[go: nahoru, domu]
1/*
2 * 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/kernel_stat.h>
14#include <linux/init.h>
15#include <linux/bootmem.h>
16#include <linux/err.h>
17#include <linux/virtio.h>
18#include <linux/virtio_config.h>
19#include <linux/slab.h>
20#include <linux/virtio_console.h>
21#include <linux/interrupt.h>
22#include <linux/virtio_ring.h>
23#include <linux/export.h>
24#include <linux/pfn.h>
25#include <asm/io.h>
26#include <asm/kvm_para.h>
27#include <asm/kvm_virtio.h>
28#include <asm/sclp.h>
29#include <asm/setup.h>
30#include <asm/irq.h>
31
32#define VIRTIO_SUBCODE_64 0x0D00
33
34/*
35 * The pointer to our (page) of device descriptions.
36 */
37static void *kvm_devices;
38static struct work_struct hotplug_work;
39
40struct kvm_device {
41	struct virtio_device vdev;
42	struct kvm_device_desc *desc;
43};
44
45#define to_kvmdev(vd) container_of(vd, struct kvm_device, vdev)
46
47/*
48 * memory layout:
49 * - kvm_device_descriptor
50 *        struct kvm_device_desc
51 * - configuration
52 *        struct kvm_vqconfig
53 * - feature bits
54 * - config space
55 */
56static struct kvm_vqconfig *kvm_vq_config(const struct kvm_device_desc *desc)
57{
58	return (struct kvm_vqconfig *)(desc + 1);
59}
60
61static u8 *kvm_vq_features(const struct kvm_device_desc *desc)
62{
63	return (u8 *)(kvm_vq_config(desc) + desc->num_vq);
64}
65
66static u8 *kvm_vq_configspace(const struct kvm_device_desc *desc)
67{
68	return kvm_vq_features(desc) + desc->feature_len * 2;
69}
70
71/*
72 * The total size of the config page used by this device (incl. desc)
73 */
74static unsigned desc_size(const struct kvm_device_desc *desc)
75{
76	return sizeof(*desc)
77		+ desc->num_vq * sizeof(struct kvm_vqconfig)
78		+ desc->feature_len * 2
79		+ desc->config_len;
80}
81
82/* This gets the device's feature bits. */
83static u32 kvm_get_features(struct virtio_device *vdev)
84{
85	unsigned int i;
86	u32 features = 0;
87	struct kvm_device_desc *desc = to_kvmdev(vdev)->desc;
88	u8 *in_features = kvm_vq_features(desc);
89
90	for (i = 0; i < min(desc->feature_len * 8, 32); i++)
91		if (in_features[i / 8] & (1 << (i % 8)))
92			features |= (1 << i);
93	return features;
94}
95
96static void kvm_finalize_features(struct virtio_device *vdev)
97{
98	unsigned int i, bits;
99	struct kvm_device_desc *desc = to_kvmdev(vdev)->desc;
100	/* Second half of bitmap is features we accept. */
101	u8 *out_features = kvm_vq_features(desc) + desc->feature_len;
102
103	/* Give virtio_ring a chance to accept features. */
104	vring_transport_features(vdev);
105
106	memset(out_features, 0, desc->feature_len);
107	bits = min_t(unsigned, desc->feature_len, sizeof(vdev->features)) * 8;
108	for (i = 0; i < bits; i++) {
109		if (test_bit(i, vdev->features))
110			out_features[i / 8] |= (1 << (i % 8));
111	}
112}
113
114/*
115 * Reading and writing elements in config space
116 */
117static void kvm_get(struct virtio_device *vdev, unsigned int offset,
118		   void *buf, unsigned len)
119{
120	struct kvm_device_desc *desc = to_kvmdev(vdev)->desc;
121
122	BUG_ON(offset + len > desc->config_len);
123	memcpy(buf, kvm_vq_configspace(desc) + offset, len);
124}
125
126static void kvm_set(struct virtio_device *vdev, unsigned int offset,
127		   const void *buf, unsigned len)
128{
129	struct kvm_device_desc *desc = to_kvmdev(vdev)->desc;
130
131	BUG_ON(offset + len > desc->config_len);
132	memcpy(kvm_vq_configspace(desc) + offset, buf, len);
133}
134
135/*
136 * The operations to get and set the status word just access
137 * the status field of the device descriptor. set_status will also
138 * make a hypercall to the host, to tell about status changes
139 */
140static u8 kvm_get_status(struct virtio_device *vdev)
141{
142	return to_kvmdev(vdev)->desc->status;
143}
144
145static void kvm_set_status(struct virtio_device *vdev, u8 status)
146{
147	BUG_ON(!status);
148	to_kvmdev(vdev)->desc->status = status;
149	kvm_hypercall1(KVM_S390_VIRTIO_SET_STATUS,
150		       (unsigned long) to_kvmdev(vdev)->desc);
151}
152
153/*
154 * To reset the device, we use the KVM_VIRTIO_RESET hypercall, using the
155 * descriptor address. The Host will zero the status and all the
156 * features.
157 */
158static void kvm_reset(struct virtio_device *vdev)
159{
160	kvm_hypercall1(KVM_S390_VIRTIO_RESET,
161		       (unsigned long) to_kvmdev(vdev)->desc);
162}
163
164/*
165 * When the virtio_ring code wants to notify the Host, it calls us here and we
166 * make a hypercall.  We hand the address  of the virtqueue so the Host
167 * knows which virtqueue we're talking about.
168 */
169static bool kvm_notify(struct virtqueue *vq)
170{
171	long rc;
172	struct kvm_vqconfig *config = vq->priv;
173
174	rc = kvm_hypercall1(KVM_S390_VIRTIO_NOTIFY, config->address);
175	if (rc < 0)
176		return false;
177	return true;
178}
179
180/*
181 * This routine finds the first virtqueue described in the configuration of
182 * this device and sets it up.
183 */
184static struct virtqueue *kvm_find_vq(struct virtio_device *vdev,
185				     unsigned index,
186				     void (*callback)(struct virtqueue *vq),
187				     const char *name)
188{
189	struct kvm_device *kdev = to_kvmdev(vdev);
190	struct kvm_vqconfig *config;
191	struct virtqueue *vq;
192	int err;
193
194	if (index >= kdev->desc->num_vq)
195		return ERR_PTR(-ENOENT);
196
197	if (!name)
198		return NULL;
199
200	config = kvm_vq_config(kdev->desc)+index;
201
202	err = vmem_add_mapping(config->address,
203			       vring_size(config->num,
204					  KVM_S390_VIRTIO_RING_ALIGN));
205	if (err)
206		goto out;
207
208	vq = vring_new_virtqueue(index, config->num, KVM_S390_VIRTIO_RING_ALIGN,
209				 vdev, true, (void *) config->address,
210				 kvm_notify, callback, name);
211	if (!vq) {
212		err = -ENOMEM;
213		goto unmap;
214	}
215
216	/*
217	 * register a callback token
218	 * The host will sent this via the external interrupt parameter
219	 */
220	config->token = (u64) vq;
221
222	vq->priv = config;
223	return vq;
224unmap:
225	vmem_remove_mapping(config->address,
226			    vring_size(config->num,
227				       KVM_S390_VIRTIO_RING_ALIGN));
228out:
229	return ERR_PTR(err);
230}
231
232static void kvm_del_vq(struct virtqueue *vq)
233{
234	struct kvm_vqconfig *config = vq->priv;
235
236	vring_del_virtqueue(vq);
237	vmem_remove_mapping(config->address,
238			    vring_size(config->num,
239				       KVM_S390_VIRTIO_RING_ALIGN));
240}
241
242static void kvm_del_vqs(struct virtio_device *vdev)
243{
244	struct virtqueue *vq, *n;
245
246	list_for_each_entry_safe(vq, n, &vdev->vqs, list)
247		kvm_del_vq(vq);
248}
249
250static int kvm_find_vqs(struct virtio_device *vdev, unsigned nvqs,
251			struct virtqueue *vqs[],
252			vq_callback_t *callbacks[],
253			const char *names[])
254{
255	struct kvm_device *kdev = to_kvmdev(vdev);
256	int i;
257
258	/* We must have this many virtqueues. */
259	if (nvqs > kdev->desc->num_vq)
260		return -ENOENT;
261
262	for (i = 0; i < nvqs; ++i) {
263		vqs[i] = kvm_find_vq(vdev, i, callbacks[i], names[i]);
264		if (IS_ERR(vqs[i]))
265			goto error;
266	}
267	return 0;
268
269error:
270	kvm_del_vqs(vdev);
271	return PTR_ERR(vqs[i]);
272}
273
274static const char *kvm_bus_name(struct virtio_device *vdev)
275{
276	return "";
277}
278
279/*
280 * The config ops structure as defined by virtio config
281 */
282static const struct virtio_config_ops kvm_vq_configspace_ops = {
283	.get_features = kvm_get_features,
284	.finalize_features = kvm_finalize_features,
285	.get = kvm_get,
286	.set = kvm_set,
287	.get_status = kvm_get_status,
288	.set_status = kvm_set_status,
289	.reset = kvm_reset,
290	.find_vqs = kvm_find_vqs,
291	.del_vqs = kvm_del_vqs,
292	.bus_name = kvm_bus_name,
293};
294
295/*
296 * The root device for the kvm virtio devices.
297 * This makes them appear as /sys/devices/kvm_s390/0,1,2 not /sys/devices/0,1,2.
298 */
299static struct device *kvm_root;
300
301/*
302 * adds a new device and register it with virtio
303 * appropriate drivers are loaded by the device model
304 */
305static void add_kvm_device(struct kvm_device_desc *d, unsigned int offset)
306{
307	struct kvm_device *kdev;
308
309	kdev = kzalloc(sizeof(*kdev), GFP_KERNEL);
310	if (!kdev) {
311		printk(KERN_EMERG "Cannot allocate kvm dev %u type %u\n",
312		       offset, d->type);
313		return;
314	}
315
316	kdev->vdev.dev.parent = kvm_root;
317	kdev->vdev.id.device = d->type;
318	kdev->vdev.config = &kvm_vq_configspace_ops;
319	kdev->desc = d;
320
321	if (register_virtio_device(&kdev->vdev) != 0) {
322		printk(KERN_ERR "Failed to register kvm device %u type %u\n",
323		       offset, d->type);
324		kfree(kdev);
325	}
326}
327
328/*
329 * scan_devices() simply iterates through the device page.
330 * The type 0 is reserved to mean "end of devices".
331 */
332static void scan_devices(void)
333{
334	unsigned int i;
335	struct kvm_device_desc *d;
336
337	for (i = 0; i < PAGE_SIZE; i += desc_size(d)) {
338		d = kvm_devices + i;
339
340		if (d->type == 0)
341			break;
342
343		add_kvm_device(d, i);
344	}
345}
346
347/*
348 * match for a kvm device with a specific desc pointer
349 */
350static int match_desc(struct device *dev, void *data)
351{
352	struct virtio_device *vdev = dev_to_virtio(dev);
353	struct kvm_device *kdev = to_kvmdev(vdev);
354
355	return kdev->desc == data;
356}
357
358/*
359 * hotplug_device tries to find changes in the device page.
360 */
361static void hotplug_devices(struct work_struct *dummy)
362{
363	unsigned int i;
364	struct kvm_device_desc *d;
365	struct device *dev;
366
367	for (i = 0; i < PAGE_SIZE; i += desc_size(d)) {
368		d = kvm_devices + i;
369
370		/* end of list */
371		if (d->type == 0)
372			break;
373
374		/* device already exists */
375		dev = device_find_child(kvm_root, d, match_desc);
376		if (dev) {
377			/* XXX check for hotplug remove */
378			put_device(dev);
379			continue;
380		}
381
382		/* new device */
383		printk(KERN_INFO "Adding new virtio device %p\n", d);
384		add_kvm_device(d, i);
385	}
386}
387
388/*
389 * we emulate the request_irq behaviour on top of s390 extints
390 */
391static void kvm_extint_handler(struct ext_code ext_code,
392			       unsigned int param32, unsigned long param64)
393{
394	struct virtqueue *vq;
395	u32 param;
396
397	if ((ext_code.subcode & 0xff00) != VIRTIO_SUBCODE_64)
398		return;
399	inc_irq_stat(IRQEXT_VRT);
400
401	/* The LSB might be overloaded, we have to mask it */
402	vq = (struct virtqueue *)(param64 & ~1UL);
403
404	/* We use ext_params to decide what this interrupt means */
405	param = param32 & VIRTIO_PARAM_MASK;
406
407	switch (param) {
408	case VIRTIO_PARAM_CONFIG_CHANGED:
409		virtio_config_changed(vq->vdev);
410		break;
411	case VIRTIO_PARAM_DEV_ADD:
412		schedule_work(&hotplug_work);
413		break;
414	case VIRTIO_PARAM_VRING_INTERRUPT:
415	default:
416		vring_interrupt(0, vq);
417		break;
418	}
419}
420
421/*
422 * For s390-virtio, we expect a page above main storage containing
423 * the virtio configuration. Try to actually load from this area
424 * in order to figure out if the host provides this page.
425 */
426static int __init test_devices_support(unsigned long addr)
427{
428	int ret = -EIO;
429
430	asm volatile(
431		"0:	lura	0,%1\n"
432		"1:	xgr	%0,%0\n"
433		"2:\n"
434		EX_TABLE(0b,2b)
435		EX_TABLE(1b,2b)
436		: "+d" (ret)
437		: "a" (addr)
438		: "0", "cc");
439	return ret;
440}
441/*
442 * Init function for virtio
443 * devices are in a single page above top of "normal" + standby mem
444 */
445static int __init kvm_devices_init(void)
446{
447	int rc;
448	unsigned long total_memory_size = sclp_get_rzm() * sclp_get_rnmax();
449
450	if (!MACHINE_IS_KVM)
451		return -ENODEV;
452
453	if (test_devices_support(total_memory_size) < 0)
454		return -ENODEV;
455
456	rc = vmem_add_mapping(total_memory_size, PAGE_SIZE);
457	if (rc)
458		return rc;
459
460	kvm_devices = (void *) total_memory_size;
461
462	kvm_root = root_device_register("kvm_s390");
463	if (IS_ERR(kvm_root)) {
464		rc = PTR_ERR(kvm_root);
465		printk(KERN_ERR "Could not register kvm_s390 root device");
466		vmem_remove_mapping(total_memory_size, PAGE_SIZE);
467		return rc;
468	}
469
470	INIT_WORK(&hotplug_work, hotplug_devices);
471
472	irq_subclass_register(IRQ_SUBCLASS_SERVICE_SIGNAL);
473	register_external_irq(EXT_IRQ_CP_SERVICE, kvm_extint_handler);
474
475	scan_devices();
476	return 0;
477}
478
479/* code for early console output with virtio_console */
480static __init int early_put_chars(u32 vtermno, const char *buf, int count)
481{
482	char scratch[17];
483	unsigned int len = count;
484
485	if (len > sizeof(scratch) - 1)
486		len = sizeof(scratch) - 1;
487	scratch[len] = '\0';
488	memcpy(scratch, buf, len);
489	kvm_hypercall1(KVM_S390_VIRTIO_NOTIFY, __pa(scratch));
490	return len;
491}
492
493static int __init s390_virtio_console_init(void)
494{
495	if (sclp_has_vt220() || sclp_has_linemode())
496		return -ENODEV;
497	return virtio_cons_early_init(early_put_chars);
498}
499console_initcall(s390_virtio_console_init);
500
501
502/*
503 * We do this after core stuff, but before the drivers.
504 */
505postcore_initcall(kvm_devices_init);
506