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Date:   Mon, 24 Jan 2022 01:37:21 -0800
From:   Christoph Hellwig <hch@infradead.org>
To:     Lu Baolu <baolu.lu@linux.intel.com>
Cc:     Joerg Roedel <joro@8bytes.org>, Jason Gunthorpe <jgg@nvidia.com>,
        Christoph Hellwig <hch@infradead.org>,
        Ben Skeggs <bskeggs@redhat.com>,
        Kevin Tian <kevin.tian@intel.com>,
        Ashok Raj <ashok.raj@intel.com>, Will Deacon <will@kernel.org>,
        Robin Murphy <robin.murphy@arm.com>,
        Alex Williamson <alex.williamson@redhat.com>,
        Eric Auger <eric.auger@redhat.com>,
        Liu Yi L <yi.l.liu@intel.com>,
        Jacob jun Pan <jacob.jun.pan@intel.com>,
        David Airlie <airlied@linux.ie>,
        Daniel Vetter <daniel@ffwll.ch>,
        Thierry Reding <thierry.reding@gmail.com>,
        Jonathan Hunter <jonathanh@nvidia.com>,
        iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 7/7] iommu: Add iommu_domain::domain_ops
Message-ID: <Ye5zUapC/YcZs7kl@infradead.org>
References: <20220124071103.2097118-1-baolu.lu@linux.intel.com>
 <20220124071103.2097118-8-baolu.lu@linux.intel.com>
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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?