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

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Message-ID: <20240911105657.iesajd4d5va3wc5y@joelS2.panther.com>
Date: Wed, 11 Sep 2024 12:56:57 +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.
> 
> > Add this handle when the
> > replacing hwpt has a valid iommufd fault object. Remove it when we
> > release ownership of the group.
> 
> The iommu_attach_handle is managed by the caller (iommufd here for
> example). Therefore, before iommu_attach_handle tries to attach a domain
> to an iopf-capable device or pasid, it should allocate the handle and
> pass it to the domain attachment interfaces.
What do you mean here?
1. Do you want to move the iommufd_init_pasid_array call up to
iommufd_hwpt_replace_device?
2. Do you want to move it further up to iommufd_device_do_replace?

Note that all this implemented on a call to replace HWPT. So a
non-iopf-capable VFIO_DEVICE_ATTACH_IOMMUFD_PT ioctl has already been
completed before the one that calls iommufd_device_do_replace.

> Conversely, the handle can
> only be freed after the domain is detached.
Do you have a function in specific where you would put the free handle
logic?

Best

-- 

Joel Granados