On 29.05.2024 04:41, Chen, Jiqian wrote:
> Hi,
> On 2024/5/17 19:50, Jan Beulich wrote:
>> On 17.05.2024 13:14, Chen, Jiqian wrote:
>>> On 2024/5/17 18:51, Jan Beulich wrote:
>>>> On 17.05.2024 12:45, Chen, Jiqian wrote:
>>>>> On 2024/5/16 22:01, Jan Beulich wrote:
>>>>>> On 16.05.2024 11:52, Jiqian Chen wrote:
>>>>>>> + if ( gsi >= nr_irqs_gsi )
>>>>>>> + {
>>>>>>> + ret = -EINVAL;
>>>>>>> + break;
>>>>>>> + }
>>>>>>> +
>>>>>>> + if ( !irq_access_permitted(current->domain, gsi) ||
>>>>>>
>>>>>> I.e. assuming IRQ == GSI? Is that a valid assumption when any number of
>>>>>> source overrides may be surfaced by ACPI?
>>>>> All irqs smaller than nr_irqs_gsi are gsi, aren't they?
>>>>
>>>> They are, but there's not necessarily a 1:1 mapping.
>>> Oh, so do I need to add a new gsi_caps to store granted gsi?
>>
>> Probably not. You ought to be able to translate between GSI and IRQ,
>> and then continue to record in / check against IRQ permissions.
> But I found in function init_irq_data:
> for ( irq = 0; irq < nr_irqs_gsi; irq++ )
> {
> int rc;
>
> desc = irq_to_desc(irq);
> desc->irq = irq;
>
> rc = init_one_irq_desc(desc);
> if ( rc )
> return rc;
> }
> Does it mean that when irq < nr_irqs_gsi, the gsi and irq is a 1:1 mapping?
No, as explained before. I also don't see how you would derive that from
the code above. "nr_irqs_gsi" describes what its name says: The number of
IRQs mapping to a (_some_) GSI. That's to tell them from the non-GSI (i.e.
mainly MSI) ones. There's no implication whatsoever on the IRQ <-> GSI
mapping.
> What's more, when using PHYSDEVOP_setup_gsi, it calls mp_register_gsi,
> and in mp_register_gsi, it uses " desc = irq_to_desc(gsi); " to get irq_desc
> directly.
Which may be wrong, while that wrong-ness may not have hit anyone in
practice (for reasons that would need working out).
> Combining above, can we consider "gsi == irq" when irq < nr_irqs_gsi ?
Again - no.
Jan
