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Date:   Mon, 24 Jan 2022 10:12:02 -0500
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Subject: Re: [PATCH v2 08/30] s390/pci: stash associated GISA designation
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To:     Pierre Morel <pmorel@linux.ibm.com>, linux-s390@vger.kernel.org,
        schnelle@linux.ibm.com
Cc:     alex.williamson@redhat.com, cohuck@redhat.com,
        farman@linux.ibm.com, borntraeger@linux.ibm.com, hca@linux.ibm.com,
        gor@linux.ibm.com, gerald.schaefer@linux.ibm.com,
        agordeev@linux.ibm.com, frankja@linux.ibm.com, david@redhat.com,
        imbrenda@linux.ibm.com, vneethv@linux.ibm.com,
        oberpar@linux.ibm.com, freude@linux.ibm.com, thuth@redhat.com,
        pasic@linux.ibm.com, kvm@vger.kernel.org,
        linux-kernel@vger.kernel.org,
        Christian Borntraeger <borntraeger@de.ibm.com>
References: <20220114203145.242984-1-mjrosato@linux.ibm.com>
 <20220114203145.242984-9-mjrosato@linux.ibm.com>
 <8bef8c96-219e-3c40-246b-b974c45a5315@linux.ibm.com>
From:   Matthew Rosato <mjrosato@linux.ibm.com>
In-Reply-To: <8bef8c96-219e-3c40-246b-b974c45a5315@linux.ibm.com>
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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.