/*
 * Copyright 2020 Advanced Micro Devices, Inc.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
 * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR
 * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
 * OTHER DEALINGS IN THE SOFTWARE.
 */

#include <linux/poll.h>
#include <linux/wait.h>
#include <linux/anon_inodes.h>
#include <uapi/linux/kfd_ioctl.h>
#include "amdgpu_vm.h"
#include "kfd_priv.h"
#include "kfd_smi_events.h"

struct kfd_smi_client {
        struct list_head list;
        struct kfifo fifo;
        wait_queue_head_t wait_queue;
        /* events enabled */
        uint64_t events;
        struct kfd_dev *dev;
        spinlock_t lock;
};

#define MAX_KFIFO_SIZE  1024

static __poll_t kfd_smi_ev_poll(struct file *, struct poll_table_struct *);
static ssize_t kfd_smi_ev_read(struct file *, char __user *, size_t, loff_t *);
static ssize_t kfd_smi_ev_write(struct file *, const char __user *, size_t,
                                loff_t *);
static int kfd_smi_ev_release(struct inode *, struct file *);

static const char kfd_smi_name[] = "kfd_smi_ev";

static const struct file_operations kfd_smi_ev_fops = {
        .owner = THIS_MODULE,
        .poll = kfd_smi_ev_poll,
        .read = kfd_smi_ev_read,
        .write = kfd_smi_ev_write,
        .release = kfd_smi_ev_release
};

static __poll_t kfd_smi_ev_poll(struct file *filep,
                                struct poll_table_struct *wait)
{
        struct kfd_smi_client *client = filep->private_data;
        __poll_t mask = 0;

        poll_wait(filep, &client->wait_queue, wait);

        spin_lock(&client->lock);
        if (!kfifo_is_empty(&client->fifo))
                mask = EPOLLIN | EPOLLRDNORM;
        spin_unlock(&client->lock);

        return mask;
}

static ssize_t kfd_smi_ev_read(struct file *filep, char __user *user,
                               size_t size, loff_t *offset)
{
        int ret;
        size_t to_copy;
        struct kfd_smi_client *client = filep->private_data;
        unsigned char *buf;

        buf = kmalloc(MAX_KFIFO_SIZE * sizeof(*buf), GFP_KERNEL);
        if (!buf)
                return -ENOMEM;

        /* kfifo_to_user can sleep so we can't use spinlock protection around
         * it. Instead, we kfifo out as spinlocked then copy them to the user.
         */
        spin_lock(&client->lock);
        to_copy = kfifo_len(&client->fifo);
        if (!to_copy) {
                spin_unlock(&client->lock);
                ret = -EAGAIN;
                goto ret_err;
        }
        to_copy = min3(size, sizeof(buf), to_copy);
        ret = kfifo_out(&client->fifo, buf, to_copy);
        spin_unlock(&client->lock);
        if (ret <= 0) {
                ret = -EAGAIN;
                goto ret_err;
        }

        ret = copy_to_user(user, buf, to_copy);
        if (ret) {
                ret = -EFAULT;
                goto ret_err;
        }

        kfree(buf);
        return to_copy;

ret_err:
        kfree(buf);
        return ret;
}

static ssize_t kfd_smi_ev_write(struct file *filep, const char __user *user,
                                size_t size, loff_t *offset)
{
        struct kfd_smi_client *client = filep->private_data;
        uint64_t events;

        if (!access_ok(user, size) || size < sizeof(events))
                return -EFAULT;
        if (copy_from_user(&events, user, sizeof(events)))
                return -EFAULT;

        WRITE_ONCE(client->events, events);

        return sizeof(events);
}

static int kfd_smi_ev_release(struct inode *inode, struct file *filep)
{
        struct kfd_smi_client *client = filep->private_data;
        struct kfd_dev *dev = client->dev;

        spin_lock(&dev->smi_lock);
        list_del_rcu(&client->list);
        spin_unlock(&dev->smi_lock);

        synchronize_rcu();
        kfifo_free(&client->fifo);
        kfree(client);

        return 0;
}

void kfd_smi_event_update_vmfault(struct kfd_dev *dev, uint16_t pasid)
{
        struct amdgpu_device *adev = (struct amdgpu_device *)dev->kgd;
        struct amdgpu_task_info task_info;
        /* VmFault msg = (hex)uint32_pid(8) + :(1) + task name(16) = 25 */
        /* 16 bytes event + 1 byte space + 25 bytes msg + 1 byte \n = 43
         */
        char fifo_in[43];
        struct kfd_smi_client *client;
        int len;

        if (list_empty(&dev->smi_clients))
                return;

        memset(&task_info, 0, sizeof(struct amdgpu_task_info));
        amdgpu_vm_get_task_info(adev, pasid, &task_info);
        /* Report VM faults from user applications, not retry from kernel */
        if (!task_info.pid)
                return;

        len = snprintf(fifo_in, 43, "%x %x:%s\n", KFD_SMI_EVENT_VMFAULT,
                task_info.pid, task_info.task_name);

        rcu_read_lock();

        list_for_each_entry_rcu(client, &dev->smi_clients, list) {
                if (!(READ_ONCE(client->events) & KFD_SMI_EVENT_VMFAULT))
                        continue;
                spin_lock(&client->lock);
                if (kfifo_avail(&client->fifo) >= len) {
                        kfifo_in(&client->fifo, fifo_in, len);
                        wake_up_all(&client->wait_queue);
                }
                else
                        pr_debug("smi_event(vmfault): no space left\n");
                spin_unlock(&client->lock);
        }

        rcu_read_unlock();
}

int kfd_smi_event_open(struct kfd_dev *dev, uint32_t *fd)
{
        struct kfd_smi_client *client;
        int ret;

        client = kzalloc(sizeof(struct kfd_smi_client), GFP_KERNEL);
        if (!client)
                return -ENOMEM;
        INIT_LIST_HEAD(&client->list);

        ret = kfifo_alloc(&client->fifo, MAX_KFIFO_SIZE, GFP_KERNEL);
        if (ret) {
                kfree(client);
                return ret;
        }

        ret = anon_inode_getfd(kfd_smi_name, &kfd_smi_ev_fops, (void *)client,
                               O_RDWR);
        if (ret < 0) {
                kfifo_free(&client->fifo);
                kfree(client);
                return ret;
        }
        *fd = ret;

        init_waitqueue_head(&client->wait_queue);
        spin_lock_init(&client->lock);
        client->events = 0;
        client->dev = dev;

        spin_lock(&dev->smi_lock);
        list_add_rcu(&client->list, &dev->smi_clients);
        spin_unlock(&dev->smi_lock);

        return 0;
}