Re: [PATCH v3 03/10] iommu/sva: Manage process address spaces

[Jacob Pan <jacob.jun.pan@linux.intel.com>]

On Thu, 20 Sep 2018 18:00:39 +0100
Jean-Philippe Brucker <jean-philippe.brucker@arm.com> wrote:

> +
> +static int io_mm_attach(struct iommu_domain *domain, struct device
> *dev,
> +			struct io_mm *io_mm, void *drvdata)
> +{
> +	int ret;
> +	bool attach_domain = true;
> +	int pasid = io_mm->pasid;
> +	struct iommu_bond *bond, *tmp;
> +	struct iommu_sva_param *param = dev->iommu_param->sva_param;
> +
> +	if (!domain->ops->mm_attach || !domain->ops->mm_detach)
> +		return -ENODEV;
> +
> +	if (pasid > param->max_pasid || pasid < param->min_pasid)
> +		return -ERANGE;
> +
> +	bond = kzalloc(sizeof(*bond), GFP_KERNEL);
> +	if (!bond)
> +		return -ENOMEM;
> +
> +	bond->domain		= domain;
> +	bond->io_mm		= io_mm;
> +	bond->dev		= dev;
> +	bond->drvdata		= drvdata;
> +
> +	spin_lock(&iommu_sva_lock);
> +	/*
> +	 * Check if this io_mm is already bound to the domain. In
> which case the
> +	 * IOMMU driver doesn't have to install the PASID table
> entry.
> +	 */
> +	list_for_each_entry(tmp, &domain->mm_list, domain_head) {
> +		if (tmp->io_mm == io_mm) {
> +			attach_domain = false;
> +			break;
> +		}
> +	}
> +
> +	ret = domain->ops->mm_attach(domain, dev, io_mm,
> attach_domain);
> +	if (ret) {
> +		kfree(bond);
> +		goto out_unlock;
> +	}
> +
> +	list_add(&bond->mm_head, &io_mm->devices);
> +	list_add(&bond->domain_head, &domain->mm_list);
> +	list_add(&bond->dev_head, &param->mm_list);
> +

I am trying to understand if mm_list is needed for both per device and
per domain. Do you always unbind and detach domain? Seems device could
use the domain->mm_list to track all mm's, true?