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Date:   Fri, 24 Mar 2023 10:40:46 -0700
From:   Nicolin Chen <nicolinc@nvidia.com>
To:     Eric Auger <eric.auger@redhat.com>
CC:     <jgg@nvidia.com>, <robin.murphy@arm.com>, <will@kernel.org>,
        <kevin.tian@intel.com>, <baolu.lu@linux.intel.com>,
        <joro@8bytes.org>, <shameerali.kolothum.thodi@huawei.com>,
        <jean-philippe@linaro.org>, <linux-arm-kernel@lists.infradead.org>,
        <iommu@lists.linux.dev>, <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v1 11/14] iommu/arm-smmu-v3: Add
 arm_smmu_domain_alloc_user
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Hi Eirc,

Thanks for the review.

On Fri, Mar 24, 2023 at 04:28:26PM +0100, Eric Auger wrote:

> > +static struct iommu_domain *
> > +__arm_smmu_domain_alloc(unsigned type,
> > +                     struct arm_smmu_domain *s2,
> > +                     struct arm_smmu_master *master,
> > +                     const struct iommu_hwpt_arm_smmuv3 *user_cfg)
> > +{
> > +     struct arm_smmu_domain *smmu_domain;
> > +     struct iommu_domain *domain;
> > +     int ret = 0;
> > +
> > +     if (type == IOMMU_DOMAIN_SVA)
> > +             return arm_smmu_sva_domain_alloc();
> > +
> > +     if (type != IOMMU_DOMAIN_UNMANAGED &&
> > +         type != IOMMU_DOMAIN_DMA &&
> > +         type != IOMMU_DOMAIN_DMA_FQ &&
> > +         type != IOMMU_DOMAIN_IDENTITY)
> > +             return NULL;
> > +
> > +     /*
> > +      * Allocate the domain and initialise some of its data structures.
> > +      * We can't really finalise the domain unless a master is given.
> > +      */
> > +     smmu_domain = kzalloc(sizeof(*smmu_domain), GFP_KERNEL);
> > +     if (!smmu_domain)
> > +             return NULL;
> > +     domain = &smmu_domain->domain;
> > +
> > +     domain->type = type;
> > +     domain->ops = arm_smmu_ops.default_domain_ops;
> Compared to the original code, that's something new. Please can you
> explain why this is added in this patch?

Yea, I probably should have mentioned in the commit message that
this function via ops->domain_alloc_user() is called by IOMMUFD
directly without a wrapper, v.s. the other callers all go with
the __iommu_domain_alloc() helper in the iommu core where an ops
pointer gets setup.

So, this is something new, in order to work with IOMMUFD.

Thanks
Nicolin