Re: [PATCH v11 07/13] iommu/vt-d: Add SVA domain support

[Baolu Lu]

On 2022/8/18 21:36, Jason Gunthorpe wrote:
> On Wed, Aug 17, 2022 at 09:20:18AM +0800, Lu Baolu wrote:
>
> > +static int intel_svm_set_dev_pasid(struct iommu_domain *domain,
> > +				   struct device *dev, ioasid_t pasid)
> > +{
> > +	struct device_domain_info *info = dev_iommu_priv_get(dev);
> > +	struct intel_iommu *iommu = info->iommu;
> > +	struct iommu_sva *sva;
> > +	int ret = 0;
> > +
> > +	mutex_lock(&pasid_mutex);
> > +	/*
> > +	 * Detach the domain if a blocking domain is set. Check the
> > +	 * right domain type once the IOMMU driver supports a real
> > +	 * blocking domain.
> > +	 */
> > +	if (!domain || domain->type == IOMMU_DOMAIN_UNMANAGED) {
> > +		intel_svm_unbind_mm(dev, pasid);
>
> See, I think this is exactly the wrong way to use the ops
>
> The blockin domain ops should have its own function that just
> unconditionally calls intel_svm_unbind_mm()
>
> > +	} else {
> > +		struct mm_struct *mm = domain->mm;
> > +
> > +		sva = intel_svm_bind_mm(iommu, dev, mm);
> > +		if (IS_ERR(sva))
> > +			ret = PTR_ERR(sva);
>
> And similarly the SVA domain should have its own op that does this SVM
> call.
>
> Muxing the ops with tests on the domain is an anti-pattern. In fact I
> would say any time you see an op testing the domain->type it is very
> suspicious.

Both agreed. Will fix them in the next version.

Best regards,
baolu