On 2024/5/29 14:31, Jan Beulich wrote:
> 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.
Because here set desc->irq = irq, and it seems there is no other place to
change this desc->irq, so, gsi 1 is considered to irq 1.
> "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.
Since you are certain that they are not equal, could you tell me where show
they are not equal or where build their mappings,
so that I can know how to do a conversion gsi from irq.
>
> Jan
--
Best regards,
Jiqian Chen.
