
> +    if (pending_interrupts & PPC_INTERRUPT_MCK) {
>          return PPC_INTERRUPT_MCK;
>      }
>  
>      /* Hypervisor decrementer exception */
> -    if (env->pending_interrupts & PPC_INTERRUPT_HDECR) {
> +    if (pending_interrupts & PPC_INTERRUPT_HDECR) {
>          /* LPCR will be clear when not supported so this will work */
>          bool hdice = !!(env->spr[SPR_LPCR] & LPCR_HDICE);
>          if ((msr_ee || !FIELD_EX64_HV(env->msr)) && hdice) {
> @@ -1737,9 +1740,9 @@ static int p7_next_unmasked_interrupt(CPUPPCState *env)
>      }
>  
>      /* External interrupt can ignore MSR:EE under some circumstances */
> -    if (env->pending_interrupts & PPC_INTERRUPT_EXT) {
> -        bool lpes0 = !!(env->spr[SPR_LPCR] & LPCR_LPES0);
> -        bool heic = !!(env->spr[SPR_LPCR] & LPCR_HEIC);
> +    if (pending_interrupts & PPC_INTERRUPT_EXT) {
> +        bool lpes0 = !!(lpcr & LPCR_LPES0);
> +        bool heic = !!(lpcr & LPCR_HEIC);
>          /* HEIC blocks delivery to the hypervisor */
>          if ((msr_ee && !(heic && FIELD_EX64_HV(env->msr) &&
>              !FIELD_EX64(env->msr, MSR, PR))) ||
> @@ -1749,10 +1752,10 @@ static int p7_next_unmasked_interrupt(CPUPPCState *env)
>      }
>      if (msr_ee != 0) {
>          /* Decrementer exception */
> -        if (env->pending_interrupts & PPC_INTERRUPT_DECR) {
> +        if (pending_interrupts & PPC_INTERRUPT_DECR) {
>              return PPC_INTERRUPT_DECR;
>          }
> -        if (env->pending_interrupts & PPC_INTERRUPT_PERFM) {
> +        if (pending_interrupts & PPC_INTERRUPT_PERFM) {
>              return PPC_INTERRUPT_PERFM;
>          }
>      }
> @@ -2022,7 +2025,8 @@ static int ppc_next_unmasked_interrupt(CPUPPCState *env)
>  #ifdef TARGET_PPC64
>      switch (env->excp_model) {
>      case POWERPC_EXCP_POWER7:
> -        return p7_next_unmasked_interrupt(env);
> +        return p7_next_unmasked_interrupt(env, env->pending_interrupts,
> +                                          env->spr[SPR_LPCR]);
>      case POWERPC_EXCP_POWER8:
>          return p8_next_unmasked_interrupt(env, env->pending_interrupts,
>                                            env->spr[SPR_LPCR]);