[Qemu-devel] [PATCH] hw/ppc/spapr: Halt CPU when powering off via RTAS call

[Qemu-devel] [PATCH] hw/ppc/spapr: Halt CPU when powering off via RTAS call

[Thomas Huth]

The LoPAPR specification defines the following for the RTAS
power-off call: "On successful operation, does not return".
However, the implementation in QEMU currently returns and runs
the guest CPU again for some more cycles. This caused some
trouble with the new ppc implementation of the kvm-unit-tests
recently. So let's make sure that the QEMU implementation
follows the spec, thus stop the CPU to make sure that the
RTAS call does not return to the guest anymore.

Signed-off-by: Thomas Huth <thuth@redhat.com>
---
 hw/ppc/spapr_rtas.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/hw/ppc/spapr_rtas.c b/hw/ppc/spapr_rtas.c
index 07ad672..b7c5ebd 100644
--- a/hw/ppc/spapr_rtas.c
+++ b/hw/ppc/spapr_rtas.c
@@ -113,6 +113,7 @@ static void rtas_power_off(PowerPCCPU *cpu, sPAPRMachineState *spapr,
         return;
     }
     qemu_system_shutdown_request();
+    cpu_stop_current();
     rtas_st(rets, 0, RTAS_OUT_SUCCESS);
 }
 
-- 
1.8.3.1

Re: [Qemu-devel] [PATCH] hw/ppc/spapr: Halt CPU when powering off via RTAS call

[Andrew Jones]

On Wed, Feb 17, 2016 at 07:23:19PM +0100, Thomas Huth wrote:
> The LoPAPR specification defines the following for the RTAS
> power-off call: "On successful operation, does not return".
> However, the implementation in QEMU currently returns and runs
> the guest CPU again for some more cycles. This caused some
> trouble with the new ppc implementation of the kvm-unit-tests
> recently. So let's make sure that the QEMU implementation
> follows the spec, thus stop the CPU to make sure that the
> RTAS call does not return to the guest anymore.
> 
> Signed-off-by: Thomas Huth <thuth@redhat.com>

Tested-by: Andrew Jones <drjones@redhat.com>

(using the new, shiny kvm-unit-tests :-)

> ---
>  hw/ppc/spapr_rtas.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/hw/ppc/spapr_rtas.c b/hw/ppc/spapr_rtas.c
> index 07ad672..b7c5ebd 100644
> --- a/hw/ppc/spapr_rtas.c
> +++ b/hw/ppc/spapr_rtas.c
> @@ -113,6 +113,7 @@ static void rtas_power_off(PowerPCCPU *cpu, sPAPRMachineState *spapr,
>          return;
>      }
>      qemu_system_shutdown_request();
> +    cpu_stop_current();
>      rtas_st(rets, 0, RTAS_OUT_SUCCESS);
>  }
>  
> -- 
> 1.8.3.1
> 
> 

Re: [Qemu-devel] [PATCH] hw/ppc/spapr: Halt CPU when powering off via RTAS call

[David Gibson]

[-- Attachment #1: Type: text/plain, Size: 1311 bytes --]

On Wed, Feb 17, 2016 at 07:23:19PM +0100, Thomas Huth wrote:
> The LoPAPR specification defines the following for the RTAS
> power-off call: "On successful operation, does not return".
> However, the implementation in QEMU currently returns and runs
> the guest CPU again for some more cycles. This caused some
> trouble with the new ppc implementation of the kvm-unit-tests
> recently. So let's make sure that the QEMU implementation
> follows the spec, thus stop the CPU to make sure that the
> RTAS call does not return to the guest anymore.
> 
> Signed-off-by: Thomas Huth <thuth@redhat.com>

Applied to ppc-for-2.6, thanks.

> ---
>  hw/ppc/spapr_rtas.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/hw/ppc/spapr_rtas.c b/hw/ppc/spapr_rtas.c
> index 07ad672..b7c5ebd 100644
> --- a/hw/ppc/spapr_rtas.c
> +++ b/hw/ppc/spapr_rtas.c
> @@ -113,6 +113,7 @@ static void rtas_power_off(PowerPCCPU *cpu, sPAPRMachineState *spapr,
>          return;
>      }
>      qemu_system_shutdown_request();
> +    cpu_stop_current();
>      rtas_st(rets, 0, RTAS_OUT_SUCCESS);
>  }
>  

-- 
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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