Re: [Qemu-devel] [PATCH 3/4] spapr: Handle "ibm, nmi-register" and "ibm, nmi-interlock" RTAS calls

[Aravinda Prasad <aravinda@linux.vnet.ibm.com>]

On Thursday 12 November 2015 02:53 PM, Thomas Huth wrote:
> On 11/11/15 18:15, Aravinda Prasad wrote:
>> This patch adds support in QEMU to handle "ibm,nmi-register"
>> and "ibm,nmi-interlock" RTAS calls.
>>
>> The machine check notification address is saved when the
>> OS issues "ibm,nmi-register" RTAS call.
>>
>> This patch also handles the case when multiple processors
>> experience machine check at or about the same time by
>> handling "ibm,nmi-interlock" call. In such cases, as per
>> PAPR, subsequent processors serialize waiting for the first
>> processor to issue the "ibm,nmi-interlock" call. The second
>> processor waits till the first processor, which also
>> received a machine check error, is done reading the error
>> log. The first processor issues "ibm,nmi-interlock" call
>> when the error log is consumed. This patch implements the
>> releasing part of the error-log while subsequent patch
>> (which builds error log) handles the locking part.
>>
>> Signed-off-by: Aravinda Prasad <aravinda@linux.vnet.ibm.com>
>> ---
>>  hw/ppc/spapr_rtas.c    |   29 +++++++++++++++++++++++++++++
>>  include/hw/ppc/spapr.h |    8 +++++++-
>>  2 files changed, 36 insertions(+), 1 deletion(-)
>>
>> diff --git a/hw/ppc/spapr_rtas.c b/hw/ppc/spapr_rtas.c
>> index 9869bc9..fd4d2af 100644
>> --- a/hw/ppc/spapr_rtas.c
>> +++ b/hw/ppc/spapr_rtas.c
>> @@ -597,6 +597,31 @@ out:
>>      rtas_st(rets, 0, rc);
>>  }
>>  
>> +static void rtas_ibm_nmi_register(PowerPCCPU *cpu,
>> +                                  sPAPRMachineState *spapr,
>> +                                  uint32_t token, uint32_t nargs,
>> +                                  target_ulong args,
>> +                                  uint32_t nret, target_ulong rets)
>> +{
>> +    qemu_mutex_init(&spapr->mc_in_progress);
>> +    spapr->guest_machine_check_addr = rtas_ld(args, 1);
>> +    rtas_st(rets, 0, RTAS_OUT_SUCCESS);
>> +}
>> +
>> +static void rtas_ibm_nmi_interlock(PowerPCCPU *cpu,
>> +                                   sPAPRMachineState *spapr,
>> +                                   uint32_t token, uint32_t nargs,
>> +                                   target_ulong args,
>> +                                   uint32_t nret, target_ulong rets)
>> +{
>> +    /*
>> +     * VCPU issuing "ibm,nmi-interlock" is done with NMI handling,
>> +     * hence unlock mc_in_progress.
>> +     */
>> +    qemu_mutex_unlock(&spapr->mc_in_progress);
>> +    rtas_st(rets, 0, RTAS_OUT_SUCCESS);
>> +}
> 
> Maybe the interlock function should return an error if the nmi_register
> function has not been called before? OTOH, RTAS is not supposed to do
> excessive parameter checking, so this is maybe not worth the effort.

This will be a simple check to see if spapr->guest_machine_check_addr is
set. I will include it.

Regards,
Aravinda

> 
>  Thomas
> 
> 

-- 
Regards,
Aravinda