Re: [PATCH v2 05/11] xen/arm: Mark device as PCI while creating one

[Oleksandr Andrushchenko <Oleksandr_Andrushchenko@xxxxxxxx>]

On 28.09.21 11:39, Jan Beulich wrote:
> On 28.09.2021 10:29, Oleksandr Andrushchenko wrote:
>> On 28.09.21 11:26, Jan Beulich wrote:
>>> On 28.09.2021 10:09, Oleksandr Andrushchenko wrote:
>>>> On 27.09.21 13:26, Jan Beulich wrote:
>>>>> On 27.09.2021 12:04, Oleksandr Andrushchenko wrote:
>>>>>> On 27.09.21 13:00, Jan Beulich wrote:
>>>>>>> On 27.09.2021 11:35, Oleksandr Andrushchenko wrote:
>>>>>>>> On 27.09.21 12:19, Jan Beulich wrote:
>>>>>>>>> On 27.09.2021 10:45, Oleksandr Andrushchenko wrote:
>>>>>>>>>> On 27.09.21 10:45, Jan Beulich wrote:
>>>>>>>>>>> On 23.09.2021 14:54, Oleksandr Andrushchenko wrote:
>>>>>>>>>>>> --- a/xen/drivers/passthrough/pci.c
>>>>>>>>>>>> +++ b/xen/drivers/passthrough/pci.c
>>>>>>>>>>>> @@ -328,6 +328,9 @@ static struct pci_dev *alloc_pdev(struct 
>>>>>>>>>>>> pci_seg *pseg, u8 bus, u8 devfn)
>>>>>>>>>>>>            *((u8*) &pdev->bus) = bus;
>>>>>>>>>>>>            *((u8*) &pdev->devfn) = devfn;
>>>>>>>>>>>>            pdev->domain = NULL;
>>>>>>>>>>>> +#ifdef CONFIG_ARM
>>>>>>>>>>>> +    pci_to_dev(pdev)->type = DEV_PCI;
>>>>>>>>>>>> +#endif
>>>>>>>>>>> I have to admit that I'm not happy about new CONFIG_<arch> 
>>>>>>>>>>> conditionals
>>>>>>>>>>> here. I'd prefer to see this done by a new arch helper, unless 
>>>>>>>>>>> there are
>>>>>>>>>>> obstacles I'm overlooking.
>>>>>>>>>> Do you mean something like arch_pci_alloc_pdev(dev)?
>>>>>>>>> I'd recommend against "alloc" in its name; "new" instead maybe?
>>>>>>>> I am fine with arch_pci_new_pdev, but arch prefix points to the fact 
>>>>>>>> that
>>>>>>>> this is just an architecture specific part of the pdev allocation 
>>>>>>>> rather than
>>>>>>>> actual pdev allocation itself, so with this respect 
>>>>>>>> arch_pci_alloc_pdev seems
>>>>>>>> more natural to me.
>>>>>>> The bulk of the function is about populating the just allocated struct.
>>>>>>> There's no arch-specific part of the allocation (so far, leaving aside
>>>>>>> MSI-X), you only want and arch-specific part of the initialization. I
>>>>>>> would agree with "alloc" in the name if further allocation was to
>>>>>>> happen there.
>>>>>> Hm, then arch_pci_init_pdev sounds more reasonable
>>>>> Fine with me.
>>>> Do we want this to be void or returning an error code? If error code is 
>>>> needed,
>>>> then we would also need a roll-back function, e.g. arch_pci_free_pdev or
>>>> arch_pci_release_pdev or arch_pci_fini_pdev or something, so it can be 
>>>> used in
>>>> case of error or in free_pdev function.
>>> I'd start with void and make it return an error (and deal with necessary
>>> cleanup) only once a need arises.
>> Sounds reasonable. For x86 I think we can deal with:
>>
>> xen/include/xen/pci.h:
>>
>> #ifdef CONFIG_ARM
>> void arch_pci_init_pdev(struct pci_dev *pdev);
>> #else
>> static inline void arch_pci_init_pdev(struct pci_dev *pdev)
>> {
>>       return 0;
>> }
>> #endif
> But that's still #ifdef-ary. We have asm/pci.h.
Sure, will define it there
>
> Jan
>
>
Thank you,

Oleksandr