Re: [PATCH v2 2/3] PCI: fold pci_get_pdev{,_by_domain}()

[Andrew Cooper <Andrew.Cooper3@xxxxxxxxxx>]

On 11/08/2022 14:26, Jan Beulich wrote:
> On 11.08.2022 15:21, Andrew Cooper wrote:
>> On 11/08/2022 11:52, Jan Beulich wrote:
>>> --- a/xen/arch/x86/irq.c
>>> +++ b/xen/arch/x86/irq.c
>>> @@ -2162,7 +2162,7 @@ int map_domain_pirq(
>>>          if ( !cpu_has_apic )
>>>              goto done;
>>>  
>>> -        pdev = pci_get_pdev_by_domain(d, msi->seg, msi->bus, msi->devfn);
>>> +        pdev = pci_get_pdev(d, PCI_SBDF(msi->seg, msi->bus, msi->devfn));
>> Oh, I should really have read this patch before trying to do the sbdf
>> conversion in patch 1.
>>
>> However, it occurs to me that this:
>>
>> diff --git a/xen/arch/x86/include/asm/msi.h b/xen/arch/x86/include/asm/msi.h
>> index 117379318f2c..6f0ab845017c 100644
>> --- a/xen/arch/x86/include/asm/msi.h
>> +++ b/xen/arch/x86/include/asm/msi.h
>> @@ -59,9 +59,14 @@
>>  #define FIX_MSIX_MAX_PAGES              512
>>  
>>  struct msi_info {
>> -    u16 seg;
>> -    u8 bus;
>> -    u8 devfn;
>> +    union {
>> +        struct {
>> +            u8 devfn;
>> +            u8 bus;
>> +            u16 seg;
>> +        };
>> +        pci_sbdf_t sbdf;
>> +    };
>>      int irq;
>>      int entry_nr;
>>      uint64_t table_base;
>>
>> will simplify several hunks in this patch, because you can just pass
>> msi->sbdf rather than reconstructing it by reversing 32 bits worth of
>> data from their in-memory representation.
> No, I'm strictly against introducing a 2nd instance of such aliasing
> (we already have one in struct pci_dev, and that's bad enough). There
> could be _only_ an "sbdf" field here, yes, but that'll have knock-on
> effects elsewhere, so wants to be a separate change. And there are far
> more places where imo we'll want to use pci_sbdf_t.

What's the likelihood of getting to that before 4.17 goes out?

I'd prefer to see it fixed, and obviously even more conversion to sbdf_t
is better.

Basically, I'm happy for the conversion to not be in this patch, as long
it's not going to get forgotten.

~Andrew