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

[Jan Beulich <jbeulich@xxxxxxxx>]

On 08.02.2022 09:06, Oleksandr Andrushchenko wrote:
> 
> 
> On 07.02.22 19:06, Jan Beulich wrote:
>> On 04.02.2022 07:34, Oleksandr Andrushchenko wrote:
>>> +static uint32_t guest_bar_ignore_read(const struct pci_dev *pdev,
>>> +                                      unsigned int reg, void *data)
>>> +{
>>> +    return 0;
>>> +}
>>> +
>>> +static int bar_ignore_access(const struct pci_dev *pdev, unsigned int reg,
>>> +                             struct vpci_bar *bar)
>>> +{
>>> +    if ( is_hardware_domain(pdev->domain) )
>>> +        return 0;
>>> +
>>> +    return vpci_add_register(pdev->vpci, guest_bar_ignore_read, NULL,
>>> +                             reg, 4, bar);
>>> +}
>> For these two functions: I'm not sure "ignore" is an appropriate
>> term here. unused_bar_read() and unused_bar() maybe? Or,
>> considering we already have VPCI_BAR_EMPTY, s/unused/empty/ ? I'm
>> also not sure we really need the is_hardware_domain() check here:
>> Returning 0 for Dom0 is going to be fine as well; there's no need
>> to fetch the value from actual hardware. The one exception might
>> be for devices with buggy BAR behavior ...
> Well, I think this should be ok, so then
> - s/guest_bar_ignore_read/empty_bar_read
> - s/bar_ignore_access/empty_bar

Hmm, seeing it, I don't think empty_bar() is a good function name.
setup_empty_bar() or empty_bar_setup() would make more clear what
the function's purpose is.

> - no is_hardware_domain check

Please wait a little to see whether Roger has any input on this aspect.

Jan