Re: [PATCH v1 11/14] iommu/arm-smmu-v3: Add arm_smmu_domain_alloc_user

[Nicolin Chen]

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