[deliverable/linux.git] / drivers / s390 / kvm / kvm_virtio.c

/*
 * kvm_virtio.c - 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/init.h>
#include <linux/bootmem.h>
#include <linux/err.h>
#include <linux/virtio.h>
#include <linux/virtio_config.h>
#include <linux/virtio_console.h>
#include <linux/interrupt.h>
#include <linux/virtio_ring.h>
#include <linux/pfn.h>
#include <asm/io.h>
#include <asm/kvm_para.h>
#include <asm/kvm_virtio.h>
#include <asm/setup.h>
#include <asm/s390_ext.h>

#define VIRTIO_SUBCODE_64 0x0D00

/*
 * The pointer to our (page) of device descriptions.
 */
static void *kvm_devices;

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 u32 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 void 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);

	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 (test_bit(i, vdev->features))
			out_features[i / 8] |= (1 << (i % 8));
	}
}

/*
 * 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 void kvm_notify(struct virtqueue *vq)
{
	struct kvm_vqconfig *config = vq->priv;

	kvm_hypercall1(KVM_S390_VIRTIO_NOTIFY, config->address);
}

/*
 * 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))
{
	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);

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

	err = vmem_add_mapping(config->address,
			       vring_size(config->num, PAGE_SIZE));
	if (err)
		goto out;

	vq = vring_new_virtqueue(config->num, vdev, (void *) config->address,
				 kvm_notify, callback);
	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, PAGE_SIZE));
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, PAGE_SIZE));
}

/*
 * The config ops structure as defined by virtio config
 */
static 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_vq = kvm_find_vq,
	.del_vq = kvm_del_vq,
};

/*
 * 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 = {
	.parent = NULL,
	.bus_id = "kvm_s390",
};

/*
 * 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);
	}
}

/*
 * we emulate the request_irq behaviour on top of s390 extints
 */
static void kvm_extint_handler(u16 code)
{
	void *data = (void *) *(long *) __LC_PFAULT_INTPARM;
	u16 subcode = S390_lowcore.cpu_addr;

	if ((subcode & 0xff00) != VIRTIO_SUBCODE_64)
		return;

	vring_interrupt(0, data);
}

/*
 * Init function for virtio
 * devices are in a single page above top of "normal" mem
 */
static int __init kvm_devices_init(void)
{
	int rc;

	if (!MACHINE_IS_KVM)
		return -ENODEV;

	rc = device_register(&kvm_root);
	if (rc) {
		printk(KERN_ERR "Could not register kvm_s390 root device");
		return rc;
	}

	rc = vmem_add_mapping(PFN_PHYS(max_pfn), PAGE_SIZE);
	if (rc) {
		device_unregister(&kvm_root);
		return rc;
	}

	kvm_devices = (void *) PFN_PHYS(max_pfn);

	ctl_set_bit(0, 9);
	register_external_interrupt(0x2603, kvm_extint_handler);

	scan_devices();
	return 0;
}

/* code for early console output with virtio_console */
static __init 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;
}

void __init s390_virtio_console_init(void)
{
	virtio_cons_early_init(early_put_chars);
}

/*
 * We do this after core stuff, but before the drivers.
 */
postcore_initcall(kvm_devices_init);
Commit	Line	Data
e976a2b9 CB	1	/*
	2	* kvm_virtio.c - virtio for kvm on s390
	3	*
	4	* Copyright IBM Corp. 2008
	5	*
	6	* This program is free software; you can redistribute it and/or modify
	7	* it under the terms of the GNU General Public License (version 2 only)
	8	* as published by the Free Software Foundation.
	9	*
	10	* Author(s): Christian Borntraeger <borntraeger@de.ibm.com>
	11	*/
	12
	13	#include <linux/init.h>
	14	#include <linux/bootmem.h>
	15	#include <linux/err.h>
	16	#include <linux/virtio.h>
	17	#include <linux/virtio_config.h>
faeba830	18	#include <linux/virtio_console.h>
e976a2b9 CB	19	#include <linux/interrupt.h>
e976a2b9 CB	20	#include <linux/virtio_ring.h>
17f34580	21	#include <linux/pfn.h>
e976a2b9 CB	22	#include <asm/io.h>
	23	#include <asm/kvm_para.h>
	24	#include <asm/kvm_virtio.h>
	25	#include <asm/setup.h>
	26	#include <asm/s390_ext.h>
	27
	28	#define VIRTIO_SUBCODE_64 0x0D00
	29
	30	/*
	31	* The pointer to our (page) of device descriptions.
	32	*/
	33	static void *kvm_devices;
	34
e976a2b9 CB	35	struct kvm_device {
	36	struct virtio_device vdev;
	37	struct kvm_device_desc *desc;
	38	};
	39
	40	#define to_kvmdev(vd) container_of(vd, struct kvm_device, vdev)
	41
	42	/*
	43	* memory layout:
	44	* - kvm_device_descriptor
	45	* struct kvm_device_desc
	46	* - configuration
	47	* struct kvm_vqconfig
	48	* - feature bits
	49	* - config space
	50	*/
	51	static struct kvm_vqconfig kvm_vq_config(const struct kvm_device_desc desc)
	52	{
	53	return (struct kvm_vqconfig *)(desc + 1);
	54	}
	55
	56	static u8 kvm_vq_features(const struct kvm_device_desc desc)
	57	{
	58	return (u8 *)(kvm_vq_config(desc) + desc->num_vq);
	59	}
	60
	61	static u8 kvm_vq_configspace(const struct kvm_device_desc desc)
	62	{
	63	return kvm_vq_features(desc) + desc->feature_len * 2;
	64	}
	65
	66	/*
	67	* The total size of the config page used by this device (incl. desc)
	68	*/
	69	static unsigned desc_size(const struct kvm_device_desc *desc)
	70	{
	71	return sizeof(*desc)
	72	+ desc->num_vq * sizeof(struct kvm_vqconfig)
	73	+ desc->feature_len * 2
	74	+ desc->config_len;
	75	}
	76
5ca9fd54 HC	77	/* This gets the device's feature bits. */
5ca9fd54 HC	78	static u32 kvm_get_features(struct virtio_device *vdev)
e976a2b9	79	{
5ca9fd54 HC	80	unsigned int i;
5ca9fd54 HC	81	u32 features = 0;
e976a2b9	82	struct kvm_device_desc *desc = to_kvmdev(vdev)->desc;
5ca9fd54	83	u8 *in_features = kvm_vq_features(desc);
e976a2b9	84
5ca9fd54 HC	85	for (i = 0; i < min(desc->feature_len * 8, 32); i++)
	86	if (in_features[i / 8] & (1 << (i % 8)))
	87	features \|= (1 << i);
	88	return features;
	89	}
e976a2b9	90
c624896e	91	static void kvm_finalize_features(struct virtio_device *vdev)
5ca9fd54	92	{
c624896e	93	unsigned int i, bits;
5ca9fd54 HC	94	struct kvm_device_desc *desc = to_kvmdev(vdev)->desc;
	95	/* Second half of bitmap is features we accept. */
	96	u8 *out_features = kvm_vq_features(desc) + desc->feature_len;
e976a2b9	97
e34f8725 RR	98	/* Give virtio_ring a chance to accept features. */
	99	vring_transport_features(vdev);
	100
5ca9fd54	101	memset(out_features, 0, desc->feature_len);
c624896e RR	102	bits = min_t(unsigned, desc->feature_len, sizeof(vdev->features)) * 8;
	103	for (i = 0; i < bits; i++) {
	104	if (test_bit(i, vdev->features))
5ca9fd54 HC	105	out_features[i / 8] \|= (1 << (i % 8));
5ca9fd54 HC	106	}
e976a2b9 CB	107	}
	108
	109	/*
	110	* Reading and writing elements in config space
	111	*/
	112	static void kvm_get(struct virtio_device *vdev, unsigned int offset,
	113	void *buf, unsigned len)
	114	{
	115	struct kvm_device_desc *desc = to_kvmdev(vdev)->desc;
	116
	117	BUG_ON(offset + len > desc->config_len);
	118	memcpy(buf, kvm_vq_configspace(desc) + offset, len);
	119	}
	120
	121	static void kvm_set(struct virtio_device *vdev, unsigned int offset,
	122	const void *buf, unsigned len)
	123	{
	124	struct kvm_device_desc *desc = to_kvmdev(vdev)->desc;
	125
	126	BUG_ON(offset + len > desc->config_len);
	127	memcpy(kvm_vq_configspace(desc) + offset, buf, len);
	128	}
	129
	130	/*
	131	* The operations to get and set the status word just access
	132	* the status field of the device descriptor. set_status will also
	133	* make a hypercall to the host, to tell about status changes
	134	*/
	135	static u8 kvm_get_status(struct virtio_device *vdev)
	136	{
	137	return to_kvmdev(vdev)->desc->status;
	138	}
	139
	140	static void kvm_set_status(struct virtio_device *vdev, u8 status)
	141	{
	142	BUG_ON(!status);
	143	to_kvmdev(vdev)->desc->status = status;
	144	kvm_hypercall1(KVM_S390_VIRTIO_SET_STATUS,
	145	(unsigned long) to_kvmdev(vdev)->desc);
	146	}
	147
	148	/*
	149	* To reset the device, we use the KVM_VIRTIO_RESET hypercall, using the
	150	* descriptor address. The Host will zero the status and all the
	151	* features.
	152	*/
	153	static void kvm_reset(struct virtio_device *vdev)
	154	{
	155	kvm_hypercall1(KVM_S390_VIRTIO_RESET,
	156	(unsigned long) to_kvmdev(vdev)->desc);
	157	}
	158
	159	/*
	160	* When the virtio_ring code wants to notify the Host, it calls us here and we
	161	* make a hypercall. We hand the address of the virtqueue so the Host
	162	* knows which virtqueue we're talking about.
	163	*/
	164	static void kvm_notify(struct virtqueue *vq)
	165	{
	166	struct kvm_vqconfig *config = vq->priv;
	167
	168	kvm_hypercall1(KVM_S390_VIRTIO_NOTIFY, config->address);
	169	}
	170
171	/*
172	* This routine finds the first virtqueue described in the configuration of
173	* this device and sets it up.
174	*/
175	static struct virtqueue kvm_find_vq(struct virtio_device vdev,
176	unsigned index,
177	void (callback)(struct virtqueue vq))
178	{
179	struct kvm_device *kdev = to_kvmdev(vdev);
180	struct kvm_vqconfig *config;
181	struct virtqueue *vq;
182	int err;
183
184	if (index >= kdev->desc->num_vq)
185	return ERR_PTR(-ENOENT);
186
187	config = kvm_vq_config(kdev->desc)+index;
188
17f34580 HC	189	err = vmem_add_mapping(config->address,
	190	vring_size(config->num, PAGE_SIZE));
	191	if (err)
e976a2b9	192	goto out;
e976a2b9 CB	193
	194	vq = vring_new_virtqueue(config->num, vdev, (void *) config->address,
	195	kvm_notify, callback);
	196	if (!vq) {
	197	err = -ENOMEM;
	198	goto unmap;
	199	}
	200
	201	/*
	202	* register a callback token
	203	* The host will sent this via the external interrupt parameter
	204	*/
	205	config->token = (u64) vq;
	206
	207	vq->priv = config;
	208	return vq;
	209	unmap:
17f34580 HC	210	vmem_remove_mapping(config->address,
17f34580 HC	211	vring_size(config->num, PAGE_SIZE));
e976a2b9 CB	212	out:
	213	return ERR_PTR(err);
	214	}
	215
	216	static void kvm_del_vq(struct virtqueue *vq)
	217	{
	218	struct kvm_vqconfig *config = vq->priv;
	219
	220	vring_del_virtqueue(vq);
17f34580 HC	221	vmem_remove_mapping(config->address,
17f34580 HC	222	vring_size(config->num, PAGE_SIZE));
e976a2b9 CB	223	}
	224
	225	/*
	226	* The config ops structure as defined by virtio config
	227	*/
	228	static struct virtio_config_ops kvm_vq_configspace_ops = {
5ca9fd54	229	.get_features = kvm_get_features,
c624896e	230	.finalize_features = kvm_finalize_features,
e976a2b9 CB	231	.get = kvm_get,
	232	.set = kvm_set,
	233	.get_status = kvm_get_status,
	234	.set_status = kvm_set_status,
	235	.reset = kvm_reset,
	236	.find_vq = kvm_find_vq,
	237	.del_vq = kvm_del_vq,
	238	};
	239
	240	/*
	241	* The root device for the kvm virtio devices.
	242	* This makes them appear as /sys/devices/kvm_s390/0,1,2 not /sys/devices/0,1,2.
	243	*/
	244	static struct device kvm_root = {
	245	.parent = NULL,
	246	.bus_id = "kvm_s390",
	247	};
	248
	249	/*
	250	* adds a new device and register it with virtio
	251	* appropriate drivers are loaded by the device model
	252	*/
b769f579	253	static void add_kvm_device(struct kvm_device_desc *d, unsigned int offset)
e976a2b9 CB	254	{
	255	struct kvm_device *kdev;
	256
	257	kdev = kzalloc(sizeof(*kdev), GFP_KERNEL);
	258	if (!kdev) {
b769f579 RR	259	printk(KERN_EMERG "Cannot allocate kvm dev %u type %u\n",
b769f579 RR	260	offset, d->type);
e976a2b9 CB	261	return;
	262	}
	263
	264	kdev->vdev.dev.parent = &kvm_root;
e976a2b9 CB	265	kdev->vdev.id.device = d->type;
	266	kdev->vdev.config = &kvm_vq_configspace_ops;
	267	kdev->desc = d;
	268
	269	if (register_virtio_device(&kdev->vdev) != 0) {
b769f579 RR	270	printk(KERN_ERR "Failed to register kvm device %u type %u\n",
b769f579 RR	271	offset, d->type);
e976a2b9 CB	272	kfree(kdev);
	273	}
	274	}
	275
	276	/*
	277	* scan_devices() simply iterates through the device page.
	278	* The type 0 is reserved to mean "end of devices".
	279	*/
	280	static void scan_devices(void)
	281	{
	282	unsigned int i;
	283	struct kvm_device_desc *d;
	284
	285	for (i = 0; i < PAGE_SIZE; i += desc_size(d)) {
	286	d = kvm_devices + i;
	287
	288	if (d->type == 0)
	289	break;
	290
b769f579	291	add_kvm_device(d, i);
e976a2b9 CB	292	}
	293	}
	294
	295	/*
	296	* we emulate the request_irq behaviour on top of s390 extints
	297	*/
	298	static void kvm_extint_handler(u16 code)
	299	{
	300	void data = (void ) (long ) __LC_PFAULT_INTPARM;
	301	u16 subcode = S390_lowcore.cpu_addr;
	302
	303	if ((subcode & 0xff00) != VIRTIO_SUBCODE_64)
	304	return;
	305
	306	vring_interrupt(0, data);
	307	}
	308
	309	/*
	310	* Init function for virtio
	311	* devices are in a single page above top of "normal" mem
	312	*/
	313	static int __init kvm_devices_init(void)
	314	{
	315	int rc;
	316
	317	if (!MACHINE_IS_KVM)
	318	return -ENODEV;
	319
	320	rc = device_register(&kvm_root);
	321	if (rc) {
	322	printk(KERN_ERR "Could not register kvm_s390 root device");
	323	return rc;
	324	}
	325
17f34580 HC	326	rc = vmem_add_mapping(PFN_PHYS(max_pfn), PAGE_SIZE);
17f34580 HC	327	if (rc) {
e976a2b9	328	device_unregister(&kvm_root);
17f34580	329	return rc;
e976a2b9 CB	330	}
e976a2b9 CB	331
17f34580	332	kvm_devices = (void *) PFN_PHYS(max_pfn);
e976a2b9 CB	333
	334	ctl_set_bit(0, 9);
	335	register_external_interrupt(0x2603, kvm_extint_handler);
	336
	337	scan_devices();
	338	return 0;
	339	}
	340
faeba830 CB	341	/* code for early console output with virtio_console */
	342	static __init int early_put_chars(u32 vtermno, const char *buf, int count)
	343	{
	344	char scratch[17];
	345	unsigned int len = count;
	346
	347	if (len > sizeof(scratch) - 1)
	348	len = sizeof(scratch) - 1;
	349	scratch[len] = '\0';
	350	memcpy(scratch, buf, len);
	351	kvm_hypercall1(KVM_S390_VIRTIO_NOTIFY, __pa(scratch));
	352	return len;
	353	}
	354
26f746f3	355	void __init s390_virtio_console_init(void)
faeba830 CB	356	{
	357	virtio_cons_early_init(early_put_chars);
	358	}
	359
e976a2b9 CB	360	/*
	361	* We do this after core stuff, but before the drivers.
	362	*/
	363	postcore_initcall(kvm_devices_init);