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

Nicolin Chen
2023-03-24T18:01:57Z

On Fri, Mar 24, 2023 at 02:50:42PM -0300, Jason Gunthorpe wrote:
> On Fri, Mar 24, 2023 at 10:40:46AM -0700, Nicolin Chen wrote:
> > 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.
>
> But using default_domain_ops is not great, the ops should be set based
> on the domain type being created and the various different flavours
> should have their own types and ops.
>
> So name the existing ops something logical like 'unmanaged_domain_ops'
> and move it out of the inline initializer.
>
> Make another ops for identity like shown here to get the ball rolling:
>
> https://lore.kernel.org/r/20230324111127.221640-1-steven.price@arm.com
>
> There is a whole bunch of tidying here to make things follow the op
> per type design.

Thanks for the suggestion. Will add a patch doing that in v2.

Nicolin