linux-kernel - Re: [PATCH RFC 04/11] iommu/vt-d: Add SVA domain support

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Date:   Mon, 21 Mar 2022 08:56:37 -0300
From:   Jason Gunthorpe <jgg@...dia.com>
To:     Lu Baolu <baolu.lu@...ux.intel.com>
Cc:     Joerg Roedel <joro@...tes.org>,
        Christoph Hellwig <hch@...radead.org>,
        Kevin Tian <kevin.tian@...el.com>,
        Ashok Raj <ashok.raj@...el.com>, Will Deacon <will@...nel.org>,
        Robin Murphy <robin.murphy@....com>,
        Jean-Philippe Brucker <jean-philippe@...aro.com>,
        Eric Auger <eric.auger@...hat.com>,
        Liu Yi L <yi.l.liu@...el.com>,
        Jacob jun Pan <jacob.jun.pan@...el.com>,
        iommu@...ts.linux-foundation.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH RFC 04/11] iommu/vt-d: Add SVA domain support

On Sun, Mar 20, 2022 at 02:40:23PM +0800, Lu Baolu wrote:
> Add support for SVA domain allocation and provide an SVA-specific
> iommu_domain_ops.
> 
> Signed-off-by: Lu Baolu <baolu.lu@...ux.intel.com>
>  include/linux/intel-iommu.h |  1 +
>  drivers/iommu/intel/iommu.c | 12 ++++++++++++
>  drivers/iommu/intel/svm.c   | 34 ++++++++++++++++++++++++++++++++++
>  3 files changed, 47 insertions(+)
> 
> diff --git a/include/linux/intel-iommu.h b/include/linux/intel-iommu.h
> index 2f9891cb3d00..c14283137fb5 100644
> +++ b/include/linux/intel-iommu.h
> @@ -744,6 +744,7 @@ void intel_svm_unbind(struct iommu_sva *handle);
>  u32 intel_svm_get_pasid(struct iommu_sva *handle);
>  int intel_svm_page_response(struct device *dev, struct iommu_fault_event *evt,
>  			    struct iommu_page_response *msg);
> +extern const struct iommu_domain_ops intel_svm_domain_ops;
>  
>  struct intel_svm_dev {
>  	struct list_head list;
> diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
> index c1b91bce1530..d55dca3eacf8 100644
> +++ b/drivers/iommu/intel/iommu.c
> @@ -4318,6 +4318,18 @@ static struct iommu_domain *intel_iommu_domain_alloc(unsigned type)
>  		return domain;
>  	case IOMMU_DOMAIN_IDENTITY:
>  		return &si_domain->domain;
> +#ifdef CONFIG_INTEL_IOMMU_SVM
> +	case IOMMU_DOMAIN_SVA:
> +		dmar_domain = alloc_domain(type);
> +		if (!dmar_domain) {
> +			pr_err("Can't allocate sva domain\n");

Don't put random pr_err's/etc in drivers. At least try to use dev_err

> +			return NULL;
> +		}
> +		domain = &dmar_domain->domain;
> +		domain->ops = &intel_svm_domain_ops;
> +
> +		return domain;
> +#endif /* CONFIG_INTEL_IOMMU_SVM */
>  	default:
>  		return NULL;
>  	}
> diff --git a/drivers/iommu/intel/svm.c b/drivers/iommu/intel/svm.c
> index ee5ecde5b318..b9f4dd7057d1 100644
> +++ b/drivers/iommu/intel/svm.c
> @@ -932,3 +932,37 @@ int intel_svm_page_response(struct device *dev,
>  	mutex_unlock(&pasid_mutex);
>  	return ret;
>  }
> +
> +static int intel_svm_attach_dev_pasid(struct iommu_domain *domain,
> +				      struct device *dev, ioasid_t pasid)
> +{
> +	struct device_domain_info *info = dev_iommu_priv_get(dev);
> +	struct mm_struct *mm = domain->sva_cookie;
> +	struct intel_iommu *iommu = info->iommu;
> +	struct iommu_sva *sva;
> +
> +	mutex_lock(&pasid_mutex);
> +	sva = intel_svm_bind_mm(iommu, dev, mm);
> +	mutex_unlock(&pasid_mutex);
> +
> +	return IS_ERR_OR_NULL(sva);

Never use IS_ERR_OR_NULL(), fix whatever is wrong in intel_svm_bind_mm()
that it can return NULL on failure.

> +const struct iommu_domain_ops intel_svm_domain_ops = {
> +	.attach_dev_pasid	= intel_svm_attach_dev_pasid,
> +	.detach_dev_pasid	= intel_svm_detach_dev_pasid,

Lets have consistent language either this is called SVA or SVM but not
both.

Jason