Re: [Qemu-devel] [PATCH v4 2/3] spapr/rtas: fix reboot of a a SMP TCG guest

[David Gibson]

On Fri, Nov 24, 2017 at 08:05:49AM +0100, Cédric Le Goater wrote:
> Just like for hot unplug CPUs, when a guest is rebooted, the secondary
> CPUs can be awaken by the decrementer and start entering SLOF at the
> same time the boot CPU is.
> 
> To be safe, let's disable on the secondaries all the exceptions which
> can cause an exit while the CPU is in power-saving mode.
> 
> Based on previous work from Nikunj A Dadhania <address@hidden>
> 
> Signed-off-by: Cédric Le Goater <address@hidden>
> Reviewed-by: David Gibson <address@hidden>

Applied to ppc-for-2.12.

> ---
> 
> Changes in v4:
> 
>  - used the 'lpcr_pm' field of PowerPCCPUClass
> 
> Changes in v3:
> 
>  - used the cpu_ppc_papr_pece_bits() helper 
> 
>  hw/ppc/spapr_cpu_core.c | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/hw/ppc/spapr_cpu_core.c b/hw/ppc/spapr_cpu_core.c
> index 3a4c17401226..a2290528542d 100644
> --- a/hw/ppc/spapr_cpu_core.c
> +++ b/hw/ppc/spapr_cpu_core.c
> @@ -26,6 +26,7 @@ static void spapr_cpu_reset(void *opaque)
>      PowerPCCPU *cpu = opaque;
>      CPUState *cs = CPU(cpu);
>      CPUPPCState *env = &cpu->env;
> +    PowerPCCPUClass *pcc = POWERPC_CPU_GET_CLASS(cpu);
>  
>      cpu_reset(cs);
>  
> @@ -35,6 +36,13 @@ static void spapr_cpu_reset(void *opaque)
>      cs->halted = 1;
>  
>      env->spr[SPR_HIOR] = 0;
> +
> +    /* Disable Power-saving mode Exit Cause exceptions for the CPU.
> +     * This can cause issues when rebooting the guest if a secondary
> +     * is awaken */
> +    if (cs != first_cpu) {
> +        env->spr[SPR_LPCR] &= ~pcc->lpcr_pm;
> +    }
>  }
>  
>  static void spapr_cpu_destroy(PowerPCCPU *cpu)

-- 
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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