/*
 * Copyright (C) 2012 Red Hat, Inc.  All rights reserved.
 *     Author: Alex Williamson <alex.williamson@redhat.com>
 *
 * 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:
 * Copyright 2010 Cisco Systems, Inc.  All rights reserved.
 * Author: Tom Lyon, pugs@cisco.com
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/device.h>
#include <linux/eventfd.h>
#include <linux/file.h>
#include <linux/interrupt.h>
#include <linux/iommu.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/notifier.h>
#include <linux/pci.h>
#include <linux/pm_runtime.h>
#include <linux/slab.h>
#include <linux/types.h>
#include <linux/uaccess.h>
#include <linux/vfio.h>
#include <linux/vgaarb.h>

#include "vfio_pci_private.h"

#define DRIVER_VERSION  "0.2"
#define DRIVER_AUTHOR   "Alex Williamson <alex.williamson@redhat.com>"
#define DRIVER_DESC     "VFIO PCI - User Level meta-driver"

static char ids[1024] __initdata;
module_param_string(ids, ids, sizeof(ids), 0);
MODULE_PARM_DESC(ids, "Initial PCI IDs to add to the vfio driver, format is \"vendor:device[:subvendor[:subdevice[:class[:class_mask]]]]\" and multiple comma separated entries can be specified");

static bool nointxmask;
module_param_named(nointxmask, nointxmask, bool, S_IRUGO | S_IWUSR);
MODULE_PARM_DESC(nointxmask,
                  "Disable support for PCI 2.3 style INTx masking.  If this resolves problems for specific devices, report lspci -vvvxxx to linux-pci@vger.kernel.org so the device can be fixed automatically via the broken_intx_masking flag.");

#ifdef CONFIG_VFIO_PCI_VGA
static bool disable_vga;
module_param(disable_vga, bool, S_IRUGO);
MODULE_PARM_DESC(disable_vga, "Disable VGA resource access through vfio-pci");
#endif

static bool disable_idle_d3;
module_param(disable_idle_d3, bool, S_IRUGO | S_IWUSR);
MODULE_PARM_DESC(disable_idle_d3,
                 "Disable using the PCI D3 low power state for idle, unused devices");

static DEFINE_MUTEX(driver_lock);

static inline bool vfio_vga_disabled(void)
{
#ifdef CONFIG_VFIO_PCI_VGA
        return disable_vga;
#else
        return true;
#endif
}

/*
 * Our VGA arbiter participation is limited since we don't know anything
 * about the device itself.  However, if the device is the only VGA device
 * downstream of a bridge and VFIO VGA support is disabled, then we can
 * safely return legacy VGA IO and memory as not decoded since the user
 * has no way to get to it and routing can be disabled externally at the
 * bridge.
 */
static unsigned int vfio_pci_set_vga_decode(void *opaque, bool single_vga)
{
        struct vfio_pci_device *vdev = opaque;
        struct pci_dev *tmp = NULL, *pdev = vdev->pdev;
        unsigned char max_busnr;
        unsigned int decodes;

        if (single_vga || !vfio_vga_disabled() || pci_is_root_bus(pdev->bus))
                return VGA_RSRC_NORMAL_IO | VGA_RSRC_NORMAL_MEM |
                       VGA_RSRC_LEGACY_IO | VGA_RSRC_LEGACY_MEM;

        max_busnr = pci_bus_max_busnr(pdev->bus);
        decodes = VGA_RSRC_NORMAL_IO | VGA_RSRC_NORMAL_MEM;

        while ((tmp = pci_get_class(PCI_CLASS_DISPLAY_VGA << 8, tmp)) != NULL) {
                if (tmp == pdev ||
                    pci_domain_nr(tmp->bus) != pci_domain_nr(pdev->bus) ||
                    pci_is_root_bus(tmp->bus))
                        continue;

                if (tmp->bus->number >= pdev->bus->number &&
                    tmp->bus->number <= max_busnr) {
                        pci_dev_put(tmp);
                        decodes |= VGA_RSRC_LEGACY_IO | VGA_RSRC_LEGACY_MEM;
                        break;
                }
        }

        return decodes;
}

static inline bool vfio_pci_is_vga(struct pci_dev *pdev)
{
        return (pdev->class >> 8) == PCI_CLASS_DISPLAY_VGA;
}

static void vfio_pci_probe_mmaps(struct vfio_pci_device *vdev)
{
        struct resource *res;
        int bar;
        struct vfio_pci_dummy_resource *dummy_res;

        INIT_LIST_HEAD(&vdev->dummy_resources_list);

        for (bar = PCI_STD_RESOURCES; bar <= PCI_STD_RESOURCE_END; bar++) {
                res = vdev->pdev->resource + bar;

                if (!IS_ENABLED(CONFIG_VFIO_PCI_MMAP))
                        goto no_mmap;

                if (!(res->flags & IORESOURCE_MEM))
                        goto no_mmap;

                /*
                 * The PCI core shouldn't set up a resource with a
                 * type but zero size. But there may be bugs that
                 * cause us to do that.
                 */
                if (!resource_size(res))
                        goto no_mmap;

                if (resource_size(res) >= PAGE_SIZE) {
                        vdev->bar_mmap_supported[bar] = true;
                        continue;
                }

                if (!(res->start & ~PAGE_MASK)) {
                        /*
                         * Add a dummy resource to reserve the remainder
                         * of the exclusive page in case that hot-add
                         * device's bar is assigned into it.
                         */
                        dummy_res = kzalloc(sizeof(*dummy_res), GFP_KERNEL);
                        if (dummy_res == NULL)
                                goto no_mmap;

                        dummy_res->resource.name = "vfio sub-page reserved";
                        dummy_res->resource.start = res->end + 1;
                        dummy_res->resource.end = res->start + PAGE_SIZE - 1;
                        dummy_res->resource.flags = res->flags;
                        if (request_resource(res->parent,
                                                &dummy_res->resource)) {
                                kfree(dummy_res);
                                goto no_mmap;
                        }
                        dummy_res->index = bar;
                        list_add(&dummy_res->res_next,
                                        &vdev->dummy_resources_list);
                        vdev->bar_mmap_supported[bar] = true;
                        continue;
                }
                /*
                 * Here we don't handle the case when the BAR is not page
                 * aligned because we can't expect the BAR will be
                 * assigned into the same location in a page in guest
                 * when we passthrough the BAR. And it's hard to access
                 * this BAR in userspace because we have no way to get
                 * the BAR's location in a page.
                 */
no_mmap:
                vdev->bar_mmap_supported[bar] = false;
        }
}

static void vfio_pci_try_bus_reset(struct vfio_pci_device *vdev);
static void vfio_pci_disable(struct vfio_pci_device *vdev);

/*
 * INTx masking requires the ability to disable INTx signaling via PCI_COMMAND
 * _and_ the ability detect when the device is asserting INTx via PCI_STATUS.
 * If a device implements the former but not the latter we would typically
 * expect broken_intx_masking be set and require an exclusive interrupt.
 * However since we do have control of the device's ability to assert INTx,
 * we can instead pretend that the device does not implement INTx, virtualizing
 * the pin register to report zero and maintaining DisINTx set on the host.
 */
static bool vfio_pci_nointx(struct pci_dev *pdev)
{
        switch (pdev->vendor) {
        case PCI_VENDOR_ID_INTEL:
                switch (pdev->device) {
                /* All i40e (XL710/X710/XXV710) 10/20/25/40GbE NICs */
                case 0x1572:
                case 0x1574:
                case 0x1580 ... 0x1581:
                case 0x1583 ... 0x158b:
                case 0x37d0 ... 0x37d2:
                        return true;
                default:
                        return false;
                }
        }

        return false;
}

static int vfio_pci_enable(struct vfio_pci_device *vdev)
{
        struct pci_dev *pdev = vdev->pdev;
        int ret;
        u16 cmd;
        u8 msix_pos;

        pci_set_power_state(pdev, PCI_D0);

        /* Don't allow our initial saved state to include busmaster */
        pci_clear_master(pdev);

        ret = pci_enable_device(pdev);
        if (ret)
                return ret;

        /* If reset fails because of the device lock, fail this path entirely */
        ret = pci_try_reset_function(pdev);
        if (ret == -EAGAIN) {
                pci_disable_device(pdev);
                return ret;
        }

        vdev->reset_works = !ret;
        pci_save_state(pdev);
        vdev->pci_saved_state = pci_store_saved_state(pdev);
        if (!vdev->pci_saved_state)
                pr_debug("%s: Couldn't store %s saved state\n",
                         __func__, dev_name(&pdev->dev));

        if (likely(!nointxmask)) {
                if (vfio_pci_nointx(pdev)) {
                        dev_info(&pdev->dev, "Masking broken INTx support\n");
                        vdev->nointx = true;
                        pci_intx(pdev, 0);
                } else
                        vdev->pci_2_3 = pci_intx_mask_supported(pdev);
        }

        pci_read_config_word(pdev, PCI_COMMAND, &cmd);
        if (vdev->pci_2_3 && (cmd & PCI_COMMAND_INTX_DISABLE)) {
                cmd &= ~PCI_COMMAND_INTX_DISABLE;
                pci_write_config_word(pdev, PCI_COMMAND, cmd);
        }

        ret = vfio_config_init(vdev);
        if (ret) {
                kfree(vdev->pci_saved_state);
                vdev->pci_saved_state = NULL;
                pci_disable_device(pdev);
                return ret;
        }

        msix_pos = pdev->msix_cap;
        if (msix_pos) {
                u16 flags;
                u32 table;

                pci_read_config_word(pdev, msix_pos + PCI_MSIX_FLAGS, &flags);
                pci_read_config_dword(pdev, msix_pos + PCI_MSIX_TABLE, &table);

                vdev->msix_bar = table & PCI_MSIX_TABLE_BIR;
                vdev->msix_offset = table & PCI_MSIX_TABLE_OFFSET;
                vdev->msix_size = ((flags & PCI_MSIX_FLAGS_QSIZE) + 1) * 16;
        } else
                vdev->msix_bar = 0xFF;

        if (!vfio_vga_disabled() && vfio_pci_is_vga(pdev))
                vdev->has_vga = true;


        if (vfio_pci_is_vga(pdev) &&
            pdev->vendor == PCI_VENDOR_ID_INTEL &&
            IS_ENABLED(CONFIG_VFIO_PCI_IGD)) {
                ret = vfio_pci_igd_init(vdev);
                if (ret) {
                        dev_warn(&vdev->pdev->dev,
                                 "Failed to setup Intel IGD regions\n");
                        vfio_pci_disable(vdev);
                        return ret;
                }
        }

        vfio_pci_probe_mmaps(vdev);

        return 0;
}

static void vfio_pci_disable(struct vfio_pci_device *vdev)
{
        struct pci_dev *pdev = vdev->pdev;
        struct vfio_pci_dummy_resource *dummy_res, *tmp;
        int i, bar;

        /* Stop the device from further DMA */
        pci_clear_master(pdev);

        vfio_pci_set_irqs_ioctl(vdev, VFIO_IRQ_SET_DATA_NONE |
                                VFIO_IRQ_SET_ACTION_TRIGGER,
                                vdev->irq_type, 0, 0, NULL);

        vdev->virq_disabled = false;

        for (i = 0; i < vdev->num_regions; i++)
                vdev->region[i].ops->release(vdev, &vdev->region[i]);

        vdev->num_regions = 0;
        kfree(vdev->region);
        vdev->region = NULL; /* don't krealloc a freed pointer */

        vfio_config_free(vdev);

        for (bar = PCI_STD_RESOURCES; bar <= PCI_STD_RESOURCE_END; bar++) {
                if (!vdev->barmap[bar])
                        continue;
                pci_iounmap(pdev, vdev->barmap[bar]);
                pci_release_selected_regions(pdev, 1 << bar);
                vdev->barmap[bar] = NULL;
        }

        list_for_each_entry_safe(dummy_res, tmp,
                                 &vdev->dummy_resources_list, res_next) {
                list_del(&dummy_res->res_next);
                release_resource(&dummy_res->resource);
                kfree(dummy_res);
        }

        vdev->needs_reset = true;

        /*
         * If we have saved state, restore it.  If we can reset the device,
         * even better.  Resetting with current state seems better than
         * nothing, but saving and restoring current state without reset
         * is just busy work.
         */
        if (pci_load_and_free_saved_state(pdev, &vdev->pci_saved_state)) {
                pr_info("%s: Couldn't reload %s saved state\n",
                        __func__, dev_name(&pdev->dev));

                if (!vdev->reset_works)
                        goto out;

                pci_save_state(pdev);
        }

        /*
         * Disable INTx and MSI, presumably to avoid spurious interrupts
         * during reset.  Stolen from pci_reset_function()
         */
        pci_write_config_word(pdev, PCI_COMMAND, PCI_COMMAND_INTX_DISABLE);

        /*
         * Try to reset the device.  The success of this is dependent on
         * being able to lock the device, which is not always possible.
         */
        if (vdev->reset_works && !pci_try_reset_function(pdev))
                vdev->needs_reset = false;

        pci_restore_state(pdev);
out:
        pci_disable_device(pdev);

        vfio_pci_try_bus_reset(vdev);

        if (!disable_idle_d3)
                pci_set_power_state(pdev, PCI_D3hot);
}

static void vfio_pci_release(void *device_data)
{
        struct vfio_pci_device *vdev = device_data;

        mutex_lock(&driver_lock);

        if (!(--vdev->refcnt)) {
                vfio_spapr_pci_eeh_release(vdev->pdev);
                vfio_pci_disable(vdev);
        }

        mutex_unlock(&driver_lock);

        module_put(THIS_MODULE);
}

static int vfio_pci_open(void *device_data)
{
        struct vfio_pci_device *vdev = device_data;
        int ret = 0;

        if (!try_module_get(THIS_MODULE))
                return -ENODEV;

        mutex_lock(&driver_lock);

        if (!vdev->refcnt) {
                ret = vfio_pci_enable(vdev);
                if (ret)
                        goto error;

                vfio_spapr_pci_eeh_open(vdev->pdev);
        }
        vdev->refcnt++;
error:
        mutex_unlock(&driver_lock);
        if (ret)
                module_put(THIS_MODULE);
        return ret;
}

static int vfio_pci_get_irq_count(struct vfio_pci_device *vdev, int irq_type)
{
        if (irq_type == VFIO_PCI_INTX_IRQ_INDEX) {
                u8 pin;
                pci_read_config_byte(vdev->pdev, PCI_INTERRUPT_PIN, &pin);
                if (IS_ENABLED(CONFIG_VFIO_PCI_INTX) && !vdev->nointx && pin)
                        return 1;

        } else if (irq_type == VFIO_PCI_MSI_IRQ_INDEX) {
                u8 pos;
                u16 flags;

                pos = vdev->pdev->msi_cap;
                if (pos) {
                        pci_read_config_word(vdev->pdev,
                                             pos + PCI_MSI_FLAGS, &flags);
                        return 1 << ((flags & PCI_MSI_FLAGS_QMASK) >> 1);
                }
        } else if (irq_type == VFIO_PCI_MSIX_IRQ_INDEX) {
                u8 pos;
                u16 flags;

                pos = vdev->pdev->msix_cap;
                if (pos) {
                        pci_read_config_word(vdev->pdev,
                                             pos + PCI_MSIX_FLAGS, &flags);

                        return (flags & PCI_MSIX_FLAGS_QSIZE) + 1;
                }
        } else if (irq_type == VFIO_PCI_ERR_IRQ_INDEX) {
                if (pci_is_pcie(vdev->pdev))
                        return 1;
        } else if (irq_type == VFIO_PCI_REQ_IRQ_INDEX) {
                return 1;
        }

        return 0;
}

static int vfio_pci_count_devs(struct pci_dev *pdev, void *data)
{
        (*(int *)data)++;
        return 0;
}

struct vfio_pci_fill_info {
        int max;
        int cur;
        struct vfio_pci_dependent_device *devices;
};

static int vfio_pci_fill_devs(struct pci_dev *pdev, void *data)
{
        struct vfio_pci_fill_info *fill = data;
        struct iommu_group *iommu_group;

        if (fill->cur == fill->max)
                return -EAGAIN; /* Something changed, try again */

        iommu_group = iommu_group_get(&pdev->dev);
        if (!iommu_group)
                return -EPERM; /* Cannot reset non-isolated devices */

        fill->devices[fill->cur].group_id = iommu_group_id(iommu_group);
        fill->devices[fill->cur].segment = pci_domain_nr(pdev->bus);
        fill->devices[fill->cur].bus = pdev->bus->number;
        fill->devices[fill->cur].devfn = pdev->devfn;
        fill->cur++;
        iommu_group_put(iommu_group);
        return 0;
}

struct vfio_pci_group_entry {
        struct vfio_group *group;
        int id;
};

struct vfio_pci_group_info {
        int count;
        struct vfio_pci_group_entry *groups;
};

static int vfio_pci_validate_devs(struct pci_dev *pdev, void *data)
{
        struct vfio_pci_group_info *info = data;
        struct iommu_group *group;
        int id, i;

        group = iommu_group_get(&pdev->dev);
        if (!group)
                return -EPERM;

        id = iommu_group_id(group);

        for (i = 0; i < info->count; i++)
                if (info->groups[i].id == id)
                        break;

        iommu_group_put(group);

        return (i == info->count) ? -EINVAL : 0;
}

static bool vfio_pci_dev_below_slot(struct pci_dev *pdev, struct pci_slot *slot)
{
        for (; pdev; pdev = pdev->bus->self)
                if (pdev->bus == slot->bus)
                        return (pdev->slot == slot);
        return false;
}

struct vfio_pci_walk_info {
        int (*fn)(struct pci_dev *, void *data);
        void *data;
        struct pci_dev *pdev;
        bool slot;
        int ret;
};

static int vfio_pci_walk_wrapper(struct pci_dev *pdev, void *data)
{
        struct vfio_pci_walk_info *walk = data;

        if (!walk->slot || vfio_pci_dev_below_slot(pdev, walk->pdev->slot))
                walk->ret = walk->fn(pdev, walk->data);

        return walk->ret;
}

static int vfio_pci_for_each_slot_or_bus(struct pci_dev *pdev,
                                         int (*fn)(struct pci_dev *,
                                                   void *data), void *data,
                                         bool slot)
{
        struct vfio_pci_walk_info walk = {
                .fn = fn, .data = data, .pdev = pdev, .slot = slot, .ret = 0,
        };

        pci_walk_bus(pdev->bus, vfio_pci_walk_wrapper, &walk);

        return walk.ret;
}

static int msix_sparse_mmap_cap(struct vfio_pci_device *vdev,
                                struct vfio_info_cap *caps)
{
        struct vfio_region_info_cap_sparse_mmap *sparse;
        size_t end, size;
        int nr_areas = 2, i = 0, ret;

        end = pci_resource_len(vdev->pdev, vdev->msix_bar);

        /* If MSI-X table is aligned to the start or end, only one area */
        if (((vdev->msix_offset & PAGE_MASK) == 0) ||
            (PAGE_ALIGN(vdev->msix_offset + vdev->msix_size) >= end))
                nr_areas = 1;

        size = sizeof(*sparse) + (nr_areas * sizeof(*sparse->areas));

        sparse = kzalloc(size, GFP_KERNEL);
        if (!sparse)
                return -ENOMEM;

        sparse->nr_areas = nr_areas;

        if (vdev->msix_offset & PAGE_MASK) {
                sparse->areas[i].offset = 0;
                sparse->areas[i].size = vdev->msix_offset & PAGE_MASK;
                i++;
        }

        if (PAGE_ALIGN(vdev->msix_offset + vdev->msix_size) < end) {
                sparse->areas[i].offset = PAGE_ALIGN(vdev->msix_offset +
                                                     vdev->msix_size);
                sparse->areas[i].size = end - sparse->areas[i].offset;
                i++;
        }

        ret = vfio_info_add_capability(caps, VFIO_REGION_INFO_CAP_SPARSE_MMAP,
                                       sparse);
        kfree(sparse);

        return ret;
}

int vfio_pci_register_dev_region(struct vfio_pci_device *vdev,
                                 unsigned int type, unsigned int subtype,
                                 const struct vfio_pci_regops *ops,
                                 size_t size, u32 flags, void *data)
{
        struct vfio_pci_region *region;

        region = krealloc(vdev->region,
                          (vdev->num_regions + 1) * sizeof(*region),
                          GFP_KERNEL);
        if (!region)
                return -ENOMEM;

        vdev->region = region;
        vdev->region[vdev->num_regions].type = type;
        vdev->region[vdev->num_regions].subtype = subtype;
        vdev->region[vdev->num_regions].ops = ops;
        vdev->region[vdev->num_regions].size = size;
        vdev->region[vdev->num_regions].flags = flags;
        vdev->region[vdev->num_regions].data = data;

        vdev->num_regions++;

        return 0;
}

static long vfio_pci_ioctl(void *device_data,
                           unsigned int cmd, unsigned long arg)
{
        struct vfio_pci_device *vdev = device_data;
        unsigned long minsz;

        if (cmd == VFIO_DEVICE_GET_INFO) {
                struct vfio_device_info info;

                minsz = offsetofend(struct vfio_device_info, num_irqs);

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

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

                info.flags = VFIO_DEVICE_FLAGS_PCI;

                if (vdev->reset_works)
                        info.flags |= VFIO_DEVICE_FLAGS_RESET;

                info.num_regions = VFIO_PCI_NUM_REGIONS + vdev->num_regions;
                info.num_irqs = VFIO_PCI_NUM_IRQS;

                return copy_to_user((void __user *)arg, &info, minsz) ?
                        -EFAULT : 0;

        } else if (cmd == VFIO_DEVICE_GET_REGION_INFO) {
                struct pci_dev *pdev = vdev->pdev;
                struct vfio_region_info info;
                struct vfio_info_cap caps = { .buf = NULL, .size = 0 };
                int i, ret;

                minsz = offsetofend(struct vfio_region_info, offset);

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

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

                switch (info.index) {
                case VFIO_PCI_CONFIG_REGION_INDEX:
                        info.offset = VFIO_PCI_INDEX_TO_OFFSET(info.index);
                        info.size = pdev->cfg_size;
                        info.flags = VFIO_REGION_INFO_FLAG_READ |
                                     VFIO_REGION_INFO_FLAG_WRITE;
                        break;
                case VFIO_PCI_BAR0_REGION_INDEX ... VFIO_PCI_BAR5_REGION_INDEX:
                        info.offset = VFIO_PCI_INDEX_TO_OFFSET(info.index);
                        info.size = pci_resource_len(pdev, info.index);
                        if (!info.size) {
                                info.flags = 0;
                                break;
                        }

                        info.flags = VFIO_REGION_INFO_FLAG_READ |
                                     VFIO_REGION_INFO_FLAG_WRITE;
                        if (vdev->bar_mmap_supported[info.index]) {
                                info.flags |= VFIO_REGION_INFO_FLAG_MMAP;
                                if (info.index == vdev->msix_bar) {
                                        ret = msix_sparse_mmap_cap(vdev, &caps);
                                        if (ret)
                                                return ret;
                                }
                        }

                        break;
                case VFIO_PCI_ROM_REGION_INDEX:
                {
                        void __iomem *io;
                        size_t size;

                        info.offset = VFIO_PCI_INDEX_TO_OFFSET(info.index);
                        info.flags = 0;

                        /* Report the BAR size, not the ROM size */
                        info.size = pci_resource_len(pdev, info.index);
                        if (!info.size) {
                                /* Shadow ROMs appear as PCI option ROMs */
                                if (pdev->resource[PCI_ROM_RESOURCE].flags &
                                                        IORESOURCE_ROM_SHADOW)
                                        info.size = 0x20000;
                                else
                                        break;
                        }

                        /* Is it really there? */
                        io = pci_map_rom(pdev, &size);
                        if (!io || !size) {
                                info.size = 0;
                                break;
                        }
                        pci_unmap_rom(pdev, io);

                        info.flags = VFIO_REGION_INFO_FLAG_READ;
                        break;
                }
                case VFIO_PCI_VGA_REGION_INDEX:
                        if (!vdev->has_vga)
                                return -EINVAL;

                        info.offset = VFIO_PCI_INDEX_TO_OFFSET(info.index);
                        info.size = 0xc0000;
                        info.flags = VFIO_REGION_INFO_FLAG_READ |
                                     VFIO_REGION_INFO_FLAG_WRITE;

                        break;
                default:
                {
                        struct vfio_region_info_cap_type cap_type;

                        if (info.index >=
                            VFIO_PCI_NUM_REGIONS + vdev->num_regions)
                                return -EINVAL;

                        i = info.index - VFIO_PCI_NUM_REGIONS;

                        info.offset = VFIO_PCI_INDEX_TO_OFFSET(info.index);
                        info.size = vdev->region[i].size;
                        info.flags = vdev->region[i].flags;

                        cap_type.type = vdev->region[i].type;
                        cap_type.subtype = vdev->region[i].subtype;

                        ret = vfio_info_add_capability(&caps,
                                                      VFIO_REGION_INFO_CAP_TYPE,
                                                      &cap_type);
                        if (ret)
                                return ret;

                }
                }

                if (caps.size) {
                        info.flags |= VFIO_REGION_INFO_FLAG_CAPS;
                        if (info.argsz < sizeof(info) + caps.size) {
                                info.argsz = sizeof(info) + caps.size;
                                info.cap_offset = 0;
                        } else {
                                vfio_info_cap_shift(&caps, sizeof(info));
                                if (copy_to_user((void __user *)arg +
                                                  sizeof(info), caps.buf,
                                                  caps.size)) {
                                        kfree(caps.buf);
                                        return -EFAULT;
                                }
                                info.cap_offset = sizeof(info);
                        }

                        kfree(caps.buf);
                }

                return copy_to_user((void __user *)arg, &info, minsz) ?
                        -EFAULT : 0;

        } else if (cmd == VFIO_DEVICE_GET_IRQ_INFO) {
                struct vfio_irq_info info;

                minsz = offsetofend(struct vfio_irq_info, count);

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

                if (info.argsz < minsz || info.index >= VFIO_PCI_NUM_IRQS)
                        return -EINVAL;

                switch (info.index) {
                case VFIO_PCI_INTX_IRQ_INDEX ... VFIO_PCI_MSIX_IRQ_INDEX:
                case VFIO_PCI_REQ_IRQ_INDEX:
                        break;
                case VFIO_PCI_ERR_IRQ_INDEX:
                        if (pci_is_pcie(vdev->pdev))
                                break;
                /* pass thru to return error */
                default:
                        return -EINVAL;
                }

                info.flags = VFIO_IRQ_INFO_EVENTFD;

                info.count = vfio_pci_get_irq_count(vdev, info.index);

                if (info.index == VFIO_PCI_INTX_IRQ_INDEX)
                        info.flags |= (VFIO_IRQ_INFO_MASKABLE |
                                       VFIO_IRQ_INFO_AUTOMASKED);
                else
                        info.flags |= VFIO_IRQ_INFO_NORESIZE;

                return copy_to_user((void __user *)arg, &info, minsz) ?
                        -EFAULT : 0;

        } else if (cmd == VFIO_DEVICE_SET_IRQS) {
                struct vfio_irq_set hdr;
                u8 *data = NULL;
                int max, ret = 0;
                size_t data_size = 0;

                minsz = offsetofend(struct vfio_irq_set, count);

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

                max = vfio_pci_get_irq_count(vdev, hdr.index);

                ret = vfio_set_irqs_validate_and_prepare(&hdr, max,
                                                 VFIO_PCI_NUM_IRQS, &data_size);
                if (ret)
                        return ret;

                if (data_size) {
                        data = memdup_user((void __user *)(arg + minsz),
                                            data_size);
                        if (IS_ERR(data))
                                return PTR_ERR(data);
                }

                mutex_lock(&vdev->igate);

                ret = vfio_pci_set_irqs_ioctl(vdev, hdr.flags, hdr.index,
                                              hdr.start, hdr.count, data);

                mutex_unlock(&vdev->igate);
                kfree(data);

                return ret;

        } else if (cmd == VFIO_DEVICE_RESET) {
                return vdev->reset_works ?
                        pci_try_reset_function(vdev->pdev) : -EINVAL;

        } else if (cmd == VFIO_DEVICE_GET_PCI_HOT_RESET_INFO) {
                struct vfio_pci_hot_reset_info hdr;
                struct vfio_pci_fill_info fill = { 0 };
                struct vfio_pci_dependent_device *devices = NULL;
                bool slot = false;
                int ret = 0;

                minsz = offsetofend(struct vfio_pci_hot_reset_info, count);

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

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

                hdr.flags = 0;

                /* Can we do a slot or bus reset or neither? */
                if (!pci_probe_reset_slot(vdev->pdev->slot))
                        slot = true;
                else if (pci_probe_reset_bus(vdev->pdev->bus))
                        return -ENODEV;

                /* How many devices are affected? */
                ret = vfio_pci_for_each_slot_or_bus(vdev->pdev,
                                                    vfio_pci_count_devs,
                                                    &fill.max, slot);
                if (ret)
                        return ret;

                WARN_ON(!fill.max); /* Should always be at least one */

                /*
                 * If there's enough space, fill it now, otherwise return
                 * -ENOSPC and the number of devices affected.
                 */
                if (hdr.argsz < sizeof(hdr) + (fill.max * sizeof(*devices))) {
                        ret = -ENOSPC;
                        hdr.count = fill.max;
                        goto reset_info_exit;
                }

                devices = kcalloc(fill.max, sizeof(*devices), GFP_KERNEL);
                if (!devices)
                        return -ENOMEM;

                fill.devices = devices;

                ret = vfio_pci_for_each_slot_or_bus(vdev->pdev,
                                                    vfio_pci_fill_devs,
                                                    &fill, slot);

                /*
                 * If a device was removed between counting and filling,
                 * we may come up short of fill.max.  If a device was
                 * added, we'll have a return of -EAGAIN above.
                 */
                if (!ret)
                        hdr.count = fill.cur;

reset_info_exit:
                if (copy_to_user((void __user *)arg, &hdr, minsz))
                        ret = -EFAULT;

                if (!ret) {
                        if (copy_to_user((void __user *)(arg + minsz), devices,
                                         hdr.count * sizeof(*devices)))
                                ret = -EFAULT;
                }

                kfree(devices);
                return ret;

        } else if (cmd == VFIO_DEVICE_PCI_HOT_RESET) {
                struct vfio_pci_hot_reset hdr;
                int32_t *group_fds;
                struct vfio_pci_group_entry *groups;
                struct vfio_pci_group_info info;
                bool slot = false;
                int i, count = 0, ret = 0;

                minsz = offsetofend(struct vfio_pci_hot_reset, count);

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

                if (hdr.argsz < minsz || hdr.flags)
                        return -EINVAL;

                /* Can we do a slot or bus reset or neither? */
                if (!pci_probe_reset_slot(vdev->pdev->slot))
                        slot = true;
                else if (pci_probe_reset_bus(vdev->pdev->bus))
                        return -ENODEV;

                /*
                 * We can't let userspace give us an arbitrarily large
                 * buffer to copy, so verify how many we think there
                 * could be.  Note groups can have multiple devices so
                 * one group per device is the max.
                 */
                ret = vfio_pci_for_each_slot_or_bus(vdev->pdev,
                                                    vfio_pci_count_devs,
                                                    &count, slot);
                if (ret)
                        return ret;

                /* Somewhere between 1 and count is OK */
                if (!hdr.count || hdr.count > count)
                        return -EINVAL;

                group_fds = kcalloc(hdr.count, sizeof(*group_fds), GFP_KERNEL);
                groups = kcalloc(hdr.count, sizeof(*groups), GFP_KERNEL);
                if (!group_fds || !groups) {
                        kfree(group_fds);
                        kfree(groups);
                        return -ENOMEM;
                }

                if (copy_from_user(group_fds, (void __user *)(arg + minsz),
                                   hdr.count * sizeof(*group_fds))) {
                        kfree(group_fds);
                        kfree(groups);
                        return -EFAULT;
                }

                /*
                 * For each group_fd, get the group through the vfio external
                 * user interface and store the group and iommu ID.  This
                 * ensures the group is held across the reset.
                 */
                for (i = 0; i < hdr.count; i++) {
                        struct vfio_group *group;
                        struct fd f = fdget(group_fds[i]);
                        if (!f.file) {
                                ret = -EBADF;

                                break;
                        }

                        group = vfio_group_get_external_user(f.file);
                        fdput(f);
                        if (IS_ERR(group)) {
                                ret = PTR_ERR(group);
                                break;
                        }

                        groups[i].group = group;
                        groups[i].id = vfio_external_user_iommu_id(group);
                }

                kfree(group_fds);

                /* release reference to groups on error */
                if (ret)
                        goto hot_reset_release;

                info.count = hdr.count;
                info.groups = groups;

                /*
                 * Test whether all the affected devices are contained
                 * by the set of groups provided by the user.
                 */
                ret = vfio_pci_for_each_slot_or_bus(vdev->pdev,
                                                    vfio_pci_validate_devs,
                                                    &info, slot);
                if (!ret)
                        /* User has access, do the reset */
                        ret = slot ? pci_try_reset_slot(vdev->pdev->slot) :
                                     pci_try_reset_bus(vdev->pdev->bus);

hot_reset_release:
                for (i--; i >= 0; i--)
                        vfio_group_put_external_user(groups[i].group);

                kfree(groups);
                return ret;
        }

        return -ENOTTY;
}

static ssize_t vfio_pci_rw(void *device_data, char __user *buf,
                           size_t count, loff_t *ppos, bool iswrite)
{
        unsigned int index = VFIO_PCI_OFFSET_TO_INDEX(*ppos);
        struct vfio_pci_device *vdev = device_data;

        if (index >= VFIO_PCI_NUM_REGIONS + vdev->num_regions)
                return -EINVAL;

        switch (index) {
        case VFIO_PCI_CONFIG_REGION_INDEX:
                return vfio_pci_config_rw(vdev, buf, count, ppos, iswrite);

        case VFIO_PCI_ROM_REGION_INDEX:
                if (iswrite)
                        return -EINVAL;
                return vfio_pci_bar_rw(vdev, buf, count, ppos, false);

        case VFIO_PCI_BAR0_REGION_INDEX ... VFIO_PCI_BAR5_REGION_INDEX:
                return vfio_pci_bar_rw(vdev, buf, count, ppos, iswrite);

        case VFIO_PCI_VGA_REGION_INDEX:
                return vfio_pci_vga_rw(vdev, buf, count, ppos, iswrite);
        default:
                index -= VFIO_PCI_NUM_REGIONS;
                return vdev->region[index].ops->rw(vdev, buf,
                                                   count, ppos, iswrite);
        }

        return -EINVAL;
}

static ssize_t vfio_pci_read(void *device_data, char __user *buf,
                             size_t count, loff_t *ppos)
{
        if (!count)
                return 0;

        return vfio_pci_rw(device_data, buf, count, ppos, false);
}

static ssize_t vfio_pci_write(void *device_data, const char __user *buf,
                              size_t count, loff_t *ppos)
{
        if (!count)
                return 0;

        return vfio_pci_rw(device_data, (char __user *)buf, count, ppos, true);
}

static int vfio_pci_mmap(void *device_data, struct vm_area_struct *vma)
{
        struct vfio_pci_device *vdev = device_data;
        struct pci_dev *pdev = vdev->pdev;
        unsigned int index;
        u64 phys_len, req_len, pgoff, req_start;
        int ret;

        index = vma->vm_pgoff >> (VFIO_PCI_OFFSET_SHIFT - PAGE_SHIFT);

        if (vma->vm_end < vma->vm_start)
                return -EINVAL;
        if ((vma->vm_flags & VM_SHARED) == 0)
                return -EINVAL;
        if (index >= VFIO_PCI_ROM_REGION_INDEX)
                return -EINVAL;
        if (!vdev->bar_mmap_supported[index])
                return -EINVAL;

        phys_len = PAGE_ALIGN(pci_resource_len(pdev, index));
        req_len = vma->vm_end - vma->vm_start;
        pgoff = vma->vm_pgoff &
                ((1U << (VFIO_PCI_OFFSET_SHIFT - PAGE_SHIFT)) - 1);
        req_start = pgoff << PAGE_SHIFT;

        if (req_start + req_len > phys_len)
                return -EINVAL;

        if (index == vdev->msix_bar) {
                /*
                 * Disallow mmaps overlapping the MSI-X table; users don't
                 * get to touch this directly.  We could find somewhere
                 * else to map the overlap, but page granularity is only
                 * a recommendation, not a requirement, so the user needs
                 * to know which bits are real.  Requiring them to mmap
                 * around the table makes that clear.
                 */

                /* If neither entirely above nor below, then it overlaps */
                if (!(req_start >= vdev->msix_offset + vdev->msix_size ||
                      req_start + req_len <= vdev->msix_offset))
                        return -EINVAL;
        }

        /*
         * Even though we don't make use of the barmap for the mmap,
         * we need to request the region and the barmap tracks that.
         */
        if (!vdev->barmap[index]) {
                ret = pci_request_selected_regions(pdev,
                                                   1 << index, "vfio-pci");
                if (ret)
                        return ret;

                vdev->barmap[index] = pci_iomap(pdev, index, 0);
                if (!vdev->barmap[index]) {
                        pci_release_selected_regions(pdev, 1 << index);
                        return -ENOMEM;
                }
        }

        vma->vm_private_data = vdev;
        vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
        vma->vm_pgoff = (pci_resource_start(pdev, index) >> PAGE_SHIFT) + pgoff;

        return remap_pfn_range(vma, vma->vm_start, vma->vm_pgoff,
                               req_len, vma->vm_page_prot);
}

static void vfio_pci_request(void *device_data, unsigned int count)
{
        struct vfio_pci_device *vdev = device_data;

        mutex_lock(&vdev->igate);

        if (vdev->req_trigger) {
                if (!(count % 10))
                        dev_notice_ratelimited(&vdev->pdev->dev,
                                "Relaying device request to user (#%u)\n",
                                count);
                eventfd_signal(vdev->req_trigger, 1);
        } else if (count == 0) {
                dev_warn(&vdev->pdev->dev,
                        "No device request channel registered, blocked until released by user\n");
        }

        mutex_unlock(&vdev->igate);
}

static const struct vfio_device_ops vfio_pci_ops = {
        .name           = "vfio-pci",
        .open           = vfio_pci_open,
        .release        = vfio_pci_release,
        .ioctl          = vfio_pci_ioctl,
        .read           = vfio_pci_read,
        .write          = vfio_pci_write,
        .mmap           = vfio_pci_mmap,
        .request        = vfio_pci_request,
};

static int vfio_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id)
{
        struct vfio_pci_device *vdev;
        struct iommu_group *group;
        int ret;

        if (pdev->hdr_type != PCI_HEADER_TYPE_NORMAL)
                return -EINVAL;

        group = vfio_iommu_group_get(&pdev->dev);
        if (!group)
                return -EINVAL;

        vdev = kzalloc(sizeof(*vdev), GFP_KERNEL);
        if (!vdev) {
                vfio_iommu_group_put(group, &pdev->dev);
                return -ENOMEM;
        }

        vdev->pdev = pdev;
        vdev->irq_type = VFIO_PCI_NUM_IRQS;
        mutex_init(&vdev->igate);
        spin_lock_init(&vdev->irqlock);

        ret = vfio_add_group_dev(&pdev->dev, &vfio_pci_ops, vdev);
        if (ret) {
                vfio_iommu_group_put(group, &pdev->dev);
                kfree(vdev);
                return ret;
        }

        if (vfio_pci_is_vga(pdev)) {
                vga_client_register(pdev, vdev, NULL, vfio_pci_set_vga_decode);
                vga_set_legacy_decoding(pdev,
                                        vfio_pci_set_vga_decode(vdev, false));
        }

        if (!disable_idle_d3) {
                /*
                 * pci-core sets the device power state to an unknown value at
                 * bootup and after being removed from a driver.  The only
                 * transition it allows from this unknown state is to D0, which
                 * typically happens when a driver calls pci_enable_device().
                 * We're not ready to enable the device yet, but we do want to
                 * be able to get to D3.  Therefore first do a D0 transition
                 * before going to D3.
                 */
                pci_set_power_state(pdev, PCI_D0);
                pci_set_power_state(pdev, PCI_D3hot);
        }

        return ret;
}

static void vfio_pci_remove(struct pci_dev *pdev)
{
        struct vfio_pci_device *vdev;

        vdev = vfio_del_group_dev(&pdev->dev);
        if (!vdev)
                return;

        vfio_iommu_group_put(pdev->dev.iommu_group, &pdev->dev);
        kfree(vdev->region);
        kfree(vdev);

        if (vfio_pci_is_vga(pdev)) {
                vga_client_register(pdev, NULL, NULL, NULL);
                vga_set_legacy_decoding(pdev,
                                VGA_RSRC_NORMAL_IO | VGA_RSRC_NORMAL_MEM |
                                VGA_RSRC_LEGACY_IO | VGA_RSRC_LEGACY_MEM);
        }

        if (!disable_idle_d3)
                pci_set_power_state(pdev, PCI_D0);
}

static pci_ers_result_t vfio_pci_aer_err_detected(struct pci_dev *pdev,
                                                  pci_channel_state_t state)
{
        struct vfio_pci_device *vdev;
        struct vfio_device *device;

        device = vfio_device_get_from_dev(&pdev->dev);
        if (device == NULL)
                return PCI_ERS_RESULT_DISCONNECT;

        vdev = vfio_device_data(device);
        if (vdev == NULL) {
                vfio_device_put(device);
                return PCI_ERS_RESULT_DISCONNECT;
        }

        mutex_lock(&vdev->igate);

        if (vdev->err_trigger)
                eventfd_signal(vdev->err_trigger, 1);

        mutex_unlock(&vdev->igate);

        vfio_device_put(device);

        return PCI_ERS_RESULT_CAN_RECOVER;
}

static const struct pci_error_handlers vfio_err_handlers = {
        .error_detected = vfio_pci_aer_err_detected,
};

static struct pci_driver vfio_pci_driver = {
        .name           = "vfio-pci",
        .id_table       = NULL, /* only dynamic ids */
        .probe          = vfio_pci_probe,
        .remove         = vfio_pci_remove,
        .err_handler    = &vfio_err_handlers,
};

struct vfio_devices {
        struct vfio_device **devices;
        int cur_index;
        int max_index;
};

static int vfio_pci_get_devs(struct pci_dev *pdev, void *data)
{
        struct vfio_devices *devs = data;
        struct vfio_device *device;

        if (devs->cur_index == devs->max_index)
                return -ENOSPC;

        device = vfio_device_get_from_dev(&pdev->dev);
        if (!device)
                return -EINVAL;

        if (pci_dev_driver(pdev) != &vfio_pci_driver) {
                vfio_device_put(device);
                return -EBUSY;
        }

        devs->devices[devs->cur_index++] = device;
        return 0;
}

/*
 * Attempt to do a bus/slot reset if there are devices affected by a reset for
 * this device that are needs_reset and all of the affected devices are unused
 * (!refcnt).  Callers are required to hold driver_lock when calling this to
 * prevent device opens and concurrent bus reset attempts.  We prevent device
 * unbinds by acquiring and holding a reference to the vfio_device.
 *
 * NB: vfio-core considers a group to be viable even if some devices are
 * bound to drivers like pci-stub or pcieport.  Here we require all devices
 * to be bound to vfio_pci since that's the only way we can be sure they
 * stay put.
 */
static void vfio_pci_try_bus_reset(struct vfio_pci_device *vdev)
{
        struct vfio_devices devs = { .cur_index = 0 };
        int i = 0, ret = -EINVAL;
        bool needs_reset = false, slot = false;
        struct vfio_pci_device *tmp;

        if (!pci_probe_reset_slot(vdev->pdev->slot))
                slot = true;
        else if (pci_probe_reset_bus(vdev->pdev->bus))
                return;

        if (vfio_pci_for_each_slot_or_bus(vdev->pdev, vfio_pci_count_devs,
                                          &i, slot) || !i)
                return;

        devs.max_index = i;
        devs.devices = kcalloc(i, sizeof(struct vfio_device *), GFP_KERNEL);
        if (!devs.devices)
                return;

        if (vfio_pci_for_each_slot_or_bus(vdev->pdev,
                                          vfio_pci_get_devs, &devs, slot))
                goto put_devs;

        for (i = 0; i < devs.cur_index; i++) {
                tmp = vfio_device_data(devs.devices[i]);
                if (tmp->needs_reset)
                        needs_reset = true;
                if (tmp->refcnt)
                        goto put_devs;
        }

        if (needs_reset)
                ret = slot ? pci_try_reset_slot(vdev->pdev->slot) :
                             pci_try_reset_bus(vdev->pdev->bus);

put_devs:
        for (i = 0; i < devs.cur_index; i++) {
                tmp = vfio_device_data(devs.devices[i]);
                if (!ret)
                        tmp->needs_reset = false;

                if (!tmp->refcnt && !disable_idle_d3)
                        pci_set_power_state(tmp->pdev, PCI_D3hot);

                vfio_device_put(devs.devices[i]);
        }

        kfree(devs.devices);
}

static void __exit vfio_pci_cleanup(void)
{
        pci_unregister_driver(&vfio_pci_driver);
        vfio_pci_uninit_perm_bits();
}

static void __init vfio_pci_fill_ids(void)
{
        char *p, *id;
        int rc;

        /* no ids passed actually */
        if (ids[0] == '\0')
                return;

        /* add ids specified in the module parameter */
        p = ids;
        while ((id = strsep(&p, ","))) {
                unsigned int vendor, device, subvendor = PCI_ANY_ID,
                        subdevice = PCI_ANY_ID, class = 0, class_mask = 0;
                int fields;

                if (!strlen(id))
                        continue;

                fields = sscanf(id, "%x:%x:%x:%x:%x:%x",
                                &vendor, &device, &subvendor, &subdevice,
                                &class, &class_mask);

                if (fields < 2) {
                        pr_warn("invalid id string \"%s\"\n", id);
                        continue;
                }

                rc = pci_add_dynid(&vfio_pci_driver, vendor, device,
                                   subvendor, subdevice, class, class_mask, 0);
                if (rc)
                        pr_warn("failed to add dynamic id [%04hx:%04hx[%04hx:%04hx]] class %#08x/%08x (%d)\n",
                                vendor, device, subvendor, subdevice,
                                class, class_mask, rc);
                else
                        pr_info("add [%04hx:%04hx[%04hx:%04hx]] class %#08x/%08x\n",
                                vendor, device, subvendor, subdevice,
                                class, class_mask);
        }
}

static int __init vfio_pci_init(void)
{
        int ret;

        /* Allocate shared config space permision data used by all devices */
        ret = vfio_pci_init_perm_bits();
        if (ret)
                return ret;

        /* Register and scan for devices */
        ret = pci_register_driver(&vfio_pci_driver);
        if (ret)
                goto out_driver;

        vfio_pci_fill_ids();

        return 0;

out_driver:
        vfio_pci_uninit_perm_bits();
        return ret;
}

module_init(vfio_pci_init);
module_exit(vfio_pci_cleanup);

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