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/s390_ext.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 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, (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 /*
 267  * The config ops structure as defined by virtio config
 268  */
 269 static struct virtio_config_ops kvm_vq_configspace_ops = {
 270         .get_features = kvm_get_features,
 271         .finalize_features = kvm_finalize_features,
 272         .get = kvm_get,
 273         .set = kvm_set,
 274         .get_status = kvm_get_status,
 275         .set_status = kvm_set_status,
 276         .reset = kvm_reset,
 277         .find_vqs = kvm_find_vqs,
 278         .del_vqs = kvm_del_vqs,
 279 };
 280
 281 /*
 282  * The root device for the kvm virtio devices.
 283  * This makes them appear as /sys/devices/kvm_s390/0,1,2 not /sys/devices/0,1,2.
 284  */
 285 static struct device *kvm_root;
 286
 287 /*
 288  * adds a new device and register it with virtio
 289  * appropriate drivers are loaded by the device model
 290  */
 291 static void add_kvm_device(struct kvm_device_desc *d, unsigned int offset)
 292 {
 293         struct kvm_device *kdev;
 294
 295         kdev = kzalloc(sizeof(*kdev), GFP_KERNEL);
 296         if (!kdev) {
 297                 printk(KERN_EMERG "Cannot allocate kvm dev %u type %u\n",
 298                        offset, d->type);
 299                 return;
 300         }
 301
 302         kdev->vdev.dev.parent = kvm_root;
 303         kdev->vdev.id.device = d->type;
 304         kdev->vdev.config = &kvm_vq_configspace_ops;
 305         kdev->desc = d;
 306
 307         if (register_virtio_device(&kdev->vdev) != 0) {
 308                 printk(KERN_ERR "Failed to register kvm device %u type %u\n",
 309                        offset, d->type);
 310                 kfree(kdev);
 311         }
 312 }
 313
 314 /*
 315  * scan_devices() simply iterates through the device page.
 316  * The type 0 is reserved to mean "end of devices".
 317  */
 318 static void scan_devices(void)
 319 {
 320         unsigned int i;
 321         struct kvm_device_desc *d;
 322
 323         for (i = 0; i < PAGE_SIZE; i += desc_size(d)) {
 324                 d = kvm_devices + i;
 325
 326                 if (d->type == 0)
 327                         break;
 328
 329                 add_kvm_device(d, i);
 330         }
 331 }
 332
 333 /*
 334  * match for a kvm device with a specific desc pointer
 335  */
 336 static int match_desc(struct device *dev, void *data)
 337 {
 338         if ((ulong)to_kvmdev(dev_to_virtio(dev))->desc == (ulong)data)
 339                 return 1;
 340
 341         return 0;
 342 }
 343
 344 /*
 345  * hotplug_device tries to find changes in the device page.
 346  */
 347 static void hotplug_devices(struct work_struct *dummy)
 348 {
 349         unsigned int i;
 350         struct kvm_device_desc *d;
 351         struct device *dev;
 352
 353         for (i = 0; i < PAGE_SIZE; i += desc_size(d)) {
 354                 d = kvm_devices + i;
 355
 356                 /* end of list */
 357                 if (d->type == 0)
 358                         break;
 359
 360                 /* device already exists */
 361                 dev = device_find_child(kvm_root, d, match_desc);
 362                 if (dev) {
 363                         /* XXX check for hotplug remove */
 364                         put_device(dev);
 365                         continue;
 366                 }
 367
 368                 /* new device */
 369                 printk(KERN_INFO "Adding new virtio device %p\n", d);
 370                 add_kvm_device(d, i);
 371         }
 372 }
 373
 374 /*
 375  * we emulate the request_irq behaviour on top of s390 extints
 376  */
 377 static void kvm_extint_handler(unsigned int ext_int_code,
 378                                unsigned int param32, unsigned long param64)
 379 {
 380         struct virtqueue *vq;
 381         u16 subcode;
 382         u32 param;
 383
 384         subcode = ext_int_code >> 16;
 385         if ((subcode & 0xff00) != VIRTIO_SUBCODE_64)
 386                 return;
 387         kstat_cpu(smp_processor_id()).irqs[EXTINT_VRT]++;
 388
 389         /* The LSB might be overloaded, we have to mask it */
 390         vq = (struct virtqueue *)(param64 & ~1UL);
 391
 392         /* We use ext_params to decide what this interrupt means */
 393         param = param32 & VIRTIO_PARAM_MASK;
 394
 395         switch (param) {
 396         case VIRTIO_PARAM_CONFIG_CHANGED:
 397         {
 398                 struct virtio_driver *drv;
 399                 drv = container_of(vq->vdev->dev.driver,
 400                                    struct virtio_driver, driver);
 401                 if (drv->config_changed)
 402                         drv->config_changed(vq->vdev);
 403
 404                 break;
 405         }
 406         case VIRTIO_PARAM_DEV_ADD:
 407                 schedule_work(&hotplug_work);
 408                 break;
 409         case VIRTIO_PARAM_VRING_INTERRUPT:
 410         default:
 411                 vring_interrupt(0, vq);
 412                 break;
 413         }
 414 }
 415
 416 /*
 417  * Init function for virtio
 418  * devices are in a single page above top of "normal" mem
 419  */
 420 static int __init kvm_devices_init(void)
 421 {
 422         int rc;
 423
 424         if (!MACHINE_IS_KVM)
 425                 return -ENODEV;
 426
 427         kvm_root = root_device_register("kvm_s390");
 428         if (IS_ERR(kvm_root)) {
 429                 rc = PTR_ERR(kvm_root);
 430                 printk(KERN_ERR "Could not register kvm_s390 root device");
 431                 return rc;
 432         }
 433
 434         rc = vmem_add_mapping(real_memory_size, PAGE_SIZE);
 435         if (rc) {
 436                 root_device_unregister(kvm_root);
 437                 return rc;
 438         }
 439
 440         kvm_devices = (void *) real_memory_size;
 441
 442         INIT_WORK(&hotplug_work, hotplug_devices);
 443
 444         ctl_set_bit(0, 9);
 445         register_external_interrupt(0x2603, kvm_extint_handler);
 446
 447         scan_devices();
 448         return 0;
 449 }
 450
 451 /* code for early console output with virtio_console */
 452 static __init int early_put_chars(u32 vtermno, const char *buf, int count)
 453 {
 454         char scratch[17];
 455         unsigned int len = count;
 456
 457         if (len > sizeof(scratch) - 1)
 458                 len = sizeof(scratch) - 1;
 459         scratch[len] = '\0';
 460         memcpy(scratch, buf, len);
 461         kvm_hypercall1(KVM_S390_VIRTIO_NOTIFY, __pa(scratch));
 462         return len;
 463 }
 464
 465 static int __init s390_virtio_console_init(void)
 466 {
 467         if (!MACHINE_IS_KVM)
 468                 return -ENODEV;
 469         return virtio_cons_early_init(early_put_chars);
 470 }
 471 console_initcall(s390_virtio_console_init);
 472
 473
 474 /*
 475  * We do this after core stuff, but before the drivers.
 476  */
 477 postcore_initcall(kvm_devices_init);