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 <nikunj@linux.vnet.ibm.com>

Signed-off-by: Cédric Le Goater <clg@kaod.org>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
---

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)
-- 
2.13.6

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 <nikunj@linux.vnet.ibm.com>
> 
> Signed-off-by: Cédric Le Goater <clg@kaod.org>
> Reviewed-by: David Gibson <david@gibson.dropbear.id.au>

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