Re: [PATCH RFC v2 06/11] iommu/vt-d: Add SVA domain support

[Jason Gunthorpe]

On Tue, Mar 29, 2022 at 01:37:55PM +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@xxxxxxxxxxxxxxx>
>  include/linux/intel-iommu.h |  1 +
>  drivers/iommu/intel/iommu.c | 10 ++++++++++
>  drivers/iommu/intel/svm.c   | 37 +++++++++++++++++++++++++++++++++++++
>  3 files changed, 48 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..5eae7cf9bee5 100644
> +++ b/drivers/iommu/intel/iommu.c
> @@ -4318,6 +4318,16 @@ 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)
> +			return NULL;
> +		domain = &dmar_domain->domain;
> +		domain->ops = &intel_svm_domain_ops;
> +
> +		return domain;
> +#endif /* CONFIG_INTEL_IOMMU_SVM */

If this is the usual pattern for drivers I would prefer to see an
alloc_sva op instead of more and more types.

Multiplexing functions is often not a great idea...

Jason