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/init.h>
  14 #include <linux/bootmem.h>
  15 #include <linux/err.h>
  16 #include <linux/virtio.h>
  17 #include <linux/virtio_config.h>
  18 #include <linux/slab.h>
  19 #include <linux/virtio_console.h>
  20 #include <linux/interrupt.h>
  21 #include <linux/virtio_ring.h>
  22 #include <linux/pfn.h>
  23 #include <asm/io.h>
  24 #include <asm/kvm_para.h>
  25 #include <asm/kvm_virtio.h>
  26 #include <asm/setup.h>
  27 #include <asm/s390_ext.h>
  28
  29 #define VIRTIO_SUBCODE_64 0x0D00
  30
  31 /*
  32  * The pointer to our (page) of device descriptions.
  33  */
  34 static void *kvm_devices;
  35 struct work_struct hotplug_work;
  36
  37 struct kvm_device {
  38         struct virtio_device vdev;
  39         struct kvm_device_desc *desc;
  40 };
  41
  42 #define to_kvmdev(vd) container_of(vd, struct kvm_device, vdev)
  43
  44 /*
  45  * memory layout:
  46  * - kvm_device_descriptor
  47  *        struct kvm_device_desc
  48  * - configuration
  49  *        struct kvm_vqconfig
  50  * - feature bits
  51  * - config space
  52  */
  53 static struct kvm_vqconfig *kvm_vq_config(const struct kvm_device_desc *desc)
  54 {
  55         return (struct kvm_vqconfig *)(desc + 1);
  56 }
  57
  58 static u8 *kvm_vq_features(const struct kvm_device_desc *desc)
  59 {
  60         return (u8 *)(kvm_vq_config(desc) + desc->num_vq);
  61 }
  62
  63 static u8 *kvm_vq_configspace(const struct kvm_device_desc *desc)
  64 {
  65         return kvm_vq_features(desc) + desc->feature_len * 2;
  66 }
  67
  68 /*
  69  * The total size of the config page used by this device (incl. desc)
  70  */
  71 static unsigned desc_size(const struct kvm_device_desc *desc)
  72 {
  73         return sizeof(*desc)
  74                 + desc->num_vq * sizeof(struct kvm_vqconfig)
  75                 + desc->feature_len * 2
  76                 + desc->config_len;
  77 }
  78
  79 /* This gets the device's feature bits. */
  80 static u32 kvm_get_features(struct virtio_device *vdev)
  81 {
  82         unsigned int i;
  83         u32 features = 0;
  84         struct kvm_device_desc *desc = to_kvmdev(vdev)->desc;
  85         u8 *in_features = kvm_vq_features(desc);
  86
  87         for (i = 0; i < min(desc->feature_len * 8, 32); i++)
  88                 if (in_features[i / 8] & (1 << (i % 8)))
  89                         features |= (1 << i);
  90         return features;
  91 }
  92
  93 static void kvm_finalize_features(struct virtio_device *vdev)
  94 {
  95         unsigned int i, bits;
  96         struct kvm_device_desc *desc = to_kvmdev(vdev)->desc;
  97         /* Second half of bitmap is features we accept. */
  98         u8 *out_features = kvm_vq_features(desc) + desc->feature_len;
  99
 100         /* Give virtio_ring a chance to accept features. */
 101         vring_transport_features(vdev);
 102
 103         memset(out_features, 0, desc->feature_len);
 104         bits = min_t(unsigned, desc->feature_len, sizeof(vdev->features)) * 8;
 105         for (i = 0; i < bits; i++) {
 106                 if (test_bit(i, vdev->features))
 107                         out_features[i / 8] |= (1 << (i % 8));
 108         }
 109 }
 110
 111 /*
 112  * Reading and writing elements in config space
 113  */
 114 static void kvm_get(struct virtio_device *vdev, unsigned int offset,
 115                    void *buf, unsigned len)
 116 {
 117         struct kvm_device_desc *desc = to_kvmdev(vdev)->desc;
 118
 119         BUG_ON(offset + len > desc->config_len);
 120         memcpy(buf, kvm_vq_configspace(desc) + offset, len);
 121 }
 122
 123 static void kvm_set(struct virtio_device *vdev, unsigned int offset,
 124                    const void *buf, unsigned len)
 125 {
 126         struct kvm_device_desc *desc = to_kvmdev(vdev)->desc;
 127
 128         BUG_ON(offset + len > desc->config_len);
 129         memcpy(kvm_vq_configspace(desc) + offset, buf, len);
 130 }
 131
 132 /*
 133  * The operations to get and set the status word just access
 134  * the status field of the device descriptor. set_status will also
 135  * make a hypercall to the host, to tell about status changes
 136  */
 137 static u8 kvm_get_status(struct virtio_device *vdev)
 138 {
 139         return to_kvmdev(vdev)->desc->status;
 140 }
 141
 142 static void kvm_set_status(struct virtio_device *vdev, u8 status)
 143 {
 144         BUG_ON(!status);
 145         to_kvmdev(vdev)->desc->status = status;
 146         kvm_hypercall1(KVM_S390_VIRTIO_SET_STATUS,
 147                        (unsigned long) to_kvmdev(vdev)->desc);
 148 }
 149
 150 /*
 151  * To reset the device, we use the KVM_VIRTIO_RESET hypercall, using the
 152  * descriptor address. The Host will zero the status and all the
 153  * features.
 154  */
 155 static void kvm_reset(struct virtio_device *vdev)
 156 {
 157         kvm_hypercall1(KVM_S390_VIRTIO_RESET,
 158                        (unsigned long) to_kvmdev(vdev)->desc);
 159 }
 160
 161 /*
 162  * When the virtio_ring code wants to notify the Host, it calls us here and we
 163  * make a hypercall.  We hand the address  of the virtqueue so the Host
 164  * knows which virtqueue we're talking about.
 165  */
 166 static void kvm_notify(struct virtqueue *vq)
 167 {
 168         struct kvm_vqconfig *config = vq->priv;
 169
 170         kvm_hypercall1(KVM_S390_VIRTIO_NOTIFY, config->address);
 171 }
 172
 173 /*
 174  * This routine finds the first virtqueue described in the configuration of
 175  * this device and sets it up.
 176  */
 177 static struct virtqueue *kvm_find_vq(struct virtio_device *vdev,
 178                                      unsigned index,
 179                                      void (*callback)(struct virtqueue *vq),
 180                                      const char *name)
 181 {
 182         struct kvm_device *kdev = to_kvmdev(vdev);
 183         struct kvm_vqconfig *config;
 184         struct virtqueue *vq;
 185         int err;
 186
 187         if (index >= kdev->desc->num_vq)
 188                 return ERR_PTR(-ENOENT);
 189
 190         config = kvm_vq_config(kdev->desc)+index;
 191
 192         err = vmem_add_mapping(config->address,
 193                                vring_size(config->num,
 194                                           KVM_S390_VIRTIO_RING_ALIGN));
 195         if (err)
 196                 goto out;
 197
 198         vq = vring_new_virtqueue(config->num, KVM_S390_VIRTIO_RING_ALIGN,
 199                                  vdev, (void *) config->address,
 200                                  kvm_notify, callback, name);
 201         if (!vq) {
 202                 err = -ENOMEM;
 203                 goto unmap;
 204         }
 205
 206         /*
 207          * register a callback token
 208          * The host will sent this via the external interrupt parameter
 209          */
 210         config->token = (u64) vq;
 211
 212         vq->priv = config;
 213         return vq;
 214 unmap:
 215         vmem_remove_mapping(config->address,
 216                             vring_size(config->num,
 217                                        KVM_S390_VIRTIO_RING_ALIGN));
 218 out:
 219         return ERR_PTR(err);
 220 }
 221
 222 static void kvm_del_vq(struct virtqueue *vq)
 223 {
 224         struct kvm_vqconfig *config = vq->priv;
 225
 226         vring_del_virtqueue(vq);
 227         vmem_remove_mapping(config->address,
 228                             vring_size(config->num,
 229                                        KVM_S390_VIRTIO_RING_ALIGN));
 230 }
 231
 232 static void kvm_del_vqs(struct virtio_device *vdev)
 233 {
 234         struct virtqueue *vq, *n;
 235
 236         list_for_each_entry_safe(vq, n, &vdev->vqs, list)
 237                 kvm_del_vq(vq);
 238 }
 239
 240 static int kvm_find_vqs(struct virtio_device *vdev, unsigned nvqs,
 241                         struct virtqueue *vqs[],
 242                         vq_callback_t *callbacks[],
 243                         const char *names[])
 244 {
 245         struct kvm_device *kdev = to_kvmdev(vdev);
 246         int i;
 247
 248         /* We must have this many virtqueues. */
 249         if (nvqs > kdev->desc->num_vq)
 250                 return -ENOENT;
 251
 252         for (i = 0; i < nvqs; ++i) {
 253                 vqs[i] = kvm_find_vq(vdev, i, callbacks[i], names[i]);
 254                 if (IS_ERR(vqs[i]))
 255                         goto error;
 256         }
 257         return 0;
 258
 259 error:
 260         kvm_del_vqs(vdev);
 261         return PTR_ERR(vqs[i]);
 262 }
 263
 264 /*
 265  * The config ops structure as defined by virtio config
 266  */
 267 static struct virtio_config_ops kvm_vq_configspace_ops = {
 268         .get_features = kvm_get_features,
 269         .finalize_features = kvm_finalize_features,
 270         .get = kvm_get,
 271         .set = kvm_set,
 272         .get_status = kvm_get_status,
 273         .set_status = kvm_set_status,
 274         .reset = kvm_reset,
 275         .find_vqs = kvm_find_vqs,
 276         .del_vqs = kvm_del_vqs,
 277 };
 278
 279 /*
 280  * The root device for the kvm virtio devices.
 281  * This makes them appear as /sys/devices/kvm_s390/0,1,2 not /sys/devices/0,1,2.
 282  */
 283 static struct device *kvm_root;
 284
 285 /*
 286  * adds a new device and register it with virtio
 287  * appropriate drivers are loaded by the device model
 288  */
 289 static void add_kvm_device(struct kvm_device_desc *d, unsigned int offset)
 290 {
 291         struct kvm_device *kdev;
 292
 293         kdev = kzalloc(sizeof(*kdev), GFP_KERNEL);
 294         if (!kdev) {
 295                 printk(KERN_EMERG "Cannot allocate kvm dev %u type %u\n",
 296                        offset, d->type);
 297                 return;
 298         }
 299
 300         kdev->vdev.dev.parent = kvm_root;
 301         kdev->vdev.id.device = d->type;
 302         kdev->vdev.config = &kvm_vq_configspace_ops;
 303         kdev->desc = d;
 304
 305         if (register_virtio_device(&kdev->vdev) != 0) {
 306                 printk(KERN_ERR "Failed to register kvm device %u type %u\n",
 307                        offset, d->type);
 308                 kfree(kdev);
 309         }
 310 }
 311
 312 /*
 313  * scan_devices() simply iterates through the device page.
 314  * The type 0 is reserved to mean "end of devices".
 315  */
 316 static void scan_devices(void)
 317 {
 318         unsigned int i;
 319         struct kvm_device_desc *d;
 320
 321         for (i = 0; i < PAGE_SIZE; i += desc_size(d)) {
 322                 d = kvm_devices + i;
 323
 324                 if (d->type == 0)
 325                         break;
 326
 327                 add_kvm_device(d, i);
 328         }
 329 }
 330
 331 /*
 332  * match for a kvm device with a specific desc pointer
 333  */
 334 static int match_desc(struct device *dev, void *data)
 335 {
 336         if ((ulong)to_kvmdev(dev_to_virtio(dev))->desc == (ulong)data)
 337                 return 1;
 338
 339         return 0;
 340 }
 341
 342 /*
 343  * hotplug_device tries to find changes in the device page.
 344  */
 345 static void hotplug_devices(struct work_struct *dummy)
 346 {
 347         unsigned int i;
 348         struct kvm_device_desc *d;
 349         struct device *dev;
 350
 351         for (i = 0; i < PAGE_SIZE; i += desc_size(d)) {
 352                 d = kvm_devices + i;
 353
 354                 /* end of list */
 355                 if (d->type == 0)
 356                         break;
 357
 358                 /* device already exists */
 359                 dev = device_find_child(kvm_root, d, match_desc);
 360                 if (dev) {
 361                         /* XXX check for hotplug remove */
 362                         put_device(dev);
 363                         continue;
 364                 }
 365
 366                 /* new device */
 367                 printk(KERN_INFO "Adding new virtio device %p\n", d);
 368                 add_kvm_device(d, i);
 369         }
 370 }
 371
 372 /*
 373  * we emulate the request_irq behaviour on top of s390 extints
 374  */
 375 static void kvm_extint_handler(unsigned int ext_int_code,
 376                                unsigned int param32, unsigned long param64)
 377 {
 378         struct virtqueue *vq;
 379         u16 subcode;
 380         u32 param;
 381
 382         subcode = ext_int_code >> 16;
 383         if ((subcode & 0xff00) != VIRTIO_SUBCODE_64)
 384                 return;
 385
 386         /* The LSB might be overloaded, we have to mask it */
 387         vq = (struct virtqueue *)(param64 & ~1UL);
 388
 389         /* We use ext_params to decide what this interrupt means */
 390         param = param32 & VIRTIO_PARAM_MASK;
 391
 392         switch (param) {
 393         case VIRTIO_PARAM_CONFIG_CHANGED:
 394         {
 395                 struct virtio_driver *drv;
 396                 drv = container_of(vq->vdev->dev.driver,
 397                                    struct virtio_driver, driver);
 398                 if (drv->config_changed)
 399                         drv->config_changed(vq->vdev);
 400
 401                 break;
 402         }
 403         case VIRTIO_PARAM_DEV_ADD:
 404                 schedule_work(&hotplug_work);
 405                 break;
 406         case VIRTIO_PARAM_VRING_INTERRUPT:
 407         default:
 408                 vring_interrupt(0, vq);
 409                 break;
 410         }
 411 }
 412
 413 /*
 414  * Init function for virtio
 415  * devices are in a single page above top of "normal" mem
 416  */
 417 static int __init kvm_devices_init(void)
 418 {
 419         int rc;
 420
 421         if (!MACHINE_IS_KVM)
 422                 return -ENODEV;
 423
 424         kvm_root = root_device_register("kvm_s390");
 425         if (IS_ERR(kvm_root)) {
 426                 rc = PTR_ERR(kvm_root);
 427                 printk(KERN_ERR "Could not register kvm_s390 root device");
 428                 return rc;
 429         }
 430
 431         rc = vmem_add_mapping(real_memory_size, PAGE_SIZE);
 432         if (rc) {
 433                 root_device_unregister(kvm_root);
 434                 return rc;
 435         }
 436
 437         kvm_devices = (void *) real_memory_size;
 438
 439         INIT_WORK(&hotplug_work, hotplug_devices);
 440
 441         ctl_set_bit(0, 9);
 442         register_external_interrupt(0x2603, kvm_extint_handler);
 443
 444         scan_devices();
 445         return 0;
 446 }
 447
 448 /* code for early console output with virtio_console */
 449 static __init int early_put_chars(u32 vtermno, const char *buf, int count)
 450 {
 451         char scratch[17];
 452         unsigned int len = count;
 453
 454         if (len > sizeof(scratch) - 1)
 455                 len = sizeof(scratch) - 1;
 456         scratch[len] = '\0';
 457         memcpy(scratch, buf, len);
 458         kvm_hypercall1(KVM_S390_VIRTIO_NOTIFY, __pa(scratch));
 459         return len;
 460 }
 461
 462 static int __init s390_virtio_console_init(void)
 463 {
 464         if (!MACHINE_IS_KVM)
 465                 return -ENODEV;
 466         return virtio_cons_early_init(early_put_chars);
 467 }
 468 console_initcall(s390_virtio_console_init);
 469
 470
 471 /*
 472  * We do this after core stuff, but before the drivers.
 473  */
 474 postcore_initcall(kvm_devices_init);