// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (c) 2023, NVIDIA CORPORATION & AFFILIATES. All rights reserved
 */

#include <linux/device.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/pci.h>
#include <linux/pm_runtime.h>
#include <linux/types.h>
#include <linux/uaccess.h>
#include <linux/vfio.h>
#include <linux/vfio_pci_core.h>
#include <linux/virtio_pci.h>
#include <linux/virtio_net.h>
#include <linux/virtio_pci_admin.h>

#include "common.h"

static int
virtiovf_issue_legacy_rw_cmd(struct virtiovf_pci_core_device *virtvdev,
                             loff_t pos, char __user *buf,
                             size_t count, bool read)
{
        bool msix_enabled =
                (virtvdev->core_device.irq_type == VFIO_PCI_MSIX_IRQ_INDEX);
        struct pci_dev *pdev = virtvdev->core_device.pdev;
        u8 *bar0_buf = virtvdev->bar0_virtual_buf;
        bool common;
        u8 offset;
        int ret;

        common = pos < VIRTIO_PCI_CONFIG_OFF(msix_enabled);
        /* offset within the relevant configuration area */
        offset = common ? pos : pos - VIRTIO_PCI_CONFIG_OFF(msix_enabled);
        mutex_lock(&virtvdev->bar_mutex);
        if (read) {
                if (common)
                        ret = virtio_pci_admin_legacy_common_io_read(pdev, offset,
                                        count, bar0_buf + pos);
                else
                        ret = virtio_pci_admin_legacy_device_io_read(pdev, offset,
                                        count, bar0_buf + pos);
                if (ret)
                        goto out;
                if (copy_to_user(buf, bar0_buf + pos, count))
                        ret = -EFAULT;
        } else {
                if (copy_from_user(bar0_buf + pos, buf, count)) {
                        ret = -EFAULT;
                        goto out;
                }

                if (common)
                        ret = virtio_pci_admin_legacy_common_io_write(pdev, offset,
                                        count, bar0_buf + pos);
                else
                        ret = virtio_pci_admin_legacy_device_io_write(pdev, offset,
                                        count, bar0_buf + pos);
        }
out:
        mutex_unlock(&virtvdev->bar_mutex);
        return ret;
}

static int
virtiovf_pci_bar0_rw(struct virtiovf_pci_core_device *virtvdev,
                     loff_t pos, char __user *buf,
                     size_t count, bool read)
{
        struct vfio_pci_core_device *core_device = &virtvdev->core_device;
        struct pci_dev *pdev = core_device->pdev;
        u16 queue_notify;
        int ret;

        if (!(le16_to_cpu(virtvdev->pci_cmd) & PCI_COMMAND_IO))
                return -EIO;

        if (pos + count > virtvdev->bar0_virtual_buf_size)
                return -EINVAL;

        ret = pm_runtime_resume_and_get(&pdev->dev);
        if (ret) {
                pci_info_ratelimited(pdev, "runtime resume failed %d\n", ret);
                return -EIO;
        }

        switch (pos) {
        case VIRTIO_PCI_QUEUE_NOTIFY:
                if (count != sizeof(queue_notify)) {
                        ret = -EINVAL;
                        goto end;
                }
                if (read) {
                        ret = vfio_pci_core_ioread16(core_device, true, &queue_notify,
                                                     virtvdev->notify_addr);
                        if (ret)
                                goto end;
                        if (copy_to_user(buf, &queue_notify,
                                         sizeof(queue_notify))) {
                                ret = -EFAULT;
                                goto end;
                        }
                } else {
                        if (copy_from_user(&queue_notify, buf, count)) {
                                ret = -EFAULT;
                                goto end;
                        }
                        ret = vfio_pci_core_iowrite16(core_device, true, queue_notify,
                                                      virtvdev->notify_addr);
                }
                break;
        default:
                ret = virtiovf_issue_legacy_rw_cmd(virtvdev, pos, buf, count,
                                                   read);
        }

end:
        pm_runtime_put(&pdev->dev);
        return ret ? ret : count;
}

static ssize_t virtiovf_pci_read_config(struct vfio_device *core_vdev,
                                        char __user *buf, size_t count,
                                        loff_t *ppos)
{
        struct virtiovf_pci_core_device *virtvdev = container_of(
                core_vdev, struct virtiovf_pci_core_device, core_device.vdev);
        loff_t pos = *ppos & VFIO_PCI_OFFSET_MASK;
        size_t register_offset;
        loff_t copy_offset;
        size_t copy_count;
        __le32 val32;
        __le16 val16;
        u8 val8;
        int ret;

        ret = vfio_pci_core_read(core_vdev, buf, count, ppos);
        if (ret < 0)
                return ret;

        if (vfio_pci_core_range_intersect_range(pos, count, PCI_DEVICE_ID,
                                                sizeof(val16), &copy_offset,
                                                &copy_count, &register_offset)) {
                val16 = cpu_to_le16(VIRTIO_TRANS_ID_NET);
                if (copy_to_user(buf + copy_offset, (void *)&val16 + register_offset, copy_count))
                        return -EFAULT;
        }

        if ((le16_to_cpu(virtvdev->pci_cmd) & PCI_COMMAND_IO) &&
            vfio_pci_core_range_intersect_range(pos, count, PCI_COMMAND,
                                                sizeof(val16), &copy_offset,
                                                &copy_count, &register_offset)) {
                if (copy_from_user((void *)&val16 + register_offset, buf + copy_offset,
                                   copy_count))
                        return -EFAULT;
                val16 |= cpu_to_le16(PCI_COMMAND_IO);
                if (copy_to_user(buf + copy_offset, (void *)&val16 + register_offset,
                                 copy_count))
                        return -EFAULT;
        }

        if (vfio_pci_core_range_intersect_range(pos, count, PCI_REVISION_ID,
                                                sizeof(val8), &copy_offset,
                                                &copy_count, &register_offset)) {
                /* Transional needs to have revision 0 */
                val8 = 0;
                if (copy_to_user(buf + copy_offset, &val8, copy_count))
                        return -EFAULT;
        }

        if (vfio_pci_core_range_intersect_range(pos, count, PCI_BASE_ADDRESS_0,
                                                sizeof(val32), &copy_offset,
                                                &copy_count, &register_offset)) {
                u32 bar_mask = ~(virtvdev->bar0_virtual_buf_size - 1);
                u32 pci_base_addr_0 = le32_to_cpu(virtvdev->pci_base_addr_0);

                val32 = cpu_to_le32((pci_base_addr_0 & bar_mask) | PCI_BASE_ADDRESS_SPACE_IO);
                if (copy_to_user(buf + copy_offset, (void *)&val32 + register_offset, copy_count))
                        return -EFAULT;
        }

        if (vfio_pci_core_range_intersect_range(pos, count, PCI_SUBSYSTEM_ID,
                                                sizeof(val16), &copy_offset,
                                                &copy_count, &register_offset)) {
                /*
                 * Transitional devices use the PCI subsystem device id as
                 * virtio device id, same as legacy driver always did.
                 */
                val16 = cpu_to_le16(VIRTIO_ID_NET);
                if (copy_to_user(buf + copy_offset, (void *)&val16 + register_offset,
                                 copy_count))
                        return -EFAULT;
        }

        if (vfio_pci_core_range_intersect_range(pos, count, PCI_SUBSYSTEM_VENDOR_ID,
                                                sizeof(val16), &copy_offset,
                                                &copy_count, &register_offset)) {
                val16 = cpu_to_le16(PCI_VENDOR_ID_REDHAT_QUMRANET);
                if (copy_to_user(buf + copy_offset, (void *)&val16 + register_offset,
                                 copy_count))
                        return -EFAULT;
        }

        return count;
}

ssize_t virtiovf_pci_core_read(struct vfio_device *core_vdev, char __user *buf,
                               size_t count, loff_t *ppos)
{
        struct virtiovf_pci_core_device *virtvdev = container_of(
                core_vdev, struct virtiovf_pci_core_device, core_device.vdev);
        unsigned int index = VFIO_PCI_OFFSET_TO_INDEX(*ppos);
        loff_t pos = *ppos & VFIO_PCI_OFFSET_MASK;

        if (!count)
                return 0;

        if (index == VFIO_PCI_CONFIG_REGION_INDEX)
                return virtiovf_pci_read_config(core_vdev, buf, count, ppos);

        if (index == VFIO_PCI_BAR0_REGION_INDEX)
                return virtiovf_pci_bar0_rw(virtvdev, pos, buf, count, true);

        return vfio_pci_core_read(core_vdev, buf, count, ppos);
}

static ssize_t virtiovf_pci_write_config(struct vfio_device *core_vdev,
                                         const char __user *buf, size_t count,
                                         loff_t *ppos)
{
        struct virtiovf_pci_core_device *virtvdev = container_of(
                core_vdev, struct virtiovf_pci_core_device, core_device.vdev);
        loff_t pos = *ppos & VFIO_PCI_OFFSET_MASK;
        size_t register_offset;
        loff_t copy_offset;
        size_t copy_count;

        if (vfio_pci_core_range_intersect_range(pos, count, PCI_COMMAND,
                                                sizeof(virtvdev->pci_cmd),
                                                &copy_offset, &copy_count,
                                                &register_offset)) {
                if (copy_from_user((void *)&virtvdev->pci_cmd + register_offset,
                                   buf + copy_offset,
                                   copy_count))
                        return -EFAULT;
        }

        if (vfio_pci_core_range_intersect_range(pos, count, PCI_BASE_ADDRESS_0,
                                                sizeof(virtvdev->pci_base_addr_0),
                                                &copy_offset, &copy_count,
                                                &register_offset)) {
                if (copy_from_user((void *)&virtvdev->pci_base_addr_0 + register_offset,
                                   buf + copy_offset,
                                   copy_count))
                        return -EFAULT;
        }

        return vfio_pci_core_write(core_vdev, buf, count, ppos);
}

ssize_t virtiovf_pci_core_write(struct vfio_device *core_vdev, const char __user *buf,
                                size_t count, loff_t *ppos)
{
        struct virtiovf_pci_core_device *virtvdev = container_of(
                core_vdev, struct virtiovf_pci_core_device, core_device.vdev);
        unsigned int index = VFIO_PCI_OFFSET_TO_INDEX(*ppos);
        loff_t pos = *ppos & VFIO_PCI_OFFSET_MASK;

        if (!count)
                return 0;

        if (index == VFIO_PCI_CONFIG_REGION_INDEX)
                return virtiovf_pci_write_config(core_vdev, buf, count, ppos);

        if (index == VFIO_PCI_BAR0_REGION_INDEX)
                return virtiovf_pci_bar0_rw(virtvdev, pos, (char __user *)buf, count, false);

        return vfio_pci_core_write(core_vdev, buf, count, ppos);
}

int virtiovf_pci_ioctl_get_region_info(struct vfio_device *core_vdev,
                                       struct vfio_region_info *info,
                                       struct vfio_info_cap *caps)
{
        struct virtiovf_pci_core_device *virtvdev = container_of(
                core_vdev, struct virtiovf_pci_core_device, core_device.vdev);

        if (info->index != VFIO_PCI_BAR0_REGION_INDEX)
                return vfio_pci_ioctl_get_region_info(core_vdev, info, caps);

        info->offset = VFIO_PCI_INDEX_TO_OFFSET(info->index);
        info->size = virtvdev->bar0_virtual_buf_size;
        info->flags = VFIO_REGION_INFO_FLAG_READ | VFIO_REGION_INFO_FLAG_WRITE;
        return 0;
}

static int virtiovf_set_notify_addr(struct virtiovf_pci_core_device *virtvdev)
{
        struct vfio_pci_core_device *core_device = &virtvdev->core_device;
        int ret;

        /*
         * Setup the BAR where the 'notify' exists to be used by vfio as well
         * This will let us mmap it only once and use it when needed.
         */
        ret = vfio_pci_core_setup_barmap(core_device,
                                         virtvdev->notify_bar);
        if (ret)
                return ret;

        virtvdev->notify_addr = core_device->barmap[virtvdev->notify_bar] +
                        virtvdev->notify_offset;
        return 0;
}

int virtiovf_open_legacy_io(struct virtiovf_pci_core_device *virtvdev)
{
        if (!virtvdev->bar0_virtual_buf)
                return 0;

        /*
         * Upon close_device() the vfio_pci_core_disable() is called
         * and will close all the previous mmaps, so it seems that the
         * valid life cycle for the 'notify' addr is per open/close.
         */
        return virtiovf_set_notify_addr(virtvdev);
}

static int virtiovf_get_device_config_size(unsigned short device)
{
        /* Network card */
        return offsetofend(struct virtio_net_config, status);
}

static int virtiovf_read_notify_info(struct virtiovf_pci_core_device *virtvdev)
{
        u64 offset;
        int ret;
        u8 bar;

        ret = virtio_pci_admin_legacy_io_notify_info(virtvdev->core_device.pdev,
                                VIRTIO_ADMIN_CMD_NOTIFY_INFO_FLAGS_OWNER_MEM,
                                &bar, &offset);
        if (ret)
                return ret;

        virtvdev->notify_bar = bar;
        virtvdev->notify_offset = offset;
        return 0;
}

static bool virtiovf_bar0_exists(struct pci_dev *pdev)
{
        struct resource *res = pdev->resource;

        return res->flags;
}

bool virtiovf_support_legacy_io(struct pci_dev *pdev)
{
        /* For now, the legacy IO functionality is supported only for virtio-net */
        return pdev->device == 0x1041 && virtio_pci_admin_has_legacy_io(pdev) &&
               !virtiovf_bar0_exists(pdev);
}

int virtiovf_init_legacy_io(struct virtiovf_pci_core_device *virtvdev)
{
        struct pci_dev *pdev = virtvdev->core_device.pdev;
        int ret;

        ret = virtiovf_read_notify_info(virtvdev);
        if (ret)
                return ret;

        virtvdev->bar0_virtual_buf_size = VIRTIO_PCI_CONFIG_OFF(true) +
                                virtiovf_get_device_config_size(pdev->device);
        BUILD_BUG_ON(!is_power_of_2(virtvdev->bar0_virtual_buf_size));
        virtvdev->bar0_virtual_buf = kzalloc(virtvdev->bar0_virtual_buf_size,
                                             GFP_KERNEL);
        if (!virtvdev->bar0_virtual_buf)
                return -ENOMEM;
        mutex_init(&virtvdev->bar_mutex);
        return 0;
}

void virtiovf_release_legacy_io(struct virtiovf_pci_core_device *virtvdev)
{
        kfree(virtvdev->bar0_virtual_buf);
}

void virtiovf_legacy_io_reset_done(struct pci_dev *pdev)
{
        struct virtiovf_pci_core_device *virtvdev = dev_get_drvdata(&pdev->dev);

        virtvdev->pci_cmd = 0;
}