Re: [PATCH 7/7] iommu: Add iommu_domain::domain_ops

[Christoph Hellwig]

On Mon, Jan 24, 2022 at 03:11:02PM +0800, Lu Baolu wrote:
> Add a domain specific callback set, domain_ops, for vendor iommu driver
> to provide domain specific operations. Move domain-specific callbacks
> from iommu_ops to the domain_ops and hook them when a domain is allocated.

Ah, that's what I meant earlier.  Perfect!

Nit:  I don't think vendor is the right term here.

Maybe something like:

iommut: split struct iommu_ops

Move the domain specific operations out of struct iommu_ops into a new
structure that only has domain specific operations.  This solves
the problem of needing to know if the method vector for a given
operation needs to be retreived from the device or th domain.

> +struct domain_ops {

This needs to keep an iommu in the name, i.e. iommu_domain_ops.

> +	phys_addr_t (*iova_to_phys)(struct iommu_domain *domain, dma_addr_t iova);

Overly long line.

> +static inline void iommu_domain_set_ops(struct iommu_domain *domain,
> +					const struct domain_ops *ops)
> +{
> +	domain->ops = ops;
> +}

Do we really need this helper?

> +static const struct domain_ops amd_domain_ops;

Can we avoid these forward declarations or would that cause too much
churn?