Re: [Qemu-devel] [PATCH v2 2/3] s390x/kvm: Handle bpb feature

[Thomas Huth <thuth@redhat.com>]

On 17.01.2018 22:12, David Hildenbrand wrote:
> On 17.01.2018 20:37, Christian Borntraeger wrote:
>> We need to handle the bpb control on reset and migration. Normally
>> stfle.82 is transparent (and the normal guest part works without
>> hypervisor activity). To prevent any issues we require full
>> host kernel support for this feature.
>>
>> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
>> ---
>>  target/s390x/cpu.c              |  1 +
>>  target/s390x/cpu.h              |  1 +
>>  target/s390x/cpu_features.c     |  1 +
>>  target/s390x/cpu_features_def.h |  1 +
>>  target/s390x/gen-features.c     |  1 +
>>  target/s390x/kvm.c              | 14 ++++++++++++++
>>  target/s390x/machine.c          | 17 +++++++++++++++++
>>  7 files changed, 36 insertions(+)
>>
>> diff --git a/target/s390x/cpu.c b/target/s390x/cpu.c
>> index ae3cee9..1577b2c 100644
>> --- a/target/s390x/cpu.c
>> +++ b/target/s390x/cpu.c
>> @@ -89,6 +89,7 @@ static void s390_cpu_reset(CPUState *s)
>>      CPUS390XState *env = &cpu->env;
>>  
>>      env->pfault_token = -1UL;
>> +    env->bpbc = 0;
> 
> As this is effectively only 1 bit, I wonder if we should also make that
> clear in QEMU
> 
> bool bpbc, VMSTATE_BOOL ...
> 
> Apart from that, looks sane.

I had the same thought when reading the patch ... apart from that, also
looks good to me.

 Thomas