> From: Jason Gunthorpe <jgg@xxxxxxxxxx>
> Sent: Wednesday, March 8, 2023 8:36 AM
>
> @@ -359,6 +360,76 @@ iommufd_device_do_attach(struct iommufd_device
> *idev,
> return NULL;
> }
>
> +static struct iommufd_hw_pagetable *
> +iommufd_device_do_replace(struct iommufd_device *idev,
> + struct iommufd_hw_pagetable *hwpt)
> +{
> + struct iommufd_group *igroup = idev->igroup;
> + struct iommufd_hw_pagetable *old_hwpt;
> + unsigned int num_devices = 0;
> + struct iommufd_device *cur;
> + int rc;
> +
> + mutex_lock(&idev->igroup->lock);
> +
> + if (hwpt == igroup->hwpt) {
> + mutex_unlock(&idev->igroup->lock);
> + return NULL;
> + }
> +
> + /* Try to upgrade the domain we have */
> + list_for_each_entry(cur, &igroup->device_list, group_item) {
> + num_devices++;
> + if (cur->enforce_cache_coherency) {
> + rc = iommufd_hw_pagetable_enforce_cc(hwpt);
> + if (rc)
> + goto err_unlock;
> + }
> + }
> +
> + old_hwpt = igroup->hwpt;
> + if (hwpt->ioas != old_hwpt->ioas) {
Do we allow this function to be used as attach/detach?
if yes old_hwpt could be NULL here.
if no an explicit check on old_hwpt!=NULL is also required.
and looks the policy for physical attach is different from the one that
Nicoline applies for access. iommufd_access_set_ioas() can behave
like normal attach/detach.
should be consistent here.
