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

[Lu Baolu]

On 2022/3/31 3:09, Jason Gunthorpe wrote:
> 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...

Robin mentioned that the iommu domain alloc/free interfaces are under
reforming. These cleanups need to wait to see what the final code looks
like.

Best regards,
baolu