xref: /linux/drivers/iommu/iommufd/driver.c (revision 1fc5a74b108fc90951890ec513ac81869f5eaff1)

// SPDX-License-Identifier: GPL-2.0-only
/* Copyright (c) 2024, NVIDIA CORPORATION & AFFILIATES
 */
#include "iommufd_private.h"

/* Driver should use a per-structure helper in include/linux/iommufd.h */
int _iommufd_object_depend(struct iommufd_object *obj_dependent,
			   struct iommufd_object *obj_depended)
{
	/* Reject self dependency that dead locks */
	if (obj_dependent == obj_depended)
		return -EINVAL;
	/* Only support dependency between two objects of the same type */
	if (obj_dependent->type != obj_depended->type)
		return -EINVAL;

	refcount_inc(&obj_depended->users);
	return 0;
}
EXPORT_SYMBOL_NS_GPL(_iommufd_object_depend, "IOMMUFD");

/* Driver should use a per-structure helper in include/linux/iommufd.h */
void _iommufd_object_undepend(struct iommufd_object *obj_dependent,
			      struct iommufd_object *obj_depended)
{
	if (WARN_ON_ONCE(obj_dependent == obj_depended ||
			 obj_dependent->type != obj_depended->type))
		return;

	refcount_dec(&obj_depended->users);
}
EXPORT_SYMBOL_NS_GPL(_iommufd_object_undepend, "IOMMUFD");

/*
 * Allocate an @offset to return to user space to use for an mmap() syscall
 *
 * Driver should use a per-structure helper in include/linux/iommufd.h
 */
int _iommufd_alloc_mmap(struct iommufd_ctx *ictx, struct iommufd_object *owner,
			phys_addr_t mmio_addr, size_t length,
			unsigned long *offset)
{
	struct iommufd_mmap *immap;
	unsigned long startp;
	int rc;

	if (!PAGE_ALIGNED(mmio_addr))
		return -EINVAL;
	if (!length || !PAGE_ALIGNED(length))
		return -EINVAL;

	immap = kzalloc_obj(*immap);
	if (!immap)
		return -ENOMEM;
	immap->owner = owner;
	immap->length = length;
	immap->mmio_addr = mmio_addr;

	/* Skip the first page to ease caller identifying the returned offset */
	rc = mtree_alloc_range(&ictx->mt_mmap, &startp, immap, immap->length,
			       PAGE_SIZE, ULONG_MAX, GFP_KERNEL);
	if (rc < 0) {
		kfree(immap);
		return rc;
	}

	/* mmap() syscall will right-shift the offset in vma->vm_pgoff too */
	immap->vm_pgoff = startp >> PAGE_SHIFT;
	*offset = startp;
	return 0;
}
EXPORT_SYMBOL_NS_GPL(_iommufd_alloc_mmap, "IOMMUFD");

/* Driver should use a per-structure helper in include/linux/iommufd.h */
void _iommufd_destroy_mmap(struct iommufd_ctx *ictx,
			   struct iommufd_object *owner, unsigned long offset)
{
	struct iommufd_mmap *immap;

	immap = mtree_erase(&ictx->mt_mmap, offset);
	WARN_ON_ONCE(!immap || immap->owner != owner);
	kfree(immap);
}
EXPORT_SYMBOL_NS_GPL(_iommufd_destroy_mmap, "IOMMUFD");

struct device *iommufd_vdevice_to_device(struct iommufd_vdevice *vdev)
{
	return vdev->idev->dev;
}
EXPORT_SYMBOL_NS_GPL(iommufd_vdevice_to_device, "IOMMUFD");

/* Caller should xa_lock(&viommu->vdevs) to protect the return value */
struct device *iommufd_viommu_find_dev(struct iommufd_viommu *viommu,
				       unsigned long vdev_id)
{
	struct iommufd_vdevice *vdev;

	lockdep_assert_held(&viommu->vdevs.xa_lock);

	vdev = xa_load(&viommu->vdevs, vdev_id);
	return vdev ? iommufd_vdevice_to_device(vdev) : NULL;
}
EXPORT_SYMBOL_NS_GPL(iommufd_viommu_find_dev, "IOMMUFD");

/* Return -ENOENT if device is not associated to the vIOMMU */
int iommufd_viommu_get_vdev_id(struct iommufd_viommu *viommu,
			       struct device *dev, unsigned long *vdev_id)
{
	struct iommufd_vdevice *vdev;
	unsigned long index;
	int rc = -ENOENT;

	if (WARN_ON_ONCE(!vdev_id))
		return -EINVAL;

	xa_lock(&viommu->vdevs);
	xa_for_each(&viommu->vdevs, index, vdev) {
		if (iommufd_vdevice_to_device(vdev) == dev) {
			*vdev_id = vdev->virt_id;
			rc = 0;
			break;
		}
	}
	xa_unlock(&viommu->vdevs);
	return rc;
}
EXPORT_SYMBOL_NS_GPL(iommufd_viommu_get_vdev_id, "IOMMUFD");

/*
 * Typically called in driver's threaded IRQ handler.
 * The @type and @event_data must be defined in include/uapi/linux/iommufd.h
 */
int iommufd_viommu_report_event(struct iommufd_viommu *viommu,
				enum iommu_veventq_type type, void *event_data,
				size_t data_len)
{
	struct iommufd_veventq *veventq;
	struct iommufd_vevent *vevent;
	int rc = 0;

	if (WARN_ON_ONCE(!data_len || !event_data))
		return -EINVAL;

	down_read(&viommu->veventqs_rwsem);

	veventq = iommufd_viommu_find_veventq(viommu, type);
	if (!veventq) {
		rc = -EOPNOTSUPP;
		goto out_unlock_veventqs;
	}

	/* Pre-allocate to avoid GFP_ATOMIC; use GFP_NOWAIT to avoid sleeping */
	vevent = kzalloc_flex(*vevent, event_data, data_len, GFP_NOWAIT);
	if (!vevent) {
		spin_lock(&veventq->common.lock);
		vevent = &veventq->lost_events_header;
		rc = -ENOMEM;
		goto out_set_header;
	}

	spin_lock(&veventq->common.lock);
	if (veventq->num_events == veventq->depth) {
		kfree(vevent);
		vevent = &veventq->lost_events_header;
		goto out_set_header;
	}
	vevent->data_len = data_len;
	memcpy(vevent->event_data, event_data, data_len);
	veventq->num_events++;

out_set_header:
	iommufd_vevent_handler(veventq, vevent);
	spin_unlock(&veventq->common.lock);
out_unlock_veventqs:
	up_read(&viommu->veventqs_rwsem);
	return rc;
}
EXPORT_SYMBOL_NS_GPL(iommufd_viommu_report_event, "IOMMUFD");

#ifdef CONFIG_IRQ_MSI_IOMMU
/*
 * Get a iommufd_sw_msi_map for the msi physical address requested by the irq
 * layer. The mapping to IOVA is global to the iommufd file descriptor, every
 * domain that is attached to a device using the same MSI parameters will use
 * the same IOVA.
 */
static struct iommufd_sw_msi_map *
iommufd_sw_msi_get_map(struct iommufd_ctx *ictx, phys_addr_t msi_addr,
		       phys_addr_t sw_msi_start)
{
	struct iommufd_sw_msi_map *cur;
	unsigned int max_pgoff = 0;

	lockdep_assert_held(&ictx->sw_msi_lock);

	list_for_each_entry(cur, &ictx->sw_msi_list, sw_msi_item) {
		if (cur->sw_msi_start != sw_msi_start)
			continue;
		max_pgoff = max(max_pgoff, cur->pgoff + 1);
		if (cur->msi_addr == msi_addr)
			return cur;
	}

	if (ictx->sw_msi_id >=
	    BITS_PER_BYTE * sizeof_field(struct iommufd_sw_msi_maps, bitmap))
		return ERR_PTR(-EOVERFLOW);

	cur = kzalloc_obj(*cur);
	if (!cur)
		return ERR_PTR(-ENOMEM);

	cur->sw_msi_start = sw_msi_start;
	cur->msi_addr = msi_addr;
	cur->pgoff = max_pgoff;
	cur->id = ictx->sw_msi_id++;
	list_add_tail(&cur->sw_msi_item, &ictx->sw_msi_list);
	return cur;
}

int iommufd_sw_msi_install(struct iommufd_ctx *ictx,
			   struct iommufd_hwpt_paging *hwpt_paging,
			   struct iommufd_sw_msi_map *msi_map)
{
	unsigned long iova;

	lockdep_assert_held(&ictx->sw_msi_lock);

	iova = msi_map->sw_msi_start + msi_map->pgoff * PAGE_SIZE;
	if (!test_bit(msi_map->id, hwpt_paging->present_sw_msi.bitmap)) {
		int rc;

		rc = iommu_map(hwpt_paging->common.domain, iova,
			       msi_map->msi_addr, PAGE_SIZE,
			       IOMMU_WRITE | IOMMU_READ | IOMMU_MMIO,
			       GFP_KERNEL_ACCOUNT);
		if (rc)
			return rc;
		__set_bit(msi_map->id, hwpt_paging->present_sw_msi.bitmap);
	}
	return 0;
}
EXPORT_SYMBOL_NS_GPL(iommufd_sw_msi_install, "IOMMUFD_INTERNAL");

/*
 * Called by the irq code if the platform translates the MSI address through the
 * IOMMU. msi_addr is the physical address of the MSI page. iommufd will
 * allocate a fd global iova for the physical page that is the same on all
 * domains and devices.
 */
int iommufd_sw_msi(struct iommu_domain *domain, struct msi_desc *desc,
		   phys_addr_t msi_addr)
{
	struct device *dev = msi_desc_to_dev(desc);
	struct iommufd_hwpt_paging *hwpt_paging;
	struct iommu_attach_handle *raw_handle;
	struct iommufd_attach_handle *handle;
	struct iommufd_sw_msi_map *msi_map;
	struct iommufd_ctx *ictx;
	unsigned long iova;
	int rc;

	/*
	 * It is safe to call iommu_attach_handle_get() here because the iommu
	 * core code invokes this under the group mutex which also prevents any
	 * change of the attach handle for the duration of this function.
	 */
	iommu_group_mutex_assert(dev);

	raw_handle =
		iommu_attach_handle_get(dev->iommu_group, IOMMU_NO_PASID, 0);
	if (IS_ERR(raw_handle))
		return 0;
	hwpt_paging = find_hwpt_paging(domain->iommufd_hwpt);

	handle = to_iommufd_handle(raw_handle);
	/* No IOMMU_RESV_SW_MSI means no change to the msi_msg */
	if (handle->idev->igroup->sw_msi_start == PHYS_ADDR_MAX)
		return 0;

	ictx = handle->idev->ictx;
	guard(mutex)(&ictx->sw_msi_lock);
	/*
	 * The input msi_addr is the exact byte offset of the MSI doorbell, we
	 * assume the caller has checked that it is contained with a MMIO region
	 * that is secure to map at PAGE_SIZE.
	 */
	msi_map = iommufd_sw_msi_get_map(handle->idev->ictx,
					 msi_addr & PAGE_MASK,
					 handle->idev->igroup->sw_msi_start);
	if (IS_ERR(msi_map))
		return PTR_ERR(msi_map);

	rc = iommufd_sw_msi_install(ictx, hwpt_paging, msi_map);
	if (rc)
		return rc;
	__set_bit(msi_map->id, handle->idev->igroup->required_sw_msi.bitmap);

	iova = msi_map->sw_msi_start + msi_map->pgoff * PAGE_SIZE;
	msi_desc_set_iommu_msi_iova(desc, iova, PAGE_SHIFT);
	return 0;
}
EXPORT_SYMBOL_NS_GPL(iommufd_sw_msi, "IOMMUFD");
#endif

MODULE_DESCRIPTION("iommufd code shared with builtin modules");
MODULE_IMPORT_NS("IOMMUFD_INTERNAL");
MODULE_LICENSE("GPL");