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/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/setup.h>
  29 #include <asm/irq.h>
  30
  31 #define VIRTIO_SUBCODE_64 0x0D00
  32
  33 /*
  34  * The pointer to our (page) of device descriptions.
  35  */
  36 static void *kvm_devices;
  37 static struct work_struct hotplug_work;
  38
  39 struct kvm_device {
  40         struct virtio_device vdev;
  41         struct kvm_device_desc *desc;
  42 };
  43
  44 #define to_kvmdev(vd) container_of(vd, struct kvm_device, vdev)
  45
  46 /*
  47  * memory layout:
  48  * - kvm_device_descriptor
  49  *        struct kvm_device_desc
  50  * - configuration
  51  *        struct kvm_vqconfig
  52  * - feature bits
  53  * - config space
  54  */
  55 static struct kvm_vqconfig *kvm_vq_config(const struct kvm_device_desc *desc)
  56 {
  57         return (struct kvm_vqconfig *)(desc + 1);
  58 }
  59
  60 static u8 *kvm_vq_features(const struct kvm_device_desc *desc)
  61 {
  62         return (u8 *)(kvm_vq_config(desc) + desc->num_vq);
  63 }
  64
  65 static u8 *kvm_vq_configspace(const struct kvm_device_desc *desc)
  66 {
  67         return kvm_vq_features(desc) + desc->feature_len * 2;
  68 }
  69
  70 /*
  71  * The total size of the config page used by this device (incl. desc)
  72  */
  73 static unsigned desc_size(const struct kvm_device_desc *desc)
  74 {
  75         return sizeof(*desc)
  76                 + desc->num_vq * sizeof(struct kvm_vqconfig)
  77                 + desc->feature_len * 2
  78                 + desc->config_len;
  79 }
  80
  81 /* This gets the device's feature bits. */
  82 static u32 kvm_get_features(struct virtio_device *vdev)
  83 {
  84         unsigned int i;
  85         u32 features = 0;
  86         struct kvm_device_desc *desc = to_kvmdev(vdev)->desc;
  87         u8 *in_features = kvm_vq_features(desc);
  88
  89         for (i = 0; i < min(desc->feature_len * 8, 32); i++)
  90                 if (in_features[i / 8] & (1 << (i % 8)))
  91                         features |= (1 << i);
  92         return features;
  93 }
  94
  95 static void kvm_finalize_features(struct virtio_device *vdev)
  96 {
  97         unsigned int i, bits;
  98         struct kvm_device_desc *desc = to_kvmdev(vdev)->desc;
  99         /* Second half of bitmap is features we accept. */
 100         u8 *out_features = kvm_vq_features(desc) + desc->feature_len;
 101
 102         /* Give virtio_ring a chance to accept features. */
 103         vring_transport_features(vdev);
 104
 105         memset(out_features, 0, desc->feature_len);
 106         bits = min_t(unsigned, desc->feature_len, sizeof(vdev->features)) * 8;
 107         for (i = 0; i < bits; i++) {
 108                 if (test_bit(i, vdev->features))
 109                         out_features[i / 8] |= (1 << (i % 8));
 110         }
 111 }
 112
 113 /*
 114  * Reading and writing elements in config space
 115  */
 116 static void kvm_get(struct virtio_device *vdev, unsigned int offset,
 117                    void *buf, unsigned len)
 118 {
 119         struct kvm_device_desc *desc = to_kvmdev(vdev)->desc;
 120
 121         BUG_ON(offset + len > desc->config_len);
 122         memcpy(buf, kvm_vq_configspace(desc) + offset, len);
 123 }
 124
 125 static void kvm_set(struct virtio_device *vdev, unsigned int offset,
 126                    const void *buf, unsigned len)
 127 {
 128         struct kvm_device_desc *desc = to_kvmdev(vdev)->desc;
 129
 130         BUG_ON(offset + len > desc->config_len);
 131         memcpy(kvm_vq_configspace(desc) + offset, buf, len);
 132 }
 133
 134 /*
 135  * The operations to get and set the status word just access
 136  * the status field of the device descriptor. set_status will also
 137  * make a hypercall to the host, to tell about status changes
 138  */
 139 static u8 kvm_get_status(struct virtio_device *vdev)
 140 {
 141         return to_kvmdev(vdev)->desc->status;
 142 }
 143
 144 static void kvm_set_status(struct virtio_device *vdev, u8 status)
 145 {
 146         BUG_ON(!status);
 147         to_kvmdev(vdev)->desc->status = status;
 148         kvm_hypercall1(KVM_S390_VIRTIO_SET_STATUS,
 149                        (unsigned long) to_kvmdev(vdev)->desc);
 150 }
 151
 152 /*
 153  * To reset the device, we use the KVM_VIRTIO_RESET hypercall, using the
 154  * descriptor address. The Host will zero the status and all the
 155  * features.
 156  */
 157 static void kvm_reset(struct virtio_device *vdev)
 158 {
 159         kvm_hypercall1(KVM_S390_VIRTIO_RESET,
 160                        (unsigned long) to_kvmdev(vdev)->desc);
 161 }
 162
 163 /*
 164  * When the virtio_ring code wants to notify the Host, it calls us here and we
 165  * make a hypercall.  We hand the address  of the virtqueue so the Host
 166  * knows which virtqueue we're talking about.
 167  */
 168 static void kvm_notify(struct virtqueue *vq)
 169 {
 170         struct kvm_vqconfig *config = vq->priv;
 171
 172         kvm_hypercall1(KVM_S390_VIRTIO_NOTIFY, config->address);
 173 }
 174
 175 /*
 176  * This routine finds the first virtqueue described in the configuration of
 177  * this device and sets it up.
 178  */
 179 static struct virtqueue *kvm_find_vq(struct virtio_device *vdev,
 180                                      unsigned index,
 181                                      void (*callback)(struct virtqueue *vq),
 182                                      const char *name)
 183 {
 184         struct kvm_device *kdev = to_kvmdev(vdev);
 185         struct kvm_vqconfig *config;
 186         struct virtqueue *vq;
 187         int err;
 188
 189         if (index >= kdev->desc->num_vq)
 190                 return ERR_PTR(-ENOENT);
 191
 192         config = kvm_vq_config(kdev->desc)+index;
 193
 194         err = vmem_add_mapping(config->address,
 195                                vring_size(config->num,
 196                                           KVM_S390_VIRTIO_RING_ALIGN));
 197         if (err)
 198                 goto out;
 199
 200         vq = vring_new_virtqueue(config->num, KVM_S390_VIRTIO_RING_ALIGN,
 201                                  vdev, true, (void *) config->address,
 202                                  kvm_notify, callback, name);
 203         if (!vq) {
 204                 err = -ENOMEM;
 205                 goto unmap;
 206         }
 207
 208         /*
 209          * register a callback token
 210          * The host will sent this via the external interrupt parameter
 211          */
 212         config->token = (u64) vq;
 213
 214         vq->priv = config;
 215         return vq;
 216 unmap:
 217         vmem_remove_mapping(config->address,
 218                             vring_size(config->num,
 219                                        KVM_S390_VIRTIO_RING_ALIGN));
 220 out:
 221         return ERR_PTR(err);
 222 }
 223
 224 static void kvm_del_vq(struct virtqueue *vq)
 225 {
 226         struct kvm_vqconfig *config = vq->priv;
 227
 228         vring_del_virtqueue(vq);
 229         vmem_remove_mapping(config->address,
 230                             vring_size(config->num,
 231                                        KVM_S390_VIRTIO_RING_ALIGN));
 232 }
 233
 234 static void kvm_del_vqs(struct virtio_device *vdev)
 235 {
 236         struct virtqueue *vq, *n;
 237
 238         list_for_each_entry_safe(vq, n, &vdev->vqs, list)
 239                 kvm_del_vq(vq);
 240 }
 241
 242 static int kvm_find_vqs(struct virtio_device *vdev, unsigned nvqs,
 243                         struct virtqueue *vqs[],
 244                         vq_callback_t *callbacks[],
 245                         const char *names[])
 246 {
 247         struct kvm_device *kdev = to_kvmdev(vdev);
 248         int i;
 249
 250         /* We must have this many virtqueues. */
 251         if (nvqs > kdev->desc->num_vq)
 252                 return -ENOENT;
 253
 254         for (i = 0; i < nvqs; ++i) {
 255                 vqs[i] = kvm_find_vq(vdev, i, callbacks[i], names[i]);
 256                 if (IS_ERR(vqs[i]))
 257                         goto error;
 258         }
 259         return 0;
 260
 261 error:
 262         kvm_del_vqs(vdev);
 263         return PTR_ERR(vqs[i]);
 264 }
 265
 266 static const char *kvm_bus_name(struct virtio_device *vdev)
 267 {
 268         return "";
 269 }
 270
 271 /*
 272  * The config ops structure as defined by virtio config
 273  */
 274 static struct virtio_config_ops kvm_vq_configspace_ops = {
 275         .get_features = kvm_get_features,
 276         .finalize_features = kvm_finalize_features,
 277         .get = kvm_get,
 278         .set = kvm_set,
 279         .get_status = kvm_get_status,
 280         .set_status = kvm_set_status,
 281         .reset = kvm_reset,
 282         .find_vqs = kvm_find_vqs,
 283         .del_vqs = kvm_del_vqs,
 284         .bus_name = kvm_bus_name,
 285 };
 286
 287 /*
 288  * The root device for the kvm virtio devices.
 289  * This makes them appear as /sys/devices/kvm_s390/0,1,2 not /sys/devices/0,1,2.
 290  */
 291 static struct device *kvm_root;
 292
 293 /*
 294  * adds a new device and register it with virtio
 295  * appropriate drivers are loaded by the device model
 296  */
 297 static void add_kvm_device(struct kvm_device_desc *d, unsigned int offset)
 298 {
 299         struct kvm_device *kdev;
 300
 301         kdev = kzalloc(sizeof(*kdev), GFP_KERNEL);
 302         if (!kdev) {
 303                 printk(KERN_EMERG "Cannot allocate kvm dev %u type %u\n",
 304                        offset, d->type);
 305                 return;
 306         }
 307
 308         kdev->vdev.dev.parent = kvm_root;
 309         kdev->vdev.id.device = d->type;
 310         kdev->vdev.config = &kvm_vq_configspace_ops;
 311         kdev->desc = d;
 312
 313         if (register_virtio_device(&kdev->vdev) != 0) {
 314                 printk(KERN_ERR "Failed to register kvm device %u type %u\n",
 315                        offset, d->type);
 316                 kfree(kdev);
 317         }
 318 }
 319
 320 /*
 321  * scan_devices() simply iterates through the device page.
 322  * The type 0 is reserved to mean "end of devices".
 323  */
 324 static void scan_devices(void)
 325 {
 326         unsigned int i;
 327         struct kvm_device_desc *d;
 328
 329         for (i = 0; i < PAGE_SIZE; i += desc_size(d)) {
 330                 d = kvm_devices + i;
 331
 332                 if (d->type == 0)
 333                         break;
 334
 335                 add_kvm_device(d, i);
 336         }
 337 }
 338
 339 /*
 340  * match for a kvm device with a specific desc pointer
 341  */
 342 static int match_desc(struct device *dev, void *data)
 343 {
 344         struct virtio_device *vdev = dev_to_virtio(dev);
 345         struct kvm_device *kdev = to_kvmdev(vdev);
 346
 347         return kdev->desc == data;
 348 }
 349
 350 /*
 351  * hotplug_device tries to find changes in the device page.
 352  */
 353 static void hotplug_devices(struct work_struct *dummy)
 354 {
 355         unsigned int i;
 356         struct kvm_device_desc *d;
 357         struct device *dev;
 358
 359         for (i = 0; i < PAGE_SIZE; i += desc_size(d)) {
 360                 d = kvm_devices + i;
 361
 362                 /* end of list */
 363                 if (d->type == 0)
 364                         break;
 365
 366                 /* device already exists */
 367                 dev = device_find_child(kvm_root, d, match_desc);
 368                 if (dev) {
 369                         /* XXX check for hotplug remove */
 370                         put_device(dev);
 371                         continue;
 372                 }
 373
 374                 /* new device */
 375                 printk(KERN_INFO "Adding new virtio device %p\n", d);
 376                 add_kvm_device(d, i);
 377         }
 378 }
 379
 380 /*
 381  * we emulate the request_irq behaviour on top of s390 extints
 382  */
 383 static void kvm_extint_handler(unsigned int ext_int_code,
 384                                unsigned int param32, unsigned long param64)
 385 {
 386         struct virtqueue *vq;
 387         u16 subcode;
 388         u32 param;
 389
 390         subcode = ext_int_code >> 16;
 391         if ((subcode & 0xff00) != VIRTIO_SUBCODE_64)
 392                 return;
 393         kstat_cpu(smp_processor_id()).irqs[EXTINT_VRT]++;
 394
 395         /* The LSB might be overloaded, we have to mask it */
 396         vq = (struct virtqueue *)(param64 & ~1UL);
 397
 398         /* We use ext_params to decide what this interrupt means */
 399         param = param32 & VIRTIO_PARAM_MASK;
 400
 401         switch (param) {
 402         case VIRTIO_PARAM_CONFIG_CHANGED:
 403         {
 404                 struct virtio_driver *drv;
 405                 drv = container_of(vq->vdev->dev.driver,
 406                                    struct virtio_driver, driver);
 407                 if (drv->config_changed)
 408                         drv->config_changed(vq->vdev);
 409
 410                 break;
 411         }
 412         case VIRTIO_PARAM_DEV_ADD:
 413                 schedule_work(&hotplug_work);
 414                 break;
 415         case VIRTIO_PARAM_VRING_INTERRUPT:
 416         default:
 417                 vring_interrupt(0, vq);
 418                 break;
 419         }
 420 }
 421
 422 /*
 423  * Init function for virtio
 424  * devices are in a single page above top of "normal" mem
 425  */
 426 static int __init kvm_devices_init(void)
 427 {
 428         int rc;
 429
 430         if (!MACHINE_IS_KVM)
 431                 return -ENODEV;
 432
 433         kvm_root = root_device_register("kvm_s390");
 434         if (IS_ERR(kvm_root)) {
 435                 rc = PTR_ERR(kvm_root);
 436                 printk(KERN_ERR "Could not register kvm_s390 root device");
 437                 return rc;
 438         }
 439
 440         rc = vmem_add_mapping(real_memory_size, PAGE_SIZE);
 441         if (rc) {
 442                 root_device_unregister(kvm_root);
 443                 return rc;
 444         }
 445
 446         kvm_devices = (void *) real_memory_size;
 447
 448         INIT_WORK(&hotplug_work, hotplug_devices);
 449
 450         service_subclass_irq_register();
 451         register_external_interrupt(0x2603, kvm_extint_handler);
 452
 453         scan_devices();
 454         return 0;
 455 }
 456
 457 /* code for early console output with virtio_console */
 458 static __init int early_put_chars(u32 vtermno, const char *buf, int count)
 459 {
 460         char scratch[17];
 461         unsigned int len = count;
 462
 463         if (len > sizeof(scratch) - 1)
 464                 len = sizeof(scratch) - 1;
 465         scratch[len] = '\0';
 466         memcpy(scratch, buf, len);
 467         kvm_hypercall1(KVM_S390_VIRTIO_NOTIFY, __pa(scratch));
 468         return len;
 469 }
 470
 471 static int __init s390_virtio_console_init(void)
 472 {
 473         if (!MACHINE_IS_KVM)
 474                 return -ENODEV;
 475         return virtio_cons_early_init(early_put_chars);
 476 }
 477 console_initcall(s390_virtio_console_init);
 478
 479
 480 /*
 481  * We do this after core stuff, but before the drivers.
 482  */
 483 postcore_initcall(kvm_devices_init);