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 */ 34static void *kvm_devices; 35 36struct kvm_device { 37 struct virtio_device vdev; 38 struct kvm_device_desc *desc; 39}; 40 41#define to_kvmdev(vd) container_of(vd, struct kvm_device, vdev) 42 43/* 44 * memory layout: 45 * - kvm_device_descriptor 46 * struct kvm_device_desc 47 * - configuration 48 * struct kvm_vqconfig 49 * - feature bits 50 * - config space 51 */ 52static struct kvm_vqconfig *kvm_vq_config(const struct kvm_device_desc *desc) 53{ 54 return (struct kvm_vqconfig *)(desc + 1); 55} 56 57static u8 *kvm_vq_features(const struct kvm_device_desc *desc) 58{ 59 return (u8 *)(kvm_vq_config(desc) + desc->num_vq); 60} 61 62static u8 *kvm_vq_configspace(const struct kvm_device_desc *desc) 63{ 64 return kvm_vq_features(desc) + desc->feature_len * 2; 65} 66 67/* 68 * The total size of the config page used by this device (incl. desc) 69 */ 70static unsigned desc_size(const struct kvm_device_desc *desc) 71{ 72 return sizeof(*desc) 73 + desc->num_vq * sizeof(struct kvm_vqconfig) 74 + desc->feature_len * 2 75 + desc->config_len; 76} 77 78/* This gets the device's feature bits. */ 79static u32 kvm_get_features(struct virtio_device *vdev) 80{ 81 unsigned int i; 82 u32 features = 0; 83 struct kvm_device_desc *desc = to_kvmdev(vdev)->desc; 84 u8 *in_features = kvm_vq_features(desc); 85 86 for (i = 0; i < min(desc->feature_len * 8, 32); i++) 87 if (in_features[i / 8] & (1 << (i % 8))) 88 features |= (1 << i); 89 return features; 90} 91 92static void kvm_finalize_features(struct virtio_device *vdev) 93{ 94 unsigned int i, bits; 95 struct kvm_device_desc *desc = to_kvmdev(vdev)->desc; 96 /* Second half of bitmap is features we accept. */ 97 u8 *out_features = kvm_vq_features(desc) + desc->feature_len; 98 99 /* Give virtio_ring a chance to accept features. */ 100 vring_transport_features(vdev); 101 102 memset(out_features, 0, desc->feature_len); 103 bits = min_t(unsigned, desc->feature_len, sizeof(vdev->features)) * 8; 104 for (i = 0; i < bits; i++) { 105 if (test_bit(i, vdev->features)) 106 out_features[i / 8] |= (1 << (i % 8)); 107 } 108} 109 110/* 111 * Reading and writing elements in config space 112 */ 113static void kvm_get(struct virtio_device *vdev, unsigned int offset, 114 void *buf, unsigned len) 115{ 116 struct kvm_device_desc *desc = to_kvmdev(vdev)->desc; 117 118 BUG_ON(offset + len > desc->config_len); 119 memcpy(buf, kvm_vq_configspace(desc) + offset, len); 120} 121 122static void kvm_set(struct virtio_device *vdev, unsigned int offset, 123 const void *buf, unsigned len) 124{ 125 struct kvm_device_desc *desc = to_kvmdev(vdev)->desc; 126 127 BUG_ON(offset + len > desc->config_len); 128 memcpy(kvm_vq_configspace(desc) + offset, buf, len); 129} 130 131/* 132 * The operations to get and set the status word just access 133 * the status field of the device descriptor. set_status will also 134 * make a hypercall to the host, to tell about status changes 135 */ 136static u8 kvm_get_status(struct virtio_device *vdev) 137{ 138 return to_kvmdev(vdev)->desc->status; 139} 140 141static void kvm_set_status(struct virtio_device *vdev, u8 status) 142{ 143 BUG_ON(!status); 144 to_kvmdev(vdev)->desc->status = status; 145 kvm_hypercall1(KVM_S390_VIRTIO_SET_STATUS, 146 (unsigned long) to_kvmdev(vdev)->desc); 147} 148 149/* 150 * To reset the device, we use the KVM_VIRTIO_RESET hypercall, using the 151 * descriptor address. The Host will zero the status and all the 152 * features. 153 */ 154static void kvm_reset(struct virtio_device *vdev) 155{ 156 kvm_hypercall1(KVM_S390_VIRTIO_RESET, 157 (unsigned long) to_kvmdev(vdev)->desc); 158} 159 160/* 161 * When the virtio_ring code wants to notify the Host, it calls us here and we 162 * make a hypercall. We hand the address of the virtqueue so the Host 163 * knows which virtqueue we're talking about. 164 */ 165static void kvm_notify(struct virtqueue *vq) 166{ 167 struct kvm_vqconfig *config = vq->priv; 168 169 kvm_hypercall1(KVM_S390_VIRTIO_NOTIFY, config->address); 170} 171 172/* 173 * This routine finds the first virtqueue described in the configuration of 174 * this device and sets it up. 175 */ 176static struct virtqueue *kvm_find_vq(struct virtio_device *vdev, 177 unsigned index, 178 void (*callback)(struct virtqueue *vq), 179 const char *name) 180{ 181 struct kvm_device *kdev = to_kvmdev(vdev); 182 struct kvm_vqconfig *config; 183 struct virtqueue *vq; 184 int err; 185 186 if (index >= kdev->desc->num_vq) 187 return ERR_PTR(-ENOENT); 188 189 config = kvm_vq_config(kdev->desc)+index; 190 191 err = vmem_add_mapping(config->address, 192 vring_size(config->num, 193 KVM_S390_VIRTIO_RING_ALIGN)); 194 if (err) 195 goto out; 196 197 vq = vring_new_virtqueue(config->num, KVM_S390_VIRTIO_RING_ALIGN, 198 vdev, (void *) config->address, 199 kvm_notify, callback, name); 200 if (!vq) { 201 err = -ENOMEM; 202 goto unmap; 203 } 204 205 /* 206 * register a callback token 207 * The host will sent this via the external interrupt parameter 208 */ 209 config->token = (u64) vq; 210 211 vq->priv = config; 212 return vq; 213unmap: 214 vmem_remove_mapping(config->address, 215 vring_size(config->num, 216 KVM_S390_VIRTIO_RING_ALIGN)); 217out: 218 return ERR_PTR(err); 219} 220 221static void kvm_del_vq(struct virtqueue *vq) 222{ 223 struct kvm_vqconfig *config = vq->priv; 224 225 vring_del_virtqueue(vq); 226 vmem_remove_mapping(config->address, 227 vring_size(config->num, 228 KVM_S390_VIRTIO_RING_ALIGN)); 229} 230 231static void kvm_del_vqs(struct virtio_device *vdev) 232{ 233 struct virtqueue *vq, *n; 234 235 list_for_each_entry_safe(vq, n, &vdev->vqs, list) 236 kvm_del_vq(vq); 237} 238 239static int kvm_find_vqs(struct virtio_device *vdev, unsigned nvqs, 240 struct virtqueue *vqs[], 241 vq_callback_t *callbacks[], 242 const char *names[]) 243{ 244 struct kvm_device *kdev = to_kvmdev(vdev); 245 int i; 246 247 /* We must have this many virtqueues. */ 248 if (nvqs > kdev->desc->num_vq) 249 return -ENOENT; 250 251 for (i = 0; i < nvqs; ++i) { 252 vqs[i] = kvm_find_vq(vdev, i, callbacks[i], names[i]); 253 if (IS_ERR(vqs[i])) 254 goto error; 255 } 256 return 0; 257 258error: 259 kvm_del_vqs(vdev); 260 return PTR_ERR(vqs[i]); 261} 262 263/* 264 * The config ops structure as defined by virtio config 265 */ 266static struct virtio_config_ops kvm_vq_configspace_ops = { 267 .get_features = kvm_get_features, 268 .finalize_features = kvm_finalize_features, 269 .get = kvm_get, 270 .set = kvm_set, 271 .get_status = kvm_get_status, 272 .set_status = kvm_set_status, 273 .reset = kvm_reset, 274 .find_vqs = kvm_find_vqs, 275 .del_vqs = kvm_del_vqs, 276}; 277 278/* 279 * The root device for the kvm virtio devices. 280 * This makes them appear as /sys/devices/kvm_s390/0,1,2 not /sys/devices/0,1,2. 281 */ 282static struct device *kvm_root; 283 284/* 285 * adds a new device and register it with virtio 286 * appropriate drivers are loaded by the device model 287 */ 288static void add_kvm_device(struct kvm_device_desc *d, unsigned int offset) 289{ 290 struct kvm_device *kdev; 291 292 kdev = kzalloc(sizeof(*kdev), GFP_KERNEL); 293 if (!kdev) { 294 printk(KERN_EMERG "Cannot allocate kvm dev %u type %u\n", 295 offset, d->type); 296 return; 297 } 298 299 kdev->vdev.dev.parent = kvm_root; 300 kdev->vdev.id.device = d->type; 301 kdev->vdev.config = &kvm_vq_configspace_ops; 302 kdev->desc = d; 303 304 if (register_virtio_device(&kdev->vdev) != 0) { 305 printk(KERN_ERR "Failed to register kvm device %u type %u\n", 306 offset, d->type); 307 kfree(kdev); 308 } 309} 310 311/* 312 * scan_devices() simply iterates through the device page. 313 * The type 0 is reserved to mean "end of devices". 314 */ 315static void scan_devices(void) 316{ 317 unsigned int i; 318 struct kvm_device_desc *d; 319 320 for (i = 0; i < PAGE_SIZE; i += desc_size(d)) { 321 d = kvm_devices + i; 322 323 if (d->type == 0) 324 break; 325 326 add_kvm_device(d, i); 327 } 328} 329 330/* 331 * we emulate the request_irq behaviour on top of s390 extints 332 */ 333static void kvm_extint_handler(u16 code) 334{ 335 struct virtqueue *vq; 336 u16 subcode; 337 int config_changed; 338 339 subcode = S390_lowcore.cpu_addr; 340 if ((subcode & 0xff00) != VIRTIO_SUBCODE_64) 341 return; 342 343 /* The LSB might be overloaded, we have to mask it */ 344 vq = (struct virtqueue *)(S390_lowcore.ext_params2 & ~1UL); 345 346 /* We use the LSB of extparam, to decide, if this interrupt is a config 347 * change or a "standard" interrupt */ 348 config_changed = S390_lowcore.ext_params & 1; 349 350 if (config_changed) { 351 struct virtio_driver *drv; 352 drv = container_of(vq->vdev->dev.driver, 353 struct virtio_driver, driver); 354 if (drv->config_changed) 355 drv->config_changed(vq->vdev); 356 } else 357 vring_interrupt(0, vq); 358} 359 360/* 361 * Init function for virtio 362 * devices are in a single page above top of "normal" mem 363 */ 364static int __init kvm_devices_init(void) 365{ 366 int rc; 367 368 if (!MACHINE_IS_KVM) 369 return -ENODEV; 370 371 kvm_root = root_device_register("kvm_s390"); 372 if (IS_ERR(kvm_root)) { 373 rc = PTR_ERR(kvm_root); 374 printk(KERN_ERR "Could not register kvm_s390 root device"); 375 return rc; 376 } 377 378 rc = vmem_add_mapping(real_memory_size, PAGE_SIZE); 379 if (rc) { 380 root_device_unregister(kvm_root); 381 return rc; 382 } 383 384 kvm_devices = (void *) real_memory_size; 385 386 ctl_set_bit(0, 9); 387 register_external_interrupt(0x2603, kvm_extint_handler); 388 389 scan_devices(); 390 return 0; 391} 392 393/* code for early console output with virtio_console */ 394static __init int early_put_chars(u32 vtermno, const char *buf, int count) 395{ 396 char scratch[17]; 397 unsigned int len = count; 398 399 if (len > sizeof(scratch) - 1) 400 len = sizeof(scratch) - 1; 401 scratch[len] = '\0'; 402 memcpy(scratch, buf, len); 403 kvm_hypercall1(KVM_S390_VIRTIO_NOTIFY, __pa(scratch)); 404 return len; 405} 406 407static int __init s390_virtio_console_init(void) 408{ 409 if (!MACHINE_IS_KVM) 410 return -ENODEV; 411 return virtio_cons_early_init(early_put_chars); 412} 413console_initcall(s390_virtio_console_init); 414 415 416/* 417 * We do this after core stuff, but before the drivers. 418 */ 419postcore_initcall(kvm_devices_init); 420