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

[Oleksandr Andrushchenko <Oleksandr_Andrushchenko@xxxxxxxx>]

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
- no is_hardware_domain check
>
>> @@ -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]);
>> +            if ( rc )
>> +                return rc;
> Elsewhere the command register is restored on error paths.
Ok, I will restore
>
> Jan
>
Thank you,
Oleksandr