The discovered bit in PGCCSR register indicates if the device has been
[linux-2.6/next.git] / drivers / lguest / lguest_device.c
blob0dc30ffde5ad7a8defc591c42a251bb9e59c35a9
1 /*P:050
2 * Lguest guests use a very simple method to describe devices. It's a
3 * series of device descriptors contained just above the top of normal Guest
4 * memory.
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
8 * information and a "virtqueue" or two to send and receive data.
9 :*/
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>
18 #include <linux/export.h>
19 #include <linux/slab.h>
20 #include <asm/io.h>
21 #include <asm/paravirt.h>
22 #include <asm/lguest_hcall.h>
24 /* The pointer to our (page) of device descriptions. */
25 static void *lguest_devices;
28 * For Guests, device memory can be used as normal memory, so we cast away the
29 * __iomem to quieten sparse.
31 static inline void *lguest_map(unsigned long phys_addr, unsigned long pages)
33 return (__force void *)ioremap_cache(phys_addr, PAGE_SIZE*pages);
36 static inline void lguest_unmap(void *addr)
38 iounmap((__force void __iomem *)addr);
41 /*D:100
42 * Each lguest device is just a virtio device plus a pointer to its entry
43 * in the lguest_devices page.
45 struct lguest_device {
46 struct virtio_device vdev;
48 /* The entry in the lguest_devices page for this device. */
49 struct lguest_device_desc *desc;
53 * Since the virtio infrastructure hands us a pointer to the virtio_device all
54 * the time, it helps to have a curt macro to get a pointer to the struct
55 * lguest_device it's enclosed in.
57 #define to_lgdev(vd) container_of(vd, struct lguest_device, vdev)
59 /*D:130
60 * Device configurations
62 * The configuration information for a device consists of one or more
63 * virtqueues, a feature bitmap, and some configuration bytes. The
64 * configuration bytes don't really matter to us: the Launcher sets them up, and
65 * the driver will look at them during setup.
67 * A convenient routine to return the device's virtqueue config array:
68 * immediately after the descriptor.
70 static struct lguest_vqconfig *lg_vq(const struct lguest_device_desc *desc)
72 return (void *)(desc + 1);
75 /* The features come immediately after the virtqueues. */
76 static u8 *lg_features(const struct lguest_device_desc *desc)
78 return (void *)(lg_vq(desc) + desc->num_vq);
81 /* The config space comes after the two feature bitmasks. */
82 static u8 *lg_config(const struct lguest_device_desc *desc)
84 return lg_features(desc) + desc->feature_len * 2;
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)
90 return sizeof(*desc)
91 + desc->num_vq * sizeof(struct lguest_vqconfig)
92 + desc->feature_len * 2
93 + desc->config_len;
96 /* This gets the device's feature bits. */
97 static u32 lg_get_features(struct virtio_device *vdev)
99 unsigned int i;
100 u32 features = 0;
101 struct lguest_device_desc *desc = to_lgdev(vdev)->desc;
102 u8 *in_features = lg_features(desc);
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);
109 return features;
113 * To notify on reset or feature finalization, we (ab)use the NOTIFY
114 * hypercall, with the descriptor address of the device.
116 static void status_notify(struct virtio_device *vdev)
118 unsigned long offset = (void *)to_lgdev(vdev)->desc - lguest_devices;
120 hcall(LHCALL_NOTIFY, (max_pfn << PAGE_SHIFT) + offset, 0, 0, 0);
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.
129 static void lg_finalize_features(struct virtio_device *vdev)
131 unsigned int i, bits;
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;
136 /* Give virtio_ring a chance to accept features. */
137 vring_transport_features(vdev);
140 * The vdev->feature array is a Linux bitmask: this isn't the same as a
141 * the simple array of bits used by lguest devices for features. So we
142 * do this slow, manual conversion which is completely general.
144 memset(out_features, 0, desc->feature_len);
145 bits = min_t(unsigned, desc->feature_len, sizeof(vdev->features)) * 8;
146 for (i = 0; i < bits; i++) {
147 if (test_bit(i, vdev->features))
148 out_features[i / 8] |= (1 << (i % 8));
151 /* Tell Host we've finished with this device's feature negotiation */
152 status_notify(vdev);
155 /* Once they've found a field, getting a copy of it is easy. */
156 static void lg_get(struct virtio_device *vdev, unsigned int offset,
157 void *buf, unsigned len)
159 struct lguest_device_desc *desc = to_lgdev(vdev)->desc;
161 /* Check they didn't ask for more than the length of the config! */
162 BUG_ON(offset + len > desc->config_len);
163 memcpy(buf, lg_config(desc) + offset, len);
166 /* Setting the contents is also trivial. */
167 static void lg_set(struct virtio_device *vdev, unsigned int offset,
168 const void *buf, unsigned len)
170 struct lguest_device_desc *desc = to_lgdev(vdev)->desc;
172 /* Check they didn't ask for more than the length of the config! */
173 BUG_ON(offset + len > desc->config_len);
174 memcpy(lg_config(desc) + offset, buf, len);
178 * The operations to get and set the status word just access the status field
179 * of the device descriptor.
181 static u8 lg_get_status(struct virtio_device *vdev)
183 return to_lgdev(vdev)->desc->status;
186 static void lg_set_status(struct virtio_device *vdev, u8 status)
188 BUG_ON(!status);
189 to_lgdev(vdev)->desc->status = status;
191 /* Tell Host immediately if we failed. */
192 if (status & VIRTIO_CONFIG_S_FAILED)
193 status_notify(vdev);
196 static void lg_reset(struct virtio_device *vdev)
198 /* 0 status means "reset" */
199 to_lgdev(vdev)->desc->status = 0;
200 status_notify(vdev);
204 * Virtqueues
206 * The other piece of infrastructure virtio needs is a "virtqueue": a way of
207 * the Guest device registering buffers for the other side to read from or
208 * write into (ie. send and receive buffers). Each device can have multiple
209 * virtqueues: for example the console driver uses one queue for sending and
210 * another for receiving.
212 * Fortunately for us, a very fast shared-memory-plus-descriptors virtqueue
213 * already exists in virtio_ring.c. We just need to connect it up.
215 * We start with the information we need to keep about each virtqueue.
218 /*D:140 This is the information we remember about each virtqueue. */
219 struct lguest_vq_info {
220 /* A copy of the information contained in the device config. */
221 struct lguest_vqconfig config;
223 /* The address where we mapped the virtio ring, so we can unmap it. */
224 void *pages;
228 * When the virtio_ring code wants to prod the Host, it calls us here and we
229 * make a hypercall. We hand the physical address of the virtqueue so the Host
230 * knows which virtqueue we're talking about.
232 static void lg_notify(struct virtqueue *vq)
235 * We store our virtqueue information in the "priv" pointer of the
236 * virtqueue structure.
238 struct lguest_vq_info *lvq = vq->priv;
240 hcall(LHCALL_NOTIFY, lvq->config.pfn << PAGE_SHIFT, 0, 0, 0);
243 /* An extern declaration inside a C file is bad form. Don't do it. */
244 extern void lguest_setup_irq(unsigned int irq);
247 * This routine finds the Nth virtqueue described in the configuration of
248 * this device and sets it up.
250 * This is kind of an ugly duckling. It'd be nicer to have a standard
251 * representation of a virtqueue in the configuration space, but it seems that
252 * everyone wants to do it differently. The KVM coders want the Guest to
253 * allocate its own pages and tell the Host where they are, but for lguest it's
254 * simpler for the Host to simply tell us where the pages are.
256 static struct virtqueue *lg_find_vq(struct virtio_device *vdev,
257 unsigned index,
258 void (*callback)(struct virtqueue *vq),
259 const char *name)
261 struct lguest_device *ldev = to_lgdev(vdev);
262 struct lguest_vq_info *lvq;
263 struct virtqueue *vq;
264 int err;
266 /* We must have this many virtqueues. */
267 if (index >= ldev->desc->num_vq)
268 return ERR_PTR(-ENOENT);
270 lvq = kmalloc(sizeof(*lvq), GFP_KERNEL);
271 if (!lvq)
272 return ERR_PTR(-ENOMEM);
275 * Make a copy of the "struct lguest_vqconfig" entry, which sits after
276 * the descriptor. We need a copy because the config space might not
277 * be aligned correctly.
279 memcpy(&lvq->config, lg_vq(ldev->desc)+index, sizeof(lvq->config));
281 printk("Mapping virtqueue %i addr %lx\n", index,
282 (unsigned long)lvq->config.pfn << PAGE_SHIFT);
283 /* Figure out how many pages the ring will take, and map that memory */
284 lvq->pages = lguest_map((unsigned long)lvq->config.pfn << PAGE_SHIFT,
285 DIV_ROUND_UP(vring_size(lvq->config.num,
286 LGUEST_VRING_ALIGN),
287 PAGE_SIZE));
288 if (!lvq->pages) {
289 err = -ENOMEM;
290 goto free_lvq;
294 * OK, tell virtio_ring.c to set up a virtqueue now we know its size
295 * and we've got a pointer to its pages.
297 vq = vring_new_virtqueue(lvq->config.num, LGUEST_VRING_ALIGN,
298 vdev, lvq->pages, lg_notify, callback, name);
299 if (!vq) {
300 err = -ENOMEM;
301 goto unmap;
304 /* Make sure the interrupt is allocated. */
305 lguest_setup_irq(lvq->config.irq);
308 * Tell the interrupt for this virtqueue to go to the virtio_ring
309 * interrupt handler.
311 * FIXME: We used to have a flag for the Host to tell us we could use
312 * the interrupt as a source of randomness: it'd be nice to have that
313 * back.
315 err = request_irq(lvq->config.irq, vring_interrupt, IRQF_SHARED,
316 dev_name(&vdev->dev), vq);
317 if (err)
318 goto destroy_vring;
321 * Last of all we hook up our 'struct lguest_vq_info" to the
322 * virtqueue's priv pointer.
324 vq->priv = lvq;
325 return vq;
327 destroy_vring:
328 vring_del_virtqueue(vq);
329 unmap:
330 lguest_unmap(lvq->pages);
331 free_lvq:
332 kfree(lvq);
333 return ERR_PTR(err);
335 /*:*/
337 /* Cleaning up a virtqueue is easy */
338 static void lg_del_vq(struct virtqueue *vq)
340 struct lguest_vq_info *lvq = vq->priv;
342 /* Release the interrupt */
343 free_irq(lvq->config.irq, vq);
344 /* Tell virtio_ring.c to free the virtqueue. */
345 vring_del_virtqueue(vq);
346 /* Unmap the pages containing the ring. */
347 lguest_unmap(lvq->pages);
348 /* Free our own queue information. */
349 kfree(lvq);
352 static void lg_del_vqs(struct virtio_device *vdev)
354 struct virtqueue *vq, *n;
356 list_for_each_entry_safe(vq, n, &vdev->vqs, list)
357 lg_del_vq(vq);
360 static int lg_find_vqs(struct virtio_device *vdev, unsigned nvqs,
361 struct virtqueue *vqs[],
362 vq_callback_t *callbacks[],
363 const char *names[])
365 struct lguest_device *ldev = to_lgdev(vdev);
366 int i;
368 /* We must have this many virtqueues. */
369 if (nvqs > ldev->desc->num_vq)
370 return -ENOENT;
372 for (i = 0; i < nvqs; ++i) {
373 vqs[i] = lg_find_vq(vdev, i, callbacks[i], names[i]);
374 if (IS_ERR(vqs[i]))
375 goto error;
377 return 0;
379 error:
380 lg_del_vqs(vdev);
381 return PTR_ERR(vqs[i]);
384 /* The ops structure which hooks everything together. */
385 static struct virtio_config_ops lguest_config_ops = {
386 .get_features = lg_get_features,
387 .finalize_features = lg_finalize_features,
388 .get = lg_get,
389 .set = lg_set,
390 .get_status = lg_get_status,
391 .set_status = lg_set_status,
392 .reset = lg_reset,
393 .find_vqs = lg_find_vqs,
394 .del_vqs = lg_del_vqs,
398 * The root device for the lguest virtio devices. This makes them appear as
399 * /sys/devices/lguest/0,1,2 not /sys/devices/0,1,2.
401 static struct device *lguest_root;
403 /*D:120
404 * This is the core of the lguest bus: actually adding a new device.
405 * It's a separate function because it's neater that way, and because an
406 * earlier version of the code supported hotplug and unplug. They were removed
407 * early on because they were never used.
409 * As Andrew Tridgell says, "Untested code is buggy code".
411 * It's worth reading this carefully: we start with a pointer to the new device
412 * descriptor in the "lguest_devices" page, and the offset into the device
413 * descriptor page so we can uniquely identify it if things go badly wrong.
415 static void add_lguest_device(struct lguest_device_desc *d,
416 unsigned int offset)
418 struct lguest_device *ldev;
420 /* Start with zeroed memory; Linux's device layer counts on it. */
421 ldev = kzalloc(sizeof(*ldev), GFP_KERNEL);
422 if (!ldev) {
423 printk(KERN_EMERG "Cannot allocate lguest dev %u type %u\n",
424 offset, d->type);
425 return;
428 /* This devices' parent is the lguest/ dir. */
429 ldev->vdev.dev.parent = lguest_root;
431 * The device type comes straight from the descriptor. There's also a
432 * device vendor field in the virtio_device struct, which we leave as
433 * 0.
435 ldev->vdev.id.device = d->type;
437 * We have a simple set of routines for querying the device's
438 * configuration information and setting its status.
440 ldev->vdev.config = &lguest_config_ops;
441 /* And we remember the device's descriptor for lguest_config_ops. */
442 ldev->desc = d;
445 * register_virtio_device() sets up the generic fields for the struct
446 * virtio_device and calls device_register(). This makes the bus
447 * infrastructure look for a matching driver.
449 if (register_virtio_device(&ldev->vdev) != 0) {
450 printk(KERN_ERR "Failed to register lguest dev %u type %u\n",
451 offset, d->type);
452 kfree(ldev);
456 /*D:110
457 * scan_devices() simply iterates through the device page. The type 0 is
458 * reserved to mean "end of devices".
460 static void scan_devices(void)
462 unsigned int i;
463 struct lguest_device_desc *d;
465 /* We start at the page beginning, and skip over each entry. */
466 for (i = 0; i < PAGE_SIZE; i += desc_size(d)) {
467 d = lguest_devices + i;
469 /* Once we hit a zero, stop. */
470 if (d->type == 0)
471 break;
473 printk("Device at %i has size %u\n", i, desc_size(d));
474 add_lguest_device(d, i);
478 /*D:105
479 * Fairly early in boot, lguest_devices_init() is called to set up the
480 * lguest device infrastructure. We check that we are a Guest by checking
481 * pv_info.name: there are other ways of checking, but this seems most
482 * obvious to me.
484 * So we can access the "struct lguest_device_desc"s easily, we map that memory
485 * and store the pointer in the global "lguest_devices". Then we register a
486 * root device from which all our devices will hang (this seems to be the
487 * correct sysfs incantation).
489 * Finally we call scan_devices() which adds all the devices found in the
490 * lguest_devices page.
492 static int __init lguest_devices_init(void)
494 if (strcmp(pv_info.name, "lguest") != 0)
495 return 0;
497 lguest_root = root_device_register("lguest");
498 if (IS_ERR(lguest_root))
499 panic("Could not register lguest root");
501 /* Devices are in a single page above top of "normal" mem */
502 lguest_devices = lguest_map(max_pfn<<PAGE_SHIFT, 1);
504 scan_devices();
505 return 0;
507 /* We do this after core stuff, but before the drivers. */
508 postcore_initcall(lguest_devices_init);
510 /*D:150
511 * At this point in the journey we used to now wade through the lguest
512 * devices themselves: net, block and console. Since they're all now virtio
513 * devices rather than lguest-specific, I've decided to ignore them. Mostly,
514 * they're kind of boring. But this does mean you'll never experience the
515 * thrill of reading the forbidden love scene buried deep in the block driver.
517 * "make Launcher" beckons, where we answer questions like "Where do Guests
518 * come from?", and "What do you do when someone asks for optimization?".