Re: [PATCH v2 08/30] s390/pci: stash associated GISA designation

Matthew Rosato
2022-01-24T15:12:10Z

On 1/24/22 9:08 AM, Pierre Morel wrote:
>
>
> On 1/14/22 21:31, Matthew Rosato wrote:
>> For passthrough devices, we will need to know the GISA designation of the
>> guest if interpretation facilities are to be used.  Setup to stash
>> this in
>> the zdev and set a default of 0 (no GISA designation) for now; a
>> subsequent
>> patch will set a valid GISA designation for passthrough devices.
>> Also, extend mpcific routines to specify this stashed designation as part
>> of the mpcific command.
>>
>> Reviewed-by: Niklas Schnelle <schnelle@linux.ibm.com>
>> Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com>
>> Reviewed-by: Eric Farman <farman@linux.ibm.com>
>> Reviewed-by: Pierre Morel <pmorel@linux.ibm.com>
>> Signed-off-by: Matthew Rosato <mjrosato@linux.ibm.com>
>> ---
>>   arch/s390/include/asm/pci.h     | 1 +
>>   arch/s390/include/asm/pci_clp.h | 3 ++-
>>   arch/s390/pci/pci.c             | 6 ++++++
>>   arch/s390/pci/pci_clp.c         | 1 +
>>   arch/s390/pci/pci_irq.c         | 5 +++++
>>   5 files changed, 15 insertions(+), 1 deletion(-)
>>
>> diff --git a/arch/s390/include/asm/pci.h b/arch/s390/include/asm/pci.h
>> index 90824be5ce9a..2474b8d30f2a 100644
>> --- a/arch/s390/include/asm/pci.h
>> +++ b/arch/s390/include/asm/pci.h
>> @@ -123,6 +123,7 @@ struct zpci_dev {
>>       enum zpci_state state;
>>       u32        fid;        /* function ID, used by sclp */
>>       u32        fh;        /* function handle, used by insn's */
>> +    u32        gd;        /* GISA designation for passthrough */
>
> I already gave my R-B, and do not want to remove it, but wouldn't it be
> possible to use more explicit names like gisa_designation instead of
> just gd.
> It would not change anything to the functionality but would facilitate
> the maintenance?
>

Honestly, I don't have a strong opinion on this one -- AFAICT struct
zpci_dev has a fair mix of short names (fh) and explicit names
(max_bus_speed).

It does require changes to this patch and various subsequent patches --
The changes are, as you say, not functional, so I think it's not a big deal?

I do think 'gisa_designation' is too verbose though -- How about just
'gisa', this is the same name used in the structure where we get this
value from (gisa in struct sie_page2)

As long as nobody objects I will s/gd/gisa/ here and in struct
clp_req_set_pci, retaining review tags.