// SPDX-License-Identifier: GPL-2.0-only

  /*
   * VFIO: IOMMU DMA mapping support for Type1 IOMMU
   *
   * Copyright (C) 2012 Red Hat, Inc.  All rights reserved.
   *     Author: Alex Williamson <alex.williamson@redhat.com>
   *

   * 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.");

  static unsigned int dma_entry_limit __read_mostly = U16_MAX;
  module_param_named(dma_entry_limit, dma_entry_limit, uint, 0644);
  MODULE_PARM_DESC(dma_entry_limit,
  		 "Maximum number of user DMA mappings per container (65535).");

  struct vfio_iommu {

  	struct list_head	domain_list;

  	struct list_head	iova_list;

  	struct vfio_domain	*external_domain; /* domain for external user */

  	struct mutex		lock;

  	struct rb_root		dma_list;

  	struct blocking_notifier_head notifier;

  	unsigned int		dma_avail;

  	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;

  	bool			lock_cap;	/* capable(CAP_IPC_LOCK) */

  	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;

  	bool			mdev_group;	/* An mdev group */

  };

  struct vfio_iova {
  	struct list_head	list;
  	dma_addr_t		start;
  	dma_addr_t		end;
  };

  /*

   * 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;
  };

  struct vfio_regions {
  	struct list_head list;
  	dma_addr_t iova;
  	phys_addr_t phys;
  	size_t len;
  };

  #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 vfio_dma *dma, long npage, bool async)

  {

  	struct mm_struct *mm;

  	int ret;

  	if (!npage)

  		return 0;

  	mm = async ? get_task_mm(dma->task) : dma->task->mm;

  	if (!mm)

  		return -ESRCH; /* process exited */

  	ret = down_write_killable(&mm->mmap_sem);
  	if (!ret) {

  		ret = __account_locked_vm(mm, abs(npage), npage > 0, dma->task,
  					  dma->lock_cap);

  		up_write(&mm->mmap_sem);

  	}

  	if (async)

  		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 follow_fault_pfn(struct vm_area_struct *vma, struct mm_struct *mm,
  			    unsigned long vaddr, unsigned long *pfn,
  			    bool write_fault)
  {
  	int ret;
  
  	ret = follow_pfn(vma, vaddr, pfn);
  	if (ret) {
  		bool unlocked = false;
  
  		ret = fixup_user_fault(NULL, mm, vaddr,
  				       FAULT_FLAG_REMOTE |
  				       (write_fault ?  FAULT_FLAG_WRITE : 0),
  				       &unlocked);
  		if (unlocked)
  			return -EAGAIN;
  
  		if (ret)
  			return ret;
  
  		ret = follow_pfn(vma, vaddr, pfn);
  	}
  
  	return ret;
  }

  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;

  	struct vm_area_struct *vmas[1];

  	unsigned int flags = 0;

  	int ret;

  	if (prot & IOMMU_WRITE)
  		flags |= FOLL_WRITE;
  
  	down_read(&mm->mmap_sem);

  	if (mm == current->mm) {

  		ret = get_user_pages(vaddr, 1, flags | FOLL_LONGTERM, page,
  				     vmas);

  	} else {

  		ret = get_user_pages_remote(NULL, mm, vaddr, 1, flags, page,

  					    vmas, NULL);
  		/*
  		 * The lifetime of a vaddr_get_pfn() page pin is
  		 * userspace-controlled. In the fs-dax case this could
  		 * lead to indefinite stalls in filesystem operations.
  		 * Disallow attempts to pin fs-dax pages via this
  		 * interface.
  		 */
  		if (ret > 0 && vma_is_fsdax(vmas[0])) {
  			ret = -EOPNOTSUPP;
  			put_page(page[0]);
  		}

  	}

  	up_read(&mm->mmap_sem);

  
  	if (ret == 1) {

  		*pfn = page_to_pfn(page[0]);
  		return 0;
  	}

  	down_read(&mm->mmap_sem);

  	vaddr = untagged_addr(vaddr);

  retry:

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

  
  	if (vma && vma->vm_flags & VM_PFNMAP) {

  		ret = follow_fault_pfn(vma, mm, vaddr, pfn, prot & IOMMU_WRITE);
  		if (ret == -EAGAIN)
  			goto retry;
  
  		if (!ret && !is_invalid_reserved_pfn(*pfn))
  			ret = -EFAULT;

  	}

  	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,

  				  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 (!dma->lock_cap && current->mm->locked_vm + 1 > limit) {

  			put_pfn(*pfn_base, dma->prot);
  			pr_warn("%s: RLIMIT_MEMLOCK (%ld) exceeded
  ", __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 (!dma->lock_cap &&

  			    current->mm->locked_vm + lock_acct + 1 > limit) {

  				put_pfn(pfn, dma->prot);

  				pr_warn("%s: RLIMIT_MEMLOCK (%ld) exceeded
  ",
  					__func__, limit << PAGE_SHIFT);

  				ret = -ENOMEM;
  				goto unpin_out;

  			}

  			lock_acct++;

  		}
  	}

  out:

  	ret = vfio_lock_acct(dma, lock_acct, false);

  
  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, locked - unlocked, true);

  
  	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, 1, true);

  		if (ret) {
  			put_pfn(*pfn_base, dma->prot);

  			if (ret == -ENOMEM)
  				pr_warn("%s: Task %s (%d) RLIMIT_MEMLOCK "
  					"(%ld) exceeded
  ", __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, -unlocked, true);

  
  	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->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);

  	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_sync_unpin(struct vfio_dma *dma, struct vfio_domain *domain,

  			    struct list_head *regions,
  			    struct iommu_iotlb_gather *iotlb_gather)

  {
  	long unlocked = 0;
  	struct vfio_regions *entry, *next;

  	iommu_tlb_sync(domain->domain, iotlb_gather);

  
  	list_for_each_entry_safe(entry, next, regions, list) {
  		unlocked += vfio_unpin_pages_remote(dma,
  						    entry->iova,
  						    entry->phys >> PAGE_SHIFT,
  						    entry->len >> PAGE_SHIFT,
  						    false);
  		list_del(&entry->list);
  		kfree(entry);
  	}
  
  	cond_resched();
  
  	return unlocked;
  }
  
  /*
   * Generally, VFIO needs to unpin remote pages after each IOTLB flush.
   * Therefore, when using IOTLB flush sync interface, VFIO need to keep track
   * of these regions (currently using a list).
   *
   * This value specifies maximum number of regions for each IOTLB flush sync.
   */
  #define VFIO_IOMMU_TLB_SYNC_MAX		512
  
  static size_t unmap_unpin_fast(struct vfio_domain *domain,
  			       struct vfio_dma *dma, dma_addr_t *iova,
  			       size_t len, phys_addr_t phys, long *unlocked,
  			       struct list_head *unmapped_list,

  			       int *unmapped_cnt,
  			       struct iommu_iotlb_gather *iotlb_gather)

  {
  	size_t unmapped = 0;
  	struct vfio_regions *entry = kzalloc(sizeof(*entry), GFP_KERNEL);
  
  	if (entry) {

  		unmapped = iommu_unmap_fast(domain->domain, *iova, len,
  					    iotlb_gather);

  
  		if (!unmapped) {
  			kfree(entry);
  		} else {

  			entry->iova = *iova;
  			entry->phys = phys;
  			entry->len  = unmapped;
  			list_add_tail(&entry->list, unmapped_list);
  
  			*iova += unmapped;
  			(*unmapped_cnt)++;
  		}
  	}
  
  	/*
  	 * Sync if the number of fast-unmap regions hits the limit
  	 * or in case of errors.
  	 */
  	if (*unmapped_cnt >= VFIO_IOMMU_TLB_SYNC_MAX || !unmapped) {

  		*unlocked += vfio_sync_unpin(dma, domain, unmapped_list,
  					     iotlb_gather);

  		*unmapped_cnt = 0;
  	}
  
  	return unmapped;
  }
  
  static size_t unmap_unpin_slow(struct vfio_domain *domain,
  			       struct vfio_dma *dma, dma_addr_t *iova,
  			       size_t len, phys_addr_t phys,
  			       long *unlocked)
  {
  	size_t unmapped = iommu_unmap(domain->domain, *iova, len);
  
  	if (unmapped) {
  		*unlocked += vfio_unpin_pages_remote(dma, *iova,
  						     phys >> PAGE_SHIFT,
  						     unmapped >> PAGE_SHIFT,
  						     false);
  		*iova += unmapped;
  		cond_resched();
  	}
  	return unmapped;
  }

  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;

  	LIST_HEAD(unmapped_region_list);

  	struct iommu_iotlb_gather iotlb_gather;

  	int unmapped_region_cnt = 0;

  	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();
  	}

  	iommu_iotlb_gather_init(&iotlb_gather);

  	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;
  		}

  		/*
  		 * First, try to use fast unmap/unpin. In case of failure,
  		 * switch to slow unmap/unpin path.
  		 */
  		unmapped = unmap_unpin_fast(domain, dma, &iova, len, phys,
  					    &unlocked, &unmapped_region_list,

  					    &unmapped_region_cnt,
  					    &iotlb_gather);

  		if (!unmapped) {
  			unmapped = unmap_unpin_slow(domain, dma, &iova, len,
  						    phys, &unlocked);
  			if (WARN_ON(!unmapped))
  				break;
  		}

  	}

  	dma->iommu_mapped = false;

  	if (unmapped_region_cnt) {
  		unlocked += vfio_sync_unpin(dma, domain, &unmapped_region_list,
  					    &iotlb_gather);
  	}

  	if (do_accounting) {

  		vfio_lock_acct(dma, -unlocked, true);

  		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);

  	iommu->dma_avail++;

  }

  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 - 1 < 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;
  }

  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)
  			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;

  	int ret = 0;
  
  	while (size) {
  		/* Pin a contiguous chunk of memory */
  		npage = vfio_pin_pages_remote(dma, vaddr + dma->size,

  					      size >> PAGE_SHIFT, &pfn, 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;
  }

  /*
   * Check dma map request is within a valid iova range
   */
  static bool vfio_iommu_iova_dma_valid(struct vfio_iommu *iommu,
  				      dma_addr_t start, dma_addr_t end)
  {
  	struct list_head *iova = &iommu->iova_list;
  	struct vfio_iova *node;
  
  	list_for_each_entry(node, iova, list) {
  		if (start >= node->start && end <= node->end)
  			return true;
  	}
  
  	/*
  	 * Check for list_empty() as well since a container with
  	 * a single mdev device will have an empty list.
  	 */
  	return list_empty(iova);
  }

  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;

  	}

  	if (!iommu->dma_avail) {
  		ret = -ENOSPC;
  		goto out_unlock;
  	}

  	if (!vfio_iommu_iova_dma_valid(iommu, iova, iova + size - 1)) {
  		ret = -EINVAL;
  		goto out_unlock;
  	}

  	dma = kzalloc(sizeof(*dma), GFP_KERNEL);
  	if (!dma) {

  		ret = -ENOMEM;
  		goto out_unlock;

  	}

  	iommu->dma_avail--;

  	dma->iova = iova;
  	dma->vaddr = vaddr;

  	dma->prot = prot;

  
  	/*
  	 * We need to be able to both add to a task's locked memory and test
  	 * against the locked memory limit and we need to be able to do both
  	 * outside of this call path as pinning can be asynchronous via the
  	 * external interfaces for mdev devices.  RLIMIT_MEMLOCK requires a
  	 * task_struct and VM locked pages requires an mm_struct, however
  	 * holding an indefinite mm reference is not recommended, therefore we
  	 * only hold a reference to a task.  We could hold a reference to
  	 * current, however QEMU uses this call path through vCPU threads,
  	 * which can be killed resulting in a NULL mm and failure in the unmap
  	 * path when called via a different thread.  Avoid this problem by
  	 * using the group_leader as threads within the same group require
  	 * both CLONE_THREAD and CLONE_VM and will therefore use the same
  	 * mm_struct.
  	 *
  	 * Previously we also used the task for testing CAP_IPC_LOCK at the
  	 * time of pinning and accounting, however has_capability() makes use
  	 * of real_cred, a copy-on-write field, so we can't guarantee that it
  	 * matches group_leader, or in fact that it might not change by the
  	 * time it's evaluated.  If a process were to call MAP_DMA with
  	 * CAP_IPC_LOCK but later drop it, it doesn't make sense that they
  	 * possibly see different results for an iommu_mapped vfio_dma vs
  	 * externally mapped.  Therefore track CAP_IPC_LOCK in vfio_dma at the
  	 * time of calling MAP_DMA.
  	 */
  	get_task_struct(current->group_leader);
  	dma->task = current->group_leader;
  	dma->lock_cap = capable(CAP_IPC_LOCK);

  	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 = NULL;

  	struct rb_node *n;

  	unsigned long limit = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT;

  	int ret;
  
  	/* Arbitrarily pick the first domain in the list for lookups */

  	if (!list_empty(&iommu->domain_list))
  		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;

  				if (WARN_ON(!d)) { /* mapped w/o a domain?! */
  					ret = -EINVAL;
  					goto unwind;
  				}

  				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, limit);

  				if (npage <= 0) {
  					WARN_ON(!npage);
  					ret = (int)npage;

  					goto unwind;

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

  			}

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

  			if (ret) {
  				if (!dma->iommu_mapped)
  					vfio_unpin_pages_remote(dma, iova,
  							phys >> PAGE_SHIFT,
  							size >> PAGE_SHIFT,
  							true);
  				goto unwind;
  			}

  			iova += size;
  		}

  	}
  
  	/* All dmas are now mapped, defer to second tree walk for unwind */
  	for (n = rb_first(&iommu->dma_list); n; n = rb_next(n)) {
  		struct vfio_dma *dma = rb_entry(n, struct vfio_dma, node);

  		dma->iommu_mapped = true;

  	}

  	return 0;

  
  unwind:
  	for (; n; n = rb_prev(n)) {
  		struct vfio_dma *dma = rb_entry(n, struct vfio_dma, node);
  		dma_addr_t iova;
  
  		if (dma->iommu_mapped) {
  			iommu_unmap(domain->domain, dma->iova, dma->size);
  			continue;
  		}
  
  		iova = dma->iova;
  		while (iova < dma->iova + dma->size) {
  			phys_addr_t phys, p;
  			size_t size;
  			dma_addr_t i;
  
  			phys = iommu_iova_to_phys(domain->domain, iova);
  			if (!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(domain->domain, i)) {
  				size += PAGE_SIZE;
  				p += PAGE_SIZE;
  				i += PAGE_SIZE;
  			}
  
  			iommu_unmap(domain->domain, iova, size);
  			vfio_unpin_pages_remote(dma, iova, phys >> PAGE_SHIFT,
  						size >> PAGE_SHIFT, true);
  		}
  	}
  
  	return ret;

  }

  /*
   * 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 list_head *group_resv_regions,
  				  phys_addr_t *base)

  {

  	struct iommu_resv_region *region;

  	bool ret = false;

  	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;

  		}
  	}

  	return ret;
  }

  static struct device *vfio_mdev_get_iommu_device(struct device *dev)
  {
  	struct device *(*fn)(struct device *dev);
  	struct device *iommu_device;
  
  	fn = symbol_get(mdev_get_iommu_device);
  	if (fn) {
  		iommu_device = fn(dev);
  		symbol_put(mdev_get_iommu_device);
  
  		return iommu_device;
  	}
  
  	return NULL;
  }
  
  static int vfio_mdev_attach_domain(struct device *dev, void *data)
  {
  	struct iommu_domain *domain = data;
  	struct device *iommu_device;
  
  	iommu_device = vfio_mdev_get_iommu_device(dev);
  	if (iommu_device) {
  		if (iommu_dev_feature_enabled(iommu_device, IOMMU_DEV_FEAT_AUX))
  			return iommu_aux_attach_device(domain, iommu_device);
  		else
  			return iommu_attach_device(domain, iommu_device);
  	}
  
  	return -EINVAL;
  }
  
  static int vfio_mdev_detach_domain(struct device *dev, void *data)
  {
  	struct iommu_domain *domain = data;
  	struct device *iommu_device;
  
  	iommu_device = vfio_mdev_get_iommu_device(dev);
  	if (iommu_device) {
  		if (iommu_dev_feature_enabled(iommu_device, IOMMU_DEV_FEAT_AUX))
  			iommu_aux_detach_device(domain, iommu_device);
  		else
  			iommu_detach_device(domain, iommu_device);
  	}
  
  	return 0;
  }
  
  static int vfio_iommu_attach_group(struct vfio_domain *domain,
  				   struct vfio_group *group)
  {
  	if (group->mdev_group)
  		return iommu_group_for_each_dev(group->iommu_group,
  						domain->domain,
  						vfio_mdev_attach_domain);
  	else
  		return iommu_attach_group(domain->domain, group->iommu_group);
  }
  
  static void vfio_iommu_detach_group(struct vfio_domain *domain,
  				    struct vfio_group *group)
  {
  	if (group->mdev_group)
  		iommu_group_for_each_dev(group->iommu_group, domain->domain,
  					 vfio_mdev_detach_domain);
  	else
  		iommu_detach_group(domain->domain, group->iommu_group);
  }

  static bool vfio_bus_is_mdev(struct bus_type *bus)
  {
  	struct bus_type *mdev_bus;
  	bool ret = false;
  
  	mdev_bus = symbol_get(mdev_bus_type);
  	if (mdev_bus) {
  		ret = (bus == mdev_bus);
  		symbol_put(mdev_bus_type);
  	}
  
  	return ret;
  }
  
  static int vfio_mdev_iommu_device(struct device *dev, void *data)
  {
  	struct device **old = data, *new;
  
  	new = vfio_mdev_get_iommu_device(dev);
  	if (!new || (*old && *old != new))
  		return -EINVAL;
  
  	*old = new;
  
  	return 0;
  }

  /*
   * This is a helper function to insert an address range to iova list.
   * The list is initially created with a single entry corresponding to
   * the IOMMU domain geometry to which the device group is attached.
   * The list aperture gets modified when a new domain is added to the
   * container if the new aperture doesn't conflict with the current one
   * or with any existing dma mappings. The list is also modified to
   * exclude any reserved regions associated with the device group.
   */
  static int vfio_iommu_iova_insert(struct list_head *head,
  				  dma_addr_t start, dma_addr_t end)
  {
  	struct vfio_iova *region;
  
  	region = kmalloc(sizeof(*region), GFP_KERNEL);
  	if (!region)
  		return -ENOMEM;
  
  	INIT_LIST_HEAD(&region->list);
  	region->start = start;
  	region->end = end;
  
  	list_add_tail(&region->list, head);
  	return 0;
  }
  
  /*
   * Check the new iommu aperture conflicts with existing aper or with any
   * existing dma mappings.
   */
  static bool vfio_iommu_aper_conflict(struct vfio_iommu *iommu,
  				     dma_addr_t start, dma_addr_t end)
  {
  	struct vfio_iova *first, *last;
  	struct list_head *iova = &iommu->iova_list;
  
  	if (list_empty(iova))
  		return false;
  
  	/* Disjoint sets, return conflict */
  	first = list_first_entry(iova, struct vfio_iova, list);
  	last = list_last_entry(iova, struct vfio_iova, list);
  	if (start > last->end || end < first->start)
  		return true;
  
  	/* Check for any existing dma mappings below the new start */
  	if (start > first->start) {
  		if (vfio_find_dma(iommu, first->start, start - first->start))
  			return true;
  	}
  
  	/* Check for any existing dma mappings beyond the new end */
  	if (end < last->end) {
  		if (vfio_find_dma(iommu, end + 1, last->end - end))
  			return true;
  	}
  
  	return false;
  }
  
  /*
   * Resize iommu iova aperture window. This is called only if the new
   * aperture has no conflict with existing aperture and dma mappings.
   */
  static int vfio_iommu_aper_resize(struct list_head *iova,
  				  dma_addr_t start, dma_addr_t end)
  {
  	struct vfio_iova *node, *next;
  
  	if (list_empty(iova))
  		return vfio_iommu_iova_insert(iova, start, end);
  
  	/* Adjust iova list start */
  	list_for_each_entry_safe(node, next, iova, list) {
  		if (start < node->start)
  			break;
  		if (start >= node->start && start < node->end) {
  			node->start = start;
  			break;
  		}
  		/* Delete nodes before new start */
  		list_del(&node->list);
  		kfree(node);
  	}
  
  	/* Adjust iova list end */
  	list_for_each_entry_safe(node, next, iova, list) {
  		if (end > node->end)
  			continue;
  		if (end > node->start && end <= node->end) {
  			node->end = end;
  			continue;
  		}
  		/* Delete nodes after new end */
  		list_del(&node->list);
  		kfree(node);
  	}
  
  	return 0;
  }

  /*
   * Check reserved region conflicts with existing dma mappings
   */
  static bool vfio_iommu_resv_conflict(struct vfio_iommu *iommu,
  				     struct list_head *resv_regions)
  {
  	struct iommu_resv_region *region;
  
  	/* Check for conflict with existing dma mappings */
  	list_for_each_entry(region, resv_regions, list) {
  		if (region->type == IOMMU_RESV_DIRECT_RELAXABLE)
  			continue;
  
  		if (vfio_find_dma(iommu, region->start, region->length))
  			return true;
  	}
  
  	return false;
  }
  
  /*
   * Check iova region overlap with  reserved regions and
   * exclude them from the iommu iova range
   */
  static int vfio_iommu_resv_exclude(struct list_head *iova,
  				   struct list_head *resv_regions)
  {
  	struct iommu_resv_region *resv;
  	struct vfio_iova *n, *next;
  
  	list_for_each_entry(resv, resv_regions, list) {
  		phys_addr_t start, end;
  
  		if (resv->type == IOMMU_RESV_DIRECT_RELAXABLE)
  			continue;
  
  		start = resv->start;
  		end = resv->start + resv->length - 1;
  
  		list_for_each_entry_safe(n, next, iova, list) {
  			int ret = 0;
  
  			/* No overlap */
  			if (start > n->end || end < n->start)
  				continue;
  			/*
  			 * Insert a new node if current node overlaps with the
  			 * reserve region to exlude that from valid iova range.
  			 * Note that, new node is inserted before the current
  			 * node and finally the current node is deleted keeping
  			 * the list updated and sorted.
  			 */
  			if (start > n->start)
  				ret = vfio_iommu_iova_insert(&n->list, n->start,
  							     start - 1);
  			if (!ret && end < n->end)
  				ret = vfio_iommu_iova_insert(&n->list, end + 1,
  							     n->end);
  			if (ret)
  				return ret;
  
  			list_del(&n->list);
  			kfree(n);
  		}
  	}
  
  	if (list_empty(iova))
  		return -EINVAL;
  
  	return 0;
  }
  
  static void vfio_iommu_resv_free(struct list_head *resv_regions)
  {
  	struct iommu_resv_region *n, *next;
  
  	list_for_each_entry_safe(n, next, resv_regions, list) {
  		list_del(&n->list);
  		kfree(n);
  	}
  }

  static void vfio_iommu_iova_free(struct list_head *iova)
  {
  	struct vfio_iova *n, *next;
  
  	list_for_each_entry_safe(n, next, iova, list) {
  		list_del(&n->list);
  		kfree(n);
  	}
  }
  
  static int vfio_iommu_iova_get_copy(struct vfio_iommu *iommu,
  				    struct list_head *iova_copy)
  {
  	struct list_head *iova = &iommu->iova_list;
  	struct vfio_iova *n;
  	int ret;
  
  	list_for_each_entry(n, iova, list) {
  		ret = vfio_iommu_iova_insert(iova_copy, n->start, n->end);
  		if (ret)
  			goto out_free;
  	}
  
  	return 0;
  
  out_free:
  	vfio_iommu_iova_free(iova_copy);
  	return ret;
  }
  
  static void vfio_iommu_iova_insert_copy(struct vfio_iommu *iommu,
  					struct list_head *iova_copy)
  {
  	struct list_head *iova = &iommu->iova_list;
  
  	vfio_iommu_iova_free(iova);
  
  	list_splice_tail(iova_copy, iova);
  }

  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;

  	int ret;

  	bool resv_msi, msi_remap;

  	phys_addr_t resv_msi_base = 0;

  	struct iommu_domain_geometry geo;
  	LIST_HEAD(iova_copy);

  	LIST_HEAD(group_resv_regions);

  	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;

  	if (vfio_bus_is_mdev(bus)) {
  		struct device *iommu_device = NULL;

  		group->mdev_group = true;
  
  		/* Determine the isolation type */
  		ret = iommu_group_for_each_dev(iommu_group, &iommu_device,
  					       vfio_mdev_iommu_device);
  		if (ret || !iommu_device) {

  			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;
  		}

  
  		bus = iommu_device->bus;

  	}

  	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 = vfio_iommu_attach_group(domain, group);

  	if (ret)
  		goto out_domain;

  	/* Get aperture info */
  	iommu_domain_get_attr(domain->domain, DOMAIN_ATTR_GEOMETRY, &geo);
  
  	if (vfio_iommu_aper_conflict(iommu, geo.aperture_start,
  				     geo.aperture_end)) {
  		ret = -EINVAL;
  		goto out_detach;
  	}

  	ret = iommu_get_group_resv_regions(iommu_group, &group_resv_regions);
  	if (ret)
  		goto out_detach;
  
  	if (vfio_iommu_resv_conflict(iommu, &group_resv_regions)) {
  		ret = -EINVAL;
  		goto out_detach;
  	}

  	/*
  	 * We don't want to work on the original iova list as the list
  	 * gets modified and in case of failure we have to retain the
  	 * original list. Get a copy here.
  	 */
  	ret = vfio_iommu_iova_get_copy(iommu, &iova_copy);
  	if (ret)
  		goto out_detach;
  
  	ret = vfio_iommu_aper_resize(&iova_copy, geo.aperture_start,
  				     geo.aperture_end);
  	if (ret)
  		goto out_detach;

  	ret = vfio_iommu_resv_exclude(&iova_copy, &group_resv_regions);
  	if (ret)
  		goto out_detach;

  	resv_msi = vfio_iommu_has_sw_msi(&group_resv_regions, &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
  ",
  		       __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) {

  			vfio_iommu_detach_group(domain, group);
  			if (!vfio_iommu_attach_group(d, group)) {

  				list_add(&group->next, &d->group_list);
  				iommu_domain_free(domain->domain);
  				kfree(domain);

  				goto done;

  			}

  			ret = vfio_iommu_attach_group(domain, 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);

  done:
  	/* Delete the old one and insert new iova list */
  	vfio_iommu_iova_insert_copy(iommu, &iova_copy);

  	mutex_unlock(&iommu->lock);

  	vfio_iommu_resv_free(&group_resv_regions);

  
  	return 0;

  
  out_detach:

  	vfio_iommu_detach_group(domain, group);

  out_domain:
  	iommu_domain_free(domain->domain);

  	vfio_iommu_iova_free(&iova_copy);

  	vfio_iommu_resv_free(&group_resv_regions);

  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, locked - unlocked, true);

  	}
  }
  
  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);

  }

  /*
   * Called when a domain is removed in detach. It is possible that
   * the removed domain decided the iova aperture window. Modify the
   * iova aperture with the smallest window among existing domains.
   */
  static void vfio_iommu_aper_expand(struct vfio_iommu *iommu,
  				   struct list_head *iova_copy)
  {
  	struct vfio_domain *domain;
  	struct iommu_domain_geometry geo;
  	struct vfio_iova *node;
  	dma_addr_t start = 0;
  	dma_addr_t end = (dma_addr_t)~0;
  
  	if (list_empty(iova_copy))
  		return;
  
  	list_for_each_entry(domain, &iommu->domain_list, next) {
  		iommu_domain_get_attr(domain->domain, DOMAIN_ATTR_GEOMETRY,
  				      &geo);
  		if (geo.aperture_start > start)
  			start = geo.aperture_start;
  		if (geo.aperture_end < end)
  			end = geo.aperture_end;
  	}
  
  	/* Modify aperture limits. The new aper is either same or bigger */
  	node = list_first_entry(iova_copy, struct vfio_iova, list);
  	node->start = start;
  	node = list_last_entry(iova_copy, struct vfio_iova, list);
  	node->end = end;
  }
  
  /*
   * Called when a group is detached. The reserved regions for that
   * group can be part of valid iova now. But since reserved regions
   * may be duplicated among groups, populate the iova valid regions
   * list again.
   */
  static int vfio_iommu_resv_refresh(struct vfio_iommu *iommu,
  				   struct list_head *iova_copy)
  {
  	struct vfio_domain *d;
  	struct vfio_group *g;
  	struct vfio_iova *node;
  	dma_addr_t start, end;
  	LIST_HEAD(resv_regions);
  	int ret;
  
  	if (list_empty(iova_copy))
  		return -EINVAL;
  
  	list_for_each_entry(d, &iommu->domain_list, next) {
  		list_for_each_entry(g, &d->group_list, next) {
  			ret = iommu_get_group_resv_regions(g->iommu_group,
  							   &resv_regions);
  			if (ret)
  				goto done;
  		}
  	}
  
  	node = list_first_entry(iova_copy, struct vfio_iova, list);
  	start = node->start;
  	node = list_last_entry(iova_copy, struct vfio_iova, list);
  	end = node->end;
  
  	/* purge the iova list and create new one */
  	vfio_iommu_iova_free(iova_copy);
  
  	ret = vfio_iommu_aper_resize(iova_copy, start, end);
  	if (ret)
  		goto done;
  
  	/* Exclude current reserved regions from iova ranges */
  	ret = vfio_iommu_resv_exclude(iova_copy, &resv_regions);
  done:
  	vfio_iommu_resv_free(&resv_regions);
  	return ret;
  }

  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;

  	LIST_HEAD(iova_copy);

  
  	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;
  		}
  	}

  	/*
  	 * Get a copy of iova list. This will be used to update
  	 * and to replace the current one later. Please note that
  	 * we will leave the original list as it is if update fails.
  	 */
  	vfio_iommu_iova_get_copy(iommu, &iova_copy);

  	list_for_each_entry(domain, &iommu->domain_list, next) {

  		group = find_iommu_group(domain, iommu_group);
  		if (!group)
  			continue;

  		vfio_iommu_detach_group(domain, 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);

  			vfio_iommu_aper_expand(iommu, &iova_copy);

  		}

  		break;

  	}

  	if (!vfio_iommu_resv_refresh(iommu, &iova_copy))
  		vfio_iommu_iova_insert_copy(iommu, &iova_copy);
  	else
  		vfio_iommu_iova_free(&iova_copy);

  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;

  		/* fall through */

  	case VFIO_TYPE1v2_IOMMU:
  		iommu->v2 = true;
  		break;
  	default:
  		kfree(iommu);
  		return ERR_PTR(-EINVAL);
  	}

  	INIT_LIST_HEAD(&iommu->domain_list);

  	INIT_LIST_HEAD(&iommu->iova_list);

  	iommu->dma_list = RB_ROOT;

  	iommu->dma_avail = dma_entry_limit;

  	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)

  			vfio_iommu_detach_group(domain, 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);

  	}

  
  	vfio_iommu_iova_free(&iommu->iova_list);

  	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 int vfio_iommu_iova_add_cap(struct vfio_info_cap *caps,
  		 struct vfio_iommu_type1_info_cap_iova_range *cap_iovas,
  		 size_t size)
  {
  	struct vfio_info_cap_header *header;
  	struct vfio_iommu_type1_info_cap_iova_range *iova_cap;
  
  	header = vfio_info_cap_add(caps, size,
  				   VFIO_IOMMU_TYPE1_INFO_CAP_IOVA_RANGE, 1);
  	if (IS_ERR(header))
  		return PTR_ERR(header);
  
  	iova_cap = container_of(header,
  				struct vfio_iommu_type1_info_cap_iova_range,
  				header);
  	iova_cap->nr_iovas = cap_iovas->nr_iovas;
  	memcpy(iova_cap->iova_ranges, cap_iovas->iova_ranges,
  	       cap_iovas->nr_iovas * sizeof(*cap_iovas->iova_ranges));
  	return 0;
  }
  
  static int vfio_iommu_iova_build_caps(struct vfio_iommu *iommu,
  				      struct vfio_info_cap *caps)
  {
  	struct vfio_iommu_type1_info_cap_iova_range *cap_iovas;
  	struct vfio_iova *iova;
  	size_t size;
  	int iovas = 0, i = 0, ret;
  
  	mutex_lock(&iommu->lock);
  
  	list_for_each_entry(iova, &iommu->iova_list, list)
  		iovas++;
  
  	if (!iovas) {
  		/*
  		 * Return 0 as a container with a single mdev device
  		 * will have an empty list
  		 */
  		ret = 0;
  		goto out_unlock;
  	}
  
  	size = sizeof(*cap_iovas) + (iovas * sizeof(*cap_iovas->iova_ranges));
  
  	cap_iovas = kzalloc(size, GFP_KERNEL);
  	if (!cap_iovas) {
  		ret = -ENOMEM;
  		goto out_unlock;
  	}
  
  	cap_iovas->nr_iovas = iovas;
  
  	list_for_each_entry(iova, &iommu->iova_list, list) {
  		cap_iovas->iova_ranges[i].start = iova->start;
  		cap_iovas->iova_ranges[i].end = iova->end;
  		i++;
  	}
  
  	ret = vfio_iommu_iova_add_cap(caps, cap_iovas, size);
  
  	kfree(cap_iovas);
  out_unlock:
  	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;

  		struct vfio_info_cap caps = { .buf = NULL, .size = 0 };
  		unsigned long capsz;
  		int ret;

  
  		minsz = offsetofend(struct vfio_iommu_type1_info, iova_pgsizes);

  		/* For backward compatibility, cannot require this */
  		capsz = offsetofend(struct vfio_iommu_type1_info, cap_offset);

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

  		if (info.argsz >= capsz) {
  			minsz = capsz;
  			info.cap_offset = 0; /* output, no-recopy necessary */
  		}

  		info.flags = VFIO_IOMMU_INFO_PGSIZES;

  		info.iova_pgsizes = vfio_pgsize_bitmap(iommu);

  		ret = vfio_iommu_iova_build_caps(iommu, &caps);
  		if (ret)
  			return ret;
  
  		if (caps.size) {
  			info.flags |= VFIO_IOMMU_INFO_CAPS;
  
  			if (info.argsz < sizeof(info) + caps.size) {
  				info.argsz = sizeof(info) + caps.size;
  			} else {
  				vfio_info_cap_shift(&caps, sizeof(info));
  				if (copy_to_user((void __user *)arg +
  						sizeof(info), caps.buf,
  						caps.size)) {
  					kfree(caps.buf);
  					return -EFAULT;
  				}
  				info.cap_offset = sizeof(info);
  			}
  
  			kfree(caps.buf);
  		}

  		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);