Re: [Qemu-devel] [PATCH 3/8] spapr: Remove unhelpful helpers from rtas_start_cpu()

["Cédric Le Goater" <clg@kaod.org>]

On 05/03/2018 08:21 AM, David Gibson wrote:
> rtas_start_cpu() calls spapr_cpu_update_tb_offset() and
> spapr_cpu_set_endianness() to initialize certain things in the new cpu's
> state.  This is the only caller of those helpers, and they're each only
> a few lines long, so we might as well just fold them into the caller.
> 
> In addition, those helpers initialize state on the new cpu to match that of
> the first cpu.  That will generally work, but might be at least logically
> incorrect if the first cpu has been set offline by the guest.  So, instead
> base the state on that of the cpu invoking the RTAS call, which is
> obviously active already.
> 
> Signed-off-by: David Gibson <david@gibson.dropbear.id.au>


Reviewed-by: Cédric Le Goater <clg@kaod.org>

> ---
>  hw/ppc/spapr_rtas.c | 38 ++++++++++++++------------------------
>  1 file changed, 14 insertions(+), 24 deletions(-)
> 
> diff --git a/hw/ppc/spapr_rtas.c b/hw/ppc/spapr_rtas.c
> index b251c130cb..df073447c5 100644
> --- a/hw/ppc/spapr_rtas.c
> +++ b/hw/ppc/spapr_rtas.c
> @@ -120,27 +120,6 @@ static void rtas_query_cpu_stopped_state(PowerPCCPU *cpu_,
>      rtas_st(rets, 0, RTAS_OUT_PARAM_ERROR);
>  }
>  
> -/*
> - * Set the timebase offset of the CPU to that of first CPU.
> - * This helps hotplugged CPU to have the correct timebase offset.
> - */
> -static void spapr_cpu_update_tb_offset(PowerPCCPU *cpu)
> -{
> -    PowerPCCPU *fcpu = POWERPC_CPU(first_cpu);
> -
> -    cpu->env.tb_env->tb_offset = fcpu->env.tb_env->tb_offset;
> -}
> -
> -static void spapr_cpu_set_endianness(PowerPCCPU *cpu)
> -{
> -    PowerPCCPU *fcpu = POWERPC_CPU(first_cpu);
> -    PowerPCCPUClass *pcc = POWERPC_CPU_GET_CLASS(fcpu);
> -
> -    if (!pcc->interrupts_big_endian(fcpu)) {
> -        cpu->env.spr[SPR_LPCR] |= LPCR_ILE;
> -    }
> -}
> -
>  static void rtas_start_cpu(PowerPCCPU *callcpu, sPAPRMachineState *spapr,
>                             uint32_t token, uint32_t nargs,
>                             target_ulong args,
> @@ -150,6 +129,7 @@ static void rtas_start_cpu(PowerPCCPU *callcpu, sPAPRMachineState *spapr,
>      PowerPCCPU *newcpu;
>      CPUPPCState *env;
>      PowerPCCPUClass *pcc;
> +    target_ulong lpcr;
>  
>      if (nargs != 3 || nret != 1) {
>          rtas_st(rets, 0, RTAS_OUT_PARAM_ERROR);
> @@ -178,10 +158,20 @@ static void rtas_start_cpu(PowerPCCPU *callcpu, sPAPRMachineState *spapr,
>      cpu_synchronize_state(CPU(newcpu));
>  
>      env->msr = (1ULL << MSR_SF) | (1ULL << MSR_ME);
> -    spapr_cpu_set_endianness(newcpu);
> -    spapr_cpu_update_tb_offset(newcpu);
> +
>      /* Enable Power-saving mode Exit Cause exceptions for the new CPU */
> -    ppc_store_lpcr(newcpu, env->spr[SPR_LPCR] | pcc->lpcr_pm);
> +    lpcr = env->spr[SPR_LPCR] | pcc->lpcr_pm;
> +    if (!pcc->interrupts_big_endian(callcpu)) {
> +        lpcr |= LPCR_ILE;
> +    }
> +    ppc_store_lpcr(newcpu, lpcr);
> +
> +    /*
> +     * Set the timebase offset of the new CPU to that of the invoking
> +     * CPU.  This helps hotplugged CPU to have the correct timebase
> +     * offset.
> +     */
> +    newcpu->env.tb_env->tb_offset = callcpu->env.tb_env->tb_offset;
>  
>      env->nip = start;
>      env->gpr[3] = r3;
>