Re: [patch 21/33] genirq/msi: Provide msi_domain_alloc_irq_at()

[Thomas Gleixner]

On Fri, Nov 18 2022 at 10:18, Reinette Chatre wrote:
>> @@ -141,7 +141,7 @@ static int msi_insert_desc(struct device *dev, struct msi_desc *desc,
>>  		if (ret)
>>  			goto fail;
>>  
>> -		desc->msi_index = index;
>> +		desc->msi_index = index - baseidx;
>
> Could msi_desc->msi_index be made bigger? The hardware I am testing
> on claims to support more IMS entries than what the u16 can
> accommodate.

Sure that's trivial. How big does it claim it is?

>> @@ -1476,9 +1476,10 @@ struct msi_map msi_domain_alloc_irq_at(struct device *dev, unsigned int domid, u
>>  				       const struct irq_affinity_desc *affdesc,
>>  				       union msi_dev_cookie *cookie)
>>  {
>> +	struct msi_ctrl ctrl = { .domid	= domid, .nirqs = 1, };
>> +	struct msi_domain_info *info;
>>  	struct irq_domain *domain;
>>  	struct msi_map map = { };
>> -	struct msi_desc *desc;
>
> (*desc is still needed)

Yes, I figured that out later :)

> Thank you very much. With the above snippet it is possible to
> allocate an IMS IRQ. I am not yet able to use the IRQ and I am working
> on more tracing to figure out why. In the mean time, I did
> just try the pci_ims_alloc_irq()/pci_ims_free_irq() flow and
> pci_ims_free_irq() triggered the WARN below:
>
> remove_proc_entry: removing non-empty directory 'irq/220', leaking at least 'idxd-portal'

Hrm, that's the irq action directory. No idea why that is not torn down.

I assume your sequence is:

  pci_ims_alloc();
  request_irq();        <- This creates it
  free_irq();           <- This removes it
  pci_ims_free();

Right?

Thanks,

        tglx