virtio: simplify config mechanism.

#include <zlib.h>

#include <assert.h>

#include <sched.h>

#include <limits.h>

#include <stddef.h>

#include "linux/lguest_launcher.h"

#include "linux/virtio_config.h"

#include "linux/virtio_net.h"

	/* The descriptor page for the devices. */

	u8 *descpage;

	/* The tail of the last descriptor. */

	unsigned int desc_used;

	/* A single linked list of devices. */

	struct device *dev;

	/* ... And an end pointer so we can easily append new devices */

	struct device **lastdev;

	/* And a pointer to the last device for easy append and also for

	 * configuration appending. */

	struct device *lastdev;

};

/* The list of Guest devices, based on command line arguments. */

#define cpu_to_le64(v64) (v64)

#define le16_to_cpu(v16) (v16)

#define le32_to_cpu(v32) (v32)

#define le64_to_cpu(v32) (v64)

#define le64_to_cpu(v64) (v64)

/*L:100 The Launcher code itself takes us out into userspace, that scary place

 * where pointers run wild and free!  Unfortunately, like most userspace

 *

 * All devices need a descriptor so the Guest knows it exists, and a "struct

 * device" so the Launcher can keep track of it.  We have common helper

 * routines to allocate them.

 *

 * This routine allocates a new "struct lguest_device_desc" from descriptor

 * table just above the Guest's normal memory.  It returns a pointer to that

 * descriptor. */

static struct lguest_device_desc *new_dev_desc(u16 type)

{

	struct lguest_device_desc *d;

 * routines to allocate and manage them. */

	/* We only have one page for all the descriptors. */

	if (devices.desc_used + sizeof(*d) > getpagesize())

		errx(1, "Too many devices");

	/* We don't need to set config_len or status: page is 0 already. */

	d = (void *)devices.descpage + devices.desc_used;

	d->type = type;

	devices.desc_used += sizeof(*d);

	return d;

/* The layout of the device page is a "struct lguest_device_desc" followed by a

 * number of virtqueue descriptors, then two sets of feature bits, then an

 * array of configuration bytes.  This routine returns the configuration

 * pointer. */

static u8 *device_config(const struct device *dev)

{

	return (void *)(dev->desc + 1)

		+ dev->desc->num_vq * sizeof(struct lguest_vqconfig)

		+ dev->desc->feature_len * 2;

}

/* Each device descriptor is followed by some configuration information.

 * Each configuration field looks like: u8 type, u8 len, [... len bytes...].

 *

 * This routine adds a new field to an existing device's descriptor.  It only

 * works for the last device, but that's OK because that's how we use it. */

static void add_desc_field(struct device *dev, u8 type, u8 len, const void *c)

/* This routine allocates a new "struct lguest_device_desc" from descriptor

 * table page just above the Guest's normal memory.  It returns a pointer to

 * that descriptor. */

static struct lguest_device_desc *new_dev_desc(u16 type)

{

	/* This is the last descriptor, right? */

	assert(devices.descpage + devices.desc_used

	       == (u8 *)(dev->desc + 1) + dev->desc->config_len);

	struct lguest_device_desc d = { .type = type };

	void *p;

	/* We only have one page of device descriptions. */

	if (devices.desc_used + 2 + len > getpagesize())

		errx(1, "Too many devices");

	/* Figure out where the next device config is, based on the last one. */

	if (devices.lastdev)

		p = device_config(devices.lastdev)

			+ devices.lastdev->desc->config_len;

	else

		p = devices.descpage;

	/* Copy in the new config header: type then length. */

	devices.descpage[devices.desc_used++] = type;

	devices.descpage[devices.desc_used++] = len;

	memcpy(devices.descpage + devices.desc_used, c, len);

	devices.desc_used += len;

	/* We only have one page for all the descriptors. */

	if (p + sizeof(d) > (void *)devices.descpage + getpagesize())

		errx(1, "Too many devices");

	/* Update the device descriptor length: two byte head then data. */

	dev->desc->config_len += 2 + len;

	/* p might not be aligned, so we memcpy in. */

	return memcpy(p, &d, sizeof(d));

}

/* This routine adds a virtqueue to a device.  We specify how many descriptors

 * the virtqueue is to have. */

/* Each device descriptor is followed by the description of its virtqueues.  We

 * specify how many descriptors the virtqueue is to have. */

static void add_virtqueue(struct device *dev, unsigned int num_descs,

			  void (*handle_output)(int fd, struct virtqueue *me))

{

	/* Initialize the vring. */

	vring_init(&vq->vring, num_descs, p, getpagesize());

	/* Add the configuration information to this device's descriptor. */

	add_desc_field(dev, VIRTIO_CONFIG_F_VIRTQUEUE,

		       sizeof(vq->config), &vq->config);

	/* Append virtqueue to this device's descriptor.  We use

	 * device_config() to get the end of the device's current virtqueues;

	 * we check that we haven't added any config or feature information

	 * yet, otherwise we'd be overwriting them. */

	assert(dev->desc->config_len == 0 && dev->desc->feature_len == 0);

	memcpy(device_config(dev), &vq->config, sizeof(vq->config));

	dev->desc->num_vq++;

	verbose("Virtqueue page %#lx\n", to_guest_phys(p));

	/* Add to tail of list, so dev->vq is first vq, dev->vq->next is

	 * second.  */

		vq->vring.used->flags = VRING_USED_F_NO_NOTIFY;

}

/* The virtqueue descriptors are followed by feature bytes. */

static void add_feature(struct device *dev, unsigned bit)

{

	u8 *features;

	/* We can't extend the feature bits once we've added config bytes */

	if (dev->desc->feature_len <= bit / CHAR_BIT) {

		assert(dev->desc->config_len == 0);

		dev->desc->feature_len = (bit / CHAR_BIT) + 1;

	}

	features = (u8 *)(dev->desc + 1)

		+ dev->desc->num_vq * sizeof(struct lguest_vqconfig);

	features[bit / CHAR_BIT] |= (1 << (bit % CHAR_BIT));

}

/* This routine sets the configuration fields for an existing device's

 * descriptor.  It only works for the last device, but that's OK because that's

 * how we use it. */

static void set_config(struct device *dev, unsigned len, const void *conf)

{

	/* Check we haven't overflowed our single page. */

	if (device_config(dev) + len > devices.descpage + getpagesize())

		errx(1, "Too many devices");

	/* Copy in the config information, and store the length. */

	memcpy(device_config(dev), conf, len);

	dev->desc->config_len = len;

}

/* This routine does all the creation and setup of a new device, including

 * calling new_dev_desc() to allocate the descriptor and device memory. */

static struct device *new_device(const char *name, u16 type, int fd,

{

	struct device *dev = malloc(sizeof(*dev));

	/* Append to device list.  Prepending to a single-linked list is

	 * easier, but the user expects the devices to be arranged on the bus

	 * in command-line order.  The first network device on the command line

	 * is eth0, the first block device /dev/vda, etc. */

	*devices.lastdev = dev;

	dev->next = NULL;

	devices.lastdev = &dev->next;

	/* Now we populate the fields one at a time. */

	dev->fd = fd;

	/* If we have an input handler for this file descriptor, then we add it

	dev->handle_input = handle_input;

	dev->name = name;

	dev->vq = NULL;

	/* Append to device list.  Prepending to a single-linked list is

	 * easier, but the user expects the devices to be arranged on the bus

	 * in command-line order.  The first network device on the command line

	 * is eth0, the first block device /dev/vda, etc. */

	if (devices.lastdev)

		devices.lastdev->next = dev;

	else

		devices.dev = dev;

	devices.lastdev = dev;

	return dev;

}

	int netfd, ipfd;

	u32 ip;

	const char *br_name = NULL;

	u8 hwaddr[6];

	struct virtio_net_config conf;

	/* We open the /dev/net/tun device and tell it we want a tap device.  A

	 * tap device is like a tun device, only somehow different.  To tell

		ip = str2ip(arg);

	/* Set up the tun device, and get the mac address for the interface. */

	configure_device(ipfd, ifr.ifr_name, ip, hwaddr);

	configure_device(ipfd, ifr.ifr_name, ip, conf.mac);

	/* Tell Guest what MAC address to use. */

	add_desc_field(dev, VIRTIO_CONFIG_NET_MAC_F, sizeof(hwaddr), hwaddr);

	add_feature(dev, VIRTIO_NET_F_MAC);

	set_config(dev, sizeof(conf), &conf);

	/* We don't seed the socket any more; setup is done. */

	/* We don't need the socket any more; setup is done. */

	close(ipfd);

	verbose("device %u: tun net %u.%u.%u.%u\n",

	struct device *dev;

	struct vblk_info *vblk;

	void *stack;

	u64 cap;

	unsigned int val;

	struct virtio_blk_config conf;

	/* This is the pipe the I/O thread will use to tell us I/O is done. */

	pipe(p);

	vblk->fd = open_or_die(filename, O_RDWR|O_LARGEFILE);

	vblk->len = lseek64(vblk->fd, 0, SEEK_END);

	/* We support barriers. */

	add_feature(dev, VIRTIO_BLK_F_BARRIER);

	/* Tell Guest how many sectors this device has. */

	cap = cpu_to_le64(vblk->len / 512);

	add_desc_field(dev, VIRTIO_CONFIG_BLK_F_CAPACITY, sizeof(cap), &cap);

	conf.capacity = cpu_to_le64(vblk->len / 512);

	/* Tell Guest not to put in too many descriptors at once: two are used

	 * for the in and out elements. */

	val = cpu_to_le32(VIRTQUEUE_NUM - 2);

	add_desc_field(dev, VIRTIO_CONFIG_BLK_F_SEG_MAX, sizeof(val), &val);

	add_feature(dev, VIRTIO_BLK_F_SEG_MAX);

	conf.seg_max = cpu_to_le32(VIRTQUEUE_NUM - 2);

	set_config(dev, sizeof(conf), &conf);

	/* The I/O thread writes to this end of the pipe when done. */

	vblk->done_fd = p[1];

	close(vblk->workpipe[0]);

	verbose("device %u: virtblock %llu sectors\n",

		devices.device_num, cap);

		devices.device_num, le64_to_cpu(conf.capacity));

}

/* That's the end of device setup. :*/

	/* First we initialize the device list.  Since console and network

	 * device receive input from a file descriptor, we keep an fdset

	 * (infds) and the maximum fd number (max_infd) with the head of the

	 * list.  We also keep a pointer to the last device, for easy appending

	 * to the list.  Finally, we keep the next interrupt number to hand out

	 * (1: remember that 0 is used by the timer). */

	 * list.  We also keep a pointer to the last device.  Finally, we keep

	 * the next interrupt number to hand out (1: remember that 0 is used by

	 * the timer). */

	FD_ZERO(&devices.infds);

	devices.max_infd = -1;

	devices.lastdev = &devices.dev;

	devices.lastdev = NULL;

	devices.next_irq = 1;

	cpu_id = 0;

{

	struct virtio_blk *vblk;

	int err, major;

	void *token;

	unsigned int len;

	u64 cap;

	u32 v;

	vblk->vdev = vdev;

	/* We expect one virtqueue, for output. */

	vblk->vq = vdev->config->find_vq(vdev, blk_done);

	vblk->vq = vdev->config->find_vq(vdev, 0, blk_done);

	if (IS_ERR(vblk->vq)) {

		err = PTR_ERR(vblk->vq);

		goto out_free_vblk;

	vblk->disk->fops = &virtblk_fops;

	/* If barriers are supported, tell block layer that queue is ordered */

	token = vdev->config->find(vdev, VIRTIO_CONFIG_BLK_F, &len);

	if (virtio_use_bit(vdev, token, len, VIRTIO_BLK_F_BARRIER))

	if (vdev->config->feature(vdev, VIRTIO_BLK_F_BARRIER))

		blk_queue_ordered(vblk->disk->queue, QUEUE_ORDERED_TAG, NULL);

	err = virtio_config_val(vdev, VIRTIO_CONFIG_BLK_F_CAPACITY, &cap);

	if (err) {

		dev_err(&vdev->dev, "Bad/missing capacity in config\n");

		goto out_cleanup_queue;

	}

	/* Host must always specify the capacity. */

	__virtio_config_val(vdev, offsetof(struct virtio_blk_config, capacity),

			    &cap);

	/* If capacity is too big, truncate with warning. */

	if ((sector_t)cap != cap) {

	}

	set_capacity(vblk->disk, cap);

	err = virtio_config_val(vdev, VIRTIO_CONFIG_BLK_F_SIZE_MAX, &v);

	/* Host can optionally specify maximum segment size and number of

	 * segments. */

	err = virtio_config_val(vdev, VIRTIO_BLK_F_SIZE_MAX,

				offsetof(struct virtio_blk_config, size_max),

				&v);

	if (!err)

		blk_queue_max_segment_size(vblk->disk->queue, v);

	else if (err != -ENOENT) {

		dev_err(&vdev->dev, "Bad SIZE_MAX in config\n");

		goto out_cleanup_queue;

	}

	err = virtio_config_val(vdev, VIRTIO_CONFIG_BLK_F_SEG_MAX, &v);

	err = virtio_config_val(vdev, VIRTIO_BLK_F_SEG_MAX,

				offsetof(struct virtio_blk_config, seg_max),

				&v);

	if (!err)

		blk_queue_max_hw_segments(vblk->disk->queue, v);

	else if (err != -ENOENT) {

		dev_err(&vdev->dev, "Bad SEG_MAX in config\n");

		goto out_cleanup_queue;

	}

	add_disk(vblk->disk);

	return 0;

out_cleanup_queue:

	blk_cleanup_queue(vblk->disk->queue);

out_put_disk:

	put_disk(vblk->disk);

out_unregister_blkdev:

	/* Find the input queue. */

	/* FIXME: This is why we want to wean off hvc: we do nothing

	 * when input comes in. */

	in_vq = vdev->config->find_vq(vdev, NULL);

	in_vq = vdev->config->find_vq(vdev, 0, NULL);

	if (IS_ERR(in_vq)) {

		err = PTR_ERR(in_vq);

		goto free;

	}

	out_vq = vdev->config->find_vq(vdev, NULL);

	out_vq = vdev->config->find_vq(vdev, 1, NULL);

	if (IS_ERR(out_vq)) {

		err = PTR_ERR(out_vq);

		goto free_in_vq;

/*D:130

 * Device configurations

 *

 * The configuration information for a device consists of a series of fields.

 * We don't really care what they are: the Launcher set them up, and the driver

 * will look at them during setup.

 * The configuration information for a device consists of one or more

 * virtqueues, a feature bitmaks, and some configuration bytes.  The

 * configuration bytes don't really matter to us: the Launcher set them up, and

 * the driver will look at them during setup.

 *

 * For us these fields come immediately after that device's descriptor in the

 * lguest_devices page.

 *

 * Each field starts with a "type" byte, a "length" byte, then that number of

 * bytes of configuration information.  The device descriptor tells us the

 * total configuration length so we know when we've reached the last field. */

 * A convenient routine to return the device's virtqueue config array:

 * immediately after the descriptor. */

static struct lguest_vqconfig *lg_vq(const struct lguest_device_desc *desc)

{

	return (void *)(desc + 1);

}

/* type + length bytes */

#define FHDR_LEN 2

/* The features come immediately after the virtqueues. */

static u8 *lg_features(const struct lguest_device_desc *desc)

{

	return (void *)(lg_vq(desc) + desc->num_vq);

}

/* This finds the first field of a given type for a device's configuration. */

static void *lg_find(struct virtio_device *vdev, u8 type, unsigned int *len)

/* The config space comes after the two feature bitmasks. */

static u8 *lg_config(const struct lguest_device_desc *desc)

{

	struct lguest_device_desc *desc = to_lgdev(vdev)->desc;

	int i;

	for (i = 0; i < desc->config_len; i += FHDR_LEN + desc->config[i+1]) {

		if (desc->config[i] == type) {

			/* Mark it used, so Host can know we looked at it, and

			 * also so we won't find the same one twice. */

			desc->config[i] |= 0x80;

			/* Remember, the second byte is the length. */

			*len = desc->config[i+1];

			/* We return a pointer to the field header. */

			return desc->config + i;

	return lg_features(desc) + desc->feature_len * 2;

}

/* The total size of the config page used by this device (incl. desc) */

static unsigned desc_size(const struct lguest_device_desc *desc)

{

	return sizeof(*desc)

		+ desc->num_vq * sizeof(struct lguest_vqconfig)

		+ desc->feature_len * 2

		+ desc->config_len;

}

	/* Not found: return NULL for failure. */

	return NULL;

/* This tests (and acknowleges) a feature bit. */

static bool lg_feature(struct virtio_device *vdev, unsigned fbit)

{

	struct lguest_device_desc *desc = to_lgdev(vdev)->desc;

	u8 *features;

	/* Obviously if they ask for a feature off the end of our feature

	 * bitmap, it's not set. */

	if (fbit / 8 > desc->feature_len)

		return false;

	/* The feature bitmap comes after the virtqueues. */

	features = lg_features(desc);

	if (!(features[fbit / 8] & (1 << (fbit % 8))))

		return false;

	/* We set the matching bit in the other half of the bitmap to tell the

	 * Host we want to use this feature.  We don't use this yet, but we

	 * could in future. */

	features[desc->feature_len + fbit / 8] |= (1 << (fbit % 8));

	return true;

}

/* Once they've found a field, getting a copy of it is easy. */

static void lg_get(struct virtio_device *vdev, void *token,

static void lg_get(struct virtio_device *vdev, unsigned int offset,

		   void *buf, unsigned len)

{

	/* Check they didn't ask for more than the length of the field! */

	BUG_ON(len > ((u8 *)token)[1]);

	memcpy(buf, token + FHDR_LEN, len);

	struct lguest_device_desc *desc = to_lgdev(vdev)->desc;

	/* Check they didn't ask for more than the length of the config! */

	BUG_ON(offset + len > desc->config_len);

	memcpy(buf, lg_config(desc) + offset, len);

}

/* Setting the contents is also trivial. */

static void lg_set(struct virtio_device *vdev, void *token,

static void lg_set(struct virtio_device *vdev, unsigned int offset,

		   const void *buf, unsigned len)

{

	BUG_ON(len > ((u8 *)token)[1]);

	memcpy(token + FHDR_LEN, buf, len);

	struct lguest_device_desc *desc = to_lgdev(vdev)->desc;

	/* Check they didn't ask for more than the length of the config! */

	BUG_ON(offset + len > desc->config_len);

	memcpy(lg_config(desc) + offset, buf, len);

}

/* The operations to get and set the status word just access the status field

 *

 * So we provide devices with a "find virtqueue and set it up" function. */

static struct virtqueue *lg_find_vq(struct virtio_device *vdev,

				    unsigned index,

				    bool (*callback)(struct virtqueue *vq))

{

	struct lguest_device *ldev = to_lgdev(vdev);

	struct lguest_vq_info *lvq;

	struct virtqueue *vq;

	unsigned int len;

	void *token;

	int err;

	/* Look for a field of the correct type to mark a virtqueue.  Note that

	 * if this succeeds, then the type will be changed so it won't be found

	 * again, and future lg_find_vq() calls will find the next

	 * virtqueue (if any). */

	token = vdev->config->find(vdev, VIRTIO_CONFIG_F_VIRTQUEUE, &len);

	if (!token)

	/* We must have this many virtqueues. */

	if (index >= ldev->desc->num_vq)

		return ERR_PTR(-ENOENT);

	lvq = kmalloc(sizeof(*lvq), GFP_KERNEL);

	if (!lvq)

		return ERR_PTR(-ENOMEM);

	/* Note: we could use a configuration space inside here, just like we

	 * do for the device.  This would allow expansion in future, because

	 * our configuration system is designed to be expansible.  But this is

	 * way easier. */

	if (len != sizeof(lvq->config)) {

		dev_err(&vdev->dev, "Unexpected virtio config len %u\n", len);

		err = -EIO;

		goto free_lvq;

	}

	/* Make a copy of the "struct lguest_vqconfig" field.  We need a copy

	 * because the config space might not be aligned correctly. */

	vdev->config->get(vdev, token, &lvq->config, sizeof(lvq->config));

	/* Make a copy of the "struct lguest_vqconfig" entry, which sits after

	 * the descriptor.  We need a copy because the config space might not

	 * be aligned correctly. */

	memcpy(&lvq->config, lg_vq(ldev->desc)+index, sizeof(lvq->config));

	printk("Mapping virtqueue %i addr %lx\n", index,

	       (unsigned long)lvq->config.pfn << PAGE_SHIFT);

	/* Figure out how many pages the ring will take, and map that memory */

	lvq->pages = lguest_map((unsigned long)lvq->config.pfn << PAGE_SHIFT,

				DIV_ROUND_UP(vring_size(lvq->config.num,

/* The ops structure which hooks everything together. */

static struct virtio_config_ops lguest_config_ops = {

	.find = lg_find,

	.feature = lg_feature,

	.get = lg_get,

	.set = lg_set,

	.get_status = lg_get_status,

	struct lguest_device_desc *d;

	/* We start at the page beginning, and skip over each entry. */

	for (i = 0; i < PAGE_SIZE; i += sizeof(*d) + d->config_len) {

	for (i = 0; i < PAGE_SIZE; i += desc_size(d)) {

		d = lguest_devices + i;

		/* Once we hit a zero, stop. */

		if (d->type == 0)

			break;

		printk("Device at %i has size %u\n", i, desc_size(d));

		add_lguest_device(d);

	}

}

static int virtnet_probe(struct virtio_device *vdev)

{

	int err;

	unsigned int len;

	struct net_device *dev;

	struct virtnet_info *vi;

	void *token;

	/* Allocate ourselves a network device with room for our info */

	dev = alloc_etherdev(sizeof(struct virtnet_info));

	SET_NETDEV_DEV(dev, &vdev->dev);

	/* Do we support "hardware" checksums? */

	token = vdev->config->find(vdev, VIRTIO_CONFIG_NET_F, &len);

	if (virtio_use_bit(vdev, token, len, VIRTIO_NET_F_NO_CSUM)) {

	if (vdev->config->feature(vdev, VIRTIO_NET_F_NO_CSUM)) {

		/* This opens up the world of extra features. */

		dev->features |= NETIF_F_HW_CSUM|NETIF_F_SG|NETIF_F_FRAGLIST;

		if (virtio_use_bit(vdev, token, len, VIRTIO_NET_F_TSO4))

		if (vdev->config->feature(vdev, VIRTIO_NET_F_TSO4))

			dev->features |= NETIF_F_TSO;

		if (virtio_use_bit(vdev, token, len, VIRTIO_NET_F_UFO))

		if (vdev->config->feature(vdev, VIRTIO_NET_F_UFO))

			dev->features |= NETIF_F_UFO;

		if (virtio_use_bit(vdev, token, len, VIRTIO_NET_F_TSO4_ECN))

		if (vdev->config->feature(vdev, VIRTIO_NET_F_TSO4_ECN))

			dev->features |= NETIF_F_TSO_ECN;

		if (virtio_use_bit(vdev, token, len, VIRTIO_NET_F_TSO6))

		if (vdev->config->feature(vdev, VIRTIO_NET_F_TSO6))

			dev->features |= NETIF_F_TSO6;

	}