Re: [PATCH v6 8/8] s390: guest support for diagnose 0x318

[David Hildenbrand <david@redhat.com>]

On 16.09.20 10:11, Thomas Huth wrote:
> On 15/09/2020 21.44, Collin Walling wrote:
>> DIAGNOSE 0x318 (diag318) is an s390 instruction that allows the storage
>> of diagnostic information that is collected by the firmware in the case
>> of hardware/firmware service events.
>>
>> QEMU handles the instruction by storing the info in the CPU state. A
>> subsequent register sync will communicate the data to the hypervisor.
>>
>> QEMU handles the migration via a VM State Description.
>>
>> This feature depends on the Extended-Length SCCB (els) feature. If
>> els is not present, then a warning will be printed and the SCLP bit
>> that allows the Linux kernel to execute the instruction will not be
>> set.
>>
>> Availability of this instruction is determined by byte 134 (aka fac134)
>> bit 0 of the SCLP Read Info block. This coincidentally expands into the
>> space used for CPU entries, which means VMs running with the diag318
>> capability may not be able to read information regarding all CPUs
>> unless the guest kernel supports an extended-length SCCB.
>>
>> This feature is not supported in protected virtualization mode.
>>
>> Signed-off-by: Collin Walling <walling@linux.ibm.com>
>> Acked-by: Janosch Frank <frankja@linux.ibm.com>
>> ---
>>  hw/s390x/sclp.c                     |  5 ++++
>>  include/hw/s390x/sclp.h             |  8 ++++++
>>  target/s390x/cpu.h                  |  2 ++
>>  target/s390x/cpu_features.h         |  1 +
>>  target/s390x/cpu_features_def.h.inc |  3 +++
>>  target/s390x/cpu_models.c           |  1 +
>>  target/s390x/gen-features.c         |  1 +
>>  target/s390x/kvm.c                  | 39 +++++++++++++++++++++++++++++
>>  target/s390x/machine.c              | 17 +++++++++++++
>>  9 files changed, 77 insertions(+)
> 
> Acked-by: Thomas Huth <thuth@redhat.com>
> 
> (I hope David could still comment on the CPU model stuff ... it looks ok
> to me here, but I got that wrong a couple of times in the past already...)
> 

Had a skim over it and it looks good to me!

Acked-by: David Hildenbrand <david@redhat.com>

-- 
Thanks,

David / dhildenb