s390/virtio: remove the old KVM virtio transport

	  Select this option if you want to run the kernel as a guest under

	  the KVM hypervisor.

config S390_GUEST_OLD_TRANSPORT

	def_bool y

	prompt "Guest support for old s390 virtio transport (DEPRECATED)"

	depends on S390_GUEST

	help

	  Enable this option to add support for the old s390-virtio

	  transport (i.e. virtio devices NOT based on virtio-ccw). This

	  type of virtio devices is only available on the experimental

	  kuli userspace or with old (< 2.6) qemu. If you are running

	  with a modern version of qemu (which supports virtio-ccw since

	  1.4 and uses it by default since version 2.4), you probably won't

	  need this.

endmenu

# as published by the Free Software Foundation.

s390-virtio-objs := virtio_ccw.o

ifdef CONFIG_S390_GUEST_OLD_TRANSPORT

s390-virtio-objs += kvm_virtio.o

endif

obj-$(CONFIG_S390_GUEST) += $(s390-virtio-objs)

/*

 * virtio for kvm on s390

 *

 * Copyright IBM Corp. 2008

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License (version 2 only)

 * as published by the Free Software Foundation.

 *

 *    Author(s): Christian Borntraeger <borntraeger@de.ibm.com>

 */

#include <linux/kernel_stat.h>

#include <linux/init.h>

#include <linux/bootmem.h>

#include <linux/err.h>

#include <linux/virtio.h>

#include <linux/virtio_config.h>

#include <linux/slab.h>

#include <linux/virtio_console.h>

#include <linux/interrupt.h>

#include <linux/virtio_ring.h>

#include <linux/export.h>

#include <linux/pfn.h>

#include <asm/io.h>

#include <asm/kvm_para.h>

#include <asm/kvm_virtio.h>

#include <asm/sclp.h>

#include <asm/setup.h>

#include <asm/irq.h>

#define VIRTIO_SUBCODE_64 0x0D00

/*

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

 */

static void *kvm_devices;

static struct work_struct hotplug_work;

struct kvm_device {

	struct virtio_device vdev;

	struct kvm_device_desc *desc;

};

#define to_kvmdev(vd) container_of(vd, struct kvm_device, vdev)

/*

 * memory layout:

 * - kvm_device_descriptor

 *        struct kvm_device_desc

 * - configuration

 *        struct kvm_vqconfig

 * - feature bits

 * - config space

 */

static struct kvm_vqconfig *kvm_vq_config(const struct kvm_device_desc *desc)

{

	return (struct kvm_vqconfig *)(desc + 1);

}

static u8 *kvm_vq_features(const struct kvm_device_desc *desc)

{

	return (u8 *)(kvm_vq_config(desc) + desc->num_vq);

}

static u8 *kvm_vq_configspace(const struct kvm_device_desc *desc)

{

	return kvm_vq_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 kvm_device_desc *desc)

{

	return sizeof(*desc)

		+ desc->num_vq * sizeof(struct kvm_vqconfig)

		+ desc->feature_len * 2

		+ desc->config_len;

}

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

static u64 kvm_get_features(struct virtio_device *vdev)

{

	unsigned int i;

	u32 features = 0;

	struct kvm_device_desc *desc = to_kvmdev(vdev)->desc;

	u8 *in_features = kvm_vq_features(desc);

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

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

			features |= (1 << i);

	return features;

}

static int kvm_finalize_features(struct virtio_device *vdev)

{

	unsigned int i, bits;

	struct kvm_device_desc *desc = to_kvmdev(vdev)->desc;

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

	u8 *out_features = kvm_vq_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);

	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));

	}

	return 0;

}

/*

 * Reading and writing elements in config space

 */

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

		   void *buf, unsigned len)

{

	struct kvm_device_desc *desc = to_kvmdev(vdev)->desc;

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

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

}

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

		   const void *buf, unsigned len)

{

	struct kvm_device_desc *desc = to_kvmdev(vdev)->desc;

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

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

}

/*

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

 * the status field of the device descriptor. set_status will also

 * make a hypercall to the host, to tell about status changes

 */

static u8 kvm_get_status(struct virtio_device *vdev)

{

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

}

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

{

	BUG_ON(!status);

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

	kvm_hypercall1(KVM_S390_VIRTIO_SET_STATUS,

		       (unsigned long) to_kvmdev(vdev)->desc);

}

/*

 * To reset the device, we use the KVM_VIRTIO_RESET hypercall, using the

 * descriptor address. The Host will zero the status and all the

 * features.

 */

static void kvm_reset(struct virtio_device *vdev)

{

	kvm_hypercall1(KVM_S390_VIRTIO_RESET,

		       (unsigned long) to_kvmdev(vdev)->desc);

}

/*

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

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

 * knows which virtqueue we're talking about.

 */

static bool kvm_notify(struct virtqueue *vq)

{

	long rc;

	struct kvm_vqconfig *config = vq->priv;

	rc = kvm_hypercall1(KVM_S390_VIRTIO_NOTIFY, config->address);

	if (rc < 0)

		return false;

	return true;

}

/*

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

 * this device and sets it up.

 */

static struct virtqueue *kvm_find_vq(struct virtio_device *vdev,

				     unsigned index,

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

				     const char *name, bool ctx)

{

	struct kvm_device *kdev = to_kvmdev(vdev);

	struct kvm_vqconfig *config;

	struct virtqueue *vq;

	int err;

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

		return ERR_PTR(-ENOENT);

	if (!name)

		return NULL;

	config = kvm_vq_config(kdev->desc)+index;

	err = vmem_add_mapping(config->address,

			       vring_size(config->num,

					  KVM_S390_VIRTIO_RING_ALIGN));

	if (err)

		goto out;

	vq = vring_new_virtqueue(index, config->num, KVM_S390_VIRTIO_RING_ALIGN,

				 vdev, true, ctx, (void *) config->address,

				 kvm_notify, callback, name);

	if (!vq) {

		err = -ENOMEM;

		goto unmap;

	}

	/*

	 * register a callback token

	 * The host will sent this via the external interrupt parameter

	 */

	config->token = (u64) vq;

	vq->priv = config;

	return vq;

unmap:

	vmem_remove_mapping(config->address,

			    vring_size(config->num,

				       KVM_S390_VIRTIO_RING_ALIGN));

out:

	return ERR_PTR(err);

}

static void kvm_del_vq(struct virtqueue *vq)

{

	struct kvm_vqconfig *config = vq->priv;

	vring_del_virtqueue(vq);

	vmem_remove_mapping(config->address,

			    vring_size(config->num,

				       KVM_S390_VIRTIO_RING_ALIGN));

}

static void kvm_del_vqs(struct virtio_device *vdev)

{

	struct virtqueue *vq, *n;

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

		kvm_del_vq(vq);

}

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

			struct virtqueue *vqs[],

			vq_callback_t *callbacks[],

			const char * const names[],

			const bool *ctx,

			struct irq_affinity *desc)

{

	struct kvm_device *kdev = to_kvmdev(vdev);

	int i;

	/* We must have this many virtqueues. */

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

		return -ENOENT;

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

		vqs[i] = kvm_find_vq(vdev, i, callbacks[i], names[i],

				     ctx ? ctx[i] : false);

		if (IS_ERR(vqs[i]))

			goto error;

	}

	return 0;

error:

	kvm_del_vqs(vdev);

	return PTR_ERR(vqs[i]);

}

static const char *kvm_bus_name(struct virtio_device *vdev)

{

	return "";

}

/*

 * The config ops structure as defined by virtio config

 */

static const struct virtio_config_ops kvm_vq_configspace_ops = {

	.get_features = kvm_get_features,

	.finalize_features = kvm_finalize_features,

	.get = kvm_get,

	.set = kvm_set,

	.get_status = kvm_get_status,

	.set_status = kvm_set_status,

	.reset = kvm_reset,

	.find_vqs = kvm_find_vqs,

	.del_vqs = kvm_del_vqs,

	.bus_name = kvm_bus_name,

};

/*

 * The root device for the kvm virtio devices.

 * This makes them appear as /sys/devices/kvm_s390/0,1,2 not /sys/devices/0,1,2.

 */

static struct device *kvm_root;

/*

 * adds a new device and register it with virtio

 * appropriate drivers are loaded by the device model

 */

static void add_kvm_device(struct kvm_device_desc *d, unsigned int offset)

{

	struct kvm_device *kdev;

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

	if (!kdev) {

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

		       offset, d->type);

		return;

	}

	kdev->vdev.dev.parent = kvm_root;

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

	kdev->vdev.config = &kvm_vq_configspace_ops;

	kdev->desc = d;

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

		printk(KERN_ERR "Failed to register kvm device %u type %u\n",

		       offset, d->type);

		kfree(kdev);

	}

}

/*

 * 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 kvm_device_desc *d;

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

		d = kvm_devices + i;

		if (d->type == 0)

			break;

		add_kvm_device(d, i);

	}

}

/*

 * match for a kvm device with a specific desc pointer

 */

static int match_desc(struct device *dev, void *data)

{

	struct virtio_device *vdev = dev_to_virtio(dev);

	struct kvm_device *kdev = to_kvmdev(vdev);

	return kdev->desc == data;

}

/*

 * hotplug_device tries to find changes in the device page.

 */

static void hotplug_devices(struct work_struct *dummy)

{

	unsigned int i;

	struct kvm_device_desc *d;

	struct device *dev;

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

		d = kvm_devices + i;

		/* end of list */

		if (d->type == 0)

			break;

		/* device already exists */

		dev = device_find_child(kvm_root, d, match_desc);

		if (dev) {

			/* XXX check for hotplug remove */

			put_device(dev);

			continue;

		}

		/* new device */

		printk(KERN_INFO "Adding new virtio device %p\n", d);

		add_kvm_device(d, i);

	}

}

/*

 * we emulate the request_irq behaviour on top of s390 extints

 */

static void kvm_extint_handler(struct ext_code ext_code,

			       unsigned int param32, unsigned long param64)

{

	struct virtqueue *vq;

	u32 param;

	if ((ext_code.subcode & 0xff00) != VIRTIO_SUBCODE_64)

		return;

	inc_irq_stat(IRQEXT_VRT);

	/* The LSB might be overloaded, we have to mask it */

	vq = (struct virtqueue *)(param64 & ~1UL);

	/* We use ext_params to decide what this interrupt means */

	param = param32 & VIRTIO_PARAM_MASK;

	switch (param) {

	case VIRTIO_PARAM_CONFIG_CHANGED:

		virtio_config_changed(vq->vdev);

		break;

	case VIRTIO_PARAM_DEV_ADD:

		schedule_work(&hotplug_work);

		break;

	case VIRTIO_PARAM_VRING_INTERRUPT:

	default:

		vring_interrupt(0, vq);

		break;

	}

}

/*

 * For s390-virtio, we expect a page above main storage containing

 * the virtio configuration. Try to actually load from this area

 * in order to figure out if the host provides this page.

 */

static int __init test_devices_support(unsigned long addr)

{

	int ret = -EIO;

	asm volatile(

		"0:	lura	0,%1\n"

		"1:	xgr	%0,%0\n"

		"2:\n"

		EX_TABLE(0b,2b)

		EX_TABLE(1b,2b)

		: "+d" (ret)

		: "a" (addr)

		: "0", "cc");

	return ret;

}

/*

 * Init function for virtio

 * devices are in a single page above top of "normal" + standby mem

 */

static int __init kvm_devices_init(void)

{

	int rc;

	unsigned long total_memory_size = sclp.rzm * sclp.rnmax;

	if (!MACHINE_IS_KVM)

		return -ENODEV;

	if (test_devices_support(total_memory_size) < 0)

		return -ENODEV;

	pr_warn("The s390-virtio transport is deprecated. Please switch to a modern host providing virtio-ccw.\n");

	rc = vmem_add_mapping(total_memory_size, PAGE_SIZE);

	if (rc)

		return rc;

	kvm_devices = (void *) total_memory_size;

	kvm_root = root_device_register("kvm_s390");

	if (IS_ERR(kvm_root)) {

		rc = PTR_ERR(kvm_root);

		printk(KERN_ERR "Could not register kvm_s390 root device");

		vmem_remove_mapping(total_memory_size, PAGE_SIZE);

		return rc;

	}

	INIT_WORK(&hotplug_work, hotplug_devices);

	irq_subclass_register(IRQ_SUBCLASS_SERVICE_SIGNAL);

	register_external_irq(EXT_IRQ_CP_SERVICE, kvm_extint_handler);

	scan_devices();

	return 0;

}

/* code for early console output with virtio_console */

static int early_put_chars(u32 vtermno, const char *buf, int count)

{

	char scratch[17];

	unsigned int len = count;

	if (len > sizeof(scratch) - 1)

		len = sizeof(scratch) - 1;

	scratch[len] = '\0';

	memcpy(scratch, buf, len);

	kvm_hypercall1(KVM_S390_VIRTIO_NOTIFY, __pa(scratch));

	return len;

}

static int __init s390_virtio_console_init(void)

{

	if (sclp.has_vt220 || sclp.has_linemode)

		return -ENODEV;

	return virtio_cons_early_init(early_put_chars);

}

console_initcall(s390_virtio_console_init);

/*

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

 */

postcore_initcall(kvm_devices_init);