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

[Jason Gunthorpe]

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)

Jason