/*
 * VFIO: IOMMU DMA mapping support for TCE on POWER
 *
 * Copyright (C) 2013 IBM Corp.  All rights reserved.
 *     Author: Alexey Kardashevskiy <aik@ozlabs.ru>
 *
 * 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_iommu_type1.c:
 * Copyright (C) 2012 Red Hat, Inc.  All rights reserved.
 *     Author: Alex Williamson <alex.williamson@redhat.com>
 */

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

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

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

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

static long try_increment_locked_vm(struct mm_struct *mm, long npages)
{
        long ret = 0, locked, lock_limit;

        if (WARN_ON_ONCE(!mm))
                return -EPERM;

        if (!npages)
                return 0;

        down_write(&mm->mmap_sem);
        locked = mm->locked_vm + npages;
        lock_limit = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT;
        if (locked > lock_limit && !capable(CAP_IPC_LOCK))
                ret = -ENOMEM;
        else
                mm->locked_vm += npages;

        pr_debug("[%d] RLIMIT_MEMLOCK +%ld %ld/%ld%s\n", current->pid,
                        npages << PAGE_SHIFT,
                        mm->locked_vm << PAGE_SHIFT,
                        rlimit(RLIMIT_MEMLOCK),
                        ret ? " - exceeded" : "");

        up_write(&mm->mmap_sem);

        return ret;
}

static void decrement_locked_vm(struct mm_struct *mm, long npages)
{
        if (!mm || !npages)
                return;

        down_write(&mm->mmap_sem);
        if (WARN_ON_ONCE(npages > mm->locked_vm))
                npages = mm->locked_vm;
        mm->locked_vm -= npages;
        pr_debug("[%d] RLIMIT_MEMLOCK -%ld %ld/%ld\n", current->pid,
                        npages << PAGE_SHIFT,
                        mm->locked_vm << PAGE_SHIFT,
                        rlimit(RLIMIT_MEMLOCK));
        up_write(&mm->mmap_sem);
}

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

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

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

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

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

        return 0;
}

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

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

        list_del(&tcemem->next);
        kfree(tcemem);

        return 0;
}

static long tce_iommu_unregister_pages(struct tce_container *container,
                __u64 vaddr, __u64 size)
{
        struct mm_iommu_table_group_mem_t *mem;
        struct tce_iommu_prereg *tcemem;
        bool found = false;

        if ((vaddr & ~PAGE_MASK) || (size & ~PAGE_MASK))
                return -EINVAL;

        mem = mm_iommu_find(container->mm, vaddr, size >> PAGE_SHIFT);
        if (!mem)
                return -ENOENT;

        list_for_each_entry(tcemem, &container->prereg_list, next) {
                if (tcemem->mem == mem) {
                        found = true;
                        break;
                }
        }

        if (!found)
                return -ENOENT;

        return tce_iommu_prereg_free(container, tcemem);
}

static long tce_iommu_register_pages(struct tce_container *container,
                __u64 vaddr, __u64 size)
{
        long ret = 0;
        struct mm_iommu_table_group_mem_t *mem = NULL;
        struct tce_iommu_prereg *tcemem;
        unsigned long entries = size >> PAGE_SHIFT;

        if ((vaddr & ~PAGE_MASK) || (size & ~PAGE_MASK) ||
                        ((vaddr + size) < vaddr))
                return -EINVAL;

        mem = mm_iommu_find(container->mm, vaddr, entries);
        if (mem) {
                list_for_each_entry(tcemem, &container->prereg_list, next) {
                        if (tcemem->mem == mem)
                                return -EBUSY;
                }
        }

        ret = mm_iommu_get(container->mm, vaddr, entries, &mem);
        if (ret)
                return ret;

        tcemem = kzalloc(sizeof(*tcemem), GFP_KERNEL);
        if (!tcemem) {
                mm_iommu_put(container->mm, mem);
                return -ENOMEM;
        }

        tcemem->mem = mem;
        list_add(&tcemem->next, &container->prereg_list);

        container->enabled = true;

        return 0;
}

static long tce_iommu_userspace_view_alloc(struct iommu_table *tbl,
                struct mm_struct *mm)
{
        unsigned long cb = _ALIGN_UP(sizeof(tbl->it_userspace[0]) *
                        tbl->it_size, PAGE_SIZE);
        unsigned long *uas;
        long ret;

        BUG_ON(tbl->it_userspace);

        ret = try_increment_locked_vm(mm, cb >> PAGE_SHIFT);
        if (ret)
                return ret;

        uas = vzalloc(cb);
        if (!uas) {
                decrement_locked_vm(mm, cb >> PAGE_SHIFT);
                return -ENOMEM;
        }
        tbl->it_userspace = uas;

        return 0;
}

static void tce_iommu_userspace_view_free(struct iommu_table *tbl,
                struct mm_struct *mm)
{
        unsigned long cb = _ALIGN_UP(sizeof(tbl->it_userspace[0]) *
                        tbl->it_size, PAGE_SIZE);

        if (!tbl->it_userspace)
                return;

        vfree(tbl->it_userspace);
        tbl->it_userspace = NULL;
        decrement_locked_vm(mm, cb >> PAGE_SHIFT);
}

static bool tce_page_is_contained(struct page *page, unsigned page_shift)
{
        /*
         * Check that the TCE table granularity is not bigger than the size of
         * a page we just found. Otherwise the hardware can get access to
         * a bigger memory chunk that it should.
         */
        return (PAGE_SHIFT + compound_order(compound_head(page))) >= page_shift;
}

static inline bool tce_groups_attached(struct tce_container *container)
{
        return !list_empty(&container->group_list);
}

static long tce_iommu_find_table(struct tce_container *container,
                phys_addr_t ioba, struct iommu_table **ptbl)
{
        long i;

        for (i = 0; i < IOMMU_TABLE_GROUP_MAX_TABLES; ++i) {
                struct iommu_table *tbl = container->tables[i];

                if (tbl) {
                        unsigned long entry = ioba >> tbl->it_page_shift;
                        unsigned long start = tbl->it_offset;
                        unsigned long end = start + tbl->it_size;

                        if ((start <= entry) && (entry < end)) {
                                *ptbl = tbl;
                                return i;
                        }
                }
        }

        return -1;
}

static int tce_iommu_find_free_table(struct tce_container *container)
{
        int i;

        for (i = 0; i < IOMMU_TABLE_GROUP_MAX_TABLES; ++i) {
                if (!container->tables[i])
                        return i;
        }

        return -ENOSPC;
}

static int tce_iommu_enable(struct tce_container *container)
{
        int ret = 0;
        unsigned long locked;
        struct iommu_table_group *table_group;
        struct tce_iommu_group *tcegrp;

        if (container->enabled)
                return -EBUSY;

        /*
         * When userspace pages are mapped into the IOMMU, they are effectively
         * locked memory, so, theoretically, we need to update the accounting
         * of locked pages on each map and unmap.  For powerpc, the map unmap
         * paths can be very hot, though, and the accounting would kill
         * performance, especially since it would be difficult to impossible
         * to handle the accounting in real mode only.
         *
         * To address that, rather than precisely accounting every page, we
         * instead account for a worst case on locked memory when the iommu is
         * enabled and disabled.  The worst case upper bound on locked memory
         * is the size of the whole iommu window, which is usually relatively
         * small (compared to total memory sizes) on POWER hardware.
         *
         * Also we don't have a nice way to fail on H_PUT_TCE due to ulimits,
         * that would effectively kill the guest at random points, much better
         * enforcing the limit based on the max that the guest can map.
         *
         * Unfortunately at the moment it counts whole tables, no matter how
         * much memory the guest has. I.e. for 4GB guest and 4 IOMMU groups
         * each with 2GB DMA window, 8GB will be counted here. The reason for
         * this is that we cannot tell here the amount of RAM used by the guest
         * as this information is only available from KVM and VFIO is
         * KVM agnostic.
         *
         * So we do not allow enabling a container without a group attached
         * as there is no way to know how much we should increment
         * the locked_vm counter.
         */
        if (!tce_groups_attached(container))
                return -ENODEV;

        tcegrp = list_first_entry(&container->group_list,
                        struct tce_iommu_group, next);
        table_group = iommu_group_get_iommudata(tcegrp->grp);
        if (!table_group)
                return -ENODEV;

        if (!table_group->tce32_size)
                return -EPERM;

        ret = tce_iommu_mm_set(container);
        if (ret)
                return ret;

        locked = table_group->tce32_size >> PAGE_SHIFT;
        ret = try_increment_locked_vm(container->mm, locked);
        if (ret)
                return ret;

        container->locked_pages = locked;

        container->enabled = true;

        return ret;
}

static void tce_iommu_disable(struct tce_container *container)
{
        if (!container->enabled)
                return;

        container->enabled = false;

        BUG_ON(!container->mm);
        decrement_locked_vm(container->mm, container->locked_pages);
}

static void *tce_iommu_open(unsigned long arg)
{
        struct tce_container *container;

        if ((arg != VFIO_SPAPR_TCE_IOMMU) && (arg != VFIO_SPAPR_TCE_v2_IOMMU)) {
                pr_err("tce_vfio: Wrong IOMMU type\n");
                return ERR_PTR(-EINVAL);
        }

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

        mutex_init(&container->lock);
        INIT_LIST_HEAD_RCU(&container->group_list);
        INIT_LIST_HEAD_RCU(&container->prereg_list);

        container->v2 = arg == VFIO_SPAPR_TCE_v2_IOMMU;

        return container;
}

static int tce_iommu_clear(struct tce_container *container,
                struct iommu_table *tbl,
                unsigned long entry, unsigned long pages);
static void tce_iommu_free_table(struct tce_container *container,
                struct iommu_table *tbl);

static void tce_iommu_release(void *iommu_data)
{
        struct tce_container *container = iommu_data;
        struct tce_iommu_group *tcegrp;
        long i;

        while (tce_groups_attached(container)) {
                tcegrp = list_first_entry(&container->group_list,
                                struct tce_iommu_group, next);
                tce_iommu_detach_group(iommu_data, tcegrp->grp);
        }

        /*
         * If VFIO created a table, it was not disposed
         * by tce_iommu_detach_group() so do it now.
         */
        for (i = 0; i < IOMMU_TABLE_GROUP_MAX_TABLES; ++i) {
                struct iommu_table *tbl = container->tables[i];

                if (!tbl)
                        continue;

                tce_iommu_clear(container, tbl, tbl->it_offset, tbl->it_size);
                tce_iommu_free_table(container, tbl);
        }

        while (!list_empty(&container->prereg_list)) {
                struct tce_iommu_prereg *tcemem;

                tcemem = list_first_entry(&container->prereg_list,
                                struct tce_iommu_prereg, next);
                WARN_ON_ONCE(tce_iommu_prereg_free(container, tcemem));
        }

        tce_iommu_disable(container);
        if (container->mm)
                mmdrop(container->mm);
        mutex_destroy(&container->lock);

        kfree(container);
}

static void tce_iommu_unuse_page(struct tce_container *container,
                unsigned long hpa)
{
        struct page *page;

        page = pfn_to_page(hpa >> PAGE_SHIFT);
        put_page(page);
}

static int tce_iommu_prereg_ua_to_hpa(struct tce_container *container,
                unsigned long tce, unsigned long size,
                unsigned long *phpa, struct mm_iommu_table_group_mem_t **pmem)
{
        long ret = 0;
        struct mm_iommu_table_group_mem_t *mem;

        mem = mm_iommu_lookup(container->mm, tce, size);
        if (!mem)
                return -EINVAL;

        ret = mm_iommu_ua_to_hpa(mem, tce, phpa);
        if (ret)
                return -EINVAL;

        *pmem = mem;

        return 0;
}

static void tce_iommu_unuse_page_v2(struct tce_container *container,
                struct iommu_table *tbl, unsigned long entry)
{
        struct mm_iommu_table_group_mem_t *mem = NULL;
        int ret;
        unsigned long hpa = 0;
        unsigned long *pua = IOMMU_TABLE_USERSPACE_ENTRY(tbl, entry);

        if (!pua)
                return;

        ret = tce_iommu_prereg_ua_to_hpa(container, *pua, IOMMU_PAGE_SIZE(tbl),
                        &hpa, &mem);
        if (ret)
                pr_debug("%s: tce %lx at #%lx was not cached, ret=%d\n",
                                __func__, *pua, entry, ret);
        if (mem)
                mm_iommu_mapped_dec(mem);

        *pua = 0;
}

static int tce_iommu_clear(struct tce_container *container,
                struct iommu_table *tbl,
                unsigned long entry, unsigned long pages)
{
        unsigned long oldhpa;
        long ret;
        enum dma_data_direction direction;

        for ( ; pages; --pages, ++entry) {
                cond_resched();

                direction = DMA_NONE;
                oldhpa = 0;
                ret = iommu_tce_xchg(tbl, entry, &oldhpa, &direction);
                if (ret)
                        continue;

                if (direction == DMA_NONE)
                        continue;

                if (container->v2) {
                        tce_iommu_unuse_page_v2(container, tbl, entry);
                        continue;
                }

                tce_iommu_unuse_page(container, oldhpa);
        }

        return 0;
}

static int tce_iommu_use_page(unsigned long tce, unsigned long *hpa)
{
        struct page *page = NULL;
        enum dma_data_direction direction = iommu_tce_direction(tce);

        if (get_user_pages_fast(tce & PAGE_MASK, 1,
                        direction != DMA_TO_DEVICE, &page) != 1)
                return -EFAULT;

        *hpa = __pa((unsigned long) page_address(page));

        return 0;
}

static long tce_iommu_build(struct tce_container *container,
                struct iommu_table *tbl,
                unsigned long entry, unsigned long tce, unsigned long pages,
                enum dma_data_direction direction)
{
        long i, ret = 0;
        struct page *page;
        unsigned long hpa;
        enum dma_data_direction dirtmp;

        for (i = 0; i < pages; ++i) {
                unsigned long offset = tce & IOMMU_PAGE_MASK(tbl) & ~PAGE_MASK;

                ret = tce_iommu_use_page(tce, &hpa);
                if (ret)
                        break;

                page = pfn_to_page(hpa >> PAGE_SHIFT);
                if (!tce_page_is_contained(page, tbl->it_page_shift)) {
                        ret = -EPERM;
                        break;
                }

                hpa |= offset;
                dirtmp = direction;
                ret = iommu_tce_xchg(tbl, entry + i, &hpa, &dirtmp);
                if (ret) {
                        tce_iommu_unuse_page(container, hpa);
                        pr_err("iommu_tce: %s failed ioba=%lx, tce=%lx, ret=%ld\n",
                                        __func__, entry << tbl->it_page_shift,
                                        tce, ret);
                        break;
                }

                if (dirtmp != DMA_NONE)
                        tce_iommu_unuse_page(container, hpa);

                tce += IOMMU_PAGE_SIZE(tbl);
        }

        if (ret)
                tce_iommu_clear(container, tbl, entry, i);

        return ret;
}

static long tce_iommu_build_v2(struct tce_container *container,
                struct iommu_table *tbl,
                unsigned long entry, unsigned long tce, unsigned long pages,
                enum dma_data_direction direction)
{
        long i, ret = 0;
        struct page *page;
        unsigned long hpa;
        enum dma_data_direction dirtmp;

        if (!tbl->it_userspace) {
                ret = tce_iommu_userspace_view_alloc(tbl, container->mm);
                if (ret)
                        return ret;
        }

        for (i = 0; i < pages; ++i) {
                struct mm_iommu_table_group_mem_t *mem = NULL;
                unsigned long *pua = IOMMU_TABLE_USERSPACE_ENTRY(tbl,
                                entry + i);

                ret = tce_iommu_prereg_ua_to_hpa(container,
                                tce, IOMMU_PAGE_SIZE(tbl), &hpa, &mem);
                if (ret)
                        break;

                page = pfn_to_page(hpa >> PAGE_SHIFT);
                if (!tce_page_is_contained(page, tbl->it_page_shift)) {
                        ret = -EPERM;
                        break;
                }

                /* Preserve offset within IOMMU page */
                hpa |= tce & IOMMU_PAGE_MASK(tbl) & ~PAGE_MASK;
                dirtmp = direction;

                /* The registered region is being unregistered */
                if (mm_iommu_mapped_inc(mem))
                        break;

                ret = iommu_tce_xchg(tbl, entry + i, &hpa, &dirtmp);
                if (ret) {
                        /* dirtmp cannot be DMA_NONE here */
                        tce_iommu_unuse_page_v2(container, tbl, entry + i);
                        pr_err("iommu_tce: %s failed ioba=%lx, tce=%lx, ret=%ld\n",
                                        __func__, entry << tbl->it_page_shift,
                                        tce, ret);
                        break;
                }

                if (dirtmp != DMA_NONE)
                        tce_iommu_unuse_page_v2(container, tbl, entry + i);

                *pua = tce;

                tce += IOMMU_PAGE_SIZE(tbl);
        }

        if (ret)
                tce_iommu_clear(container, tbl, entry, i);

        return ret;
}

static long tce_iommu_create_table(struct tce_container *container,
                        struct iommu_table_group *table_group,
                        int num,
                        __u32 page_shift,
                        __u64 window_size,
                        __u32 levels,
                        struct iommu_table **ptbl)
{
        long ret, table_size;

        table_size = table_group->ops->get_table_size(page_shift, window_size,
                        levels);
        if (!table_size)
                return -EINVAL;

        ret = try_increment_locked_vm(container->mm, table_size >> PAGE_SHIFT);
        if (ret)
                return ret;

        ret = table_group->ops->create_table(table_group, num,
                        page_shift, window_size, levels, ptbl);

        WARN_ON(!ret && !(*ptbl)->it_ops->free);
        WARN_ON(!ret && ((*ptbl)->it_allocated_size != table_size));

        return ret;
}

static void tce_iommu_free_table(struct tce_container *container,
                struct iommu_table *tbl)
{
        unsigned long pages = tbl->it_allocated_size >> PAGE_SHIFT;

        tce_iommu_userspace_view_free(tbl, container->mm);
        iommu_tce_table_put(tbl);
        decrement_locked_vm(container->mm, pages);
}

static long tce_iommu_create_window(struct tce_container *container,
                __u32 page_shift, __u64 window_size, __u32 levels,
                __u64 *start_addr)
{
        struct tce_iommu_group *tcegrp;
        struct iommu_table_group *table_group;
        struct iommu_table *tbl = NULL;
        long ret, num;

        num = tce_iommu_find_free_table(container);
        if (num < 0)
                return num;

        /* Get the first group for ops::create_table */
        tcegrp = list_first_entry(&container->group_list,
                        struct tce_iommu_group, next);
        table_group = iommu_group_get_iommudata(tcegrp->grp);
        if (!table_group)
                return -EFAULT;

        if (!(table_group->pgsizes & (1ULL << page_shift)))
                return -EINVAL;

        if (!table_group->ops->set_window || !table_group->ops->unset_window ||
                        !table_group->ops->get_table_size ||
                        !table_group->ops->create_table)
                return -EPERM;

        /* Create TCE table */
        ret = tce_iommu_create_table(container, table_group, num,
                        page_shift, window_size, levels, &tbl);
        if (ret)
                return ret;

        BUG_ON(!tbl->it_ops->free);

        /*
         * Program the table to every group.
         * Groups have been tested for compatibility at the attach time.
         */
        list_for_each_entry(tcegrp, &container->group_list, next) {
                table_group = iommu_group_get_iommudata(tcegrp->grp);

                ret = table_group->ops->set_window(table_group, num, tbl);
                if (ret)
                        goto unset_exit;
        }

        container->tables[num] = tbl;

        /* Return start address assigned by platform in create_table() */
        *start_addr = tbl->it_offset << tbl->it_page_shift;

        return 0;

unset_exit:
        list_for_each_entry(tcegrp, &container->group_list, next) {
                table_group = iommu_group_get_iommudata(tcegrp->grp);
                table_group->ops->unset_window(table_group, num);
        }
        tce_iommu_free_table(container, tbl);

        return ret;
}

static long tce_iommu_remove_window(struct tce_container *container,
                __u64 start_addr)
{
        struct iommu_table_group *table_group = NULL;
        struct iommu_table *tbl;
        struct tce_iommu_group *tcegrp;
        int num;

        num = tce_iommu_find_table(container, start_addr, &tbl);
        if (num < 0)
                return -EINVAL;

        BUG_ON(!tbl->it_size);

        /* Detach groups from IOMMUs */
        list_for_each_entry(tcegrp, &container->group_list, next) {
                table_group = iommu_group_get_iommudata(tcegrp->grp);

                /*
                 * SPAPR TCE IOMMU exposes the default DMA window to
                 * the guest via dma32_window_start/size of
                 * VFIO_IOMMU_SPAPR_TCE_GET_INFO. Some platforms allow
                 * the userspace to remove this window, some do not so
                 * here we check for the platform capability.
                 */
                if (!table_group->ops || !table_group->ops->unset_window)
                        return -EPERM;

                table_group->ops->unset_window(table_group, num);
        }

        /* Free table */
        tce_iommu_clear(container, tbl, tbl->it_offset, tbl->it_size);
        tce_iommu_free_table(container, tbl);
        container->tables[num] = NULL;

        return 0;
}

static long tce_iommu_create_default_window(struct tce_container *container)
{
        long ret;
        __u64 start_addr = 0;
        struct tce_iommu_group *tcegrp;
        struct iommu_table_group *table_group;

        if (!container->def_window_pending)
                return 0;

        if (!tce_groups_attached(container))
                return -ENODEV;

        tcegrp = list_first_entry(&container->group_list,
                        struct tce_iommu_group, next);
        table_group = iommu_group_get_iommudata(tcegrp->grp);
        if (!table_group)
                return -ENODEV;

        ret = tce_iommu_create_window(container, IOMMU_PAGE_SHIFT_4K,
                        table_group->tce32_size, 1, &start_addr);
        WARN_ON_ONCE(!ret && start_addr);

        if (!ret)
                container->def_window_pending = false;

        return ret;
}

static long tce_iommu_ioctl(void *iommu_data,
                                 unsigned int cmd, unsigned long arg)
{
        struct tce_container *container = iommu_data;
        unsigned long minsz, ddwsz;
        long ret;

        switch (cmd) {
        case VFIO_CHECK_EXTENSION:
                switch (arg) {
                case VFIO_SPAPR_TCE_IOMMU:
                case VFIO_SPAPR_TCE_v2_IOMMU:
                        ret = 1;
                        break;
                default:
                        ret = vfio_spapr_iommu_eeh_ioctl(NULL, cmd, arg);
                        break;
                }

                return (ret < 0) ? 0 : ret;
        }

        /*
         * Sanity check to prevent one userspace from manipulating
         * another userspace mm.
         */
        BUG_ON(!container);
        if (container->mm && container->mm != current->mm)
                return -EPERM;

        switch (cmd) {
        case VFIO_IOMMU_SPAPR_TCE_GET_INFO: {
                struct vfio_iommu_spapr_tce_info info;
                struct tce_iommu_group *tcegrp;
                struct iommu_table_group *table_group;

                if (!tce_groups_attached(container))
                        return -ENXIO;

                tcegrp = list_first_entry(&container->group_list,
                                struct tce_iommu_group, next);
                table_group = iommu_group_get_iommudata(tcegrp->grp);

                if (!table_group)
                        return -ENXIO;

                minsz = offsetofend(struct vfio_iommu_spapr_tce_info,
                                dma32_window_size);

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

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

                info.dma32_window_start = table_group->tce32_start;
                info.dma32_window_size = table_group->tce32_size;
                info.flags = 0;
                memset(&info.ddw, 0, sizeof(info.ddw));

                if (table_group->max_dynamic_windows_supported &&
                                container->v2) {
                        info.flags |= VFIO_IOMMU_SPAPR_INFO_DDW;
                        info.ddw.pgsizes = table_group->pgsizes;
                        info.ddw.max_dynamic_windows_supported =
                                table_group->max_dynamic_windows_supported;
                        info.ddw.levels = table_group->max_levels;
                }

                ddwsz = offsetofend(struct vfio_iommu_spapr_tce_info, ddw);

                if (info.argsz >= ddwsz)
                        minsz = ddwsz;

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

                return 0;
        }
        case VFIO_IOMMU_MAP_DMA: {
                struct vfio_iommu_type1_dma_map param;
                struct iommu_table *tbl = NULL;
                long num;
                enum dma_data_direction direction;

                if (!container->enabled)
                        return -EPERM;

                minsz = offsetofend(struct vfio_iommu_type1_dma_map, size);

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

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

                if (param.flags & ~(VFIO_DMA_MAP_FLAG_READ |
                                VFIO_DMA_MAP_FLAG_WRITE))
                        return -EINVAL;

                ret = tce_iommu_create_default_window(container);
                if (ret)
                        return ret;

                num = tce_iommu_find_table(container, param.iova, &tbl);
                if (num < 0)
                        return -ENXIO;

                if ((param.size & ~IOMMU_PAGE_MASK(tbl)) ||
                                (param.vaddr & ~IOMMU_PAGE_MASK(tbl)))
                        return -EINVAL;

                /* iova is checked by the IOMMU API */
                if (param.flags & VFIO_DMA_MAP_FLAG_READ) {
                        if (param.flags & VFIO_DMA_MAP_FLAG_WRITE)
                                direction = DMA_BIDIRECTIONAL;
                        else
                                direction = DMA_TO_DEVICE;
                } else {
                        if (param.flags & VFIO_DMA_MAP_FLAG_WRITE)
                                direction = DMA_FROM_DEVICE;
                        else
                                return -EINVAL;
                }

                ret = iommu_tce_put_param_check(tbl, param.iova, param.vaddr);
                if (ret)
                        return ret;

                if (container->v2)
                        ret = tce_iommu_build_v2(container, tbl,
                                        param.iova >> tbl->it_page_shift,
                                        param.vaddr,
                                        param.size >> tbl->it_page_shift,
                                        direction);
                else
                        ret = tce_iommu_build(container, tbl,
                                        param.iova >> tbl->it_page_shift,
                                        param.vaddr,
                                        param.size >> tbl->it_page_shift,
                                        direction);

                iommu_flush_tce(tbl);

                return ret;
        }
        case VFIO_IOMMU_UNMAP_DMA: {
                struct vfio_iommu_type1_dma_unmap param;
                struct iommu_table *tbl = NULL;
                long num;

                if (!container->enabled)
                        return -EPERM;

                minsz = offsetofend(struct vfio_iommu_type1_dma_unmap,
                                size);

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

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

                /* No flag is supported now */
                if (param.flags)
                        return -EINVAL;

                ret = tce_iommu_create_default_window(container);
                if (ret)
                        return ret;

                num = tce_iommu_find_table(container, param.iova, &tbl);
                if (num < 0)
                        return -ENXIO;

                if (param.size & ~IOMMU_PAGE_MASK(tbl))
                        return -EINVAL;

                ret = iommu_tce_clear_param_check(tbl, param.iova, 0,
                                param.size >> tbl->it_page_shift);
                if (ret)
                        return ret;

                ret = tce_iommu_clear(container, tbl,
                                param.iova >> tbl->it_page_shift,
                                param.size >> tbl->it_page_shift);
                iommu_flush_tce(tbl);

                return ret;
        }
        case VFIO_IOMMU_SPAPR_REGISTER_MEMORY: {
                struct vfio_iommu_spapr_register_memory param;

                if (!container->v2)
                        break;

                minsz = offsetofend(struct vfio_iommu_spapr_register_memory,
                                size);

                ret = tce_iommu_mm_set(container);
                if (ret)
                        return ret;

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

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

                /* No flag is supported now */
                if (param.flags)
                        return -EINVAL;

                mutex_lock(&container->lock);
                ret = tce_iommu_register_pages(container, param.vaddr,
                                param.size);
                mutex_unlock(&container->lock);

                return ret;
        }
        case VFIO_IOMMU_SPAPR_UNREGISTER_MEMORY: {
                struct vfio_iommu_spapr_register_memory param;

                if (!container->v2)
                        break;

                if (!container->mm)
                        return -EPERM;

                minsz = offsetofend(struct vfio_iommu_spapr_register_memory,
                                size);

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

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

                /* No flag is supported now */
                if (param.flags)
                        return -EINVAL;

                mutex_lock(&container->lock);
                ret = tce_iommu_unregister_pages(container, param.vaddr,
                                param.size);
                mutex_unlock(&container->lock);

                return ret;
        }
        case VFIO_IOMMU_ENABLE:
                if (container->v2)
                        break;

                mutex_lock(&container->lock);
                ret = tce_iommu_enable(container);
                mutex_unlock(&container->lock);
                return ret;


        case VFIO_IOMMU_DISABLE:
                if (container->v2)
                        break;

                mutex_lock(&container->lock);
                tce_iommu_disable(container);
                mutex_unlock(&container->lock);
                return 0;

        case VFIO_EEH_PE_OP: {
                struct tce_iommu_group *tcegrp;

                ret = 0;
                list_for_each_entry(tcegrp, &container->group_list, next) {
                        ret = vfio_spapr_iommu_eeh_ioctl(tcegrp->grp,
                                        cmd, arg);
                        if (ret)
                                return ret;
                }
                return ret;
        }

        case VFIO_IOMMU_SPAPR_TCE_CREATE: {
                struct vfio_iommu_spapr_tce_create create;

                if (!container->v2)
                        break;

                ret = tce_iommu_mm_set(container);
                if (ret)
                        return ret;

                if (!tce_groups_attached(container))
                        return -ENXIO;

                minsz = offsetofend(struct vfio_iommu_spapr_tce_create,
                                start_addr);

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

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

                if (create.flags)
                        return -EINVAL;

                mutex_lock(&container->lock);

                ret = tce_iommu_create_default_window(container);
                if (!ret)
                        ret = tce_iommu_create_window(container,
                                        create.page_shift,
                                        create.window_size, create.levels,
                                        &create.start_addr);

                mutex_unlock(&container->lock);

                if (!ret && copy_to_user((void __user *)arg, &create, minsz))
                        ret = -EFAULT;

                return ret;
        }
        case VFIO_IOMMU_SPAPR_TCE_REMOVE: {
                struct vfio_iommu_spapr_tce_remove remove;

                if (!container->v2)
                        break;

                ret = tce_iommu_mm_set(container);
                if (ret)
                        return ret;

                if (!tce_groups_attached(container))
                        return -ENXIO;

                minsz = offsetofend(struct vfio_iommu_spapr_tce_remove,
                                start_addr);

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

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

                if (remove.flags)
                        return -EINVAL;

                if (container->def_window_pending && !remove.start_addr) {
                        container->def_window_pending = false;
                        return 0;
                }

                mutex_lock(&container->lock);

                ret = tce_iommu_remove_window(container, remove.start_addr);

                mutex_unlock(&container->lock);

                return ret;
        }
        }

        return -ENOTTY;
}

static void tce_iommu_release_ownership(struct tce_container *container,
                struct iommu_table_group *table_group)
{
        int i;

        for (i = 0; i < IOMMU_TABLE_GROUP_MAX_TABLES; ++i) {
                struct iommu_table *tbl = container->tables[i];

                if (!tbl)
                        continue;

                tce_iommu_clear(container, tbl, tbl->it_offset, tbl->it_size);
                tce_iommu_userspace_view_free(tbl, container->mm);
                if (tbl->it_map)
                        iommu_release_ownership(tbl);

                container->tables[i] = NULL;
        }
}

static int tce_iommu_take_ownership(struct tce_container *container,
                struct iommu_table_group *table_group)
{
        int i, j, rc = 0;

        for (i = 0; i < IOMMU_TABLE_GROUP_MAX_TABLES; ++i) {
                struct iommu_table *tbl = table_group->tables[i];

                if (!tbl || !tbl->it_map)
                        continue;

                rc = iommu_take_ownership(tbl);
                if (rc) {
                        for (j = 0; j < i; ++j)
                                iommu_release_ownership(
                                                table_group->tables[j]);

                        return rc;
                }
        }

        for (i = 0; i < IOMMU_TABLE_GROUP_MAX_TABLES; ++i)
                container->tables[i] = table_group->tables[i];

        return 0;
}

static void tce_iommu_release_ownership_ddw(struct tce_container *container,
                struct iommu_table_group *table_group)
{
        long i;

        if (!table_group->ops->unset_window) {
                WARN_ON_ONCE(1);
                return;
        }

        for (i = 0; i < IOMMU_TABLE_GROUP_MAX_TABLES; ++i)
                table_group->ops->unset_window(table_group, i);

        table_group->ops->release_ownership(table_group);
}

static long tce_iommu_take_ownership_ddw(struct tce_container *container,
                struct iommu_table_group *table_group)
{
        long i, ret = 0;

        if (!table_group->ops->create_table || !table_group->ops->set_window ||
                        !table_group->ops->release_ownership) {
                WARN_ON_ONCE(1);
                return -EFAULT;
        }

        table_group->ops->take_ownership(table_group);

        /* Set all windows to the new group */
        for (i = 0; i < IOMMU_TABLE_GROUP_MAX_TABLES; ++i) {
                struct iommu_table *tbl = container->tables[i];

                if (!tbl)
                        continue;

                ret = table_group->ops->set_window(table_group, i, tbl);
                if (ret)
                        goto release_exit;
        }

        return 0;

release_exit:
        for (i = 0; i < IOMMU_TABLE_GROUP_MAX_TABLES; ++i)
                table_group->ops->unset_window(table_group, i);

        table_group->ops->release_ownership(table_group);

        return ret;
}

static int tce_iommu_attach_group(void *iommu_data,
                struct iommu_group *iommu_group)
{
        int ret;
        struct tce_container *container = iommu_data;
        struct iommu_table_group *table_group;
        struct tce_iommu_group *tcegrp = NULL;

        mutex_lock(&container->lock);

        /* pr_debug("tce_vfio: Attaching group #%u to iommu %p\n",
                        iommu_group_id(iommu_group), iommu_group); */
        table_group = iommu_group_get_iommudata(iommu_group);
        if (!table_group) {
                ret = -ENODEV;
                goto unlock_exit;
        }

        if (tce_groups_attached(container) && (!table_group->ops ||
                        !table_group->ops->take_ownership ||
                        !table_group->ops->release_ownership)) {
                ret = -EBUSY;
                goto unlock_exit;
        }

        /* Check if new group has the same iommu_ops (i.e. compatible) */
        list_for_each_entry(tcegrp, &container->group_list, next) {
                struct iommu_table_group *table_group_tmp;

                if (tcegrp->grp == iommu_group) {
                        pr_warn("tce_vfio: Group %d is already attached\n",
                                        iommu_group_id(iommu_group));
                        ret = -EBUSY;
                        goto unlock_exit;
                }
                table_group_tmp = iommu_group_get_iommudata(tcegrp->grp);
                if (table_group_tmp->ops->create_table !=
                                table_group->ops->create_table) {
                        pr_warn("tce_vfio: Group %d is incompatible with group %d\n",
                                        iommu_group_id(iommu_group),
                                        iommu_group_id(tcegrp->grp));
                        ret = -EPERM;
                        goto unlock_exit;
                }
        }

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

        if (!table_group->ops || !table_group->ops->take_ownership ||
                        !table_group->ops->release_ownership) {
                if (container->v2) {
                        ret = -EPERM;
                        goto unlock_exit;
                }
                ret = tce_iommu_take_ownership(container, table_group);
        } else {
                if (!container->v2) {
                        ret = -EPERM;
                        goto unlock_exit;
                }
                ret = tce_iommu_take_ownership_ddw(container, table_group);
                if (!tce_groups_attached(container) && !container->tables[0])
                        container->def_window_pending = true;
        }

        if (!ret) {
                tcegrp->grp = iommu_group;
                list_add(&tcegrp->next, &container->group_list);
        }

unlock_exit:
        if (ret && tcegrp)
                kfree(tcegrp);

        mutex_unlock(&container->lock);

        return ret;
}

static void tce_iommu_detach_group(void *iommu_data,
                struct iommu_group *iommu_group)
{
        struct tce_container *container = iommu_data;
        struct iommu_table_group *table_group;
        bool found = false;
        struct tce_iommu_group *tcegrp;

        mutex_lock(&container->lock);

        list_for_each_entry(tcegrp, &container->group_list, next) {
                if (tcegrp->grp == iommu_group) {
                        found = true;
                        break;
                }
        }

        if (!found) {
                pr_warn("tce_vfio: detaching unattached group #%u\n",
                                iommu_group_id(iommu_group));
                goto unlock_exit;
        }

        list_del(&tcegrp->next);
        kfree(tcegrp);

        table_group = iommu_group_get_iommudata(iommu_group);
        BUG_ON(!table_group);

        if (!table_group->ops || !table_group->ops->release_ownership)
                tce_iommu_release_ownership(container, table_group);
        else
                tce_iommu_release_ownership_ddw(container, table_group);

unlock_exit:
        mutex_unlock(&container->lock);
}

const struct vfio_iommu_driver_ops tce_iommu_driver_ops = {
        .name           = "iommu-vfio-powerpc",
        .owner          = THIS_MODULE,
        .open           = tce_iommu_open,
        .release        = tce_iommu_release,
        .ioctl          = tce_iommu_ioctl,
        .attach_group   = tce_iommu_attach_group,
        .detach_group   = tce_iommu_detach_group,
};

static int __init tce_iommu_init(void)
{
        return vfio_register_iommu_driver(&tce_iommu_driver_ops);
}

static void __exit tce_iommu_cleanup(void)
{
        vfio_unregister_iommu_driver(&tce_iommu_driver_ops);
}

module_init(tce_iommu_init);
module_exit(tce_iommu_cleanup);

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