Re: [PATCH v6 06/13] vpci/header: implement guest BAR register handlers

[Oleksandr Andrushchenko <Oleksandr_Andrushchenko@xxxxxxxx>]

On 08.02.22 12:15, Jan Beulich wrote:
> On 08.02.2022 10:57, Oleksandr Andrushchenko wrote:
>> On 08.02.22 11:48, Jan Beulich wrote:
>>> On 08.02.2022 10:31, Oleksandr Andrushchenko wrote:
>>>> On 08.02.22 11:25, Roger Pau Monné wrote:
>>>>> On Fri, Feb 04, 2022 at 08:34:52AM +0200, Oleksandr Andrushchenko wrote:
>>>>>> @@ -516,6 +594,11 @@ static int init_bars(struct pci_dev *pdev)
>>>>>>             if ( (val & PCI_BASE_ADDRESS_SPACE) == 
>>>>>> PCI_BASE_ADDRESS_SPACE_IO )
>>>>>>             {
>>>>>>                 bars[i].type = VPCI_BAR_IO;
>>>>>> +
>>>>>> +            rc = bar_ignore_access(pdev, reg, &bars[i]);
>>>>> This is wrong: you only want to ignore access to IO BARs for Arm, for
>>>>> x86 we should keep the previous behavior. Even more if you go with
>>>>> Jan's suggestions to make bar_ignore_access also applicable to dom0.
>>>> How do we want this?
>>>> #ifdef CONFIG_ARM?
>>> Afaic better via a new, dedicated CONFIG_HAVE_* setting, which x86 selects
>>> but Arm doesn't. Unless we have one already, of course ...
>> Could you please be more specific on the name you see appropriate?
> I'm pretty sure Linux has something similar, so I'd like to ask that
> you go look there.
Not sure, but I can have a look
>   I'm sorry to say this a little bluntly, but I'm
> really in need of doing something beyond answering your mails
Well, if answers were to be a bit more specific and not so general
some time, this could definitely be helpful and save a lot of time trying
to guess what other party has in their mind.
>   (and
> in part re-stating the same thing again and again).
I have no comments on this.
>
>> And do you realize that this is going to be a single user of such a
>> setting?
> Yes, but I'm not sure this is going to remain just a single use.
> Furthermore every CONFIG_<arch> is problematic as soon as a new port
> is being worked on. If we wanted to go with a CONFIG_<arch> here, imo
> it ought to be CONFIG_X86, not CONFIG_ARM, as I/O ports are really an
> x86-specific thing (which has propagated into other architectures in
> more or less strange ways, but never as truly I/O ports).
I am fine using CONFIG_X86
@Roger, are you ok with that?
>
> Jan
>
Thank you,
Oleksandr