/*
 * VFIO: IOMMU DMA mapping support for Type1 IOMMU
 *
 * Copyright (C) 2012 Red Hat, Inc.  All rights reserved.
 *     Author: Alex Williamson <alex.williamson@redhat.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * Derived from original vfio:
 * Copyright 2010 Cisco Systems, Inc.  All rights reserved.
 * Author: Tom Lyon, pugs@cisco.com
 *
 * We arbitrarily define a Type1 IOMMU as one matching the below code.
 * It could be called the x86 IOMMU as it's designed for AMD-Vi & Intel
 * VT-d, but that makes it harder to re-use as theoretically anyone
 * implementing a similar IOMMU could make use of this.  We expect the
 * IOMMU to support the IOMMU API and have few to no restrictions around
 * the IOVA range that can be mapped.  The Type1 IOMMU is currently
 * optimized for relatively static mappings of a userspace process with
 * userpsace pages pinned into memory.  We also assume devices and IOMMU
 * domains are PCI based as the IOMMU API is still centered around a
 * device/bus interface rather than a group interface.
 */

#include <linux/compat.h>
#include <linux/device.h>
#include <linux/fs.h>
#include <linux/iommu.h>
#include <linux/module.h>
#include <linux/mm.h>
#include <linux/rbtree.h>
#include <linux/sched/signal.h>
#include <linux/sched/mm.h>
#include <linux/slab.h>
#include <linux/uaccess.h>
#include <linux/vfio.h>
#include <linux/workqueue.h>
#include <linux/mdev.h>
#include <linux/notifier.h>
#include <linux/dma-iommu.h>
#include <linux/irqdomain.h>

#define DRIVER_VERSION  "0.2"
#define DRIVER_AUTHOR   "Alex Williamson <alex.williamson@redhat.com>"
#define DRIVER_DESC     "Type1 IOMMU driver for VFIO"

static bool allow_unsafe_interrupts;
module_param_named(allow_unsafe_interrupts,
		   allow_unsafe_interrupts, bool, S_IRUGO | S_IWUSR);
MODULE_PARM_DESC(allow_unsafe_interrupts,
		 "Enable VFIO IOMMU support for on platforms without interrupt remapping support.");

static bool disable_hugepages;
module_param_named(disable_hugepages,
		   disable_hugepages, bool, S_IRUGO | S_IWUSR);
MODULE_PARM_DESC(disable_hugepages,
		 "Disable VFIO IOMMU support for IOMMU hugepages.");

struct vfio_iommu {
	struct list_head	domain_list;
	struct vfio_domain	*external_domain; /* domain for external user */
	struct mutex		lock;
	struct rb_root		dma_list;
	struct blocking_notifier_head notifier;
	bool			v2;
	bool			nesting;
};

struct vfio_domain {
	struct iommu_domain	*domain;
	struct list_head	next;
	struct list_head	group_list;
	int			prot;		/* IOMMU_CACHE */
	bool			fgsp;		/* Fine-grained super pages */
};

struct vfio_dma {
	struct rb_node		node;
	dma_addr_t		iova;		/* Device address */
	unsigned long		vaddr;		/* Process virtual addr */
	size_t			size;		/* Map size (bytes) */
	int			prot;		/* IOMMU_READ/WRITE */
	bool			iommu_mapped;
	struct task_struct	*task;
	struct rb_root		pfn_list;	/* Ex-user pinned pfn list */
};

struct vfio_group {
	struct iommu_group	*iommu_group;
	struct list_head	next;
};

/*
 * Guest RAM pinning working set or DMA target
 */
struct vfio_pfn {
	struct rb_node		node;
	dma_addr_t		iova;		/* Device address */
	unsigned long		pfn;		/* Host pfn */
	atomic_t		ref_count;
};

#define IS_IOMMU_CAP_DOMAIN_IN_CONTAINER(iommu)	\
					(!list_empty(&iommu->domain_list))

static int put_pfn(unsigned long pfn, int prot);

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

static struct vfio_dma *vfio_find_dma(struct vfio_iommu *iommu,
				      dma_addr_t start, size_t size)
{
	struct rb_node *node = iommu->dma_list.rb_node;

	while (node) {
		struct vfio_dma *dma = rb_entry(node, struct vfio_dma, node);

		if (start + size <= dma->iova)
			node = node->rb_left;
		else if (start >= dma->iova + dma->size)
			node = node->rb_right;
		else
			return dma;
	}

	return NULL;
}

static void vfio_link_dma(struct vfio_iommu *iommu, struct vfio_dma *new)
{
	struct rb_node **link = &iommu->dma_list.rb_node, *parent = NULL;
	struct vfio_dma *dma;

	while (*link) {
		parent = *link;
		dma = rb_entry(parent, struct vfio_dma, node);

		if (new->iova + new->size <= dma->iova)
			link = &(*link)->rb_left;
		else
			link = &(*link)->rb_right;
	}

	rb_link_node(&new->node, parent, link);
	rb_insert_color(&new->node, &iommu->dma_list);
}

static void vfio_unlink_dma(struct vfio_iommu *iommu, struct vfio_dma *old)
{
	rb_erase(&old->node, &iommu->dma_list);
}

/*
 * Helper Functions for host iova-pfn list
 */
static struct vfio_pfn *vfio_find_vpfn(struct vfio_dma *dma, dma_addr_t iova)
{
	struct vfio_pfn *vpfn;
	struct rb_node *node = dma->pfn_list.rb_node;

	while (node) {
		vpfn = rb_entry(node, struct vfio_pfn, node);

		if (iova < vpfn->iova)
			node = node->rb_left;
		else if (iova > vpfn->iova)
			node = node->rb_right;
		else
			return vpfn;
	}
	return NULL;
}

static void vfio_link_pfn(struct vfio_dma *dma,
			  struct vfio_pfn *new)
{
	struct rb_node **link, *parent = NULL;
	struct vfio_pfn *vpfn;

	link = &dma->pfn_list.rb_node;
	while (*link) {
		parent = *link;
		vpfn = rb_entry(parent, struct vfio_pfn, node);

		if (new->iova < vpfn->iova)
			link = &(*link)->rb_left;
		else
			link = &(*link)->rb_right;
	}

	rb_link_node(&new->node, parent, link);
	rb_insert_color(&new->node, &dma->pfn_list);
}

static void vfio_unlink_pfn(struct vfio_dma *dma, struct vfio_pfn *old)
{
	rb_erase(&old->node, &dma->pfn_list);
}

static int vfio_add_to_pfn_list(struct vfio_dma *dma, dma_addr_t iova,
				unsigned long pfn)
{
	struct vfio_pfn *vpfn;

	vpfn = kzalloc(sizeof(*vpfn), GFP_KERNEL);
	if (!vpfn)
		return -ENOMEM;

	vpfn->iova = iova;
	vpfn->pfn = pfn;
	atomic_set(&vpfn->ref_count, 1);
	vfio_link_pfn(dma, vpfn);
	return 0;
}

static void vfio_remove_from_pfn_list(struct vfio_dma *dma,
				      struct vfio_pfn *vpfn)
{
	vfio_unlink_pfn(dma, vpfn);
	kfree(vpfn);
}

static struct vfio_pfn *vfio_iova_get_vfio_pfn(struct vfio_dma *dma,
					       unsigned long iova)
{
	struct vfio_pfn *vpfn = vfio_find_vpfn(dma, iova);

	if (vpfn)
		atomic_inc(&vpfn->ref_count);
	return vpfn;
}

static int vfio_iova_put_vfio_pfn(struct vfio_dma *dma, struct vfio_pfn *vpfn)
{
	int ret = 0;

	if (atomic_dec_and_test(&vpfn->ref_count)) {
		ret = put_pfn(vpfn->pfn, dma->prot);
		vfio_remove_from_pfn_list(dma, vpfn);
	}
	return ret;
}

static int vfio_lock_acct(struct task_struct *task, long npage, bool *lock_cap)
{
	struct mm_struct *mm;
	bool is_current;
	int ret;

	if (!npage)
		return 0;

	is_current = (task->mm == current->mm);

	mm = is_current ? task->mm : get_task_mm(task);
	if (!mm)
		return -ESRCH; /* process exited */

	ret = down_write_killable(&mm->mmap_sem);
	if (!ret) {
		if (npage > 0) {
			if (lock_cap ? !*lock_cap :
			    !has_capability(task, CAP_IPC_LOCK)) {
				unsigned long limit;

				limit = task_rlimit(task,
						RLIMIT_MEMLOCK) >> PAGE_SHIFT;

				if (mm->locked_vm + npage > limit)
					ret = -ENOMEM;
			}
		}

		if (!ret)
			mm->locked_vm += npage;

		up_write(&mm->mmap_sem);
	}

	if (!is_current)
		mmput(mm);

	return ret;
}

/*
 * Some mappings aren't backed by a struct page, for example an mmap'd
 * MMIO range for our own or another device.  These use a different
 * pfn conversion and shouldn't be tracked as locked pages.
 */
static bool is_invalid_reserved_pfn(unsigned long pfn)
{
	if (pfn_valid(pfn)) {
		bool reserved;
		struct page *tail = pfn_to_page(pfn);
		struct page *head = compound_head(tail);
		reserved = !!(PageReserved(head));
		if (head != tail) {
			/*
			 * "head" is not a dangling pointer
			 * (compound_head takes care of that)
			 * but the hugepage may have been split
			 * from under us (and we may not hold a
			 * reference count on the head page so it can
			 * be reused before we run PageReferenced), so
			 * we've to check PageTail before returning
			 * what we just read.
			 */
			smp_rmb();
			if (PageTail(tail))
				return reserved;
		}
		return PageReserved(tail);
	}

	return true;
}

static int put_pfn(unsigned long pfn, int prot)
{
	if (!is_invalid_reserved_pfn(pfn)) {
		struct page *page = pfn_to_page(pfn);
		if (prot & IOMMU_WRITE)
			SetPageDirty(page);
		put_page(page);
		return 1;
	}
	return 0;
}

static int vaddr_get_pfn(struct mm_struct *mm, unsigned long vaddr,
			 int prot, unsigned long *pfn)
{
	struct page *page[1];
	struct vm_area_struct *vma;
	int ret;

	if (mm == current->mm) {
		ret = get_user_pages_fast(vaddr, 1, !!(prot & IOMMU_WRITE),
					  page);
	} else {
		unsigned int flags = 0;

		if (prot & IOMMU_WRITE)
			flags |= FOLL_WRITE;

		down_read(&mm->mmap_sem);
		ret = get_user_pages_remote(NULL, mm, vaddr, 1, flags, page,
					    NULL, NULL);
		up_read(&mm->mmap_sem);
	}

	if (ret == 1) {
		*pfn = page_to_pfn(page[0]);
		return 0;
	}

	down_read(&mm->mmap_sem);

	vma = find_vma_intersection(mm, vaddr, vaddr + 1);

	if (vma && vma->vm_flags & VM_PFNMAP) {
		*pfn = ((vaddr - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
		if (is_invalid_reserved_pfn(*pfn))
			ret = 0;
	}

	up_read(&mm->mmap_sem);
	return ret;
}

/*
 * Attempt to pin pages.  We really don't want to track all the pfns and
 * the iommu can only map chunks of consecutive pfns anyway, so get the
 * first page and all consecutive pages with the same locking.
 */
static long vfio_pin_pages_remote(struct vfio_dma *dma, unsigned long vaddr,
				  long npage, unsigned long *pfn_base,
				  bool lock_cap, unsigned long limit)
{
	unsigned long pfn = 0;
	long ret, pinned = 0, lock_acct = 0;
	bool rsvd;
	dma_addr_t iova = vaddr - dma->vaddr + dma->iova;

	/* This code path is only user initiated */
	if (!current->mm)
		return -ENODEV;

	ret = vaddr_get_pfn(current->mm, vaddr, dma->prot, pfn_base);
	if (ret)
		return ret;

	pinned++;
	rsvd = is_invalid_reserved_pfn(*pfn_base);

	/*
	 * Reserved pages aren't counted against the user, externally pinned
	 * pages are already counted against the user.
	 */
	if (!rsvd && !vfio_find_vpfn(dma, iova)) {
		if (!lock_cap && current->mm->locked_vm + 1 > limit) {
			put_pfn(*pfn_base, dma->prot);
			pr_warn("%s: RLIMIT_MEMLOCK (%ld) exceeded\n", __func__,
					limit << PAGE_SHIFT);
			return -ENOMEM;
		}
		lock_acct++;
	}

	if (unlikely(disable_hugepages))
		goto out;

	/* Lock all the consecutive pages from pfn_base */
	for (vaddr += PAGE_SIZE, iova += PAGE_SIZE; pinned < npage;
	     pinned++, vaddr += PAGE_SIZE, iova += PAGE_SIZE) {
		ret = vaddr_get_pfn(current->mm, vaddr, dma->prot, &pfn);
		if (ret)
			break;

		if (pfn != *pfn_base + pinned ||
		    rsvd != is_invalid_reserved_pfn(pfn)) {
			put_pfn(pfn, dma->prot);
			break;
		}

		if (!rsvd && !vfio_find_vpfn(dma, iova)) {
			if (!lock_cap &&
			    current->mm->locked_vm + lock_acct + 1 > limit) {
				put_pfn(pfn, dma->prot);
				pr_warn("%s: RLIMIT_MEMLOCK (%ld) exceeded\n",
					__func__, limit << PAGE_SHIFT);
				ret = -ENOMEM;
				goto unpin_out;
			}
			lock_acct++;
		}
	}

out:
	ret = vfio_lock_acct(current, lock_acct, &lock_cap);

unpin_out:
	if (ret) {
		if (!rsvd) {
			for (pfn = *pfn_base ; pinned ; pfn++, pinned--)
				put_pfn(pfn, dma->prot);
		}

		return ret;
	}

	return pinned;
}

static long vfio_unpin_pages_remote(struct vfio_dma *dma, dma_addr_t iova,
				    unsigned long pfn, long npage,
				    bool do_accounting)
{
	long unlocked = 0, locked = 0;
	long i;

	for (i = 0; i < npage; i++, iova += PAGE_SIZE) {
		if (put_pfn(pfn++, dma->prot)) {
			unlocked++;
			if (vfio_find_vpfn(dma, iova))
				locked++;
		}
	}

	if (do_accounting)
		vfio_lock_acct(dma->task, locked - unlocked, NULL);

	return unlocked;
}

static int vfio_pin_page_external(struct vfio_dma *dma, unsigned long vaddr,
				  unsigned long *pfn_base, bool do_accounting)
{
	struct mm_struct *mm;
	int ret;

	mm = get_task_mm(dma->task);
	if (!mm)
		return -ENODEV;

	ret = vaddr_get_pfn(mm, vaddr, dma->prot, pfn_base);
	if (!ret && do_accounting && !is_invalid_reserved_pfn(*pfn_base)) {
		ret = vfio_lock_acct(dma->task, 1, NULL);
		if (ret) {
			put_pfn(*pfn_base, dma->prot);
			if (ret == -ENOMEM)
				pr_warn("%s: Task %s (%d) RLIMIT_MEMLOCK "
					"(%ld) exceeded\n", __func__,
					dma->task->comm, task_pid_nr(dma->task),
					task_rlimit(dma->task, RLIMIT_MEMLOCK));
		}
	}

	mmput(mm);
	return ret;
}

static int vfio_unpin_page_external(struct vfio_dma *dma, dma_addr_t iova,
				    bool do_accounting)
{
	int unlocked;
	struct vfio_pfn *vpfn = vfio_find_vpfn(dma, iova);

	if (!vpfn)
		return 0;

	unlocked = vfio_iova_put_vfio_pfn(dma, vpfn);

	if (do_accounting)
		vfio_lock_acct(dma->task, -unlocked, NULL);

	return unlocked;
}

static int vfio_iommu_type1_pin_pages(void *iommu_data,
				      unsigned long *user_pfn,
				      int npage, int prot,
				      unsigned long *phys_pfn)
{
	struct vfio_iommu *iommu = iommu_data;
	int i, j, ret;
	unsigned long remote_vaddr;
	struct vfio_dma *dma;
	bool do_accounting;

	if (!iommu || !user_pfn || !phys_pfn)
		return -EINVAL;

	/* Supported for v2 version only */
	if (!iommu->v2)
		return -EACCES;

	mutex_lock(&iommu->lock);

	/* Fail if notifier list is empty */
	if ((!iommu->external_domain) || (!iommu->notifier.head)) {
		ret = -EINVAL;
		goto pin_done;
	}

	/*
	 * If iommu capable domain exist in the container then all pages are
	 * already pinned and accounted. Accouting should be done if there is no
	 * iommu capable domain in the container.
	 */
	do_accounting = !IS_IOMMU_CAP_DOMAIN_IN_CONTAINER(iommu);

	for (i = 0; i < npage; i++) {
		dma_addr_t iova;
		struct vfio_pfn *vpfn;

		iova = user_pfn[i] << PAGE_SHIFT;
		dma = vfio_find_dma(iommu, iova, PAGE_SIZE);
		if (!dma) {
			ret = -EINVAL;
			goto pin_unwind;
		}

		if ((dma->prot & prot) != prot) {
			ret = -EPERM;
			goto pin_unwind;
		}

		vpfn = vfio_iova_get_vfio_pfn(dma, iova);
		if (vpfn) {
			phys_pfn[i] = vpfn->pfn;
			continue;
		}

		remote_vaddr = dma->vaddr + iova - dma->iova;
		ret = vfio_pin_page_external(dma, remote_vaddr, &phys_pfn[i],
					     do_accounting);
		if (ret)
			goto pin_unwind;

		ret = vfio_add_to_pfn_list(dma, iova, phys_pfn[i]);
		if (ret) {
			vfio_unpin_page_external(dma, iova, do_accounting);
			goto pin_unwind;
		}
	}

	ret = i;
	goto pin_done;

pin_unwind:
	phys_pfn[i] = 0;
	for (j = 0; j < i; j++) {
		dma_addr_t iova;

		iova = user_pfn[j] << PAGE_SHIFT;
		dma = vfio_find_dma(iommu, iova, PAGE_SIZE);
		vfio_unpin_page_external(dma, iova, do_accounting);
		phys_pfn[j] = 0;
	}
pin_done:
	mutex_unlock(&iommu->lock);
	return ret;
}

static int vfio_iommu_type1_unpin_pages(void *iommu_data,
					unsigned long *user_pfn,
					int npage)
{
	struct vfio_iommu *iommu = iommu_data;
	bool do_accounting;
	int i;

	if (!iommu || !user_pfn)
		return -EINVAL;

	/* Supported for v2 version only */
	if (!iommu->v2)
		return -EACCES;

	mutex_lock(&iommu->lock);

	if (!iommu->external_domain) {
		mutex_unlock(&iommu->lock);
		return -EINVAL;
	}

	do_accounting = !IS_IOMMU_CAP_DOMAIN_IN_CONTAINER(iommu);
	for (i = 0; i < npage; i++) {
		struct vfio_dma *dma;
		dma_addr_t iova;

		iova = user_pfn[i] << PAGE_SHIFT;
		dma = vfio_find_dma(iommu, iova, PAGE_SIZE);
		if (!dma)
			goto unpin_exit;
		vfio_unpin_page_external(dma, iova, do_accounting);
	}

unpin_exit:
	mutex_unlock(&iommu->lock);
	return i > npage ? npage : (i > 0 ? i : -EINVAL);
}

static long vfio_unmap_unpin(struct vfio_iommu *iommu, struct vfio_dma *dma,
			     bool do_accounting)
{
	dma_addr_t iova = dma->iova, end = dma->iova + dma->size;
	struct vfio_domain *domain, *d;
	long unlocked = 0;

	if (!dma->size)
		return 0;

	if (!IS_IOMMU_CAP_DOMAIN_IN_CONTAINER(iommu))
		return 0;

	/*
	 * We use the IOMMU to track the physical addresses, otherwise we'd
	 * need a much more complicated tracking system.  Unfortunately that
	 * means we need to use one of the iommu domains to figure out the
	 * pfns to unpin.  The rest need to be unmapped in advance so we have
	 * no iommu translations remaining when the pages are unpinned.
	 */
	domain = d = list_first_entry(&iommu->domain_list,
				      struct vfio_domain, next);

	list_for_each_entry_continue(d, &iommu->domain_list, next) {
		iommu_unmap(d->domain, dma->iova, dma->size);
		cond_resched();
	}

	while (iova < end) {
		size_t unmapped, len;
		phys_addr_t phys, next;

		phys = iommu_iova_to_phys(domain->domain, iova);
		if (WARN_ON(!phys)) {
			iova += PAGE_SIZE;
			continue;
		}

		/*
		 * To optimize for fewer iommu_unmap() calls, each of which
		 * may require hardware cache flushing, try to find the
		 * largest contiguous physical memory chunk to unmap.
		 */
		for (len = PAGE_SIZE;
		     !domain->fgsp && iova + len < end; len += PAGE_SIZE) {
			next = iommu_iova_to_phys(domain->domain, iova + len);
			if (next != phys + len)
				break;
		}

		unmapped = iommu_unmap(domain->domain, iova, len);
		if (WARN_ON(!unmapped))
			break;

		unlocked += vfio_unpin_pages_remote(dma, iova,
						    phys >> PAGE_SHIFT,
						    unmapped >> PAGE_SHIFT,
						    false);
		iova += unmapped;

		cond_resched();
	}

	dma->iommu_mapped = false;
	if (do_accounting) {
		vfio_lock_acct(dma->task, -unlocked, NULL);
		return 0;
	}
	return unlocked;
}

static void vfio_remove_dma(struct vfio_iommu *iommu, struct vfio_dma *dma)
{
	vfio_unmap_unpin(iommu, dma, true);
	vfio_unlink_dma(iommu, dma);
	put_task_struct(dma->task);
	kfree(dma);
}

static unsigned long vfio_pgsize_bitmap(struct vfio_iommu *iommu)
{
	struct vfio_domain *domain;
	unsigned long bitmap = ULONG_MAX;

	mutex_lock(&iommu->lock);
	list_for_each_entry(domain, &iommu->domain_list, next)
		bitmap &= domain->domain->pgsize_bitmap;
	mutex_unlock(&iommu->lock);

	/*
	 * In case the IOMMU supports page sizes smaller than PAGE_SIZE
	 * we pretend PAGE_SIZE is supported and hide sub-PAGE_SIZE sizes.
	 * That way the user will be able to map/unmap buffers whose size/
	 * start address is aligned with PAGE_SIZE. Pinning code uses that
	 * granularity while iommu driver can use the sub-PAGE_SIZE size
	 * to map the buffer.
	 */
	if (bitmap & ~PAGE_MASK) {
		bitmap &= PAGE_MASK;
		bitmap |= PAGE_SIZE;
	}

	return bitmap;
}

static int vfio_dma_do_unmap(struct vfio_iommu *iommu,
			     struct vfio_iommu_type1_dma_unmap *unmap)
{
	uint64_t mask;
	struct vfio_dma *dma, *dma_last = NULL;
	size_t unmapped = 0;
	int ret = 0, retries = 0;

	mask = ((uint64_t)1 << __ffs(vfio_pgsize_bitmap(iommu))) - 1;

	if (unmap->iova & mask)
		return -EINVAL;
	if (!unmap->size || unmap->size & mask)
		return -EINVAL;
	if (unmap->iova + unmap->size < unmap->iova ||
	    unmap->size > SIZE_MAX)
		return -EINVAL;

	WARN_ON(mask & PAGE_MASK);
again:
	mutex_lock(&iommu->lock);

	/*
	 * vfio-iommu-type1 (v1) - User mappings were coalesced together to
	 * avoid tracking individual mappings.  This means that the granularity
	 * of the original mapping was lost and the user was allowed to attempt
	 * to unmap any range.  Depending on the contiguousness of physical
	 * memory and page sizes supported by the IOMMU, arbitrary unmaps may
	 * or may not have worked.  We only guaranteed unmap granularity
	 * matching the original mapping; even though it was untracked here,
	 * the original mappings are reflected in IOMMU mappings.  This
	 * resulted in a couple unusual behaviors.  First, if a range is not
	 * able to be unmapped, ex. a set of 4k pages that was mapped as a
	 * 2M hugepage into the IOMMU, the unmap ioctl returns success but with
	 * a zero sized unmap.  Also, if an unmap request overlaps the first
	 * address of a hugepage, the IOMMU will unmap the entire hugepage.
	 * This also returns success and the returned unmap size reflects the
	 * actual size unmapped.
	 *
	 * We attempt to maintain compatibility with this "v1" interface, but
	 * we take control out of the hands of the IOMMU.  Therefore, an unmap
	 * request offset from the beginning of the original mapping will
	 * return success with zero sized unmap.  And an unmap request covering
	 * the first iova of mapping will unmap the entire range.
	 *
	 * The v2 version of this interface intends to be more deterministic.
	 * Unmap requests must fully cover previous mappings.  Multiple
	 * mappings may still be unmaped by specifying large ranges, but there
	 * must not be any previous mappings bisected by the range.  An error
	 * will be returned if these conditions are not met.  The v2 interface
	 * will only return success and a size of zero if there were no
	 * mappings within the range.
	 */
	if (iommu->v2) {
		dma = vfio_find_dma(iommu, unmap->iova, 1);
		if (dma && dma->iova != unmap->iova) {
			ret = -EINVAL;
			goto unlock;
		}
		dma = vfio_find_dma(iommu, unmap->iova + unmap->size - 1, 0);
		if (dma && dma->iova + dma->size != unmap->iova + unmap->size) {
			ret = -EINVAL;
			goto unlock;
		}
	}

	while ((dma = vfio_find_dma(iommu, unmap->iova, unmap->size))) {
		if (!iommu->v2 && unmap->iova > dma->iova)
			break;
		/*
		 * Task with same address space who mapped this iova range is
		 * allowed to unmap the iova range.
		 */
		if (dma->task->mm != current->mm)
			break;

		if (!RB_EMPTY_ROOT(&dma->pfn_list)) {
			struct vfio_iommu_type1_dma_unmap nb_unmap;

			if (dma_last == dma) {
				BUG_ON(++retries > 10);
			} else {
				dma_last = dma;
				retries = 0;
			}

			nb_unmap.iova = dma->iova;
			nb_unmap.size = dma->size;

			/*
			 * Notify anyone (mdev vendor drivers) to invalidate and
			 * unmap iovas within the range we're about to unmap.
			 * Vendor drivers MUST unpin pages in response to an
			 * invalidation.
			 */
			mutex_unlock(&iommu->lock);
			blocking_notifier_call_chain(&iommu->notifier,
						    VFIO_IOMMU_NOTIFY_DMA_UNMAP,
						    &nb_unmap);
			goto again;
		}
		unmapped += dma->size;
		vfio_remove_dma(iommu, dma);
	}

unlock:
	mutex_unlock(&iommu->lock);

	/* Report how much was unmapped */
	unmap->size = unmapped;

	return ret;
}

/*
 * Turns out AMD IOMMU has a page table bug where it won't map large pages
 * to a region that previously mapped smaller pages.  This should be fixed
 * soon, so this is just a temporary workaround to break mappings down into
 * PAGE_SIZE.  Better to map smaller pages than nothing.
 */
static int map_try_harder(struct vfio_domain *domain, dma_addr_t iova,
			  unsigned long pfn, long npage, int prot)
{
	long i;
	int ret = 0;

	for (i = 0; i < npage; i++, pfn++, iova += PAGE_SIZE) {
		ret = iommu_map(domain->domain, iova,
				(phys_addr_t)pfn << PAGE_SHIFT,
				PAGE_SIZE, prot | domain->prot);
		if (ret)
			break;
	}

	for (; i < npage && i > 0; i--, iova -= PAGE_SIZE)
		iommu_unmap(domain->domain, iova, PAGE_SIZE);

	return ret;
}

static int vfio_iommu_map(struct vfio_iommu *iommu, dma_addr_t iova,
			  unsigned long pfn, long npage, int prot)
{
	struct vfio_domain *d;
	int ret;

	list_for_each_entry(d, &iommu->domain_list, next) {
		ret = iommu_map(d->domain, iova, (phys_addr_t)pfn << PAGE_SHIFT,
				npage << PAGE_SHIFT, prot | d->prot);
		if (ret) {
			if (ret != -EBUSY ||
			    map_try_harder(d, iova, pfn, npage, prot))
				goto unwind;
		}

		cond_resched();
	}

	return 0;

unwind:
	list_for_each_entry_continue_reverse(d, &iommu->domain_list, next)
		iommu_unmap(d->domain, iova, npage << PAGE_SHIFT);

	return ret;
}

static int vfio_pin_map_dma(struct vfio_iommu *iommu, struct vfio_dma *dma,
			    size_t map_size)
{
	dma_addr_t iova = dma->iova;
	unsigned long vaddr = dma->vaddr;
	size_t size = map_size;
	long npage;
	unsigned long pfn, limit = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT;
	bool lock_cap = capable(CAP_IPC_LOCK);
	int ret = 0;

	while (size) {
		/* Pin a contiguous chunk of memory */
		npage = vfio_pin_pages_remote(dma, vaddr + dma->size,
					      size >> PAGE_SHIFT, &pfn,
					      lock_cap, limit);
		if (npage <= 0) {
			WARN_ON(!npage);
			ret = (int)npage;
			break;
		}

		/* Map it! */
		ret = vfio_iommu_map(iommu, iova + dma->size, pfn, npage,
				     dma->prot);
		if (ret) {
			vfio_unpin_pages_remote(dma, iova + dma->size, pfn,
						npage, true);
			break;
		}

		size -= npage << PAGE_SHIFT;
		dma->size += npage << PAGE_SHIFT;
	}

	dma->iommu_mapped = true;

	if (ret)
		vfio_remove_dma(iommu, dma);

	return ret;
}

static int vfio_dma_do_map(struct vfio_iommu *iommu,
			   struct vfio_iommu_type1_dma_map *map)
{
	dma_addr_t iova = map->iova;
	unsigned long vaddr = map->vaddr;
	size_t size = map->size;
	int ret = 0, prot = 0;
	uint64_t mask;
	struct vfio_dma *dma;

	/* Verify that none of our __u64 fields overflow */
	if (map->size != size || map->vaddr != vaddr || map->iova != iova)
		return -EINVAL;

	mask = ((uint64_t)1 << __ffs(vfio_pgsize_bitmap(iommu))) - 1;

	WARN_ON(mask & PAGE_MASK);

	/* READ/WRITE from device perspective */
	if (map->flags & VFIO_DMA_MAP_FLAG_WRITE)
		prot |= IOMMU_WRITE;
	if (map->flags & VFIO_DMA_MAP_FLAG_READ)
		prot |= IOMMU_READ;

	if (!prot || !size || (size | iova | vaddr) & mask)
		return -EINVAL;

	/* Don't allow IOVA or virtual address wrap */
	if (iova + size - 1 < iova || vaddr + size - 1 < vaddr)
		return -EINVAL;

	mutex_lock(&iommu->lock);

	if (vfio_find_dma(iommu, iova, size)) {
		ret = -EEXIST;
		goto out_unlock;
	}

	dma = kzalloc(sizeof(*dma), GFP_KERNEL);
	if (!dma) {
		ret = -ENOMEM;
		goto out_unlock;
	}

	dma->iova = iova;
	dma->vaddr = vaddr;
	dma->prot = prot;
	get_task_struct(current);
	dma->task = current;
	dma->pfn_list = RB_ROOT;

	/* Insert zero-sized and grow as we map chunks of it */
	vfio_link_dma(iommu, dma);

	/* Don't pin and map if container doesn't contain IOMMU capable domain*/
	if (!IS_IOMMU_CAP_DOMAIN_IN_CONTAINER(iommu))
		dma->size = size;
	else
		ret = vfio_pin_map_dma(iommu, dma, size);

out_unlock:
	mutex_unlock(&iommu->lock);
	return ret;
}

static int vfio_bus_type(struct device *dev, void *data)
{
	struct bus_type **bus = data;

	if (*bus && *bus != dev->bus)
		return -EINVAL;

	*bus = dev->bus;

	return 0;
}

static int vfio_iommu_replay(struct vfio_iommu *iommu,
			     struct vfio_domain *domain)
{
	struct vfio_domain *d;
	struct rb_node *n;
	unsigned long limit = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT;
	bool lock_cap = capable(CAP_IPC_LOCK);
	int ret;

	/* Arbitrarily pick the first domain in the list for lookups */
	d = list_first_entry(&iommu->domain_list, struct vfio_domain, next);
	n = rb_first(&iommu->dma_list);

	for (; n; n = rb_next(n)) {
		struct vfio_dma *dma;
		dma_addr_t iova;

		dma = rb_entry(n, struct vfio_dma, node);
		iova = dma->iova;

		while (iova < dma->iova + dma->size) {
			phys_addr_t phys;
			size_t size;

			if (dma->iommu_mapped) {
				phys_addr_t p;
				dma_addr_t i;

				phys = iommu_iova_to_phys(d->domain, iova);

				if (WARN_ON(!phys)) {
					iova += PAGE_SIZE;
					continue;
				}

				size = PAGE_SIZE;
				p = phys + size;
				i = iova + size;
				while (i < dma->iova + dma->size &&
				       p == iommu_iova_to_phys(d->domain, i)) {
					size += PAGE_SIZE;
					p += PAGE_SIZE;
					i += PAGE_SIZE;
				}
			} else {
				unsigned long pfn;
				unsigned long vaddr = dma->vaddr +
						     (iova - dma->iova);
				size_t n = dma->iova + dma->size - iova;
				long npage;

				npage = vfio_pin_pages_remote(dma, vaddr,
							      n >> PAGE_SHIFT,
							      &pfn, lock_cap,
							      limit);
				if (npage <= 0) {
					WARN_ON(!npage);
					ret = (int)npage;
					return ret;
				}

				phys = pfn << PAGE_SHIFT;
				size = npage << PAGE_SHIFT;
			}

			ret = iommu_map(domain->domain, iova, phys,
					size, dma->prot | domain->prot);
			if (ret)
				return ret;

			iova += size;
		}
		dma->iommu_mapped = true;
	}
	return 0;
}

/*
 * We change our unmap behavior slightly depending on whether the IOMMU
 * supports fine-grained superpages.  IOMMUs like AMD-Vi will use a superpage
 * for practically any contiguous power-of-two mapping we give it.  This means
 * we don't need to look for contiguous chunks ourselves to make unmapping
 * more efficient.  On IOMMUs with coarse-grained super pages, like Intel VT-d
 * with discrete 2M/1G/512G/1T superpages, identifying contiguous chunks
 * significantly boosts non-hugetlbfs mappings and doesn't seem to hurt when
 * hugetlbfs is in use.
 */
static void vfio_test_domain_fgsp(struct vfio_domain *domain)
{
	struct page *pages;
	int ret, order = get_order(PAGE_SIZE * 2);

	pages = alloc_pages(GFP_KERNEL | __GFP_ZERO, order);
	if (!pages)
		return;

	ret = iommu_map(domain->domain, 0, page_to_phys(pages), PAGE_SIZE * 2,
			IOMMU_READ | IOMMU_WRITE | domain->prot);
	if (!ret) {
		size_t unmapped = iommu_unmap(domain->domain, 0, PAGE_SIZE);

		if (unmapped == PAGE_SIZE)
			iommu_unmap(domain->domain, PAGE_SIZE, PAGE_SIZE);
		else
			domain->fgsp = true;
	}

	__free_pages(pages, order);
}

static struct vfio_group *find_iommu_group(struct vfio_domain *domain,
					   struct iommu_group *iommu_group)
{
	struct vfio_group *g;

	list_for_each_entry(g, &domain->group_list, next) {
		if (g->iommu_group == iommu_group)
			return g;
	}

	return NULL;
}

static bool vfio_iommu_has_sw_msi(struct iommu_group *group, phys_addr_t *base)
{
	struct list_head group_resv_regions;
	struct iommu_resv_region *region, *next;
	bool ret = false;

	INIT_LIST_HEAD(&group_resv_regions);
	iommu_get_group_resv_regions(group, &group_resv_regions);
	list_for_each_entry(region, &group_resv_regions, list) {
		/*
		 * The presence of any 'real' MSI regions should take
		 * precedence over the software-managed one if the
		 * IOMMU driver happens to advertise both types.
		 */
		if (region->type == IOMMU_RESV_MSI) {
			ret = false;
			break;
		}

		if (region->type == IOMMU_RESV_SW_MSI) {
			*base = region->start;
			ret = true;
		}
	}
	list_for_each_entry_safe(region, next, &group_resv_regions, list)
		kfree(region);
	return ret;
}

static int vfio_iommu_type1_attach_group(void *iommu_data,
					 struct iommu_group *iommu_group)
{
	struct vfio_iommu *iommu = iommu_data;
	struct vfio_group *group;
	struct vfio_domain *domain, *d;
	struct bus_type *bus = NULL, *mdev_bus;
	int ret;
	bool resv_msi, msi_remap;
	phys_addr_t resv_msi_base;

	mutex_lock(&iommu->lock);

	list_for_each_entry(d, &iommu->domain_list, next) {
		if (find_iommu_group(d, iommu_group)) {
			mutex_unlock(&iommu->lock);
			return -EINVAL;
		}
	}

	if (iommu->external_domain) {
		if (find_iommu_group(iommu->external_domain, iommu_group)) {
			mutex_unlock(&iommu->lock);
			return -EINVAL;
		}
	}

	group = kzalloc(sizeof(*group), GFP_KERNEL);
	domain = kzalloc(sizeof(*domain), GFP_KERNEL);
	if (!group || !domain) {
		ret = -ENOMEM;
		goto out_free;
	}

	group->iommu_group = iommu_group;

	/* Determine bus_type in order to allocate a domain */
	ret = iommu_group_for_each_dev(iommu_group, &bus, vfio_bus_type);
	if (ret)
		goto out_free;

	mdev_bus = symbol_get(mdev_bus_type);

	if (mdev_bus) {
		if ((bus == mdev_bus) && !iommu_present(bus)) {
			symbol_put(mdev_bus_type);
			if (!iommu->external_domain) {
				INIT_LIST_HEAD(&domain->group_list);
				iommu->external_domain = domain;
			} else
				kfree(domain);

			list_add(&group->next,
				 &iommu->external_domain->group_list);
			mutex_unlock(&iommu->lock);
			return 0;
		}
		symbol_put(mdev_bus_type);
	}

	domain->domain = iommu_domain_alloc(bus);
	if (!domain->domain) {
		ret = -EIO;
		goto out_free;
	}

	if (iommu->nesting) {
		int attr = 1;

		ret = iommu_domain_set_attr(domain->domain, DOMAIN_ATTR_NESTING,
					    &attr);
		if (ret)
			goto out_domain;
	}

	ret = iommu_attach_group(domain->domain, iommu_group);
	if (ret)
		goto out_domain;

	resv_msi = vfio_iommu_has_sw_msi(iommu_group, &resv_msi_base);

	INIT_LIST_HEAD(&domain->group_list);
	list_add(&group->next, &domain->group_list);

	msi_remap = irq_domain_check_msi_remap() ||
		    iommu_capable(bus, IOMMU_CAP_INTR_REMAP);

	if (!allow_unsafe_interrupts && !msi_remap) {
		pr_warn("%s: No interrupt remapping support.  Use the module param \"allow_unsafe_interrupts\" to enable VFIO IOMMU support on this platform\n",
		       __func__);
		ret = -EPERM;
		goto out_detach;
	}

	if (iommu_capable(bus, IOMMU_CAP_CACHE_COHERENCY))
		domain->prot |= IOMMU_CACHE;

	/*
	 * Try to match an existing compatible domain.  We don't want to
	 * preclude an IOMMU driver supporting multiple bus_types and being
	 * able to include different bus_types in the same IOMMU domain, so
	 * we test whether the domains use the same iommu_ops rather than
	 * testing if they're on the same bus_type.
	 */
	list_for_each_entry(d, &iommu->domain_list, next) {
		if (d->domain->ops == domain->domain->ops &&
		    d->prot == domain->prot) {
			iommu_detach_group(domain->domain, iommu_group);
			if (!iommu_attach_group(d->domain, iommu_group)) {
				list_add(&group->next, &d->group_list);
				iommu_domain_free(domain->domain);
				kfree(domain);
				mutex_unlock(&iommu->lock);
				return 0;
			}

			ret = iommu_attach_group(domain->domain, iommu_group);
			if (ret)
				goto out_domain;
		}
	}

	vfio_test_domain_fgsp(domain);

	/* replay mappings on new domains */
	ret = vfio_iommu_replay(iommu, domain);
	if (ret)
		goto out_detach;

	if (resv_msi) {
		ret = iommu_get_msi_cookie(domain->domain, resv_msi_base);
		if (ret)
			goto out_detach;
	}

	list_add(&domain->next, &iommu->domain_list);

	mutex_unlock(&iommu->lock);

	return 0;

out_detach:
	iommu_detach_group(domain->domain, iommu_group);
out_domain:
	iommu_domain_free(domain->domain);
out_free:
	kfree(domain);
	kfree(group);
	mutex_unlock(&iommu->lock);
	return ret;
}

static void vfio_iommu_unmap_unpin_all(struct vfio_iommu *iommu)
{
	struct rb_node *node;

	while ((node = rb_first(&iommu->dma_list)))
		vfio_remove_dma(iommu, rb_entry(node, struct vfio_dma, node));
}

static void vfio_iommu_unmap_unpin_reaccount(struct vfio_iommu *iommu)
{
	struct rb_node *n, *p;

	n = rb_first(&iommu->dma_list);
	for (; n; n = rb_next(n)) {
		struct vfio_dma *dma;
		long locked = 0, unlocked = 0;

		dma = rb_entry(n, struct vfio_dma, node);
		unlocked += vfio_unmap_unpin(iommu, dma, false);
		p = rb_first(&dma->pfn_list);
		for (; p; p = rb_next(p)) {
			struct vfio_pfn *vpfn = rb_entry(p, struct vfio_pfn,
							 node);

			if (!is_invalid_reserved_pfn(vpfn->pfn))
				locked++;
		}
		vfio_lock_acct(dma->task, locked - unlocked, NULL);
	}
}

static void vfio_sanity_check_pfn_list(struct vfio_iommu *iommu)
{
	struct rb_node *n;

	n = rb_first(&iommu->dma_list);
	for (; n; n = rb_next(n)) {
		struct vfio_dma *dma;

		dma = rb_entry(n, struct vfio_dma, node);

		if (WARN_ON(!RB_EMPTY_ROOT(&dma->pfn_list)))
			break;
	}
	/* mdev vendor driver must unregister notifier */
	WARN_ON(iommu->notifier.head);
}

static void vfio_iommu_type1_detach_group(void *iommu_data,
					  struct iommu_group *iommu_group)
{
	struct vfio_iommu *iommu = iommu_data;
	struct vfio_domain *domain;
	struct vfio_group *group;

	mutex_lock(&iommu->lock);

	if (iommu->external_domain) {
		group = find_iommu_group(iommu->external_domain, iommu_group);
		if (group) {
			list_del(&group->next);
			kfree(group);

			if (list_empty(&iommu->external_domain->group_list)) {
				vfio_sanity_check_pfn_list(iommu);

				if (!IS_IOMMU_CAP_DOMAIN_IN_CONTAINER(iommu))
					vfio_iommu_unmap_unpin_all(iommu);

				kfree(iommu->external_domain);
				iommu->external_domain = NULL;
			}
			goto detach_group_done;
		}
	}

	list_for_each_entry(domain, &iommu->domain_list, next) {
		group = find_iommu_group(domain, iommu_group);
		if (!group)
			continue;

		iommu_detach_group(domain->domain, iommu_group);
		list_del(&group->next);
		kfree(group);
		/*
		 * Group ownership provides privilege, if the group list is
		 * empty, the domain goes away. If it's the last domain with
		 * iommu and external domain doesn't exist, then all the
		 * mappings go away too. If it's the last domain with iommu and
		 * external domain exist, update accounting
		 */
		if (list_empty(&domain->group_list)) {
			if (list_is_singular(&iommu->domain_list)) {
				if (!iommu->external_domain)
					vfio_iommu_unmap_unpin_all(iommu);
				else
					vfio_iommu_unmap_unpin_reaccount(iommu);
			}
			iommu_domain_free(domain->domain);
			list_del(&domain->next);
			kfree(domain);
		}
		break;
	}

detach_group_done:
	mutex_unlock(&iommu->lock);
}

static void *vfio_iommu_type1_open(unsigned long arg)
{
	struct vfio_iommu *iommu;

	iommu = kzalloc(sizeof(*iommu), GFP_KERNEL);
	if (!iommu)
		return ERR_PTR(-ENOMEM);

	switch (arg) {
	case VFIO_TYPE1_IOMMU:
		break;
	case VFIO_TYPE1_NESTING_IOMMU:
		iommu->nesting = true;
	case VFIO_TYPE1v2_IOMMU:
		iommu->v2 = true;
		break;
	default:
		kfree(iommu);
		return ERR_PTR(-EINVAL);
	}

	INIT_LIST_HEAD(&iommu->domain_list);
	iommu->dma_list = RB_ROOT;
	mutex_init(&iommu->lock);
	BLOCKING_INIT_NOTIFIER_HEAD(&iommu->notifier);

	return iommu;
}

static void vfio_release_domain(struct vfio_domain *domain, bool external)
{
	struct vfio_group *group, *group_tmp;

	list_for_each_entry_safe(group, group_tmp,
				 &domain->group_list, next) {
		if (!external)
			iommu_detach_group(domain->domain, group->iommu_group);
		list_del(&group->next);
		kfree(group);
	}

	if (!external)
		iommu_domain_free(domain->domain);
}

static void vfio_iommu_type1_release(void *iommu_data)
{
	struct vfio_iommu *iommu = iommu_data;
	struct vfio_domain *domain, *domain_tmp;

	if (iommu->external_domain) {
		vfio_release_domain(iommu->external_domain, true);
		vfio_sanity_check_pfn_list(iommu);
		kfree(iommu->external_domain);
	}

	vfio_iommu_unmap_unpin_all(iommu);

	list_for_each_entry_safe(domain, domain_tmp,
				 &iommu->domain_list, next) {
		vfio_release_domain(domain, false);
		list_del(&domain->next);
		kfree(domain);
	}
	kfree(iommu);
}

static int vfio_domains_have_iommu_cache(struct vfio_iommu *iommu)
{
	struct vfio_domain *domain;
	int ret = 1;

	mutex_lock(&iommu->lock);
	list_for_each_entry(domain, &iommu->domain_list, next) {
		if (!(domain->prot & IOMMU_CACHE)) {
			ret = 0;
			break;
		}
	}
	mutex_unlock(&iommu->lock);

	return ret;
}

static long vfio_iommu_type1_ioctl(void *iommu_data,
				   unsigned int cmd, unsigned long arg)
{
	struct vfio_iommu *iommu = iommu_data;
	unsigned long minsz;

	if (cmd == VFIO_CHECK_EXTENSION) {
		switch (arg) {
		case VFIO_TYPE1_IOMMU:
		case VFIO_TYPE1v2_IOMMU:
		case VFIO_TYPE1_NESTING_IOMMU:
			return 1;
		case VFIO_DMA_CC_IOMMU:
			if (!iommu)
				return 0;
			return vfio_domains_have_iommu_cache(iommu);
		default:
			return 0;
		}
	} else if (cmd == VFIO_IOMMU_GET_INFO) {
		struct vfio_iommu_type1_info info;

		minsz = offsetofend(struct vfio_iommu_type1_info, iova_pgsizes);

		if (copy_from_user(&info, (void __user *)arg, minsz))
			return -EFAULT;

		if (info.argsz < minsz)
			return -EINVAL;

		info.flags = VFIO_IOMMU_INFO_PGSIZES;

		info.iova_pgsizes = vfio_pgsize_bitmap(iommu);

		return copy_to_user((void __user *)arg, &info, minsz) ?
			-EFAULT : 0;

	} else if (cmd == VFIO_IOMMU_MAP_DMA) {
		struct vfio_iommu_type1_dma_map map;
		uint32_t mask = VFIO_DMA_MAP_FLAG_READ |
				VFIO_DMA_MAP_FLAG_WRITE;

		minsz = offsetofend(struct vfio_iommu_type1_dma_map, size);

		if (copy_from_user(&map, (void __user *)arg, minsz))
			return -EFAULT;

		if (map.argsz < minsz || map.flags & ~mask)
			return -EINVAL;

		return vfio_dma_do_map(iommu, &map);

	} else if (cmd == VFIO_IOMMU_UNMAP_DMA) {
		struct vfio_iommu_type1_dma_unmap unmap;
		long ret;

		minsz = offsetofend(struct vfio_iommu_type1_dma_unmap, size);

		if (copy_from_user(&unmap, (void __user *)arg, minsz))
			return -EFAULT;

		if (unmap.argsz < minsz || unmap.flags)
			return -EINVAL;

		ret = vfio_dma_do_unmap(iommu, &unmap);
		if (ret)
			return ret;

		return copy_to_user((void __user *)arg, &unmap, minsz) ?
			-EFAULT : 0;
	}

	return -ENOTTY;
}

static int vfio_iommu_type1_register_notifier(void *iommu_data,
					      unsigned long *events,
					      struct notifier_block *nb)
{
	struct vfio_iommu *iommu = iommu_data;

	/* clear known events */
	*events &= ~VFIO_IOMMU_NOTIFY_DMA_UNMAP;

	/* refuse to register if still events remaining */
	if (*events)
		return -EINVAL;

	return blocking_notifier_chain_register(&iommu->notifier, nb);
}

static int vfio_iommu_type1_unregister_notifier(void *iommu_data,
						struct notifier_block *nb)
{
	struct vfio_iommu *iommu = iommu_data;

	return blocking_notifier_chain_unregister(&iommu->notifier, nb);
}

static const struct vfio_iommu_driver_ops vfio_iommu_driver_ops_type1 = {
	.name			= "vfio-iommu-type1",
	.owner			= THIS_MODULE,
	.open			= vfio_iommu_type1_open,
	.release		= vfio_iommu_type1_release,
	.ioctl			= vfio_iommu_type1_ioctl,
	.attach_group		= vfio_iommu_type1_attach_group,
	.detach_group		= vfio_iommu_type1_detach_group,
	.pin_pages		= vfio_iommu_type1_pin_pages,
	.unpin_pages		= vfio_iommu_type1_unpin_pages,
	.register_notifier	= vfio_iommu_type1_register_notifier,
	.unregister_notifier	= vfio_iommu_type1_unregister_notifier,
};

static int __init vfio_iommu_type1_init(void)
{
	return vfio_register_iommu_driver(&vfio_iommu_driver_ops_type1);
}

static void __exit vfio_iommu_type1_cleanup(void)
{
	vfio_unregister_iommu_driver(&vfio_iommu_driver_ops_type1);
}

module_init(vfio_iommu_type1_init);
module_exit(vfio_iommu_type1_cleanup);

MODULE_VERSION(DRIVER_VERSION);
MODULE_LICENSE("GPL v2");
MODULE_AUTHOR(DRIVER_AUTHOR);
MODULE_DESCRIPTION(DRIVER_DESC);