Re: [PATCH v3 07/10] target/ppc: optimize p8 exception handling routines

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

On Fri Sep 13, 2024 at 2:13 PM AEST, Harsh Prateek Bora wrote:
> Most of the p8 exception handling accesses env->pending_interrupts and
> env->spr[SPR_LPCR] at multiple places. Passing it directly as local
> variables simplifies the code and avoids multiple indirect accesses.

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

>
> Signed-off-by: Harsh Prateek Bora <harshpb@linux.ibm.com>
> ---
>  target/ppc/excp_helper.c | 60 +++++++++++++++++++++-------------------
>  1 file changed, 32 insertions(+), 28 deletions(-)
>
> diff --git a/target/ppc/excp_helper.c b/target/ppc/excp_helper.c
> index c7641898ca..c0828aac88 100644
> --- a/target/ppc/excp_helper.c
> +++ b/target/ppc/excp_helper.c
> @@ -1765,39 +1765,42 @@ static int p7_next_unmasked_interrupt(CPUPPCState *env)
>      PPC_INTERRUPT_CEXT | PPC_INTERRUPT_WDT | PPC_INTERRUPT_CDOORBELL |  \
>      PPC_INTERRUPT_FIT | PPC_INTERRUPT_PIT | PPC_INTERRUPT_THERM)
>  
> -static int p8_interrupt_powersave(CPUPPCState *env)
> +static int p8_interrupt_powersave(uint32_t pending_interrupts,
> +                                  target_ulong lpcr)
>  {
> -    if ((env->pending_interrupts & PPC_INTERRUPT_EXT) &&
> -        (env->spr[SPR_LPCR] & LPCR_P8_PECE2)) {
> +    if ((pending_interrupts & PPC_INTERRUPT_EXT) &&
> +        (lpcr & LPCR_P8_PECE2)) {
>          return PPC_INTERRUPT_EXT;
>      }
> -    if ((env->pending_interrupts & PPC_INTERRUPT_DECR) &&
> -        (env->spr[SPR_LPCR] & LPCR_P8_PECE3)) {
> +    if ((pending_interrupts & PPC_INTERRUPT_DECR) &&
> +        (lpcr & LPCR_P8_PECE3)) {
>          return PPC_INTERRUPT_DECR;
>      }
> -    if ((env->pending_interrupts & PPC_INTERRUPT_MCK) &&
> -        (env->spr[SPR_LPCR] & LPCR_P8_PECE4)) {
> +    if ((pending_interrupts & PPC_INTERRUPT_MCK) &&
> +        (lpcr & LPCR_P8_PECE4)) {
>          return PPC_INTERRUPT_MCK;
>      }
> -    if ((env->pending_interrupts & PPC_INTERRUPT_HMI) &&
> -        (env->spr[SPR_LPCR] & LPCR_P8_PECE4)) {
> +    if ((pending_interrupts & PPC_INTERRUPT_HMI) &&
> +        (lpcr & LPCR_P8_PECE4)) {
>          return PPC_INTERRUPT_HMI;
>      }
> -    if ((env->pending_interrupts & PPC_INTERRUPT_DOORBELL) &&
> -        (env->spr[SPR_LPCR] & LPCR_P8_PECE0)) {
> +    if ((pending_interrupts & PPC_INTERRUPT_DOORBELL) &&
> +        (lpcr & LPCR_P8_PECE0)) {
>          return PPC_INTERRUPT_DOORBELL;
>      }
> -    if ((env->pending_interrupts & PPC_INTERRUPT_HDOORBELL) &&
> -        (env->spr[SPR_LPCR] & LPCR_P8_PECE1)) {
> +    if ((pending_interrupts & PPC_INTERRUPT_HDOORBELL) &&
> +        (lpcr & LPCR_P8_PECE1)) {
>          return PPC_INTERRUPT_HDOORBELL;
>      }
> -    if (env->pending_interrupts & PPC_INTERRUPT_RESET) {
> +    if (pending_interrupts & PPC_INTERRUPT_RESET) {
>          return PPC_INTERRUPT_RESET;
>      }
>      return 0;
>  }
>  
> -static int p8_next_unmasked_interrupt(CPUPPCState *env)
> +static int p8_next_unmasked_interrupt(CPUPPCState *env,
> +                                      uint32_t pending_interrupts,
> +                                      target_ulong lpcr)
>  {
>      CPUState *cs = env_cpu(env);
>  
> @@ -1808,18 +1811,18 @@ static int p8_next_unmasked_interrupt(CPUPPCState *env)
>  
>      if (cs->halted) {
>          /* LPCR[PECE] controls which interrupts can exit power-saving mode */
> -        return p8_interrupt_powersave(env);
> +        return p8_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);
> +        bool hdice = !!(lpcr & LPCR_HDICE);
>          if ((msr_ee || !FIELD_EX64_HV(env->msr)) && hdice) {
>              /* HDEC clears on delivery */
>              return PPC_INTERRUPT_HDECR;
> @@ -1827,9 +1830,9 @@ static int p8_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))) ||
> @@ -1839,20 +1842,20 @@ static int p8_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_DOORBELL) {
> +        if (pending_interrupts & PPC_INTERRUPT_DOORBELL) {
>              return PPC_INTERRUPT_DOORBELL;
>          }
> -        if (env->pending_interrupts & PPC_INTERRUPT_HDOORBELL) {
> +        if (pending_interrupts & PPC_INTERRUPT_HDOORBELL) {
>              return PPC_INTERRUPT_HDOORBELL;
>          }
> -        if (env->pending_interrupts & PPC_INTERRUPT_PERFM) {
> +        if (pending_interrupts & PPC_INTERRUPT_PERFM) {
>              return PPC_INTERRUPT_PERFM;
>          }
>          /* EBB exception */
> -        if (env->pending_interrupts & PPC_INTERRUPT_EBB) {
> +        if (pending_interrupts & PPC_INTERRUPT_EBB) {
>              /*
>               * EBB exception must be taken in problem state and
>               * with BESCR_GE set.
> @@ -2021,7 +2024,8 @@ static int ppc_next_unmasked_interrupt(CPUPPCState *env)
>      case POWERPC_EXCP_POWER7:
>          return p7_next_unmasked_interrupt(env);
>      case POWERPC_EXCP_POWER8:
> -        return p8_next_unmasked_interrupt(env);
> +        return p8_next_unmasked_interrupt(env, env->pending_interrupts,
> +                                          env->spr[SPR_LPCR]);
>      case POWERPC_EXCP_POWER9:
>      case POWERPC_EXCP_POWER10:
>      case POWERPC_EXCP_POWER11: