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

[Jan Beulich <jbeulich@xxxxxxxx>]

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.

> Preferably with something to this effect included, Reviewed-by: Andrew
> Cooper <andrew.cooper3@xxxxxxxxxx>

Thanks.

Jan