linux-kernel - Re: [PATCH 5/6] iommu: init pasid array while doing domain

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Message-ID: <f4ea2a66-49ac-41ae-94c4-2832f08303f1@linux.intel.com>
Date: Thu, 12 Sep 2024 12:17:35 +0800
From: Baolu Lu <baolu.lu@...ux.intel.com>
To: Joel Granados <j.granados@...sung.com>
Cc: baolu.lu@...ux.intel.com, David Woodhouse <dwmw2@...radead.org>,
 Joerg Roedel <joro@...tes.org>, Will Deacon <will@...nel.org>,
 Robin Murphy <robin.murphy@....com>, Jason Gunthorpe <jgg@...pe.ca>,
 Kevin Tian <kevin.tian@...el.com>, Klaus Jensen <its@...elevant.dk>,
 linux-kernel@...r.kernel.org, iommu@...ts.linux.dev
Subject: Re: [PATCH 5/6] iommu: init pasid array while doing domain_replace
 and iopf is active

On 9/11/24 5:55 PM, Joel Granados wrote:
> On Thu, Sep 05, 2024 at 11:30:05AM +0800, Baolu Lu wrote:
>> On 9/4/24 9:17 PM, Joel Granados via B4 Relay wrote:
>>> From: Joel Granados<j.granados@...sung.com>
>>>
>>> iommu_report_device_fault expects a pasid array to have an
>>> iommu_attach_handle when a fault is detected.
>> The iommu_attach_handle is expected only when an iopf-capable domain is
>> attached to the device or PASID. The iommu_report_device_fault() treats
>> it as a fault when a fault occurs, but no iopf-capable domain is
>> attached.
> I don't follow. The way that I read it: if the pasid_array x-array does
> not have an iommu_attach_handle indexed by either fault->prm.pasid or
> IOMMU_NO_PASID, it will follow the err_bad_iopf and return -EINVAL
> (please correct me if I'm wrong). So the iommu_attach_handle is*always*
> expected.
> 
> Would it be more clear for it to be:
> """
> The iommu_report_device_fault function expects the pasid_array x-array
> to have an iommu_attach_handle indexed by a PASID. Add one indexed with
> IOMMU_NO_PASID when the replacing HWPT has a valid iommufd fault object.
> Remove it when we release ownership of the group.

Can you please explain why iommu core needs to remove the attach handle
when the ownership of the group is changed?

Thanks,
baolu