linux-kernel - Re: [PATCH v1 12/14] iommu/arm-smmu-v3: Support IOMMU_DOMAIN

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Message-ID: <ZB3jMSOL5A+E5D82@nvidia.com>
Date:   Fri, 24 Mar 2023 14:51:45 -0300
From:   Jason Gunthorpe <jgg@...dia.com>
To:     Nicolin Chen <nicolinc@...dia.com>
Cc:     Eric Auger <eric.auger@...hat.com>, robin.murphy@....com,
        will@...nel.org, kevin.tian@...el.com, baolu.lu@...ux.intel.com,
        joro@...tes.org, shameerali.kolothum.thodi@...wei.com,
        jean-philippe@...aro.org, linux-arm-kernel@...ts.infradead.org,
        iommu@...ts.linux.dev, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v1 12/14] iommu/arm-smmu-v3: Support IOMMU_DOMAIN_NESTED
 type of allocations

On Fri, Mar 24, 2023 at 10:50:34AM -0700, Nicolin Chen wrote:
> On Fri, Mar 24, 2023 at 04:44:58PM +0100, Eric Auger wrote:
> > > @@ -2923,8 +2949,16 @@ arm_smmu_domain_alloc_user(struct device *dev, struct iommu_domain *parent,
> > >       const struct iommu_hwpt_arm_smmuv3 *user_cfg = user_data;
> > >       struct arm_smmu_master *master = dev_iommu_priv_get(dev);
> > >       unsigned type = IOMMU_DOMAIN_UNMANAGED;
> > > +     struct arm_smmu_domain *s2 = NULL;
> > > +
> > > +     if (parent) {
> > > +             if (parent->ops != arm_smmu_ops.default_domain_ops)
> > > +                     return NULL;
> > > +             type = IOMMU_DOMAIN_NESTED;
> > > +             s2 = to_smmu_domain(parent);
> > > +     }
> > Please can you explain the (use) case where !parent. This creates an
> > unmanaged S1?
> 
> It creates an unmanaged type of a domain. The decision to mark
> it as an unmanaged S1 or an unmanaged S2 domain, is done in the
> finalise() function that it checks the S2 flag and set a stage
> accordingly.

This also needs to be fixed up, the alloc_user should not return
incompletely initialized domains.

Jason