drivers/s390/kvm/kvm_virtio.c

   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/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/pfn.h>
  24 #include <asm/io.h>
  25 #include <asm/kvm_para.h>
  26 #include <asm/kvm_virtio.h>
  27 #include <asm/setup.h>
  28 #include <asm/irq.h>
  29
  30 #define VIRTIO_SUBCODE_64 0x0D00
  31
  32 /*
  33  * The pointer to our (page) of device descriptions.
  34  */
  35 static void *kvm_devices;
  36 struct work_struct hotplug_work;
  37
  38 struct kvm_device {
  39         struct virtio_device vdev;
  40         struct kvm_device_desc *desc;
  41 };
  42
  43 #define to_kvmdev(vd) container_of(vd, struct kvm_device, vdev)
  44
  45 /*
  46  * memory layout:
  47  * - kvm_device_descriptor
  48  *        struct kvm_device_desc
  49  * - configuration
  50  *        struct kvm_vqconfig
  51  * - feature bits
  52  * - config space
  53  */
  54 static struct kvm_vqconfig *kvm_vq_config(const struct kvm_device_desc *desc)
  55 {
  56         return (struct kvm_vqconfig *)(desc + 1);
  57 }
  58
  59 static u8 *kvm_vq_features(const struct kvm_device_desc *desc)
  60 {
  61         return (u8 *)(kvm_vq_config(desc) + desc->num_vq);
  62 }
  63
  64 static u8 *kvm_vq_configspace(const struct kvm_device_desc *desc)
  65 {
  66         return kvm_vq_features(desc) + desc->feature_len * 2;
  67 }
  68
  69 /*
  70  * The total size of the config page used by this device (incl. desc)
  71  */
  72 static unsigned desc_size(const struct kvm_device_desc *desc)
  73 {
  74         return sizeof(*desc)
  75                 + desc->num_vq * sizeof(struct kvm_vqconfig)
  76                 + desc->feature_len * 2
  77                 + desc->config_len;
  78 }
  79
  80 /* This gets the device's feature bits. */
  81 static u32 kvm_get_features(struct virtio_device *vdev)
  82 {
  83         unsigned int i;
  84         u32 features = 0;
  85         struct kvm_device_desc *desc = to_kvmdev(vdev)->desc;
  86         u8 *in_features = kvm_vq_features(desc);
  87
  88         for (i = 0; i < min(desc->feature_len * 8, 32); i++)
  89                 if (in_features[i / 8] & (1 << (i % 8)))
  90                         features |= (1 << i);
  91         return features;
  92 }
  93
  94 static void kvm_finalize_features(struct virtio_device *vdev)
  95 {
  96         unsigned int i, bits;
  97         struct kvm_device_desc *desc = to_kvmdev(vdev)->desc;
  98         /* Second half of bitmap is features we accept. */
  99         u8 *out_features = kvm_vq_features(desc) + desc->feature_len;
 100
 101         /* Give virtio_ring a chance to accept features. */
 102         vring_transport_features(vdev);
 103
 104         memset(out_features, 0, desc->feature_len);
 105         bits = min_t(unsigned, desc->feature_len, sizeof(vdev->features)) * 8;
 106         for (i = 0; i < bits; i++) {
 107                 if (test_bit(i, vdev->features))
 108                         out_features[i / 8] |= (1 << (i % 8));
 109         }
 110 }
 111
 112 /*
 113  * Reading and writing elements in config space
 114  */
 115 static void kvm_get(struct virtio_device *vdev, unsigned int offset,
 116                    void *buf, unsigned len)
 117 {
 118         struct kvm_device_desc *desc = to_kvmdev(vdev)->desc;
 119
 120         BUG_ON(offset + len > desc->config_len);
 121         memcpy(buf, kvm_vq_configspace(desc) + offset, len);
 122 }
 123
 124 static void kvm_set(struct virtio_device *vdev, unsigned int offset,
 125                    const void *buf, unsigned len)
 126 {
 127         struct kvm_device_desc *desc = to_kvmdev(vdev)->desc;
 128
 129         BUG_ON(offset + len > desc->config_len);
 130         memcpy(kvm_vq_configspace(desc) + offset, buf, len);
 131 }
 132
 133 /*
 134  * The operations to get and set the status word just access
 135  * the status field of the device descriptor. set_status will also
 136  * make a hypercall to the host, to tell about status changes
 137  */
 138 static u8 kvm_get_status(struct virtio_device *vdev)
 139 {
 140         return to_kvmdev(vdev)->desc->status;
 141 }
 142
 143 static void kvm_set_status(struct virtio_device *vdev, u8 status)
 144 {
 145         BUG_ON(!status);
 146         to_kvmdev(vdev)->desc->status = status;
 147         kvm_hypercall1(KVM_S390_VIRTIO_SET_STATUS,
 148                        (unsigned long) to_kvmdev(vdev)->desc);
 149 }
 150
 151 /*
 152  * To reset the device, we use the KVM_VIRTIO_RESET hypercall, using the
 153  * descriptor address. The Host will zero the status and all the
 154  * features.
 155  */
 156 static void kvm_reset(struct virtio_device *vdev)
 157 {
 158         kvm_hypercall1(KVM_S390_VIRTIO_RESET,
 159                        (unsigned long) to_kvmdev(vdev)->desc);
 160 }
 161
 162 /*
 163  * When the virtio_ring code wants to notify the Host, it calls us here and we
 164  * make a hypercall.  We hand the address  of the virtqueue so the Host
 165  * knows which virtqueue we're talking about.
 166  */
 167 static void kvm_notify(struct virtqueue *vq)
 168 {
 169         struct kvm_vqconfig *config = vq->priv;
 170
 171         kvm_hypercall1(KVM_S390_VIRTIO_NOTIFY, config->address);
 172 }
 173
 174 /*
 175  * This routine finds the first virtqueue described in the configuration of
 176  * this device and sets it up.
 177  */
 178 static struct virtqueue *kvm_find_vq(struct virtio_device *vdev,
 179                                      unsigned index,
 180                                      void (*callback)(struct virtqueue *vq),
 181                                      const char *name)
 182 {
 183         struct kvm_device *kdev = to_kvmdev(vdev);
 184         struct kvm_vqconfig *config;
 185         struct virtqueue *vq;
 186         int err;
 187
 188         if (index >= kdev->desc->num_vq)
 189                 return ERR_PTR(-ENOENT);
 190
 191         config = kvm_vq_config(kdev->desc)+index;
 192
 193         err = vmem_add_mapping(config->address,
 194                                vring_size(config->num,
 195                                           KVM_S390_VIRTIO_RING_ALIGN));
 196         if (err)
 197                 goto out;
 198
 199         vq = vring_new_virtqueue(config->num, KVM_S390_VIRTIO_RING_ALIGN,
 200                                  vdev, (void *) config->address,
 201                                  kvm_notify, callback, name);
 202         if (!vq) {
 203                 err = -ENOMEM;
 204                 goto unmap;
 205         }
 206
 207         /*
 208          * register a callback token
 209          * The host will sent this via the external interrupt parameter
 210          */
 211         config->token = (u64) vq;
 212
 213         vq->priv = config;
 214         return vq;
 215 unmap:
 216         vmem_remove_mapping(config->address,
 217                             vring_size(config->num,
 218                                        KVM_S390_VIRTIO_RING_ALIGN));
 219 out:
 220         return ERR_PTR(err);
 221 }
 222
 223 static void kvm_del_vq(struct virtqueue *vq)
 224 {
 225         struct kvm_vqconfig *config = vq->priv;
 226
 227         vring_del_virtqueue(vq);
 228         vmem_remove_mapping(config->address,
 229                             vring_size(config->num,
 230                                        KVM_S390_VIRTIO_RING_ALIGN));
 231 }
 232
 233 static void kvm_del_vqs(struct virtio_device *vdev)
 234 {
 235         struct virtqueue *vq, *n;
 236
 237         list_for_each_entry_safe(vq, n, &vdev->vqs, list)
 238                 kvm_del_vq(vq);
 239 }
 240
 241 static int kvm_find_vqs(struct virtio_device *vdev, unsigned nvqs,
 242                         struct virtqueue *vqs[],
 243                         vq_callback_t *callbacks[],
 244                         const char *names[])
 245 {
 246         struct kvm_device *kdev = to_kvmdev(vdev);
 247         int i;
 248
 249         /* We must have this many virtqueues. */
 250         if (nvqs > kdev->desc->num_vq)
 251                 return -ENOENT;
 252
 253         for (i = 0; i < nvqs; ++i) {
 254                 vqs[i] = kvm_find_vq(vdev, i, callbacks[i], names[i]);
 255                 if (IS_ERR(vqs[i]))
 256                         goto error;
 257         }
 258         return 0;
 259
 260 error:
 261         kvm_del_vqs(vdev);
 262         return PTR_ERR(vqs[i]);
 263 }
 264
 265 /*
 266  * The config ops structure as defined by virtio config
 267  */
 268 static struct virtio_config_ops kvm_vq_configspace_ops = {
 269         .get_features = kvm_get_features,
 270         .finalize_features = kvm_finalize_features,
 271         .get = kvm_get,
 272         .set = kvm_set,
 273         .get_status = kvm_get_status,
 274         .set_status = kvm_set_status,
 275         .reset = kvm_reset,
 276         .find_vqs = kvm_find_vqs,
 277         .del_vqs = kvm_del_vqs,
 278 };
 279
 280 /*
 281  * The root device for the kvm virtio devices.
 282  * This makes them appear as /sys/devices/kvm_s390/0,1,2 not /sys/devices/0,1,2.
 283  */
 284 static struct device *kvm_root;
 285
 286 /*
 287  * adds a new device and register it with virtio
 288  * appropriate drivers are loaded by the device model
 289  */
 290 static void add_kvm_device(struct kvm_device_desc *d, unsigned int offset)
 291 {
 292         struct kvm_device *kdev;
 293
 294         kdev = kzalloc(sizeof(*kdev), GFP_KERNEL);
 295         if (!kdev) {
 296                 printk(KERN_EMERG "Cannot allocate kvm dev %u type %u\n",
 297                        offset, d->type);
 298                 return;
 299         }
 300
 301         kdev->vdev.dev.parent = kvm_root;
 302         kdev->vdev.id.device = d->type;
 303         kdev->vdev.config = &kvm_vq_configspace_ops;
 304         kdev->desc = d;
 305
 306         if (register_virtio_device(&kdev->vdev) != 0) {
 307                 printk(KERN_ERR "Failed to register kvm device %u type %u\n",
 308                        offset, d->type);
 309                 kfree(kdev);
 310         }
 311 }
 312
 313 /*
 314  * scan_devices() simply iterates through the device page.
 315  * The type 0 is reserved to mean "end of devices".
 316  */
 317 static void scan_devices(void)
 318 {
 319         unsigned int i;
 320         struct kvm_device_desc *d;
 321
 322         for (i = 0; i < PAGE_SIZE; i += desc_size(d)) {
 323                 d = kvm_devices + i;
 324
 325                 if (d->type == 0)
 326                         break;
 327
 328                 add_kvm_device(d, i);
 329         }
 330 }
 331
 332 /*
 333  * match for a kvm device with a specific desc pointer
 334  */
 335 static int match_desc(struct device *dev, void *data)
 336 {
 337         if ((ulong)to_kvmdev(dev_to_virtio(dev))->desc == (ulong)data)
 338                 return 1;
 339
 340         return 0;
 341 }
 342
 343 /*
 344  * hotplug_device tries to find changes in the device page.
 345  */
 346 static void hotplug_devices(struct work_struct *dummy)
 347 {
 348         unsigned int i;
 349         struct kvm_device_desc *d;
 350         struct device *dev;
 351
 352         for (i = 0; i < PAGE_SIZE; i += desc_size(d)) {
 353                 d = kvm_devices + i;
 354
 355                 /* end of list */
 356                 if (d->type == 0)
 357                         break;
 358
 359                 /* device already exists */
 360                 dev = device_find_child(kvm_root, d, match_desc);
 361                 if (dev) {
 362                         /* XXX check for hotplug remove */
 363                         put_device(dev);
 364                         continue;
 365                 }
 366
 367                 /* new device */
 368                 printk(KERN_INFO "Adding new virtio device %p\n", d);
 369                 add_kvm_device(d, i);
 370         }
 371 }
 372
 373 /*
 374  * we emulate the request_irq behaviour on top of s390 extints
 375  */
 376 static void kvm_extint_handler(unsigned int ext_int_code,
 377                                unsigned int param32, unsigned long param64)
 378 {
 379         struct virtqueue *vq;
 380         u16 subcode;
 381         u32 param;
 382
 383         subcode = ext_int_code >> 16;
 384         if ((subcode & 0xff00) != VIRTIO_SUBCODE_64)
 385                 return;
 386         kstat_cpu(smp_processor_id()).irqs[EXTINT_VRT]++;
 387
 388         /* The LSB might be overloaded, we have to mask it */
 389         vq = (struct virtqueue *)(param64 & ~1UL);
 390
 391         /* We use ext_params to decide what this interrupt means */
 392         param = param32 & VIRTIO_PARAM_MASK;
 393
 394         switch (param) {
 395         case VIRTIO_PARAM_CONFIG_CHANGED:
 396         {
 397                 struct virtio_driver *drv;
 398                 drv = container_of(vq->vdev->dev.driver,
 399                                    struct virtio_driver, driver);
 400                 if (drv->config_changed)
 401                         drv->config_changed(vq->vdev);
 402
 403                 break;
 404         }
 405         case VIRTIO_PARAM_DEV_ADD:
 406                 schedule_work(&hotplug_work);
 407                 break;
 408         case VIRTIO_PARAM_VRING_INTERRUPT:
 409         default:
 410                 vring_interrupt(0, vq);
 411                 break;
 412         }
 413 }
 414
 415 /*
 416  * Init function for virtio
 417  * devices are in a single page above top of "normal" mem
 418  */
 419 static int __init kvm_devices_init(void)
 420 {
 421         int rc;
 422
 423         if (!MACHINE_IS_KVM)
 424                 return -ENODEV;
 425
 426         kvm_root = root_device_register("kvm_s390");
 427         if (IS_ERR(kvm_root)) {
 428                 rc = PTR_ERR(kvm_root);
 429                 printk(KERN_ERR "Could not register kvm_s390 root device");
 430                 return rc;
 431         }
 432
 433         rc = vmem_add_mapping(real_memory_size, PAGE_SIZE);
 434         if (rc) {
 435                 root_device_unregister(kvm_root);
 436                 return rc;
 437         }
 438
 439         kvm_devices = (void *) real_memory_size;
 440
 441         INIT_WORK(&hotplug_work, hotplug_devices);
 442
 443         service_subclass_irq_register();
 444         register_external_interrupt(0x2603, kvm_extint_handler);
 445
 446         scan_devices();
 447         return 0;
 448 }
 449
 450 /* code for early console output with virtio_console */
 451 static __init int early_put_chars(u32 vtermno, const char *buf, int count)
 452 {
 453         char scratch[17];
 454         unsigned int len = count;
 455
 456         if (len > sizeof(scratch) - 1)
 457                 len = sizeof(scratch) - 1;
 458         scratch[len] = '\0';
 459         memcpy(scratch, buf, len);
 460         kvm_hypercall1(KVM_S390_VIRTIO_NOTIFY, __pa(scratch));
 461         return len;
 462 }
 463
 464 static int __init s390_virtio_console_init(void)
 465 {
 466         if (!MACHINE_IS_KVM)
 467                 return -ENODEV;
 468         return virtio_cons_early_init(early_put_chars);
 469 }
 470 console_initcall(s390_virtio_console_init);
 471
 472
 473 /*
 474  * We do this after core stuff, but before the drivers.
 475  */
 476 postcore_initcall(kvm_devices_init);