#include <stdint.h>
#include <string.h>
#include <stdlib.h>
#include <stdio.h>
#include <errno.h>

#include <unistd.h>
#include <fcntl.h>
#include <sys/types.h>
#include <linux/vfio.h>
#include <sys/ioctl.h>

#define err(x) do { perror(x); exit(1); } while (0)
#define die(...) do { fprintf(stderr, __VA_ARGS__); fputc('\n', stderr); exit(1); } while (0)

int main() {
    // Open vfio container
    int ret;
    int container = open("/dev/vfio/vfio", O_RDWR);
    if (container < 0)
        err("open vfio container");
    if (ioctl(container, VFIO_GET_API_VERSION) != VFIO_API_VERSION)
        die("Unknown VFIO API version! Recompile?");

    // Check IOMMU mode support
    if (!ioctl(container, VFIO_CHECK_EXTENSION, VFIO_SPAPR_TCE_v2_IOMMU))
        die("SPAPR iommu mode is not supported");

    // Open vfio group 0
    int group = open("/dev/vfio/0", O_RDWR);
    if (group < 0)
        err("open vfio group");

    // Check if group is viable
    struct vfio_group_status group_status = { .argsz = sizeof(group_status) };
    ioctl(group, VFIO_GROUP_GET_STATUS, &group_status);
    if (!(group_status.flags & VFIO_GROUP_FLAGS_VIABLE))
        die("VFIO Group 0 is not viable!");

    // Add the group to the container
    ret = ioctl(group, VFIO_GROUP_SET_CONTAINER, &container);
    if (ret < 0)
        err("VFIO_GROUP_SET_CONTAINER");

    // Set IOMMU mode
    ret = ioctl(container, VFIO_SET_IOMMU, VFIO_SPAPR_TCE_v2_IOMMU);
    if (ret < 0)
        err("VFIO_SET_IOMMU");

    // Get device handle
    int device = ioctl(group, VFIO_GROUP_GET_DEVICE_FD, "0000:00:00.0" /* ivshmem device */);
    if (device < 0)
        err("VFIO_GROUP_GET_DEVICE_FD");

    // Get device info
    struct vfio_device_info device_info = { .argsz = sizeof(device_info) };
    ret = ioctl(device, VFIO_DEVICE_GET_INFO, &device_info);
    if (ret < 0)
        err("VFIO_DEVICE_GET_INFO");
}