Re: [Qemu-devel] [Qemu-ppc] [PATCH v4] ppc: spapr-rtas - implement os-term rtas call

[Tyrel Datwyler <turtle.in.the.kernel@gmail.com>]

On 06/27/2014 12:37 AM, Nikunj A Dadhania wrote:
> PAPR compliant guest calls this in absence of kdump. This finally
> reaches the guest and can be handled according to the policies set by
> higher level tools(like taking dump) for further analysis by tools like
> crash.
> 
> Linux kernel calls this only when the extended version of os,term is
> implemented to make sure that a return to the linux kernel is gauranteed.
> 
> CC: Benjamin Herrenschmidt <benh@au1.ibm.com>
> CC: Anton Blanchard <anton@samba.org>
> CC: Alexander Graf <agraf@suse.de>
> Signed-off-by: Nikunj A Dadhania <nikunj@linux.vnet.ibm.com>
> 
> ---
> 
> v2: rebase to ppcnext
> v3: Do not stop the VM, and update comments
> v4: update spapr_register_rtas and qapi_event changes
> ---
>  hw/ppc/spapr_rtas.c | 36 ++++++++++++++++++++++++++++++++++++
>  1 file changed, 36 insertions(+)
> 
> diff --git a/hw/ppc/spapr_rtas.c b/hw/ppc/spapr_rtas.c
> index 9ba1ba6..b11de41 100644
> --- a/hw/ppc/spapr_rtas.c
> +++ b/hw/ppc/spapr_rtas.c
> @@ -277,6 +277,38 @@ static void rtas_ibm_set_system_parameter(PowerPCCPU *cpu,
>      rtas_st(rets, 0, ret);
>  }
>  
> +static void rtas_ibm_os_term(PowerPCCPU *cpu,
> +                            sPAPREnvironment *spapr,
> +                            uint32_t token, uint32_t nargs,
> +                            target_ulong args,
> +                            uint32_t nret, target_ulong rets)
> +{
> +    target_ulong ret = 0;
> +
> +    qapi_event_send_guest_panicked(GUEST_PANIC_ACTION_PAUSE, &error_abort);
> +
> +    rtas_st(rets, 0, ret);
> +}
> +
> +/*
> + * According to PAPR, rtas ibm,os-term, does not gaurantee a return
> + * back to the guest cpu.
> + *
> + * While an additional ibm,extended-os-term property indicates that
> + * rtas call return will always occur. Below function implements a
> + * place holder for the same.
> + */

PAPR defines ibm,extended-os-term as a null encoded property not a rtas
function. It should be added to the device tree in the
spapr_create_fdt_skel function under the "rtas" node. The following
should suffice.

_FDT((fdt_property(fdt, "ibm,extended-os-term", NULL, 0)));

-Tyrel

> +static void rtas_ibm_ext_os_term(PowerPCCPU *cpu,
> +                            sPAPREnvironment *spapr,
> +                            uint32_t token, uint32_t nargs,
> +                            target_ulong args,
> +                            uint32_t nret, target_ulong rets)
> +{
> +    target_ulong ret = RTAS_OUT_NOT_SUPPORTED;
> +
> +    rtas_st(rets, 0, ret);
> +}
> +
>  static struct rtas_call {
>      const char *name;
>      spapr_rtas_fn fn;
> @@ -404,6 +436,10 @@ static void core_rtas_register_types(void)
>      spapr_rtas_register(RTAS_IBM_SET_SYSTEM_PARAMETER,
>                          "ibm,set-system-parameter",
>                          rtas_ibm_set_system_parameter);
> +    spapr_rtas_register(RTAS_IBM_OS_TERM, "ibm,os-term",
> +                        rtas_ibm_os_term);
> +    spapr_rtas_register(RTAS_IBM_EXTENDED_OS_TERM, "ibm,extended-os-term",
> +                        rtas_ibm_ext_os_term);
>  }
>  
>  type_init(core_rtas_register_types)
>