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Date:   Tue, 10 Oct 2023 13:43:55 -0300
From:   Jason Gunthorpe <jgg@nvidia.com>
To:     Yi Liu <yi.l.liu@intel.com>
Cc:     joro@8bytes.org, alex.williamson@redhat.com, kevin.tian@intel.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 v2 6/6] iommu/vt-d: Add domain_alloc_user op
Message-ID: <20231010164355.GA74795@nvidia.com>
References: <20230928071528.26258-1-yi.l.liu@intel.com>
 <20230928071528.26258-7-yi.l.liu@intel.com>
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On Thu, Sep 28, 2023 at 12:15:28AM -0700, Yi Liu wrote:
> This adds the domain_alloc_user op implementation. It supports allocating
> domains to be used as parent under nested translation.
> 
> Signed-off-by: Yi Liu <yi.l.liu@intel.com>
> ---
>  drivers/iommu/intel/iommu.c | 28 ++++++++++++++++++++++++++++
>  1 file changed, 28 insertions(+)
> 
> diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
> index 5db283c17e0d..017aed5813d8 100644
> --- a/drivers/iommu/intel/iommu.c
> +++ b/drivers/iommu/intel/iommu.c
> @@ -4074,6 +4074,33 @@ 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;
> +
> +	if (flags & (~IOMMU_HWPT_ALLOC_NEST_PARENT))
> +		return ERR_PTR(-EOPNOTSUPP);
> +
> +	iommu = device_to_iommu(dev, NULL, NULL);
> +	if (!iommu)
> +		return ERR_PTR(-ENODEV);

Why isn't this just

	struct device_domain_info *info = dev_iommu_priv_get(dev)
	struct intel_iommu *iommu = info->iommu

???

Same question for almost all other calls to this function! The one in
probe is reasonable, but I don't think it should be ever called again.

I'm going to leave this, but please make a series cleaning all the
device_to_iommu() stuff next cycle..

Jason