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 */ 36static void *kvm_devices; 37static struct work_struct hotplug_work; 38 39struct 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 */ 55static struct kvm_vqconfig *kvm_vq_config(const struct kvm_device_desc *desc) 56{ 57 return (struct kvm_vqconfig *)(desc + 1); 58} 59 60static u8 *kvm_vq_features(const struct kvm_device_desc *desc) 61{ 62 return (u8 *)(kvm_vq_config(desc) + desc->num_vq); 63} 64 65static 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 */ 73static 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. */ 82static 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 95static 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 */ 116static 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 125static 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 */ 139static u8 kvm_get_status(struct virtio_device *vdev) 140{ 141 return to_kvmdev(vdev)->desc->status; 142} 143 144static 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 */ 157static 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 */ 168static 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 */ 179static 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; 216unmap: 217 vmem_remove_mapping(config->address, 218 vring_size(config->num, 219 KVM_S390_VIRTIO_RING_ALIGN)); 220out: 221 return ERR_PTR(err); 222} 223 224static 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 234static 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 242static 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 261error: 262 kvm_del_vqs(vdev); 263 return PTR_ERR(vqs[i]); 264} 265 266static 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 */ 274static 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 */ 291static 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 */ 297static 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 */ 324static 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 */ 342static 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 */ 353static 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 */ 383static 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 */ 426static 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 */ 458static __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 471static 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} 477console_initcall(s390_virtio_console_init); 478 479 480/* 481 * We do this after core stuff, but before the drivers. 482 */ 483postcore_initcall(kvm_devices_init); 484