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Commit | Line | Data |
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2e04ef76 RR |
1 | /*P:050 |
2 | * Lguest guests use a very simple method to describe devices. It's a | |
a6bd8e13 | 3 | * series of device descriptors contained just above the top of normal Guest |
19f1537b RR |
4 | * memory. |
5 | * | |
6 | * We use the standard "virtio" device infrastructure, which provides us with a | |
7 | * console, a network and a block driver. Each one expects some configuration | |
2e04ef76 RR |
8 | * information and a "virtqueue" or two to send and receive data. |
9 | :*/ | |
19f1537b RR |
10 | #include <linux/init.h> |
11 | #include <linux/bootmem.h> | |
12 | #include <linux/lguest_launcher.h> | |
13 | #include <linux/virtio.h> | |
14 | #include <linux/virtio_config.h> | |
15 | #include <linux/interrupt.h> | |
16 | #include <linux/virtio_ring.h> | |
17 | #include <linux/err.h> | |
39a0e33d | 18 | #include <linux/export.h> |
5a0e3ad6 | 19 | #include <linux/slab.h> |
19f1537b RR |
20 | #include <asm/io.h> |
21 | #include <asm/paravirt.h> | |
22 | #include <asm/lguest_hcall.h> | |
23 | ||
24 | /* The pointer to our (page) of device descriptions. */ | |
25 | static void *lguest_devices; | |
26 | ||
2e04ef76 RR |
27 | /* |
28 | * For Guests, device memory can be used as normal memory, so we cast away the | |
29 | * __iomem to quieten sparse. | |
30 | */ | |
19f1537b RR |
31 | static inline void *lguest_map(unsigned long phys_addr, unsigned long pages) |
32 | { | |
e27810f1 | 33 | return (__force void *)ioremap_cache(phys_addr, PAGE_SIZE*pages); |
19f1537b RR |
34 | } |
35 | ||
36 | static inline void lguest_unmap(void *addr) | |
37 | { | |
38 | iounmap((__force void __iomem *)addr); | |
39 | } | |
40 | ||
2e04ef76 RR |
41 | /*D:100 |
42 | * Each lguest device is just a virtio device plus a pointer to its entry | |
43 | * in the lguest_devices page. | |
44 | */ | |
19f1537b RR |
45 | struct lguest_device { |
46 | struct virtio_device vdev; | |
47 | ||
48 | /* The entry in the lguest_devices page for this device. */ | |
49 | struct lguest_device_desc *desc; | |
50 | }; | |
51 | ||
2e04ef76 RR |
52 | /* |
53 | * Since the virtio infrastructure hands us a pointer to the virtio_device all | |
19f1537b | 54 | * the time, it helps to have a curt macro to get a pointer to the struct |
2e04ef76 RR |
55 | * lguest_device it's enclosed in. |
56 | */ | |
25478445 | 57 | #define to_lgdev(vd) container_of(vd, struct lguest_device, vdev) |
19f1537b RR |
58 | |
59 | /*D:130 | |
60 | * Device configurations | |
61 | * | |
a586d4f6 | 62 | * The configuration information for a device consists of one or more |
a6bd8e13 | 63 | * virtqueues, a feature bitmap, and some configuration bytes. The |
6e5aa7ef | 64 | * configuration bytes don't really matter to us: the Launcher sets them up, and |
a586d4f6 | 65 | * the driver will look at them during setup. |
19f1537b | 66 | * |
a586d4f6 | 67 | * A convenient routine to return the device's virtqueue config array: |
2e04ef76 RR |
68 | * immediately after the descriptor. |
69 | */ | |
a586d4f6 RR |
70 | static struct lguest_vqconfig *lg_vq(const struct lguest_device_desc *desc) |
71 | { | |
72 | return (void *)(desc + 1); | |
73 | } | |
19f1537b | 74 | |
a586d4f6 RR |
75 | /* The features come immediately after the virtqueues. */ |
76 | static u8 *lg_features(const struct lguest_device_desc *desc) | |
77 | { | |
78 | return (void *)(lg_vq(desc) + desc->num_vq); | |
79 | } | |
19f1537b | 80 | |
a586d4f6 RR |
81 | /* The config space comes after the two feature bitmasks. */ |
82 | static u8 *lg_config(const struct lguest_device_desc *desc) | |
19f1537b | 83 | { |
a586d4f6 RR |
84 | return lg_features(desc) + desc->feature_len * 2; |
85 | } | |
19f1537b | 86 | |
a586d4f6 RR |
87 | /* The total size of the config page used by this device (incl. desc) */ |
88 | static unsigned desc_size(const struct lguest_device_desc *desc) | |
89 | { | |
90 | return sizeof(*desc) | |
91 | + desc->num_vq * sizeof(struct lguest_vqconfig) | |
92 | + desc->feature_len * 2 | |
93 | + desc->config_len; | |
94 | } | |
95 | ||
c45a6816 | 96 | /* This gets the device's feature bits. */ |
d0254773 | 97 | static u64 lg_get_features(struct virtio_device *vdev) |
a586d4f6 | 98 | { |
c45a6816 RR |
99 | unsigned int i; |
100 | u32 features = 0; | |
a586d4f6 | 101 | struct lguest_device_desc *desc = to_lgdev(vdev)->desc; |
c45a6816 RR |
102 | u8 *in_features = lg_features(desc); |
103 | ||
104 | /* We do this the slow but generic way. */ | |
105 | for (i = 0; i < min(desc->feature_len * 8, 32); i++) | |
106 | if (in_features[i / 8] & (1 << (i % 8))) | |
107 | features |= (1 << i); | |
108 | ||
109 | return features; | |
110 | } | |
111 | ||
3c3ed482 RR |
112 | /* |
113 | * To notify on reset or feature finalization, we (ab)use the NOTIFY | |
114 | * hypercall, with the descriptor address of the device. | |
115 | */ | |
116 | static void status_notify(struct virtio_device *vdev) | |
117 | { | |
118 | unsigned long offset = (void *)to_lgdev(vdev)->desc - lguest_devices; | |
119 | ||
120 | hcall(LHCALL_NOTIFY, (max_pfn << PAGE_SHIFT) + offset, 0, 0, 0); | |
121 | } | |
122 | ||
2e04ef76 RR |
123 | /* |
124 | * The virtio core takes the features the Host offers, and copies the ones | |
125 | * supported by the driver into the vdev->features array. Once that's all | |
126 | * sorted out, this routine is called so we can tell the Host which features we | |
127 | * understand and accept. | |
128 | */ | |
5c609a5e | 129 | static int lg_finalize_features(struct virtio_device *vdev) |
c45a6816 | 130 | { |
c624896e | 131 | unsigned int i, bits; |
c45a6816 RR |
132 | struct lguest_device_desc *desc = to_lgdev(vdev)->desc; |
133 | /* Second half of bitmap is features we accept. */ | |
134 | u8 *out_features = lg_features(desc) + desc->feature_len; | |
135 | ||
e34f8725 RR |
136 | /* Give virtio_ring a chance to accept features. */ |
137 | vring_transport_features(vdev); | |
138 | ||
93d389f8 MT |
139 | /* Make sure we don't have any features > 32 bits! */ |
140 | BUG_ON((u32)vdev->features != vdev->features); | |
141 | ||
2e04ef76 | 142 | /* |
e16e12be MT |
143 | * Since lguest is currently x86-only, we're little-endian. That |
144 | * means we could just memcpy. But it's not time critical, and in | |
145 | * case someone copies this code, we do it the slow, obvious way. | |
2e04ef76 | 146 | */ |
c45a6816 | 147 | memset(out_features, 0, desc->feature_len); |
c624896e RR |
148 | bits = min_t(unsigned, desc->feature_len, sizeof(vdev->features)) * 8; |
149 | for (i = 0; i < bits; i++) { | |
e16e12be | 150 | if (__virtio_test_bit(vdev, i)) |
c45a6816 RR |
151 | out_features[i / 8] |= (1 << (i % 8)); |
152 | } | |
3c3ed482 RR |
153 | |
154 | /* Tell Host we've finished with this device's feature negotiation */ | |
155 | status_notify(vdev); | |
5c609a5e MT |
156 | |
157 | return 0; | |
19f1537b RR |
158 | } |
159 | ||
160 | /* Once they've found a field, getting a copy of it is easy. */ | |
a586d4f6 | 161 | static void lg_get(struct virtio_device *vdev, unsigned int offset, |
19f1537b RR |
162 | void *buf, unsigned len) |
163 | { | |
a586d4f6 RR |
164 | struct lguest_device_desc *desc = to_lgdev(vdev)->desc; |
165 | ||
166 | /* Check they didn't ask for more than the length of the config! */ | |
167 | BUG_ON(offset + len > desc->config_len); | |
168 | memcpy(buf, lg_config(desc) + offset, len); | |
19f1537b RR |
169 | } |
170 | ||
171 | /* Setting the contents is also trivial. */ | |
a586d4f6 | 172 | static void lg_set(struct virtio_device *vdev, unsigned int offset, |
19f1537b RR |
173 | const void *buf, unsigned len) |
174 | { | |
a586d4f6 RR |
175 | struct lguest_device_desc *desc = to_lgdev(vdev)->desc; |
176 | ||
177 | /* Check they didn't ask for more than the length of the config! */ | |
178 | BUG_ON(offset + len > desc->config_len); | |
179 | memcpy(lg_config(desc) + offset, buf, len); | |
19f1537b RR |
180 | } |
181 | ||
2e04ef76 RR |
182 | /* |
183 | * The operations to get and set the status word just access the status field | |
184 | * of the device descriptor. | |
185 | */ | |
19f1537b RR |
186 | static u8 lg_get_status(struct virtio_device *vdev) |
187 | { | |
188 | return to_lgdev(vdev)->desc->status; | |
189 | } | |
190 | ||
191 | static void lg_set_status(struct virtio_device *vdev, u8 status) | |
192 | { | |
6e5aa7ef | 193 | BUG_ON(!status); |
3c3ed482 RR |
194 | to_lgdev(vdev)->desc->status = status; |
195 | ||
196 | /* Tell Host immediately if we failed. */ | |
197 | if (status & VIRTIO_CONFIG_S_FAILED) | |
198 | status_notify(vdev); | |
19f1537b RR |
199 | } |
200 | ||
6e5aa7ef RR |
201 | static void lg_reset(struct virtio_device *vdev) |
202 | { | |
3c3ed482 RR |
203 | /* 0 status means "reset" */ |
204 | to_lgdev(vdev)->desc->status = 0; | |
205 | status_notify(vdev); | |
6e5aa7ef RR |
206 | } |
207 | ||
19f1537b RR |
208 | /* |
209 | * Virtqueues | |
210 | * | |
211 | * The other piece of infrastructure virtio needs is a "virtqueue": a way of | |
212 | * the Guest device registering buffers for the other side to read from or | |
213 | * write into (ie. send and receive buffers). Each device can have multiple | |
e1e72965 RR |
214 | * virtqueues: for example the console driver uses one queue for sending and |
215 | * another for receiving. | |
19f1537b RR |
216 | * |
217 | * Fortunately for us, a very fast shared-memory-plus-descriptors virtqueue | |
218 | * already exists in virtio_ring.c. We just need to connect it up. | |
219 | * | |
220 | * We start with the information we need to keep about each virtqueue. | |
221 | */ | |
222 | ||
223 | /*D:140 This is the information we remember about each virtqueue. */ | |
1842f23c | 224 | struct lguest_vq_info { |
19f1537b RR |
225 | /* A copy of the information contained in the device config. */ |
226 | struct lguest_vqconfig config; | |
227 | ||
228 | /* The address where we mapped the virtio ring, so we can unmap it. */ | |
229 | void *pages; | |
230 | }; | |
231 | ||
2e04ef76 RR |
232 | /* |
233 | * When the virtio_ring code wants to prod the Host, it calls us here and we | |
a6bd8e13 | 234 | * make a hypercall. We hand the physical address of the virtqueue so the Host |
2e04ef76 RR |
235 | * knows which virtqueue we're talking about. |
236 | */ | |
46f9c2b9 | 237 | static bool lg_notify(struct virtqueue *vq) |
19f1537b | 238 | { |
2e04ef76 RR |
239 | /* |
240 | * We store our virtqueue information in the "priv" pointer of the | |
241 | * virtqueue structure. | |
242 | */ | |
19f1537b RR |
243 | struct lguest_vq_info *lvq = vq->priv; |
244 | ||
091ebf07 | 245 | hcall(LHCALL_NOTIFY, lvq->config.pfn << PAGE_SHIFT, 0, 0, 0); |
46f9c2b9 | 246 | return true; |
19f1537b RR |
247 | } |
248 | ||
6db6a5f3 | 249 | /* An extern declaration inside a C file is bad form. Don't do it. */ |
b6c96c02 | 250 | extern int lguest_setup_irq(unsigned int irq); |
6db6a5f3 | 251 | |
2e04ef76 | 252 | /* |
a91d74a3 | 253 | * This routine finds the Nth virtqueue described in the configuration of |
19f1537b RR |
254 | * this device and sets it up. |
255 | * | |
256 | * This is kind of an ugly duckling. It'd be nicer to have a standard | |
257 | * representation of a virtqueue in the configuration space, but it seems that | |
e1e72965 | 258 | * everyone wants to do it differently. The KVM coders want the Guest to |
19f1537b RR |
259 | * allocate its own pages and tell the Host where they are, but for lguest it's |
260 | * simpler for the Host to simply tell us where the pages are. | |
2e04ef76 | 261 | */ |
19f1537b | 262 | static struct virtqueue *lg_find_vq(struct virtio_device *vdev, |
a586d4f6 | 263 | unsigned index, |
9499f5e7 RR |
264 | void (*callback)(struct virtqueue *vq), |
265 | const char *name) | |
19f1537b | 266 | { |
a586d4f6 | 267 | struct lguest_device *ldev = to_lgdev(vdev); |
19f1537b RR |
268 | struct lguest_vq_info *lvq; |
269 | struct virtqueue *vq; | |
19f1537b RR |
270 | int err; |
271 | ||
6457f126 MT |
272 | if (!name) |
273 | return NULL; | |
274 | ||
a586d4f6 RR |
275 | /* We must have this many virtqueues. */ |
276 | if (index >= ldev->desc->num_vq) | |
19f1537b RR |
277 | return ERR_PTR(-ENOENT); |
278 | ||
279 | lvq = kmalloc(sizeof(*lvq), GFP_KERNEL); | |
280 | if (!lvq) | |
281 | return ERR_PTR(-ENOMEM); | |
282 | ||
2e04ef76 RR |
283 | /* |
284 | * Make a copy of the "struct lguest_vqconfig" entry, which sits after | |
a586d4f6 | 285 | * the descriptor. We need a copy because the config space might not |
2e04ef76 RR |
286 | * be aligned correctly. |
287 | */ | |
a586d4f6 | 288 | memcpy(&lvq->config, lg_vq(ldev->desc)+index, sizeof(lvq->config)); |
19f1537b | 289 | |
a586d4f6 RR |
290 | printk("Mapping virtqueue %i addr %lx\n", index, |
291 | (unsigned long)lvq->config.pfn << PAGE_SHIFT); | |
19f1537b RR |
292 | /* Figure out how many pages the ring will take, and map that memory */ |
293 | lvq->pages = lguest_map((unsigned long)lvq->config.pfn << PAGE_SHIFT, | |
42b36cc0 | 294 | DIV_ROUND_UP(vring_size(lvq->config.num, |
2966af73 | 295 | LGUEST_VRING_ALIGN), |
19f1537b RR |
296 | PAGE_SIZE)); |
297 | if (!lvq->pages) { | |
298 | err = -ENOMEM; | |
299 | goto free_lvq; | |
300 | } | |
301 | ||
2e04ef76 RR |
302 | /* |
303 | * OK, tell virtio_ring.c to set up a virtqueue now we know its size | |
7b21e34f RR |
304 | * and we've got a pointer to its pages. Note that we set weak_barriers |
305 | * to 'true': the host just a(nother) SMP CPU, so we only need inter-cpu | |
306 | * barriers. | |
2e04ef76 | 307 | */ |
17bb6d40 | 308 | vq = vring_new_virtqueue(index, lvq->config.num, LGUEST_VRING_ALIGN, vdev, |
7b21e34f | 309 | true, lvq->pages, lg_notify, callback, name); |
19f1537b RR |
310 | if (!vq) { |
311 | err = -ENOMEM; | |
312 | goto unmap; | |
313 | } | |
314 | ||
6db6a5f3 | 315 | /* Make sure the interrupt is allocated. */ |
b6c96c02 SP |
316 | err = lguest_setup_irq(lvq->config.irq); |
317 | if (err) | |
318 | goto destroy_vring; | |
6db6a5f3 | 319 | |
2e04ef76 RR |
320 | /* |
321 | * Tell the interrupt for this virtqueue to go to the virtio_ring | |
322 | * interrupt handler. | |
323 | * | |
324 | * FIXME: We used to have a flag for the Host to tell us we could use | |
19f1537b | 325 | * the interrupt as a source of randomness: it'd be nice to have that |
2e04ef76 RR |
326 | * back. |
327 | */ | |
19f1537b | 328 | err = request_irq(lvq->config.irq, vring_interrupt, IRQF_SHARED, |
bda53cd5 | 329 | dev_name(&vdev->dev), vq); |
19f1537b | 330 | if (err) |
b6c96c02 | 331 | goto free_desc; |
19f1537b | 332 | |
2e04ef76 RR |
333 | /* |
334 | * Last of all we hook up our 'struct lguest_vq_info" to the | |
335 | * virtqueue's priv pointer. | |
336 | */ | |
19f1537b RR |
337 | vq->priv = lvq; |
338 | return vq; | |
339 | ||
b6c96c02 SP |
340 | free_desc: |
341 | irq_free_desc(lvq->config.irq); | |
19f1537b RR |
342 | destroy_vring: |
343 | vring_del_virtqueue(vq); | |
344 | unmap: | |
345 | lguest_unmap(lvq->pages); | |
346 | free_lvq: | |
347 | kfree(lvq); | |
348 | return ERR_PTR(err); | |
349 | } | |
350 | /*:*/ | |
351 | ||
352 | /* Cleaning up a virtqueue is easy */ | |
353 | static void lg_del_vq(struct virtqueue *vq) | |
354 | { | |
355 | struct lguest_vq_info *lvq = vq->priv; | |
356 | ||
74b2553f RR |
357 | /* Release the interrupt */ |
358 | free_irq(lvq->config.irq, vq); | |
19f1537b RR |
359 | /* Tell virtio_ring.c to free the virtqueue. */ |
360 | vring_del_virtqueue(vq); | |
361 | /* Unmap the pages containing the ring. */ | |
362 | lguest_unmap(lvq->pages); | |
363 | /* Free our own queue information. */ | |
364 | kfree(lvq); | |
365 | } | |
366 | ||
d2a7ddda MT |
367 | static void lg_del_vqs(struct virtio_device *vdev) |
368 | { | |
369 | struct virtqueue *vq, *n; | |
370 | ||
371 | list_for_each_entry_safe(vq, n, &vdev->vqs, list) | |
372 | lg_del_vq(vq); | |
373 | } | |
374 | ||
375 | static int lg_find_vqs(struct virtio_device *vdev, unsigned nvqs, | |
376 | struct virtqueue *vqs[], | |
377 | vq_callback_t *callbacks[], | |
378 | const char *names[]) | |
379 | { | |
380 | struct lguest_device *ldev = to_lgdev(vdev); | |
381 | int i; | |
382 | ||
383 | /* We must have this many virtqueues. */ | |
384 | if (nvqs > ldev->desc->num_vq) | |
385 | return -ENOENT; | |
386 | ||
387 | for (i = 0; i < nvqs; ++i) { | |
388 | vqs[i] = lg_find_vq(vdev, i, callbacks[i], names[i]); | |
389 | if (IS_ERR(vqs[i])) | |
390 | goto error; | |
391 | } | |
392 | return 0; | |
393 | ||
394 | error: | |
395 | lg_del_vqs(vdev); | |
396 | return PTR_ERR(vqs[i]); | |
397 | } | |
398 | ||
66846048 RJ |
399 | static const char *lg_bus_name(struct virtio_device *vdev) |
400 | { | |
401 | return ""; | |
402 | } | |
403 | ||
19f1537b | 404 | /* The ops structure which hooks everything together. */ |
93503932 | 405 | static const struct virtio_config_ops lguest_config_ops = { |
c45a6816 | 406 | .get_features = lg_get_features, |
c624896e | 407 | .finalize_features = lg_finalize_features, |
19f1537b RR |
408 | .get = lg_get, |
409 | .set = lg_set, | |
410 | .get_status = lg_get_status, | |
411 | .set_status = lg_set_status, | |
6e5aa7ef | 412 | .reset = lg_reset, |
d2a7ddda MT |
413 | .find_vqs = lg_find_vqs, |
414 | .del_vqs = lg_del_vqs, | |
66846048 | 415 | .bus_name = lg_bus_name, |
19f1537b RR |
416 | }; |
417 | ||
2e04ef76 RR |
418 | /* |
419 | * The root device for the lguest virtio devices. This makes them appear as | |
420 | * /sys/devices/lguest/0,1,2 not /sys/devices/0,1,2. | |
421 | */ | |
ff8561c4 | 422 | static struct device *lguest_root; |
19f1537b | 423 | |
2e04ef76 RR |
424 | /*D:120 |
425 | * This is the core of the lguest bus: actually adding a new device. | |
19f1537b RR |
426 | * It's a separate function because it's neater that way, and because an |
427 | * earlier version of the code supported hotplug and unplug. They were removed | |
428 | * early on because they were never used. | |
429 | * | |
430 | * As Andrew Tridgell says, "Untested code is buggy code". | |
431 | * | |
432 | * It's worth reading this carefully: we start with a pointer to the new device | |
b769f579 | 433 | * descriptor in the "lguest_devices" page, and the offset into the device |
2e04ef76 RR |
434 | * descriptor page so we can uniquely identify it if things go badly wrong. |
435 | */ | |
b769f579 RR |
436 | static void add_lguest_device(struct lguest_device_desc *d, |
437 | unsigned int offset) | |
19f1537b RR |
438 | { |
439 | struct lguest_device *ldev; | |
440 | ||
2e04ef76 | 441 | /* Start with zeroed memory; Linux's device layer counts on it. */ |
19f1537b RR |
442 | ldev = kzalloc(sizeof(*ldev), GFP_KERNEL); |
443 | if (!ldev) { | |
b769f579 RR |
444 | printk(KERN_EMERG "Cannot allocate lguest dev %u type %u\n", |
445 | offset, d->type); | |
19f1537b RR |
446 | return; |
447 | } | |
448 | ||
449 | /* This devices' parent is the lguest/ dir. */ | |
ff8561c4 | 450 | ldev->vdev.dev.parent = lguest_root; |
a91d74a3 RR |
451 | /* |
452 | * The device type comes straight from the descriptor. There's also a | |
453 | * device vendor field in the virtio_device struct, which we leave as | |
454 | * 0. | |
455 | */ | |
19f1537b | 456 | ldev->vdev.id.device = d->type; |
2e04ef76 RR |
457 | /* |
458 | * We have a simple set of routines for querying the device's | |
459 | * configuration information and setting its status. | |
460 | */ | |
19f1537b RR |
461 | ldev->vdev.config = &lguest_config_ops; |
462 | /* And we remember the device's descriptor for lguest_config_ops. */ | |
463 | ldev->desc = d; | |
464 | ||
2e04ef76 RR |
465 | /* |
466 | * register_virtio_device() sets up the generic fields for the struct | |
19f1537b | 467 | * virtio_device and calls device_register(). This makes the bus |
2e04ef76 RR |
468 | * infrastructure look for a matching driver. |
469 | */ | |
19f1537b | 470 | if (register_virtio_device(&ldev->vdev) != 0) { |
b769f579 RR |
471 | printk(KERN_ERR "Failed to register lguest dev %u type %u\n", |
472 | offset, d->type); | |
19f1537b RR |
473 | kfree(ldev); |
474 | } | |
475 | } | |
476 | ||
2e04ef76 RR |
477 | /*D:110 |
478 | * scan_devices() simply iterates through the device page. The type 0 is | |
479 | * reserved to mean "end of devices". | |
480 | */ | |
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481 | static void scan_devices(void) |
482 | { | |
483 | unsigned int i; | |
484 | struct lguest_device_desc *d; | |
485 | ||
486 | /* We start at the page beginning, and skip over each entry. */ | |
a586d4f6 | 487 | for (i = 0; i < PAGE_SIZE; i += desc_size(d)) { |
19f1537b RR |
488 | d = lguest_devices + i; |
489 | ||
490 | /* Once we hit a zero, stop. */ | |
491 | if (d->type == 0) | |
492 | break; | |
493 | ||
a586d4f6 | 494 | printk("Device at %i has size %u\n", i, desc_size(d)); |
b769f579 | 495 | add_lguest_device(d, i); |
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496 | } |
497 | } | |
498 | ||
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499 | /*D:105 |
500 | * Fairly early in boot, lguest_devices_init() is called to set up the | |
19f1537b RR |
501 | * lguest device infrastructure. We check that we are a Guest by checking |
502 | * pv_info.name: there are other ways of checking, but this seems most | |
503 | * obvious to me. | |
504 | * | |
505 | * So we can access the "struct lguest_device_desc"s easily, we map that memory | |
506 | * and store the pointer in the global "lguest_devices". Then we register a | |
507 | * root device from which all our devices will hang (this seems to be the | |
508 | * correct sysfs incantation). | |
509 | * | |
510 | * Finally we call scan_devices() which adds all the devices found in the | |
2e04ef76 RR |
511 | * lguest_devices page. |
512 | */ | |
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513 | static int __init lguest_devices_init(void) |
514 | { | |
515 | if (strcmp(pv_info.name, "lguest") != 0) | |
516 | return 0; | |
517 | ||
ff8561c4 MM |
518 | lguest_root = root_device_register("lguest"); |
519 | if (IS_ERR(lguest_root)) | |
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520 | panic("Could not register lguest root"); |
521 | ||
522 | /* Devices are in a single page above top of "normal" mem */ | |
523 | lguest_devices = lguest_map(max_pfn<<PAGE_SHIFT, 1); | |
524 | ||
525 | scan_devices(); | |
526 | return 0; | |
527 | } | |
528 | /* We do this after core stuff, but before the drivers. */ | |
529 | postcore_initcall(lguest_devices_init); | |
530 | ||
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531 | /*D:150 |
532 | * At this point in the journey we used to now wade through the lguest | |
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533 | * devices themselves: net, block and console. Since they're all now virtio |
534 | * devices rather than lguest-specific, I've decided to ignore them. Mostly, | |
535 | * they're kind of boring. But this does mean you'll never experience the | |
536 | * thrill of reading the forbidden love scene buried deep in the block driver. | |
537 | * | |
538 | * "make Launcher" beckons, where we answer questions like "Where do Guests | |
2e04ef76 RR |
539 | * come from?", and "What do you do when someone asks for optimization?". |
540 | */ |