drivers/iommu/iommufd/hw_pagetable.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (c) 2021-2022, NVIDIA CORPORATION & AFFILIATES
 */
#include <linux/iommu.h>

#include "iommufd_private.h"

void iommufd_hw_pagetable_destroy(struct iommufd_object *obj)
{
	struct iommufd_hw_pagetable *hwpt =
		container_of(obj, struct iommufd_hw_pagetable, obj);

	WARN_ON(!list_empty(&hwpt->devices));

	if (!list_empty(&hwpt->hwpt_item)) {
		mutex_lock(&hwpt->ioas->mutex);
		list_del(&hwpt->hwpt_item);
		mutex_unlock(&hwpt->ioas->mutex);

		iopt_table_remove_domain(&hwpt->ioas->iopt, hwpt->domain);
	}

	if (hwpt->domain)
		iommu_domain_free(hwpt->domain);

	refcount_dec(&hwpt->ioas->obj.users);
	mutex_destroy(&hwpt->devices_lock);
}

/**
 * iommufd_hw_pagetable_alloc() - Get an iommu_domain for a device
 * @ictx: iommufd context
 * @ioas: IOAS to associate the domain with
 * @idev: Device to get an iommu_domain for
 * @immediate_attach: True if idev should be attached to the hwpt
 *
 * Allocate a new iommu_domain and return it as a hw_pagetable. The HWPT
 * will be linked to the given ioas and upon return the underlying iommu_domain
 * is fully popoulated.
 */
struct iommufd_hw_pagetable *
iommufd_hw_pagetable_alloc(struct iommufd_ctx *ictx, struct iommufd_ioas *ioas,
			   struct iommufd_device *idev, bool immediate_attach)
{
	struct iommufd_hw_pagetable *hwpt;
	int rc;

	lockdep_assert_held(&ioas->mutex);

	hwpt = iommufd_object_alloc(ictx, hwpt, IOMMUFD_OBJ_HW_PAGETABLE);
	if (IS_ERR(hwpt))
		return hwpt;

	INIT_LIST_HEAD(&hwpt->devices);
	INIT_LIST_HEAD(&hwpt->hwpt_item);
	mutex_init(&hwpt->devices_lock);
	/* Pairs with iommufd_hw_pagetable_destroy() */
	refcount_inc(&ioas->obj.users);
	hwpt->ioas = ioas;

	hwpt->domain = iommu_domain_alloc(idev->dev->bus);
	if (!hwpt->domain) {
		rc = -ENOMEM;
		goto out_abort;
	}

	mutex_lock(&hwpt->devices_lock);

	/*
	 * immediate_attach exists only to accommodate iommu drivers that cannot
	 * directly allocate a domain. These drivers do not finish creating the
	 * domain until attach is completed. Thus we must have this call
	 * sequence. Once those drivers are fixed this should be removed.
	 */
	if (immediate_attach) {
		rc = iommufd_hw_pagetable_attach(hwpt, idev);
		if (rc)
			goto out_unlock;
	}

	rc = iopt_table_add_domain(&hwpt->ioas->iopt, hwpt->domain);
	if (rc)
		goto out_detach;
	list_add_tail(&hwpt->hwpt_item, &hwpt->ioas->hwpt_list);

	if (immediate_attach) {
		/* See iommufd_device_do_attach() */
		refcount_inc(&hwpt->obj.users);
		idev->hwpt = hwpt;
		list_add(&idev->devices_item, &hwpt->devices);
	}

	mutex_unlock(&hwpt->devices_lock);
	return hwpt;

out_detach:
	if (immediate_attach)
		iommufd_hw_pagetable_detach(hwpt, idev);
out_unlock:
	mutex_unlock(&hwpt->devices_lock);
out_abort:
	iommufd_object_abort_and_destroy(ictx, &hwpt->obj);
	return ERR_PTR(rc);
}