Re: [patch 02/39] iommu/vt-d: Remove bogus check for multi MSI-X

Thomas Gleixner
2022-11-16T17:02:37Z

On Wed, Nov 16 2022 at 07:52, Ashok Raj wrote:
> On Fri, Nov 11, 2022 at 02:54:17PM +0100, Thomas Gleixner wrote:
>> PCI/Multi-MSI is MSI specific and not supported for MSI-X.
>>
>> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
>> ---
>> drivers/iommu/intel/irq_remapping.c | 3 +--
>> 1 file changed, 1 insertion(+), 2 deletions(-)
>>
>> --- a/drivers/iommu/intel/irq_remapping.c
>> +++ b/drivers/iommu/intel/irq_remapping.c
>> @@ -1334,8 +1334,7 @@ static int intel_irq_remapping_alloc(str
>>
>> if (!info || !iommu)
>> return -EINVAL;
>> - if (nr_irqs > 1 && info->type != X86_IRQ_ALLOC_TYPE_PCI_MSI &&
>> - info->type != X86_IRQ_ALLOC_TYPE_PCI_MSIX)
>> + if (nr_irqs > 1 && info->type != X86_IRQ_ALLOC_TYPE_PCI_MSI)
>> return -EINVAL;
>>
>> /*
>>
>
> This check is only making sure that when multi-msi is requested that the
> type has to be either MSI/MSIX.

MSI-X does not support multi vector allocations on a single entry.

> Wouldn't this change return -EINVAL when type = MSIX?

Rightfully so. MSIX vectors are allocated one by one. Has been that way
forever.

Thanks,

tglx