linux-kernel - RE: [PATCH 1/2] iommu: Add static iommu_ops->release

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Date: Wed, 28 Feb 2024 03:08:11 +0000
From: "Tian, Kevin" <kevin.tian@...el.com>
To: Baolu Lu <baolu.lu@...ux.intel.com>, Joerg Roedel <joro@...tes.org>, "Will
 Deacon" <will@...nel.org>, Robin Murphy <robin.murphy@....com>, "Jason
 Gunthorpe" <jgg@...pe.ca>, "Badger, Eric" <ebadger@...estorage.com>
CC: "iommu@...ts.linux.dev" <iommu@...ts.linux.dev>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>, "Jason
 Gunthorpe" <jgg@...dia.com>
Subject: RE: [PATCH 1/2] iommu: Add static iommu_ops->release_domain

> From: Baolu Lu <baolu.lu@...ux.intel.com>
> Sent: Wednesday, February 28, 2024 9:14 AM
> 
> On 2/27/24 3:32 PM, Tian, Kevin wrote:
> >> From: Lu Baolu<baolu.lu@...ux.intel.com>
> >> Sent: Friday, February 23, 2024 1:13 PM
> >>
> >>
> >> +	/*
> >> +	 * If the iommu driver provides release_domain then the core code
> >> +	 * ensures that domain is attached prior to calling release_device.
> >> +	 * Drivers can use this to enforce a translation on the idle iommu.
> > 'enforce a translation' is confusing in the context of blocking/identity
> > domain.
> 
> Blocking or identity domain is also kind of a translation from the
> core's perspective. The core does not care what type of translation the
> release_domain is; it just enforces this type of translation before
> device release if the driver has specified one.
> 

OK.

btw you may also want to update the following comment together:

	/*
	 * release_device() must stop using any attached domain on the device.
	 * If there are still other devices in the group they are not effected
	 * by this callback.
	 *
	 * The IOMMU driver must set the device to either an identity or
	 * blocking translation and stop using any domain pointer, as it is
	 * going to be freed.
	 */

all the purpose is to set the device to identity or blocking, either via attaching
to an explicit release_domain or implicitly by release_device().