linux-kernel - Re: [PATCH] iommu/vt-d: Check for non-NULL domain on device release

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Date: Thu, 22 Feb 2024 19:53:51 +0800
From: Baolu Lu <baolu.lu@...ux.intel.com>
To: Jason Gunthorpe <jgg@...pe.ca>
Cc: baolu.lu@...ux.intel.com, Eric Badger <ebadger@...estorage.com>,
 David Woodhouse <dwmw2@...radead.org>, Joerg Roedel <joro@...tes.org>,
 Will Deacon <will@...nel.org>, Robin Murphy <robin.murphy@....com>,
 "open list:INTEL IOMMU (VT-d)" <iommu@...ts.linux.dev>,
 open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] iommu/vt-d: Check for non-NULL domain on device release

On 2024/2/21 23:40, Jason Gunthorpe wrote:
> On Wed, Jan 31, 2024 at 03:10:53PM +0800, Baolu Lu wrote:
>> I like this suggestion.
>>
>> Currently, the device_release callback for an iommu driver does the
>> following:
>>
>> a) Silent IOMMU DMA translation. This is done by detaching the existing
>>     domain from the IOMMU and bringing the IOMMU into a blocking state
>>     (some drivers might be in identity state);
>> b) Releases the resources allocated in the probe callback and restores
>>     the device to its previous state before the probe.
>>
>>  From my understanding of your suggestion, we should move a) out of the
>> release callback and make it a special domain, which could be a blocking
>> domain or identity domain, depending on the iommu hardware.
>>
>> In the end, the release_device callback of an iommu driver should focus
>> on the opposite operation of device_probe. This makes the concept
>> clearer.
> Right
> 
> Can someone make some patches to fix Eric's bug? We don't really need
> to do the release_domain stuff if the driver just self-attaches one of
> its known static domain types (blocking/identity)

I will follow up with a formal patch series.

Best regards,
baolu