vfio_pci.c

Go to the documentation of this file.

/*
 * Copyright (C) 2012 Red Hat, Inc.  All rights reserved.
 *     Author: Alex Williamson <[email protected]>
 *
 * 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, [email protected]
 */

#include <linux/device.h>
#include <linux/eventfd.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 "vfio_pci_private.h"

#define DRIVER_VERSION  "0.2"
#define DRIVER_AUTHOR   "Alex Williamson <[email protected]>"
#define DRIVER_DESC     "VFIO PCI - User Level meta-driver"

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 [email protected] so the device can be fixed automatically via the broken_intx_masking flag.");

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

    vdev->reset_works = (pci_reset_function(pdev) == 0);
    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));

    ret = vfio_config_init(vdev);
    if (ret)
        goto out;

    if (likely(!nointxmask))
        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);
    }

    msix_pos = pci_find_capability(pdev, PCI_CAP_ID_MSIX);
    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_FLAGS_BIRMASK;
        vdev->msix_offset = table & ~PCI_MSIX_FLAGS_BIRMASK;
        vdev->msix_size = ((flags & PCI_MSIX_FLAGS_QSIZE) + 1) * 16;
    } else
        vdev->msix_bar = 0xFF;

    ret = pci_enable_device(pdev);
    if (ret)
        goto out;

    return ret;

out:
    kfree(vdev->pci_saved_state);
    vdev->pci_saved_state = NULL;
    vfio_config_free(vdev);
    return ret;
}

static void vfio_pci_disable(struct vfio_pci_device *vdev)
{
    int bar;

    pci_disable_device(vdev->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;

    vfio_config_free(vdev);

    pci_reset_function(vdev->pdev);

    if (pci_load_and_free_saved_state(vdev->pdev,
                      &vdev->pci_saved_state) == 0)
        pci_restore_state(vdev->pdev);
    else
        pr_info("%s: Couldn't reload %s saved state\n",
            __func__, dev_name(&vdev->pdev->dev));

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

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

    if (atomic_dec_and_test(&vdev->refcnt))
        vfio_pci_disable(vdev);

    module_put(THIS_MODULE);
}

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

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

    if (atomic_inc_return(&vdev->refcnt) == 1) {
        int ret = vfio_pci_enable(vdev);
        if (ret) {
            module_put(THIS_MODULE);
            return ret;
        }
    }

    return 0;
}

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 (pin)
            return 1;

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

        pos = pci_find_capability(vdev->pdev, PCI_CAP_ID_MSI);
        if (pos) {
            pci_read_config_word(vdev->pdev,
                         pos + PCI_MSI_FLAGS, &flags);

            return 1 << (flags & PCI_MSI_FLAGS_QMASK);
        }
    } else if (irq_type == VFIO_PCI_MSIX_IRQ_INDEX) {
        u8 pos;
        u16 flags;

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

            return (flags & PCI_MSIX_FLAGS_QSIZE) + 1;
        }
    }

    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;
        info.num_irqs = VFIO_PCI_NUM_IRQS;

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

    } else if (cmd == VFIO_DEVICE_GET_REGION_INFO) {
        struct pci_dev *pdev = vdev->pdev;
        struct vfio_region_info info;

        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 (pci_resource_flags(pdev, info.index) &
                IORESOURCE_MEM && info.size >= PAGE_SIZE)
                info.flags |= VFIO_REGION_INFO_FLAG_MMAP;
            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)
                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;
        }
        default:
            return -EINVAL;
        }

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

    } 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;

        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);

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

        minsz = offsetofend(struct vfio_irq_set, count);

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

        if (hdr.argsz < minsz || hdr.index >= VFIO_PCI_NUM_IRQS ||
            hdr.flags & ~(VFIO_IRQ_SET_DATA_TYPE_MASK |
                  VFIO_IRQ_SET_ACTION_TYPE_MASK))
            return -EINVAL;

        if (!(hdr.flags & VFIO_IRQ_SET_DATA_NONE)) {
            size_t size;

            if (hdr.flags & VFIO_IRQ_SET_DATA_BOOL)
                size = sizeof(uint8_t);
            else if (hdr.flags & VFIO_IRQ_SET_DATA_EVENTFD)
                size = sizeof(int32_t);
            else
                return -EINVAL;

            if (hdr.argsz - minsz < hdr.count * size ||
                hdr.count > vfio_pci_get_irq_count(vdev, hdr.index))
                return -EINVAL;

            data = kmalloc(hdr.count * size, GFP_KERNEL);
            if (!data)
                return -ENOMEM;

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

        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_reset_function(vdev->pdev) : -EINVAL;

    return -ENOTTY;
}

static ssize_t vfio_pci_read(void *device_data, char __user *buf,
                 size_t count, loff_t *ppos)
{
    unsigned int index = VFIO_PCI_OFFSET_TO_INDEX(*ppos);
    struct vfio_pci_device *vdev = device_data;
    struct pci_dev *pdev = vdev->pdev;

    if (index >= VFIO_PCI_NUM_REGIONS)
        return -EINVAL;

    if (index == VFIO_PCI_CONFIG_REGION_INDEX)
        return vfio_pci_config_readwrite(vdev, buf, count, ppos, false);
    else if (index == VFIO_PCI_ROM_REGION_INDEX)
        return vfio_pci_mem_readwrite(vdev, buf, count, ppos, false);
    else if (pci_resource_flags(pdev, index) & IORESOURCE_IO)
        return vfio_pci_io_readwrite(vdev, buf, count, ppos, false);
    else if (pci_resource_flags(pdev, index) & IORESOURCE_MEM)
        return vfio_pci_mem_readwrite(vdev, buf, count, ppos, false);

    return -EINVAL;
}

static ssize_t vfio_pci_write(void *device_data, const char __user *buf,
                  size_t count, loff_t *ppos)
{
    unsigned int index = VFIO_PCI_OFFSET_TO_INDEX(*ppos);
    struct vfio_pci_device *vdev = device_data;
    struct pci_dev *pdev = vdev->pdev;

    if (index >= VFIO_PCI_NUM_REGIONS)
        return -EINVAL;

    if (index == VFIO_PCI_CONFIG_REGION_INDEX)
        return vfio_pci_config_readwrite(vdev, (char __user *)buf,
                         count, ppos, true);
    else if (index == VFIO_PCI_ROM_REGION_INDEX)
        return -EINVAL;
    else if (pci_resource_flags(pdev, index) & IORESOURCE_IO)
        return vfio_pci_io_readwrite(vdev, (char __user *)buf,
                         count, ppos, true);
    else if (pci_resource_flags(pdev, index) & IORESOURCE_MEM) {
        return vfio_pci_mem_readwrite(vdev, (char __user *)buf,
                          count, ppos, true);
    }

    return -EINVAL;
}

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 (!(pci_resource_flags(pdev, index) & IORESOURCE_MEM))
        return -EINVAL;

    phys_len = 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 (phys_len < PAGE_SIZE || 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);
    }

    vma->vm_private_data = vdev;
    vma->vm_flags |= VM_IO | VM_DONTEXPAND | VM_DONTDUMP;
    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 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,
};

static int vfio_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id)
{
    u8 type;
    struct vfio_pci_device *vdev;
    struct iommu_group *group;
    int ret;

    pci_read_config_byte(pdev, PCI_HEADER_TYPE, &type);
    if ((type & PCI_HEADER_TYPE) != PCI_HEADER_TYPE_NORMAL)
        return -EINVAL;

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

    vdev = kzalloc(sizeof(*vdev), GFP_KERNEL);
    if (!vdev) {
        iommu_group_put(group);
        return -ENOMEM;
    }

    vdev->pdev = pdev;
    vdev->irq_type = VFIO_PCI_NUM_IRQS;
    mutex_init(&vdev->igate);
    spin_lock_init(&vdev->irqlock);
    atomic_set(&vdev->refcnt, 0);

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

    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;

    iommu_group_put(pdev->dev.iommu_group);
    kfree(vdev);
}

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

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

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;

    /* Start the virqfd cleanup handler */
    ret = vfio_pci_virqfd_init();
    if (ret)
        goto out_virqfd;

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

    return 0;

out_virqfd:
    vfio_pci_virqfd_exit();
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);