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Date:   Wed, 20 Sep 2023 10:05:22 -0300
From:   Jason Gunthorpe <jgg@nvidia.com>
To:     Baolu Lu <baolu.lu@linux.intel.com>
Cc:     Yi Liu <yi.l.liu@intel.com>, joro@8bytes.org,
        alex.williamson@redhat.com, kevin.tian@intel.com,
        robin.murphy@arm.com, cohuck@redhat.com, eric.auger@redhat.com,
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        chao.p.peng@linux.intel.com, yi.y.sun@linux.intel.com,
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        shameerali.kolothum.thodi@huawei.com, lulu@redhat.com,
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        linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org,
        zhenzhong.duan@intel.com, joao.m.martins@oracle.com
Subject: Re: [PATCH 6/6] iommu/vt-d: Add domain_alloc_user op
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On Wed, Sep 20, 2023 at 01:28:41PM +0800, Baolu Lu wrote:
> > 
> > diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
> > index 5db283c17e0d..491bcde1ff96 100644
> > --- a/drivers/iommu/intel/iommu.c
> > +++ b/drivers/iommu/intel/iommu.c
> > @@ -4074,6 +4074,25 @@ static struct iommu_domain *intel_iommu_domain_alloc(unsigned type)
> >   	return NULL;
> >   }
> > +static struct iommu_domain *
> > +intel_iommu_domain_alloc_user(struct device *dev, u32 flags)
> > +{
> > +	struct iommu_domain *domain;
> > +	struct intel_iommu *iommu;
> > +
> > +	iommu = device_to_iommu(dev, NULL, NULL);
> > +	if (!iommu)
> > +		return ERR_PTR(-ENODEV);
> > +
> > +	if ((flags & IOMMU_HWPT_ALLOC_NEST_PARENT) && !ecap_nest(iommu->ecap))
> > +		return ERR_PTR(-EOPNOTSUPP);

There is a check missing for supported flags

 if (flags & (~IOMMU_HWPT_ALLOC_NEST_PARENT))
	return ERR_PTR(-EOPNOTSUPP);

> > +
> > +	domain = iommu_domain_alloc(dev->bus);
> 
> No need to bounce between core and driver. Just,
> 
> 	intel_iommu_domain_alloc(IOMMU_DOMAIN_UNMANAGED);
> 
> and fully initialize it before return.

If you are going to do that then intel_iommu_domain_alloc() should
fully initialize the domain, not here.

Jason