path: root/drivers/vfio/vfio_iommu_spapr_tce.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * VFIO: IOMMU DMA mapping support for TCE on POWER
 *
 * Copyright (C) 2013 IBM Corp.  All rights reserved.
 *     Author: Alexey Kardashevskiy <aik@ozlabs.ru>
 *
 * Derived from original vfio_iommu_type1.c:
 * Copyright (C) 2012 Red Hat, Inc.  All rights reserved.
 *     Author: Alex Williamson <alex.williamson@redhat.com>
 */

#include <linux/module.h>
#include <linux/pci.h>
#include <linux/slab.h>
#include <linux/uaccess.h>
#include <linux/err.h>
#include <linux/vfio.h>
#include <linux/vmalloc.h>
#include <linux/sched/mm.h>
#include <linux/sched/signal.h>
#include <linux/mm.h>

#include <asm/iommu.h>
#include <asm/tce.h>
#include <asm/mmu_context.h>

#define DRIVER_VERSION  "0.1"
#define DRIVER_AUTHOR   "aik@ozlabs.ru"
#define DRIVER_DESC     "VFIO IOMMU SPAPR TCE"

static void tce_iommu_detach_group(void *iommu_data,
		struct iommu_group *iommu_group);

/*
 * VFIO IOMMU fd for SPAPR_TCE IOMMU implementation
 *
 * This code handles mapping and unmapping of user data buffers
 * into DMA'ble space using the IOMMU
 */

struct tce_iommu_group {
	struct list_head next;
	struct iommu_group *grp;
};

/*
 * A container needs to remember which preregistered region  it has
 * referenced to do proper cleanup at the userspace process exit.
 */
struct tce_iommu_prereg {
	struct list_head next;
	struct mm_iommu_table_group_mem_t *mem;
};

/*
 * The container descriptor supports only a single group per container.
 * Required by the API as the container is not supplied with the IOMMU group
 * at the moment of initialization.
 */
struct tce_container {
	struct mutex lock;
	bool enabled;
	bool v2;
	bool def_window_pending;
	unsigned long locked_pages;
	struct mm_struct *mm;
	struct iommu_table *tables[IOMMU_TABLE_GROUP_MAX_TABLES];
	struct list_head group_list;
	struct list_head prereg_list;
};

static long tce_iommu_mm_set(struct tce_container *container)
{
	if (container->mm) {
		if (container->mm == current->mm)
			return 0;
		return -EPERM;
	}
	BUG_ON(!current->mm);
	container->mm = current->mm;
	atomic_inc(&container->mm->mm_count);

	return 0;
}

static long tce_iommu_prereg_free(struct tce_container *container,
		struct tce_iommu_prereg *tcemem)
{
	long ret;

	ret = mm_iommu_put(container->mm, tcemem->mem);
	if (ret)
		return ret;

	list_del(&tcemem