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

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Message-ID: <20240911095544.4ad3u6jxgsdsymhj@joelS2.panther.com>
Date: Wed, 11 Sep 2024 11:55:44 +0200
From: Joel Granados <j.granados@...sung.com>
To: Baolu Lu <baolu.lu@...ux.intel.com>
CC: 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 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.
"""

best

-- 

Joel Granados