path: root/drivers/iommu/virtio-iommu.c

// SPDX-License-Identifier: GPL-2.0
/*
 * Virtio driver for the paravirtualized IOMMU
 *
 * Copyright (C) 2019 Arm Limited
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/amba/bus.h>
#include <linux/delay.h>
#include <linux/dma-iommu.h>
#include <linux/freezer.h>
#include <linux/interval_tree.h>
#include <linux/iommu.h>
#include <linux/module.h>
#include <linux/of_iommu.h>
#include <linux/of_platform.h>
#include <linux/pci.h>
#include <linux/platform_device.h>
#include <linux/virtio.h>
#include <linux/virtio_config.h>
#include <linux/virtio_ids.h>
#include <linux/wait.h>

#include <uapi/linux/virtio_iommu.h>

#define MSI_IOVA_BASE			0x8000000
#define MSI_IOVA_LENGTH			0x100000

#define VIOMMU_REQUEST_VQ		0
#define VIOMMU_EVENT_VQ			1
#define VIOMMU_NR_VQS			2

struct viommu_dev {
	struct iommu_device		iommu;
	struct device			*dev;
	struct virtio_device		*vdev;

	struct ida			domain_ids;

	struct virtqueue		*vqs[VIOMMU_NR_VQS];
	spinlock_t			request_lock;
	struct list_head		requests;
	void				*evts;

	/* Device configuration */
	struct iommu_domain_geometry	geometry;
	u64				pgsize_bitmap;
	u32				first_domain;
	u32				last_domain;
	/* Supported MAP flags */
	u32				map_flags;
	u32				probe_size;
};

struct viommu_mapping {
	phys_addr_t			paddr;
	struct interval_tree_node	iova;
	u32				flags;
};

struct viommu_domain {
	struct iommu_domain		domain;
	struct viommu_dev		*viommu;
	struct mutex			mutex; /* protects viommu pointer */
	unsigned int			id;
	u32				map_flags;

	spinlock_t			mappings_lock;
	struct rb_root_cached		mappings;

	unsigned long			nr_endpoints;
};

struct viommu_endpoint {
	struct device			*dev;
	struct viommu_dev		*viommu;
	struct viommu_domain		*vdomain;
	struct list_head		resv_regions;
};

struct viommu_request {
	struct list_head		list;
	void				*writeback;
	unsigned int			write_offset;
	unsigned int			len;
	char				buf[];
};

#define VIOMMU_FAULT_RESV_MASK		0xffffff00

struct viommu_event {
	union {
		u32			head;
		struct virtio_iommu_fault fault;
	};
};

#define to_viommu_domain(domain)	\
	container_of(domain, struct viommu_domain, domain)

static int viommu_get_req_errno(void *buf, size_t len)
{
	struct virtio_iommu_req_tail *tail = buf + len - sizeof(*tail);

	switch (tail->status) {
	case VIRTIO_IOMMU_S_OK:
		return 0;
	case VIRTIO_IOMMU_S_UNSUPP:
		return -ENOSYS;
	case VIRTIO_IOMMU_S_INVAL:
		return -EINVAL;
	case VIRTIO_IOMMU_S_RANGE:
		return -ERANGE;
	case VIRTIO_IOMMU_S_NOENT:
		return -ENOENT;
	case VIRTIO_IOMMU_S_FAULT:
		return -EFAULT;
	case VIRTIO_IOMMU_S_NOMEM:
		return -ENOMEM;
	case VIRTIO_IOMMU_S_IOERR:
	case VIRTIO_IOMMU_S_DEVERR:
	default:
		return -EIO;
	}
}

static void viommu_set_req_status(void *buf, size_t len, int status)
{
	struct virtio_iommu_req_tail *tail = buf + len - sizeof(*tail);

	tail->status = status;
}

static off_t viommu_get_write_desc_offset(struct viommu_dev *viommu,
					  struct virtio_iommu_req_head *req,
					  size_t len)
{
	size_t tail_size = sizeof(struct virtio_iommu_req_tail);

	if (req->type == VIRTIO_IOMMU_T_PROBE)
		return len - viommu->probe_size - tail_size;

	return len - tail_size;
}

/*
 * __viommu_sync_req - Complete all in-flight requests
 *
 * Wait for all added requests to complete. When this function returns, all
 * requests that were in-flight at the time of the call have completed.
 */
static int __viommu_sync_req(struct viommu_dev *viommu)
{
	unsigned int len;
	size_t write_len;
	struct viommu_request *req;
	struct virtqueue *vq = viommu->vqs[VIOMMU_REQUEST_VQ];

	assert_spin_locked(&viommu->request_lock);

	virtqueue_kick(vq);

	while (!list_empty(&viommu->requests)) {
		len = 0;
		req = virtqueue_get_buf(vq, &len);
		if (!req)
			continue;

		if (!len)
			viommu_set_req_status(req->buf, req->len,
					      VIRTIO_IOMMU_S_IOERR);

		write_len = req->len - req->write_offset;
		if (req->writeback && len