// SPDX-License-Identifier: GPL-2.0

  #define _GNU_SOURCE
  #include <getopt.h>

  #include <limits.h>

  #include <string.h>
  #include <poll.h>
  #include <sys/eventfd.h>
  #include <stdlib.h>
  #include <assert.h>
  #include <unistd.h>
  #include <sys/ioctl.h>
  #include <sys/stat.h>
  #include <sys/types.h>
  #include <fcntl.h>

  #include <stdbool.h>

  #include <linux/virtio_types.h>

  #include <linux/vhost.h>
  #include <linux/virtio.h>
  #include <linux/virtio_ring.h>
  #include "../../drivers/vhost/test.h"

  #define RANDOM_BATCH -1

  /* Unused */
  void *__kmalloc_fake, *__kfree_ignore_start, *__kfree_ignore_end;

  struct vq_info {
  	int kick;
  	int call;
  	int num;
  	int idx;
  	void *ring;
  	/* copy used for control */
  	struct vring vring;
  	struct virtqueue *vq;
  };
  
  struct vdev_info {
  	struct virtio_device vdev;
  	int control;
  	struct pollfd fds[1];
  	struct vq_info vqs[1];
  	int nvqs;
  	void *buf;
  	size_t buf_size;
  	struct vhost_memory *mem;
  };

  static const struct vhost_vring_file no_backend = { .fd = -1 },
  				     backend = { .fd = 1 };

  static const struct vhost_vring_state null_state = {};

  bool vq_notify(struct virtqueue *vq)

  {
  	struct vq_info *info = vq->priv;
  	unsigned long long v = 1;
  	int r;
  	r = write(info->kick, &v, sizeof v);
  	assert(r == sizeof v);

  	return true;

  }
  
  void vq_callback(struct virtqueue *vq)
  {
  }
  
  
  void vhost_vq_setup(struct vdev_info *dev, struct vq_info *info)
  {
  	struct vhost_vring_state state = { .index = info->idx };
  	struct vhost_vring_file file = { .index = info->idx };

  	unsigned long long features = dev->vdev.features;

  	struct vhost_vring_addr addr = {
  		.index = info->idx,
  		.desc_user_addr = (uint64_t)(unsigned long)info->vring.desc,
  		.avail_user_addr = (uint64_t)(unsigned long)info->vring.avail,
  		.used_user_addr = (uint64_t)(unsigned long)info->vring.used,
  	};
  	int r;
  	r = ioctl(dev->control, VHOST_SET_FEATURES, &features);
  	assert(r >= 0);
  	state.num = info->vring.num;
  	r = ioctl(dev->control, VHOST_SET_VRING_NUM, &state);
  	assert(r >= 0);
  	state.num = 0;
  	r = ioctl(dev->control, VHOST_SET_VRING_BASE, &state);
  	assert(r >= 0);
  	r = ioctl(dev->control, VHOST_SET_VRING_ADDR, &addr);
  	assert(r >= 0);
  	file.fd = info->kick;
  	r = ioctl(dev->control, VHOST_SET_VRING_KICK, &file);
  	assert(r >= 0);
  	file.fd = info->call;
  	r = ioctl(dev->control, VHOST_SET_VRING_CALL, &file);
  	assert(r >= 0);
  }

  static void vq_reset(struct vq_info *info, int num, struct virtio_device *vdev)
  {
  	if (info->vq)
  		vring_del_virtqueue(info->vq);
  
  	memset(info->ring, 0, vring_size(num, 4096));
  	vring_init(&info->vring, num, info->ring, 4096);
  	info->vq = __vring_new_virtqueue(info->idx, info->vring, vdev, true,
  					 false, vq_notify, vq_callback, "test");
  	assert(info->vq);
  	info->vq->priv = info;
  }

  static void vq_info_add(struct vdev_info *dev, int num)
  {
  	struct vq_info *info = &dev->vqs[dev->nvqs];
  	int r;
  	info->idx = dev->nvqs;
  	info->kick = eventfd(0, EFD_NONBLOCK);
  	info->call = eventfd(0, EFD_NONBLOCK);
  	r = posix_memalign(&info->ring, 4096, vring_size(num, 4096));
  	assert(r >= 0);

  	vq_reset(info, num, &dev->vdev);

  	vhost_vq_setup(dev, info);
  	dev->fds[info->idx].fd = info->call;
  	dev->fds[info->idx].events = POLLIN;
  	dev->nvqs++;
  }
  
  static void vdev_info_init(struct vdev_info* dev, unsigned long long features)
  {
  	int r;
  	memset(dev, 0, sizeof *dev);

  	dev->vdev.features = features;

  	INIT_LIST_HEAD(&dev->vdev.vqs);

  	dev->buf_size = 1024;
  	dev->buf = malloc(dev->buf_size);
  	assert(dev->buf);
          dev->control = open("/dev/vhost-test", O_RDWR);
  	assert(dev->control >= 0);
  	r = ioctl(dev->control, VHOST_SET_OWNER, NULL);
  	assert(r >= 0);
  	dev->mem = malloc(offsetof(struct vhost_memory, regions) +
  			  sizeof dev->mem->regions[0]);
  	assert(dev->mem);
  	memset(dev->mem, 0, offsetof(struct vhost_memory, regions) +
                            sizeof dev->mem->regions[0]);
  	dev->mem->nregions = 1;
  	dev->mem->regions[0].guest_phys_addr = (long)dev->buf;
  	dev->mem->regions[0].userspace_addr = (long)dev->buf;
  	dev->mem->regions[0].memory_size = dev->buf_size;
  	r = ioctl(dev->control, VHOST_SET_MEM_TABLE, dev->mem);
  	assert(r >= 0);
  }
  
  /* TODO: this is pretty bad: we get a cache line bounce
   * for the wait queue on poll and another one on read,
   * plus the read which is there just to clear the
   * current state. */
  static void wait_for_interrupt(struct vdev_info *dev)
  {
  	int i;
  	unsigned long long val;
  	poll(dev->fds, dev->nvqs, -1);
  	for (i = 0; i < dev->nvqs; ++i)
  		if (dev->fds[i].revents & POLLIN) {
  			read(dev->fds[i].fd, &val, sizeof val);
  		}
  }

  static void run_test(struct vdev_info *dev, struct vq_info *vq,

  		     bool delayed, int batch, int reset_n, int bufs)

  {
  	struct scatterlist sl;

  	long started = 0, completed = 0, next_reset = reset_n;

  	long completed_before, started_before;

  	int r, test = 1;
  	unsigned len;
  	long long spurious = 0;

  	const bool random_batch = batch == RANDOM_BATCH;

  	r = ioctl(dev->control, VHOST_TEST_RUN, &test);
  	assert(r >= 0);

  	if (!reset_n) {
  		next_reset = INT_MAX;
  	}

  	for (;;) {
  		virtqueue_disable_cb(vq->vq);
  		completed_before = completed;

  		started_before = started;

  		do {

  			const bool reset = completed > next_reset;

  			if (random_batch)
  				batch = (random() % vq->vring.num) + 1;

  			while (started < bufs &&
  			       (started - completed) < batch) {

  				sg_init_one(&sl, dev->buf, dev->buf_size);

  				r = virtqueue_add_outbuf(vq->vq, &sl, 1,
  							 dev->buf + started,
  							 GFP_ATOMIC);

  				if (unlikely(r != 0)) {
  					if (r == -ENOSPC &&
  					    started > started_before)
  						r = 0;
  					else

  						r = -1;

  					break;

  				}

  
  				++started;
  
  				if (unlikely(!virtqueue_kick(vq->vq))) {
  					r = -1;
  					break;
  				}
  			}
  
  			if (started >= bufs)

  				r = -1;

  			if (reset) {
  				r = ioctl(dev->control, VHOST_TEST_SET_BACKEND,
  					  &no_backend);
  				assert(!r);
  			}

  			/* Flush out completed bufs if any */

  			while (virtqueue_get_buf(vq->vq, &len)) {

  				++completed;
  				r = 0;
  			}

  			if (reset) {

  				struct vhost_vring_state s = { .index = 0 };
  
  				vq_reset(vq, vq->vring.num, &dev->vdev);
  
  				r = ioctl(dev->control, VHOST_GET_VRING_BASE,
  					  &s);
  				assert(!r);
  
  				s.num = 0;
  				r = ioctl(dev->control, VHOST_SET_VRING_BASE,
  					  &null_state);
  				assert(!r);

  				r = ioctl(dev->control, VHOST_TEST_SET_BACKEND,
  					  &backend);
  				assert(!r);

  				started = completed;

  				while (completed > next_reset)
  					next_reset += completed;
  			}

  		} while (r == 0);

  		if (completed == completed_before && started == started_before)

  			++spurious;
  		assert(completed <= bufs);
  		assert(started <= bufs);
  		if (completed == bufs)
  			break;

  		if (delayed) {
  			if (virtqueue_enable_cb_delayed(vq->vq))
  				wait_for_interrupt(dev);
  		} else {
  			if (virtqueue_enable_cb(vq->vq))
  				wait_for_interrupt(dev);

  		}
  	}
  	test = 0;
  	r = ioctl(dev->control, VHOST_TEST_RUN, &test);
  	assert(r >= 0);

  	fprintf(stderr,
  		"spurious wakeups: 0x%llx started=0x%lx completed=0x%lx
  ",
  		spurious, started, completed);

  }
  
  const char optstring[] = "h";
  const struct option longopts[] = {
  	{
  		.name = "help",
  		.val = 'h',
  	},
  	{

  		.name = "event-idx",
  		.val = 'E',
  	},
  	{
  		.name = "no-event-idx",
  		.val = 'e',
  	},
  	{

  		.name = "indirect",
  		.val = 'I',
  	},
  	{
  		.name = "no-indirect",
  		.val = 'i',
  	},
  	{

  		.name = "virtio-1",
  		.val = '1',
  	},
  	{
  		.name = "no-virtio-1",
  		.val = '0',
  	},
  	{

  		.name = "delayed-interrupt",
  		.val = 'D',
  	},
  	{
  		.name = "no-delayed-interrupt",
  		.val = 'd',
  	},
  	{

  		.name = "batch",
  		.val = 'b',
  		.has_arg = required_argument,
  	},
  	{

  		.name = "reset",
  		.val = 'r',
  		.has_arg = optional_argument,
  	},
  	{

  	}
  };

  static void help(void)

  {

  	fprintf(stderr, "Usage: virtio_test [--help]"
  		" [--no-indirect]"
  		" [--no-event-idx]"

  		" [--no-virtio-1]"

  		" [--delayed-interrupt]"

  		" [--batch=random/N]"

  		" [--reset=N]"

  		"
  ");

  }
  
  int main(int argc, char **argv)
  {
  	struct vdev_info dev;

  	unsigned long long features = (1ULL << VIRTIO_RING_F_INDIRECT_DESC) |

  		(1ULL << VIRTIO_RING_F_EVENT_IDX) | (1ULL << VIRTIO_F_VERSION_1);

  	long batch = 1, reset = 0;

  	int o;

  	bool delayed = false;

  
  	for (;;) {
  		o = getopt_long(argc, argv, optstring, longopts, NULL);
  		switch (o) {
  		case -1:
  			goto done;
  		case '?':
  			help();
  			exit(2);

  		case 'e':
  			features &= ~(1ULL << VIRTIO_RING_F_EVENT_IDX);
  			break;

  		case 'h':
  			help();
  			goto done;
  		case 'i':
  			features &= ~(1ULL << VIRTIO_RING_F_INDIRECT_DESC);
  			break;

  		case '0':
  			features &= ~(1ULL << VIRTIO_F_VERSION_1);
  			break;

  		case 'D':
  			delayed = true;
  			break;

  		case 'b':

  			if (0 == strcmp(optarg, "random")) {
  				batch = RANDOM_BATCH;
  			} else {
  				batch = strtol(optarg, NULL, 10);
  				assert(batch > 0);
  				assert(batch < (long)INT_MAX + 1);
  			}

  			break;

  		case 'r':
  			if (!optarg) {
  				reset = 1;
  			} else {
  				reset = strtol(optarg, NULL, 10);
  				assert(reset > 0);
  				assert(reset < (long)INT_MAX + 1);
  			}
  			break;

  		default:
  			assert(0);
  			break;
  		}
  	}
  
  done:
  	vdev_info_init(&dev, features);
  	vq_info_add(&dev, 256);

  	run_test(&dev, &dev.vqs[0], delayed, batch, reset, 0x100000);

  	return 0;
  }