/*
 * Copyright (C) 2010-2012 Advanced Micro Devices, Inc.
 * Author: Joerg Roedel <jroedel@suse.de>
 *
 * 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.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
 */

#include <linux/mmu_notifier.h>
#include <linux/amd-iommu.h>
#include <linux/mm_types.h>
#include <linux/profile.h>
#include <linux/module.h>
#include <linux/sched.h>
#include <linux/iommu.h>
#include <linux/wait.h>
#include <linux/pci.h>
#include <linux/gfp.h>

#include "amd_iommu_types.h"
#include "amd_iommu_proto.h"

MODULE_LICENSE("GPL v2");
MODULE_AUTHOR("Joerg Roedel <jroedel@suse.de>");

#define MAX_DEVICES             0x10000
#define PRI_QUEUE_SIZE          512

struct pri_queue {
        atomic_t inflight;
        bool finish;
        int status;
};

struct pasid_state {
        struct list_head list;                  /* For global state-list */
        atomic_t count;                         /* Reference count */
        unsigned mmu_notifier_count;            /* Counting nested mmu_notifier
                                                   calls */
        struct mm_struct *mm;                   /* mm_struct for the faults */
        struct mmu_notifier mn;                 /* mmu_notifier handle */
        struct pri_queue pri[PRI_QUEUE_SIZE];   /* PRI tag states */
        struct device_state *device_state;      /* Link to our device_state */
        int pasid;                              /* PASID index */
        bool invalid;                           /* Used during setup and
                                                   teardown of the pasid */
        spinlock_t lock;                        /* Protect pri_queues and
                                                   mmu_notifer_count */
        wait_queue_head_t wq;                   /* To wait for count == 0 */
};

struct device_state {
        struct list_head list;
        u16 devid;
        atomic_t count;
        struct pci_dev *pdev;
        struct pasid_state **states;
        struct iommu_domain *domain;
        int pasid_levels;
        int max_pasids;
        amd_iommu_invalid_ppr_cb inv_ppr_cb;
        amd_iommu_invalidate_ctx inv_ctx_cb;
        spinlock_t lock;
        wait_queue_head_t wq;
};

struct fault {
        struct work_struct work;
        struct device_state *dev_state;
        struct pasid_state *state;
        struct mm_struct *mm;
        u64 address;
        u16 devid;
        u16 pasid;
        u16 tag;
        u16 finish;
        u16 flags;
};

static LIST_HEAD(state_list);
static spinlock_t state_lock;

static struct workqueue_struct *iommu_wq;

static void free_pasid_states(struct device_state *dev_state);

static u16 device_id(struct pci_dev *pdev)
{
        u16 devid;

        devid = pdev->bus->number;
        devid = (devid << 8) | pdev->devfn;

        return devid;
}

static struct device_state *__get_device_state(u16 devid)
{
        struct device_state *dev_state;

        list_for_each_entry(dev_state, &state_list, list) {
                if (dev_state->devid == devid)
                        return dev_state;
        }

        return NULL;
}

static struct device_state *get_device_state(u16 devid)
{
        struct device_state *dev_state;
        unsigned long flags;

        spin_lock_irqsave(&state_lock, flags);
        dev_state = __get_device_state(devid);
        if (dev_state != NULL)
                atomic_inc(&dev_state->count);
        spin_unlock_irqrestore(&state_lock, flags);

        return dev_state;
}

static void free_device_state(struct device_state *dev_state)
{
        struct iommu_group *group;

        /*
         * First detach device from domain - No more PRI requests will arrive
         * from that device after it is unbound from the IOMMUv2 domain.
         */
        group = iommu_group_get(&dev_state->pdev->dev);
        if (WARN_ON(!group))
                return;

        iommu_detach_group(dev_state->domain, group);

        iommu_group_put(group);

        /* Everything is down now, free the IOMMUv2 domain */
        iommu_domain_free(dev_state->domain);

        /* Finally get rid of the device-state */
        kfree(dev_state);
}

static void put_device_state(struct device_state *dev_state)
{
        if (atomic_dec_and_test(&dev_state->count))
                wake_up(&dev_state->wq);
}

/* Must be called under dev_state->lock */
static struct pasid_state **__get_pasid_state_ptr(struct device_state *dev_state,
                                                  int pasid, bool alloc)
{
        struct pasid_state **root, **ptr;
        int level, index;

        level = dev_state->pasid_levels;
        root  = dev_state->states;

        while (true) {

                index = (pasid >> (9 * level)) & 0x1ff;
                ptr   = &root[index];

                if (level == 0)
                        break;

                if (*ptr == NULL) {
                        if (!alloc)
                                return NULL;

                        *ptr = (void *)get_zeroed_page(GFP_ATOMIC);
                        if (*ptr == NULL)
                                return NULL;
                }

                root   = (struct pasid_state **)*ptr;
                level -= 1;
        }

        return ptr;
}

static int set_pasid_state(struct device_state *dev_state,
                           struct pasid_state *pasid_state,
                           int pasid)
{
        struct pasid_state **ptr;
        unsigned long flags;
        int ret;

        spin_lock_irqsave(&dev_state->lock, flags);
        ptr = __get_pasid_state_ptr(dev_state, pasid, true);

        ret = -ENOMEM;
        if (ptr == NULL)
                goto out_unlock;

        ret = -ENOMEM;
        if (*ptr != NULL)
                goto out_unlock;

        *ptr = pasid_state;

        ret = 0;

out_unlock:
        spin_unlock_irqrestore(&dev_state->lock, flags);

        return ret;
}

static void clear_pasid_state(struct device_state *dev_state, int pasid)
{
        struct pasid_state **ptr;
        unsigned long flags;

        spin_lock_irqsave(&dev_state->lock, flags);
        ptr = __get_pasid_state_ptr(dev_state, pasid, true);

        if (ptr == NULL)
                goto out_unlock;

        *ptr = NULL;

out_unlock:
        spin_unlock_irqrestore(&dev_state->lock, flags);
}

static struct pasid_state *get_pasid_state(struct device_state *dev_state,
                                           int pasid)
{
        struct pasid_state **ptr, *ret = NULL;
        unsigned long flags;

        spin_lock_irqsave(&dev_state->lock, flags);
        ptr = __get_pasid_state_ptr(dev_state, pasid, false);

        if (ptr == NULL)
                goto out_unlock;

        ret = *ptr;
        if (ret)
                atomic_inc(&ret->count);

out_unlock:
        spin_unlock_irqrestore(&dev_state->lock, flags);

        return ret;
}

static void free_pasid_state(struct pasid_state *pasid_state)
{
        kfree(pasid_state);
}

static void put_pasid_state(struct pasid_state *pasid_state)
{
        if (atomic_dec_and_test(&pasid_state->count))
                wake_up(&pasid_state->wq);
}

static void put_pasid_state_wait(struct pasid_state *pasid_state)
{
        atomic_dec(&pasid_state->count);
        wait_event(pasid_state->wq, !atomic_read(&pasid_state->count));
        free_pasid_state(pasid_state);
}

static void unbind_pasid(struct pasid_state *pasid_state)
{
        struct iommu_domain *domain;

        domain = pasid_state->device_state->domain;

        /*
         * Mark pasid_state as invalid, no more faults will we added to the
         * work queue after this is visible everywhere.
         */
        pasid_state->invalid = true;

        /* Make sure this is visible */
        smp_wmb();

        /* After this the device/pasid can't access the mm anymore */
        amd_iommu_domain_clear_gcr3(domain, pasid_state->pasid);

        /* Make sure no more pending faults are in the queue */
        flush_workqueue(iommu_wq);
}

static void free_pasid_states_level1(struct pasid_state **tbl)
{
        int i;

        for (i = 0; i < 512; ++i) {
                if (tbl[i] == NULL)
                        continue;

                free_page((unsigned long)tbl[i]);
        }
}

static void free_pasid_states_level2(struct pasid_state **tbl)
{
        struct pasid_state **ptr;
        int i;

        for (i = 0; i < 512; ++i) {
                if (tbl[i] == NULL)
                        continue;

                ptr = (struct pasid_state **)tbl[i];
                free_pasid_states_level1(ptr);
        }
}

static void free_pasid_states(struct device_state *dev_state)
{
        struct pasid_state *pasid_state;
        int i;

        for (i = 0; i < dev_state->max_pasids; ++i) {
                pasid_state = get_pasid_state(dev_state, i);
                if (pasid_state == NULL)
                        continue;

                put_pasid_state(pasid_state);

                /*
                 * This will call the mn_release function and
                 * unbind the PASID
                 */
                mmu_notifier_unregister(&pasid_state->mn, pasid_state->mm);

                put_pasid_state_wait(pasid_state); /* Reference taken in
                                                      amd_iommu_bind_pasid */

                /* Drop reference taken in amd_iommu_bind_pasid */
                put_device_state(dev_state);
        }

        if (dev_state->pasid_levels == 2)
                free_pasid_states_level2(dev_state->states);
        else if (dev_state->pasid_levels == 1)
                free_pasid_states_level1(dev_state->states);
        else
                BUG_ON(dev_state->pasid_levels != 0);

        free_page((unsigned long)dev_state->states);
}

static struct pasid_state *mn_to_state(struct mmu_notifier *mn)
{
        return container_of(mn, struct pasid_state, mn);
}

static void __mn_flush_page(struct mmu_notifier *mn,
                            unsigned long address)
{
        struct pasid_state *pasid_state;
        struct device_state *dev_state;

        pasid_state = mn_to_state(mn);
        dev_state   = pasid_state->device_state;

        amd_iommu_flush_page(dev_state->domain, pasid_state->pasid, address);
}

static int mn_clear_flush_young(struct mmu_notifier *mn,
                                struct mm_struct *mm,
                                unsigned long start,
                                unsigned long end)
{
        for (; start < end; start += PAGE_SIZE)
                __mn_flush_page(mn, start);

        return 0;
}

static void mn_invalidate_page(struct mmu_notifier *mn,
                               struct mm_struct *mm,
                               unsigned long address)
{
        __mn_flush_page(mn, address);
}

static void mn_invalidate_range(struct mmu_notifier *mn,
                                struct mm_struct *mm,
                                unsigned long start, unsigned long end)
{
        struct pasid_state *pasid_state;
        struct device_state *dev_state;

        pasid_state = mn_to_state(mn);
        dev_state   = pasid_state->device_state;

        if ((start ^ (end - 1)) < PAGE_SIZE)
                amd_iommu_flush_page(dev_state->domain, pasid_state->pasid,
                                     start);
        else
                amd_iommu_flush_tlb(dev_state->domain, pasid_state->pasid);
}

static void mn_release(struct mmu_notifier *mn, struct mm_struct *mm)
{
        struct pasid_state *pasid_state;
        struct device_state *dev_state;
        bool run_inv_ctx_cb;

        might_sleep();

        pasid_state    = mn_to_state(mn);
        dev_state      = pasid_state->device_state;
        run_inv_ctx_cb = !pasid_state->invalid;

        if (run_inv_ctx_cb && dev_state->inv_ctx_cb)
                dev_state->inv_ctx_cb(dev_state->pdev, pasid_state->pasid);

        unbind_pasid(pasid_state);
}

static struct mmu_notifier_ops iommu_mn = {
        .release                = mn_release,
        .clear_flush_young      = mn_clear_flush_young,
        .invalidate_page        = mn_invalidate_page,
        .invalidate_range       = mn_invalidate_range,
};

static void set_pri_tag_status(struct pasid_state *pasid_state,
                               u16 tag, int status)
{
        unsigned long flags;

        spin_lock_irqsave(&pasid_state->lock, flags);
        pasid_state->pri[tag].status = status;
        spin_unlock_irqrestore(&pasid_state->lock, flags);
}

static void finish_pri_tag(struct device_state *dev_state,
                           struct pasid_state *pasid_state,
                           u16 tag)
{
        unsigned long flags;

        spin_lock_irqsave(&pasid_state->lock, flags);
        if (atomic_dec_and_test(&pasid_state->pri[tag].inflight) &&
            pasid_state->pri[tag].finish) {
                amd_iommu_complete_ppr(dev_state->pdev, pasid_state->pasid,
                                       pasid_state->pri[tag].status, tag);
                pasid_state->pri[tag].finish = false;
                pasid_state->pri[tag].status = PPR_SUCCESS;
        }
        spin_unlock_irqrestore(&pasid_state->lock, flags);
}

static void handle_fault_error(struct fault *fault)
{
        int status;

        if (!fault->dev_state->inv_ppr_cb) {
                set_pri_tag_status(fault->state, fault->tag, PPR_INVALID);
                return;
        }

        status = fault->dev_state->inv_ppr_cb(fault->dev_state->pdev,
                                              fault->pasid,
                                              fault->address,
                                              fault->flags);
        switch (status) {
        case AMD_IOMMU_INV_PRI_RSP_SUCCESS:
                set_pri_tag_status(fault->state, fault->tag, PPR_SUCCESS);
                break;
        case AMD_IOMMU_INV_PRI_RSP_INVALID:
                set_pri_tag_status(fault->state, fault->tag, PPR_INVALID);
                break;
        case AMD_IOMMU_INV_PRI_RSP_FAIL:
                set_pri_tag_status(fault->state, fault->tag, PPR_FAILURE);
                break;
        default:
                BUG();
        }
}

static void do_fault(struct work_struct *work)
{
        struct fault *fault = container_of(work, struct fault, work);
        struct mm_struct *mm;
        struct vm_area_struct *vma;
        u64 address;
        int ret, write;

        write = !!(fault->flags & PPR_FAULT_WRITE);

        mm = fault->state->mm;
        address = fault->address;

        down_read(&mm->mmap_sem);
        vma = find_extend_vma(mm, address);
        if (!vma || address < vma->vm_start) {
                /* failed to get a vma in the right range */
                up_read(&mm->mmap_sem);
                handle_fault_error(fault);
                goto out;
        }

        if (!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE))) {
                /* handle_mm_fault would BUG_ON() */
                up_read(&mm->mmap_sem);
                handle_fault_error(fault);
                goto out;
        }

        ret = handle_mm_fault(mm, vma, address, write);
        if (ret & VM_FAULT_ERROR) {
                /* failed to service fault */
                up_read(&mm->mmap_sem);
                handle_fault_error(fault);
                goto out;
        }

        up_read(&mm->mmap_sem);

out:
        finish_pri_tag(fault->dev_state, fault->state, fault->tag);

        put_pasid_state(fault->state);

        kfree(fault);
}

static int ppr_notifier(struct notifier_block *nb, unsigned long e, void *data)
{
        struct amd_iommu_fault *iommu_fault;
        struct pasid_state *pasid_state;
        struct device_state *dev_state;
        unsigned long flags;
        struct fault *fault;
        bool finish;
        u16 tag;
        int ret;

        iommu_fault = data;
        tag         = iommu_fault->tag & 0x1ff;
        finish      = (iommu_fault->tag >> 9) & 1;

        ret = NOTIFY_DONE;
        dev_state = get_device_state(iommu_fault->device_id);
        if (dev_state == NULL)
                goto out;

        pasid_state = get_pasid_state(dev_state, iommu_fault->pasid);
        if (pasid_state == NULL || pasid_state->invalid) {
                /* We know the device but not the PASID -> send INVALID */
                amd_iommu_complete_ppr(dev_state->pdev, iommu_fault->pasid,
                                       PPR_INVALID, tag);
                goto out_drop_state;
        }

        spin_lock_irqsave(&pasid_state->lock, flags);
        atomic_inc(&pasid_state->pri[tag].inflight);
        if (finish)
                pasid_state->pri[tag].finish = true;
        spin_unlock_irqrestore(&pasid_state->lock, flags);

        fault = kzalloc(sizeof(*fault), GFP_ATOMIC);
        if (fault == NULL) {
                /* We are OOM - send success and let the device re-fault */
                finish_pri_tag(dev_state, pasid_state, tag);
                goto out_drop_state;
        }

        fault->dev_state = dev_state;
        fault->address   = iommu_fault->address;
        fault->state     = pasid_state;
        fault->tag       = tag;
        fault->finish    = finish;
        fault->pasid     = iommu_fault->pasid;
        fault->flags     = iommu_fault->flags;
        INIT_WORK(&fault->work, do_fault);

        queue_work(iommu_wq, &fault->work);

        ret = NOTIFY_OK;

out_drop_state:

        if (ret != NOTIFY_OK && pasid_state)
                put_pasid_state(pasid_state);

        put_device_state(dev_state);

out:
        return ret;
}

static struct notifier_block ppr_nb = {
        .notifier_call = ppr_notifier,
};

int amd_iommu_bind_pasid(struct pci_dev *pdev, int pasid,
                         struct task_struct *task)
{
        struct pasid_state *pasid_state;
        struct device_state *dev_state;
        struct mm_struct *mm;
        u16 devid;
        int ret;

        might_sleep();

        if (!amd_iommu_v2_supported())
                return -ENODEV;

        devid     = device_id(pdev);
        dev_state = get_device_state(devid);

        if (dev_state == NULL)
                return -EINVAL;

        ret = -EINVAL;
        if (pasid < 0 || pasid >= dev_state->max_pasids)
                goto out;

        ret = -ENOMEM;
        pasid_state = kzalloc(sizeof(*pasid_state), GFP_KERNEL);
        if (pasid_state == NULL)
                goto out;


        atomic_set(&pasid_state->count, 1);
        init_waitqueue_head(&pasid_state->wq);
        spin_lock_init(&pasid_state->lock);

        mm                        = get_task_mm(task);
        pasid_state->mm           = mm;
        pasid_state->device_state = dev_state;
        pasid_state->pasid        = pasid;
        pasid_state->invalid      = true; /* Mark as valid only if we are
                                             done with setting up the pasid */
        pasid_state->mn.ops       = &iommu_mn;

        if (pasid_state->mm == NULL)
                goto out_free;

        mmu_notifier_register(&pasid_state->mn, mm);

        ret = set_pasid_state(dev_state, pasid_state, pasid);
        if (ret)
                goto out_unregister;

        ret = amd_iommu_domain_set_gcr3(dev_state->domain, pasid,
                                        __pa(pasid_state->mm->pgd));
        if (ret)
                goto out_clear_state;

        /* Now we are ready to handle faults */
        pasid_state->invalid = false;

        /*
         * Drop the reference to the mm_struct here. We rely on the
         * mmu_notifier release call-back to inform us when the mm
         * is going away.
         */
        mmput(mm);

        return 0;

out_clear_state:
        clear_pasid_state(dev_state, pasid);

out_unregister:
        mmu_notifier_unregister(&pasid_state->mn, mm);

out_free:
        mmput(mm);
        free_pasid_state(pasid_state);

out:
        put_device_state(dev_state);

        return ret;
}
EXPORT_SYMBOL(amd_iommu_bind_pasid);

void amd_iommu_unbind_pasid(struct pci_dev *pdev, int pasid)
{
        struct pasid_state *pasid_state;
        struct device_state *dev_state;
        u16 devid;

        might_sleep();

        if (!amd_iommu_v2_supported())
                return;

        devid = device_id(pdev);
        dev_state = get_device_state(devid);
        if (dev_state == NULL)
                return;

        if (pasid < 0 || pasid >= dev_state->max_pasids)
                goto out;

        pasid_state = get_pasid_state(dev_state, pasid);
        if (pasid_state == NULL)
                goto out;
        /*
         * Drop reference taken here. We are safe because we still hold
         * the reference taken in the amd_iommu_bind_pasid function.
         */
        put_pasid_state(pasid_state);

        /* Clear the pasid state so that the pasid can be re-used */
        clear_pasid_state(dev_state, pasid_state->pasid);

        /*
         * Call mmu_notifier_unregister to drop our reference
         * to pasid_state->mm
         */
        mmu_notifier_unregister(&pasid_state->mn, pasid_state->mm);

        put_pasid_state_wait(pasid_state); /* Reference taken in
                                              amd_iommu_bind_pasid */
out:
        /* Drop reference taken in this function */
        put_device_state(dev_state);

        /* Drop reference taken in amd_iommu_bind_pasid */
        put_device_state(dev_state);
}
EXPORT_SYMBOL(amd_iommu_unbind_pasid);

int amd_iommu_init_device(struct pci_dev *pdev, int pasids)
{
        struct device_state *dev_state;
        struct iommu_group *group;
        unsigned long flags;
        int ret, tmp;
        u16 devid;

        might_sleep();

        if (!amd_iommu_v2_supported())
                return -ENODEV;

        if (pasids <= 0 || pasids > (PASID_MASK + 1))
                return -EINVAL;

        devid = device_id(pdev);

        dev_state = kzalloc(sizeof(*dev_state), GFP_KERNEL);
        if (dev_state == NULL)
                return -ENOMEM;

        spin_lock_init(&dev_state->lock);
        init_waitqueue_head(&dev_state->wq);
        dev_state->pdev  = pdev;
        dev_state->devid = devid;

        tmp = pasids;
        for (dev_state->pasid_levels = 0; (tmp - 1) & ~0x1ff; tmp >>= 9)
                dev_state->pasid_levels += 1;

        atomic_set(&dev_state->count, 1);
        dev_state->max_pasids = pasids;

        ret = -ENOMEM;
        dev_state->states = (void *)get_zeroed_page(GFP_KERNEL);
        if (dev_state->states == NULL)
                goto out_free_dev_state;

        dev_state->domain = iommu_domain_alloc(&pci_bus_type);
        if (dev_state->domain == NULL)
                goto out_free_states;

        amd_iommu_domain_direct_map(dev_state->domain);

        ret = amd_iommu_domain_enable_v2(dev_state->domain, pasids);
        if (ret)
                goto out_free_domain;

        group = iommu_group_get(&pdev->dev);
        if (!group)
                goto out_free_domain;

        ret = iommu_attach_group(dev_state->domain, group);
        if (ret != 0)
                goto out_drop_group;

        iommu_group_put(group);

        spin_lock_irqsave(&state_lock, flags);

        if (__get_device_state(devid) != NULL) {
                spin_unlock_irqrestore(&state_lock, flags);
                ret = -EBUSY;
                goto out_free_domain;
        }

        list_add_tail(&dev_state->list, &state_list);

        spin_unlock_irqrestore(&state_lock, flags);

        return 0;

out_drop_group:
        iommu_group_put(group);

out_free_domain:
        iommu_domain_free(dev_state->domain);

out_free_states:
        free_page((unsigned long)dev_state->states);

out_free_dev_state:
        kfree(dev_state);

        return ret;
}
EXPORT_SYMBOL(amd_iommu_init_device);

void amd_iommu_free_device(struct pci_dev *pdev)
{
        struct device_state *dev_state;
        unsigned long flags;
        u16 devid;

        if (!amd_iommu_v2_supported())
                return;

        devid = device_id(pdev);

        spin_lock_irqsave(&state_lock, flags);

        dev_state = __get_device_state(devid);
        if (dev_state == NULL) {
                spin_unlock_irqrestore(&state_lock, flags);
                return;
        }

        list_del(&dev_state->list);

        spin_unlock_irqrestore(&state_lock, flags);

        /* Get rid of any remaining pasid states */
        free_pasid_states(dev_state);

        put_device_state(dev_state);
        /*
         * Wait until the last reference is dropped before freeing
         * the device state.
         */
        wait_event(dev_state->wq, !atomic_read(&dev_state->count));
        free_device_state(dev_state);
}
EXPORT_SYMBOL(amd_iommu_free_device);

int amd_iommu_set_invalid_ppr_cb(struct pci_dev *pdev,
                                 amd_iommu_invalid_ppr_cb cb)
{
        struct device_state *dev_state;
        unsigned long flags;
        u16 devid;
        int ret;

        if (!amd_iommu_v2_supported())
                return -ENODEV;

        devid = device_id(pdev);

        spin_lock_irqsave(&state_lock, flags);

        ret = -EINVAL;
        dev_state = __get_device_state(devid);
        if (dev_state == NULL)
                goto out_unlock;

        dev_state->inv_ppr_cb = cb;

        ret = 0;

out_unlock:
        spin_unlock_irqrestore(&state_lock, flags);

        return ret;
}
EXPORT_SYMBOL(amd_iommu_set_invalid_ppr_cb);

int amd_iommu_set_invalidate_ctx_cb(struct pci_dev *pdev,
                                    amd_iommu_invalidate_ctx cb)
{
        struct device_state *dev_state;
        unsigned long flags;
        u16 devid;
        int ret;

        if (!amd_iommu_v2_supported())
                return -ENODEV;

        devid = device_id(pdev);

        spin_lock_irqsave(&state_lock, flags);

        ret = -EINVAL;
        dev_state = __get_device_state(devid);
        if (dev_state == NULL)
                goto out_unlock;

        dev_state->inv_ctx_cb = cb;

        ret = 0;

out_unlock:
        spin_unlock_irqrestore(&state_lock, flags);

        return ret;
}
EXPORT_SYMBOL(amd_iommu_set_invalidate_ctx_cb);

static int __init amd_iommu_v2_init(void)
{
        int ret;

        pr_info("AMD IOMMUv2 driver by Joerg Roedel <jroedel@suse.de>\n");

        if (!amd_iommu_v2_supported()) {
                pr_info("AMD IOMMUv2 functionality not available on this system\n");
                /*
                 * Load anyway to provide the symbols to other modules
                 * which may use AMD IOMMUv2 optionally.
                 */
                return 0;
        }

        spin_lock_init(&state_lock);

        ret = -ENOMEM;
        iommu_wq = create_workqueue("amd_iommu_v2");
        if (iommu_wq == NULL)
                goto out;

        amd_iommu_register_ppr_notifier(&ppr_nb);

        return 0;

out:
        return ret;
}

static void __exit amd_iommu_v2_exit(void)
{
        struct device_state *dev_state;
        int i;

        if (!amd_iommu_v2_supported())
                return;

        amd_iommu_unregister_ppr_notifier(&ppr_nb);

        flush_workqueue(iommu_wq);

        /*
         * The loop below might call flush_workqueue(), so call
         * destroy_workqueue() after it
         */
        for (i = 0; i < MAX_DEVICES; ++i) {
                dev_state = get_device_state(i);

                if (dev_state == NULL)
                        continue;

                WARN_ON_ONCE(1);

                put_device_state(dev_state);
                amd_iommu_free_device(dev_state->pdev);
        }

        destroy_workqueue(iommu_wq);
}

module_init(amd_iommu_v2_init);
module_exit(amd_iommu_v2_exit);