2 * virtio for kvm on s390
4 * Copyright IBM Corp. 2008
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.
10 * Author(s): Christian Borntraeger <borntraeger@de.ibm.com>
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>
26 #include <asm/kvm_para.h>
27 #include <asm/kvm_virtio.h>
29 #include <asm/setup.h>
32 #define VIRTIO_SUBCODE_64 0x0D00
35 * The pointer to our (page) of device descriptions.
37 static void *kvm_devices;
38 static struct work_struct hotplug_work;
41 struct virtio_device vdev;
42 struct kvm_device_desc *desc;
45 #define to_kvmdev(vd) container_of(vd, struct kvm_device, vdev)
49 * - kvm_device_descriptor
50 * struct kvm_device_desc
56 static struct kvm_vqconfig *kvm_vq_config(const struct kvm_device_desc *desc)
58 return (struct kvm_vqconfig *)(desc + 1);
61 static u8 *kvm_vq_features(const struct kvm_device_desc *desc)
63 return (u8 *)(kvm_vq_config(desc) + desc->num_vq);
66 static u8 *kvm_vq_configspace(const struct kvm_device_desc *desc)
68 return kvm_vq_features(desc) + desc->feature_len * 2;
72 * The total size of the config page used by this device (incl. desc)
74 static unsigned desc_size(const struct kvm_device_desc *desc)
77 + desc->num_vq * sizeof(struct kvm_vqconfig)
78 + desc->feature_len * 2
82 /* This gets the device's feature bits. */
83 static u32 kvm_get_features(struct virtio_device *vdev)
87 struct kvm_device_desc *desc = to_kvmdev(vdev)->desc;
88 u8 *in_features = kvm_vq_features(desc);
90 for (i = 0; i < min(desc->feature_len * 8, 32); i++)
91 if (in_features[i / 8] & (1 << (i % 8)))
96 static void kvm_finalize_features(struct virtio_device *vdev)
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;
103 /* Give virtio_ring a chance to accept features. */
104 vring_transport_features(vdev);
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));
115 * Reading and writing elements in config space
117 static void kvm_get(struct virtio_device *vdev, unsigned int offset,
118 void *buf, unsigned len)
120 struct kvm_device_desc *desc = to_kvmdev(vdev)->desc;
122 BUG_ON(offset + len > desc->config_len);
123 memcpy(buf, kvm_vq_configspace(desc) + offset, len);
126 static void kvm_set(struct virtio_device *vdev, unsigned int offset,
127 const void *buf, unsigned len)
129 struct kvm_device_desc *desc = to_kvmdev(vdev)->desc;
131 BUG_ON(offset + len > desc->config_len);
132 memcpy(kvm_vq_configspace(desc) + offset, buf, len);
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
140 static u8 kvm_get_status(struct virtio_device *vdev)
142 return to_kvmdev(vdev)->desc->status;
145 static void kvm_set_status(struct virtio_device *vdev, u8 status)
148 to_kvmdev(vdev)->desc->status = status;
149 kvm_hypercall1(KVM_S390_VIRTIO_SET_STATUS,
150 (unsigned long) to_kvmdev(vdev)->desc);
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
158 static void kvm_reset(struct virtio_device *vdev)
160 kvm_hypercall1(KVM_S390_VIRTIO_RESET,
161 (unsigned long) to_kvmdev(vdev)->desc);
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.
169 static void kvm_notify(struct virtqueue *vq)
171 struct kvm_vqconfig *config = vq->priv;
173 kvm_hypercall1(KVM_S390_VIRTIO_NOTIFY, config->address);
177 * This routine finds the first virtqueue described in the configuration of
178 * this device and sets it up.
180 static struct virtqueue *kvm_find_vq(struct virtio_device *vdev,
182 void (*callback)(struct virtqueue *vq),
185 struct kvm_device *kdev = to_kvmdev(vdev);
186 struct kvm_vqconfig *config;
187 struct virtqueue *vq;
190 if (index >= kdev->desc->num_vq)
191 return ERR_PTR(-ENOENT);
193 config = kvm_vq_config(kdev->desc)+index;
195 err = vmem_add_mapping(config->address,
196 vring_size(config->num,
197 KVM_S390_VIRTIO_RING_ALIGN));
201 vq = vring_new_virtqueue(index, config->num, KVM_S390_VIRTIO_RING_ALIGN,
202 vdev, true, (void *) config->address,
203 kvm_notify, callback, name);
210 * register a callback token
211 * The host will sent this via the external interrupt parameter
213 config->token = (u64) vq;
218 vmem_remove_mapping(config->address,
219 vring_size(config->num,
220 KVM_S390_VIRTIO_RING_ALIGN));
225 static void kvm_del_vq(struct virtqueue *vq)
227 struct kvm_vqconfig *config = vq->priv;
229 vring_del_virtqueue(vq);
230 vmem_remove_mapping(config->address,
231 vring_size(config->num,
232 KVM_S390_VIRTIO_RING_ALIGN));
235 static void kvm_del_vqs(struct virtio_device *vdev)
237 struct virtqueue *vq, *n;
239 list_for_each_entry_safe(vq, n, &vdev->vqs, list)
243 static int kvm_find_vqs(struct virtio_device *vdev, unsigned nvqs,
244 struct virtqueue *vqs[],
245 vq_callback_t *callbacks[],
248 struct kvm_device *kdev = to_kvmdev(vdev);
251 /* We must have this many virtqueues. */
252 if (nvqs > kdev->desc->num_vq)
255 for (i = 0; i < nvqs; ++i) {
256 vqs[i] = kvm_find_vq(vdev, i, callbacks[i], names[i]);
264 return PTR_ERR(vqs[i]);
267 static const char *kvm_bus_name(struct virtio_device *vdev)
273 * The config ops structure as defined by virtio config
275 static struct virtio_config_ops kvm_vq_configspace_ops = {
276 .get_features = kvm_get_features,
277 .finalize_features = kvm_finalize_features,
280 .get_status = kvm_get_status,
281 .set_status = kvm_set_status,
283 .find_vqs = kvm_find_vqs,
284 .del_vqs = kvm_del_vqs,
285 .bus_name = kvm_bus_name,
289 * The root device for the kvm virtio devices.
290 * This makes them appear as /sys/devices/kvm_s390/0,1,2 not /sys/devices/0,1,2.
292 static struct device *kvm_root;
295 * adds a new device and register it with virtio
296 * appropriate drivers are loaded by the device model
298 static void add_kvm_device(struct kvm_device_desc *d, unsigned int offset)
300 struct kvm_device *kdev;
302 kdev = kzalloc(sizeof(*kdev), GFP_KERNEL);
304 printk(KERN_EMERG "Cannot allocate kvm dev %u type %u\n",
309 kdev->vdev.dev.parent = kvm_root;
310 kdev->vdev.id.device = d->type;
311 kdev->vdev.config = &kvm_vq_configspace_ops;
314 if (register_virtio_device(&kdev->vdev) != 0) {
315 printk(KERN_ERR "Failed to register kvm device %u type %u\n",
322 * scan_devices() simply iterates through the device page.
323 * The type 0 is reserved to mean "end of devices".
325 static void scan_devices(void)
328 struct kvm_device_desc *d;
330 for (i = 0; i < PAGE_SIZE; i += desc_size(d)) {
336 add_kvm_device(d, i);
341 * match for a kvm device with a specific desc pointer
343 static int match_desc(struct device *dev, void *data)
345 struct virtio_device *vdev = dev_to_virtio(dev);
346 struct kvm_device *kdev = to_kvmdev(vdev);
348 return kdev->desc == data;
352 * hotplug_device tries to find changes in the device page.
354 static void hotplug_devices(struct work_struct *dummy)
357 struct kvm_device_desc *d;
360 for (i = 0; i < PAGE_SIZE; i += desc_size(d)) {
367 /* device already exists */
368 dev = device_find_child(kvm_root, d, match_desc);
370 /* XXX check for hotplug remove */
376 printk(KERN_INFO "Adding new virtio device %p\n", d);
377 add_kvm_device(d, i);
382 * we emulate the request_irq behaviour on top of s390 extints
384 static void kvm_extint_handler(struct ext_code ext_code,
385 unsigned int param32, unsigned long param64)
387 struct virtqueue *vq;
390 if ((ext_code.subcode & 0xff00) != VIRTIO_SUBCODE_64)
392 kstat_cpu(smp_processor_id()).irqs[EXTINT_VRT]++;
394 /* The LSB might be overloaded, we have to mask it */
395 vq = (struct virtqueue *)(param64 & ~1UL);
397 /* We use ext_params to decide what this interrupt means */
398 param = param32 & VIRTIO_PARAM_MASK;
401 case VIRTIO_PARAM_CONFIG_CHANGED:
403 struct virtio_driver *drv;
404 drv = container_of(vq->vdev->dev.driver,
405 struct virtio_driver, driver);
406 if (drv->config_changed)
407 drv->config_changed(vq->vdev);
411 case VIRTIO_PARAM_DEV_ADD:
412 schedule_work(&hotplug_work);
414 case VIRTIO_PARAM_VRING_INTERRUPT:
416 vring_interrupt(0, vq);
422 * Init function for virtio
423 * devices are in a single page above top of "normal" mem
425 static int __init kvm_devices_init(void)
432 kvm_root = root_device_register("kvm_s390");
433 if (IS_ERR(kvm_root)) {
434 rc = PTR_ERR(kvm_root);
435 printk(KERN_ERR "Could not register kvm_s390 root device");
439 rc = vmem_add_mapping(real_memory_size, PAGE_SIZE);
441 root_device_unregister(kvm_root);
445 kvm_devices = (void *) real_memory_size;
447 INIT_WORK(&hotplug_work, hotplug_devices);
449 service_subclass_irq_register();
450 register_external_interrupt(0x2603, kvm_extint_handler);
456 /* code for early console output with virtio_console */
457 static __init int early_put_chars(u32 vtermno, const char *buf, int count)
460 unsigned int len = count;
462 if (len > sizeof(scratch) - 1)
463 len = sizeof(scratch) - 1;
465 memcpy(scratch, buf, len);
466 kvm_hypercall1(KVM_S390_VIRTIO_NOTIFY, __pa(scratch));
470 static int __init s390_virtio_console_init(void)
472 if (sclp_has_vt220() || sclp_has_linemode())
474 return virtio_cons_early_init(early_put_chars);
476 console_initcall(s390_virtio_console_init);
480 * We do this after core stuff, but before the drivers.
482 postcore_initcall(kvm_devices_init);