RE: [PATCH v7 06/10] iommu/sva: Refactoring iommu_sva_bind/unbind_device()

[Tian, Kevin]

> From: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>
> Sent: Thursday, May 19, 2022 3:21 PM
> 
> The existing iommu SVA interfaces are implemented by calling the SVA
> specific iommu ops provided by the IOMMU drivers. There's no need for
> any SVA specific ops in iommu_ops vector anymore as we can achieve
> this through the generic attach/detach_dev_pasid domain ops.

set/block_pasid_dev, to be consistent.

> +
> +	mutex_lock(&iommu_sva_lock);
> +	/* Search for an existing domain. */
> +	domain = iommu_get_domain_for_dev_pasid(dev, mm->pasid);
> +	if (domain) {
> +		sva_domain = to_sva_domain(domain);
> +		refcount_inc(&sva_domain->bond.users);
> +		goto out_success;
> +	}
> +

why would one device/pasid be bound to a mm more than once?