Re: [PATCH 4/5] iommu/vt-d: Add support for static identity domain

[Jason Gunthorpe]

On Mon, Nov 20, 2023 at 07:29:43PM +0800, Lu Baolu wrote:

> @@ -2311,6 +2316,13 @@ static int device_def_domain_type(struct device *dev)
>  			return IOMMU_DOMAIN_IDENTITY;
>  	}
>  
> +	/*
> +	 * Hardware does not support the passthrough translation mode.
> +	 * Always use a dynamaic mapping domain.
> +	 */
> +	if (!ecap_pass_through(iommu->ecap))
> +		return IOMMU_DOMAIN_DMA;
> +

Doesn't this return from def_domain_type completely prevent using an
identity domain?

I thought the point of this was to allow the identity domain but have
it be translating?

Jason