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Subject: Re: [PATCH RFC v2 02/18] irq/dev-msi: Add support for a new DEV_MSI
 irq domain
To:     Jason Gunthorpe <jgg@nvidia.com>
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From:   "Dey, Megha" <megha.dey@intel.com>
Message-ID: <17351360-a880-f651-2a99-6f9817b99e03@intel.com>
Date:   Fri, 7 Aug 2020 13:31:59 -0700
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On 8/7/2020 11:39 AM, Jason Gunthorpe wrote:
> On Fri, Aug 07, 2020 at 10:54:51AM -0700, Dey, Megha wrote:
>
>> So from the hierarchical domain standpoint, we will have:
>> - For DSA device: vector->intel-IR->IDXD
>> - For Jason's device: root domain-> domain A-> Jason's device's IRQ domain
>> - For any other intel IMS device in the future which
>>      does not require interrupt remapping: vector->new device IRQ domain
>>      requires interrupt remapping: vector->intel-IR->new device IRQ domain
> I think you need a better classification than Jason's device or
> Intel's device :)
hehe yeah, for sure, just wanted to get my point across :)
>
> Shouldn't the two cases be either you take the parent domain from the
> IOMMU or you take the parent domain from the pci device?

Hmm yeah this makes sense..

Although in the case of DSA, we find the iommu corresponding to the 
parent PCI device.

>
> What other choices could a PCI driver make?
Currently I think based on the devices we have, I don't think there are 
any others
>
> Jason