lguest: remove support for lguest bus.

# Guest requires the device configuration and probing code.

obj-$(CONFIG_LGUEST_GUEST) += lguest_device.o

# Host requires the other files, which can be a module.

# Host requires the other files, which can be a module.

obj-$(CONFIG_LGUEST)	+= lg.o

obj-$(CONFIG_LGUEST)	+= lg.o

lg-y = core.o hypercalls.o page_tables.o interrupts_and_traps.o \

lg-y = core.o hypercalls.o page_tables.o interrupts_and_traps.o \

/*P:050

 * Lguest guests use a very simple method to describe devices.  It's a

 * series of device descriptors contained just above the top of normal Guest

 * memory.

 *

 * We use the standard "virtio" device infrastructure, which provides us with a

 * console, a network and a block driver.  Each one expects some configuration

 * information and a "virtqueue" or two to send and receive data.

:*/

#include <linux/init.h>

#include <linux/bootmem.h>

#include <linux/lguest_launcher.h>

#include <linux/virtio.h>

#include <linux/virtio_config.h>

#include <linux/interrupt.h>

#include <linux/virtio_ring.h>

#include <linux/err.h>

#include <linux/export.h>

#include <linux/slab.h>

#include <asm/io.h>

#include <asm/paravirt.h>

#include <asm/lguest_hcall.h>

/* The pointer to our (page) of device descriptions. */

static void *lguest_devices;

/*

 * For Guests, device memory can be used as normal memory, so we cast away the

 * __iomem to quieten sparse.

 */

static inline void *lguest_map(unsigned long phys_addr, unsigned long pages)

{

	return (__force void *)ioremap_cache(phys_addr, PAGE_SIZE*pages);

}

static inline void lguest_unmap(void *addr)

{

	iounmap((__force void __iomem *)addr);

}

/*D:100

 * Each lguest device is just a virtio device plus a pointer to its entry

 * in the lguest_devices page.

 */

struct lguest_device {

	struct virtio_device vdev;

	/* The entry in the lguest_devices page for this device. */

	struct lguest_device_desc *desc;

};

/*

 * Since the virtio infrastructure hands us a pointer to the virtio_device all

 * the time, it helps to have a curt macro to get a pointer to the struct

 * lguest_device it's enclosed in.

 */

#define to_lgdev(vd) container_of(vd, struct lguest_device, vdev)

/*D:130

 * Device configurations

 *

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

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

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

 * the driver will look at them during setup.

 *

 * 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);

}

/* 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);

}

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

static u8 *lg_config(const struct lguest_device_desc *desc)

{

	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;

}

/* This gets the device's feature bits. */

static u64 lg_get_features(struct virtio_device *vdev)

{

	unsigned int i;

	u32 features = 0;

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

	u8 *in_features = lg_features(desc);

	/* We do this the slow but generic way. */

	for (i = 0; i < min(desc->feature_len * 8, 32); i++)

		if (in_features[i / 8] & (1 << (i % 8)))

			features |= (1 << i);

	return features;

}

/*

 * To notify on reset or feature finalization, we (ab)use the NOTIFY

 * hypercall, with the descriptor address of the device.

 */

static void status_notify(struct virtio_device *vdev)

{

	unsigned long offset = (void *)to_lgdev(vdev)->desc - lguest_devices;

	hcall(LHCALL_NOTIFY, (max_pfn << PAGE_SHIFT) + offset, 0, 0, 0);

}

/*

 * The virtio core takes the features the Host offers, and copies the ones

 * supported by the driver into the vdev->features array.  Once that's all

 * sorted out, this routine is called so we can tell the Host which features we

 * understand and accept.

 */

static int lg_finalize_features(struct virtio_device *vdev)

{

	unsigned int i, bits;

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

	/* Second half of bitmap is features we accept. */

	u8 *out_features = lg_features(desc) + desc->feature_len;

	/* Give virtio_ring a chance to accept features. */

	vring_transport_features(vdev);

	/* Make sure we don't have any features > 32 bits! */

	BUG_ON((u32)vdev->features != vdev->features);

	/*

	 * Since lguest is currently x86-only, we're little-endian.  That

	 * means we could just memcpy.  But it's not time critical, and in

	 * case someone copies this code, we do it the slow, obvious way.

	 */

	memset(out_features, 0, desc->feature_len);

	bits = min_t(unsigned, desc->feature_len, sizeof(vdev->features)) * 8;

	for (i = 0; i < bits; i++) {

		if (__virtio_test_bit(vdev, i))

			out_features[i / 8] |= (1 << (i % 8));

	}

	/* Tell Host we've finished with this device's feature negotiation */

	status_notify(vdev);

	return 0;

}

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

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

		   void *buf, unsigned 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, unsigned int offset,

		   const void *buf, unsigned 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

 * of the device descriptor.

 */

static u8 lg_get_status(struct virtio_device *vdev)

{

	return to_lgdev(vdev)->desc->status;

}

static void lg_set_status(struct virtio_device *vdev, u8 status)

{

	BUG_ON(!status);

	to_lgdev(vdev)->desc->status = status;

	/* Tell Host immediately if we failed. */

	if (status & VIRTIO_CONFIG_S_FAILED)

		status_notify(vdev);

}

static void lg_reset(struct virtio_device *vdev)

{

	/* 0 status means "reset" */

	to_lgdev(vdev)->desc->status = 0;

	status_notify(vdev);

}

/*

 * Virtqueues

 *

 * The other piece of infrastructure virtio needs is a "virtqueue": a way of

 * the Guest device registering buffers for the other side to read from or

 * write into (ie. send and receive buffers).  Each device can have multiple

 * virtqueues: for example the console driver uses one queue for sending and

 * another for receiving.

 *

 * Fortunately for us, a very fast shared-memory-plus-descriptors virtqueue

 * already exists in virtio_ring.c.  We just need to connect it up.

 *

 * We start with the information we need to keep about each virtqueue.

 */

/*D:140 This is the information we remember about each virtqueue. */

struct lguest_vq_info {

	/* A copy of the information contained in the device config. */

	struct lguest_vqconfig config;

	/* The address where we mapped the virtio ring, so we can unmap it. */

	void *pages;

};

/*

 * When the virtio_ring code wants to prod the Host, it calls us here and we

 * make a hypercall.  We hand the physical address of the virtqueue so the Host

 * knows which virtqueue we're talking about.

 */

static bool lg_notify(struct virtqueue *vq)

{

	/*

	 * We store our virtqueue information in the "priv" pointer of the

	 * virtqueue structure.

	 */

	struct lguest_vq_info *lvq = vq->priv;

	hcall(LHCALL_NOTIFY, lvq->config.pfn << PAGE_SHIFT, 0, 0, 0);

	return true;

}

/* An extern declaration inside a C file is bad form.  Don't do it. */

extern int lguest_setup_irq(unsigned int irq);

/*

 * This routine finds the Nth virtqueue described in the configuration of

 * this device and sets it up.

 *

 * This is kind of an ugly duckling.  It'd be nicer to have a standard

 * representation of a virtqueue in the configuration space, but it seems that

 * everyone wants to do it differently.  The KVM coders want the Guest to

 * allocate its own pages and tell the Host where they are, but for lguest it's

 * simpler for the Host to simply tell us where the pages are.

 */

static struct virtqueue *lg_find_vq(struct virtio_device *vdev,

				    unsigned index,

				    void (*callback)(struct virtqueue *vq),

				    const char *name)

{

	struct lguest_device *ldev = to_lgdev(vdev);

	struct lguest_vq_info *lvq;

	struct virtqueue *vq;

	int err;

	if (!name)

		return NULL;

	/* 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);

	/*

	 * 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,

							LGUEST_VRING_ALIGN),

					     PAGE_SIZE));

	if (!lvq->pages) {

		err = -ENOMEM;

		goto free_lvq;

	}

	/*

	 * OK, tell virtio_ring.c to set up a virtqueue now we know its size

	 * and we've got a pointer to its pages.  Note that we set weak_barriers

	 * to 'true': the host just a(nother) SMP CPU, so we only need inter-cpu

	 * barriers.

	 */

	vq = vring_new_virtqueue(index, lvq->config.num, LGUEST_VRING_ALIGN, vdev,

				 true, lvq->pages, lg_notify, callback, name);

	if (!vq) {

		err = -ENOMEM;

		goto unmap;

	}

	/* Make sure the interrupt is allocated. */

	err = lguest_setup_irq(lvq->config.irq);

	if (err)

		goto destroy_vring;

	/*

	 * Tell the interrupt for this virtqueue to go to the virtio_ring

	 * interrupt handler.

	 *

	 * FIXME: We used to have a flag for the Host to tell us we could use

	 * the interrupt as a source of randomness: it'd be nice to have that

	 * back.

	 */

	err = request_irq(lvq->config.irq, vring_interrupt, IRQF_SHARED,

			  dev_name(&vdev->dev), vq);

	if (err)

		goto free_desc;

	/*

	 * Last of all we hook up our 'struct lguest_vq_info" to the

	 * virtqueue's priv pointer.

	 */

	vq->priv = lvq;

	return vq;

free_desc:

	irq_free_desc(lvq->config.irq);

destroy_vring:

	vring_del_virtqueue(vq);

unmap:

	lguest_unmap(lvq->pages);

free_lvq:

	kfree(lvq);

	return ERR_PTR(err);

}

/*:*/

/* Cleaning up a virtqueue is easy */

static void lg_del_vq(struct virtqueue *vq)

{

	struct lguest_vq_info *lvq = vq->priv;

	/* Release the interrupt */

	free_irq(lvq->config.irq, vq);

	/* Tell virtio_ring.c to free the virtqueue. */

	vring_del_virtqueue(vq);

	/* Unmap the pages containing the ring. */

	lguest_unmap(lvq->pages);

	/* Free our own queue information. */

	kfree(lvq);

}

static void lg_del_vqs(struct virtio_device *vdev)

{

	struct virtqueue *vq, *n;

	list_for_each_entry_safe(vq, n, &vdev->vqs, list)

		lg_del_vq(vq);

}

static int lg_find_vqs(struct virtio_device *vdev, unsigned nvqs,

		       struct virtqueue *vqs[],

		       vq_callback_t *callbacks[],

		       const char *names[])

{

	struct lguest_device *ldev = to_lgdev(vdev);

	int i;

	/* We must have this many virtqueues. */

	if (nvqs > ldev->desc->num_vq)

		return -ENOENT;

	for (i = 0; i < nvqs; ++i) {

		vqs[i] = lg_find_vq(vdev, i, callbacks[i], names[i]);

		if (IS_ERR(vqs[i]))

			goto error;

	}

	return 0;

error:

	lg_del_vqs(vdev);

	return PTR_ERR(vqs[i]);

}

static const char *lg_bus_name(struct virtio_device *vdev)

{

	return "";

}

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

static const struct virtio_config_ops lguest_config_ops = {

	.get_features = lg_get_features,

	.finalize_features = lg_finalize_features,

	.get = lg_get,

	.set = lg_set,

	.get_status = lg_get_status,

	.set_status = lg_set_status,

	.reset = lg_reset,

	.find_vqs = lg_find_vqs,

	.del_vqs = lg_del_vqs,

	.bus_name = lg_bus_name,

};

/*

 * The root device for the lguest virtio devices.  This makes them appear as

 * /sys/devices/lguest/0,1,2 not /sys/devices/0,1,2.

 */

static struct device *lguest_root;

/*D:120

 * This is the core of the lguest bus: actually adding a new device.

 * It's a separate function because it's neater that way, and because an

 * earlier version of the code supported hotplug and unplug.  They were removed

 * early on because they were never used.

 *

 * As Andrew Tridgell says, "Untested code is buggy code".

 *

 * It's worth reading this carefully: we start with a pointer to the new device

 * descriptor in the "lguest_devices" page, and the offset into the device

 * descriptor page so we can uniquely identify it if things go badly wrong.

 */

static void add_lguest_device(struct lguest_device_desc *d,

			      unsigned int offset)

{

	struct lguest_device *ldev;

	/* Start with zeroed memory; Linux's device layer counts on it. */

	ldev = kzalloc(sizeof(*ldev), GFP_KERNEL);

	if (!ldev) {

		printk(KERN_EMERG "Cannot allocate lguest dev %u type %u\n",

		       offset, d->type);

		return;

	}

	/* This devices' parent is the lguest/ dir. */

	ldev->vdev.dev.parent = lguest_root;

	/*

	 * The device type comes straight from the descriptor.  There's also a

	 * device vendor field in the virtio_device struct, which we leave as

	 * 0.

	 */

	ldev->vdev.id.device = d->type;

	/*

	 * We have a simple set of routines for querying the device's

	 * configuration information and setting its status.

	 */

	ldev->vdev.config = &lguest_config_ops;

	/* And we remember the device's descriptor for lguest_config_ops. */

	ldev->desc = d;

	/*

	 * register_virtio_device() sets up the generic fields for the struct

	 * virtio_device and calls device_register().  This makes the bus

	 * infrastructure look for a matching driver.

	 */

	if (register_virtio_device(&ldev->vdev) != 0) {

		printk(KERN_ERR "Failed to register lguest dev %u type %u\n",

		       offset, d->type);

		kfree(ldev);

	}

}

/*D:110

 * scan_devices() simply iterates through the device page.  The type 0 is

 * reserved to mean "end of devices".

 */

static void scan_devices(void)

{

	unsigned int i;

	struct lguest_device_desc *d;

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

	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, i);

	}

}

/*D:105

 * Fairly early in boot, lguest_devices_init() is called to set up the

 * lguest device infrastructure.  We check that we are a Guest by checking

 * pv_info.name: there are other ways of checking, but this seems most

 * obvious to me.

 *

 * So we can access the "struct lguest_device_desc"s easily, we map that memory

 * and store the pointer in the global "lguest_devices".  Then we register a

 * root device from which all our devices will hang (this seems to be the

 * correct sysfs incantation).

 *

 * Finally we call scan_devices() which adds all the devices found in the

 * lguest_devices page.

 */

static int __init lguest_devices_init(void)

{

	if (strcmp(pv_info.name, "lguest") != 0)

		return 0;

	lguest_root = root_device_register("lguest");

	if (IS_ERR(lguest_root))

		panic("Could not register lguest root");

	/* Devices are in a single page above top of "normal" mem */

	lguest_devices = lguest_map(max_pfn<<PAGE_SHIFT, 1);

	scan_devices();

	return 0;

}

/* We do this after core stuff, but before the drivers. */

postcore_initcall(lguest_devices_init);

/*D:150

 * At this point in the journey we used to now wade through the lguest

 * devices themselves: net, block and console.  Since they're all now virtio

 * devices rather than lguest-specific, I've decided to ignore them.  Mostly,

 * they're kind of boring.  But this does mean you'll never experience the

 * thrill of reading the forbidden love scene buried deep in the block driver.

 *

 * "make Launcher" beckons, where we answer questions like "Where do Guests

 * come from?", and "What do you do when someone asks for optimization?".

 */