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Rusty Russell2e04ef72009-07-30 16:03:45 -06001/*P:050
2 * Lguest guests use a very simple method to describe devices. It's a
Rusty Russella6bd8e12008-03-28 11:05:53 -05003 * series of device descriptors contained just above the top of normal Guest
Rusty Russell19f15372007-10-22 11:24:21 +10004 * 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
Rusty Russell2e04ef72009-07-30 16:03:45 -06008 * information and a "virtqueue" or two to send and receive data.
9:*/
Rusty Russell19f15372007-10-22 11:24:21 +100010#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>
Paul Gortmaker39a0e332011-07-21 13:03:20 -040018#include <linux/export.h>
Tejun Heo5a0e3ad2010-03-24 17:04:11 +090019#include <linux/slab.h>
Rusty Russell19f15372007-10-22 11:24:21 +100020#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. */
25static void *lguest_devices;
26
Rusty Russell2e04ef72009-07-30 16:03:45 -060027/*
28 * For Guests, device memory can be used as normal memory, so we cast away the
29 * __iomem to quieten sparse.
30 */
Rusty Russell19f15372007-10-22 11:24:21 +100031static inline void *lguest_map(unsigned long phys_addr, unsigned long pages)
32{
Rusty Russelle27810f2008-05-30 15:09:40 -050033 return (__force void *)ioremap_cache(phys_addr, PAGE_SIZE*pages);
Rusty Russell19f15372007-10-22 11:24:21 +100034}
35
36static inline void lguest_unmap(void *addr)
37{
38 iounmap((__force void __iomem *)addr);
39}
40
Rusty Russell2e04ef72009-07-30 16:03:45 -060041/*D:100
42 * Each lguest device is just a virtio device plus a pointer to its entry
43 * in the lguest_devices page.
44 */
Rusty Russell19f15372007-10-22 11:24:21 +100045struct 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
Rusty Russell2e04ef72009-07-30 16:03:45 -060052/*
53 * Since the virtio infrastructure hands us a pointer to the virtio_device all
Rusty Russell19f15372007-10-22 11:24:21 +100054 * the time, it helps to have a curt macro to get a pointer to the struct
Rusty Russell2e04ef72009-07-30 16:03:45 -060055 * lguest_device it's enclosed in.
56 */
Alexey Dobriyan25478442008-02-08 04:20:14 -080057#define to_lgdev(vd) container_of(vd, struct lguest_device, vdev)
Rusty Russell19f15372007-10-22 11:24:21 +100058
59/*D:130
60 * Device configurations
61 *
Rusty Russella586d4f2008-02-04 23:49:56 -050062 * The configuration information for a device consists of one or more
Rusty Russella6bd8e12008-03-28 11:05:53 -050063 * virtqueues, a feature bitmap, and some configuration bytes. The
Rusty Russell6e5aa7e2008-02-04 23:50:03 -050064 * configuration bytes don't really matter to us: the Launcher sets them up, and
Rusty Russella586d4f2008-02-04 23:49:56 -050065 * the driver will look at them during setup.
Rusty Russell19f15372007-10-22 11:24:21 +100066 *
Rusty Russella586d4f2008-02-04 23:49:56 -050067 * A convenient routine to return the device's virtqueue config array:
Rusty Russell2e04ef72009-07-30 16:03:45 -060068 * immediately after the descriptor.
69 */
Rusty Russella586d4f2008-02-04 23:49:56 -050070static struct lguest_vqconfig *lg_vq(const struct lguest_device_desc *desc)
71{
72 return (void *)(desc + 1);
73}
Rusty Russell19f15372007-10-22 11:24:21 +100074
Rusty Russella586d4f2008-02-04 23:49:56 -050075/* The features come immediately after the virtqueues. */
76static u8 *lg_features(const struct lguest_device_desc *desc)
77{
78 return (void *)(lg_vq(desc) + desc->num_vq);
79}
Rusty Russell19f15372007-10-22 11:24:21 +100080
Rusty Russella586d4f2008-02-04 23:49:56 -050081/* The config space comes after the two feature bitmasks. */
82static u8 *lg_config(const struct lguest_device_desc *desc)
83{
84 return lg_features(desc) + desc->feature_len * 2;
85}
86
87/* The total size of the config page used by this device (incl. desc) */
88static 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
Rusty Russellc45a6812008-05-02 21:50:50 -050096/* This gets the device's feature bits. */
97static u32 lg_get_features(struct virtio_device *vdev)
Rusty Russell19f15372007-10-22 11:24:21 +100098{
Rusty Russellc45a6812008-05-02 21:50:50 -050099 unsigned int i;
100 u32 features = 0;
Rusty Russell19f15372007-10-22 11:24:21 +1000101 struct lguest_device_desc *desc = to_lgdev(vdev)->desc;
Rusty Russellc45a6812008-05-02 21:50:50 -0500102 u8 *in_features = lg_features(desc);
Rusty Russell19f15372007-10-22 11:24:21 +1000103
Rusty Russellc45a6812008-05-02 21:50:50 -0500104 /* 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);
Rusty Russell19f15372007-10-22 11:24:21 +1000108
Rusty Russellc45a6812008-05-02 21:50:50 -0500109 return features;
110}
Rusty Russella586d4f2008-02-04 23:49:56 -0500111
Rusty Russell2e04ef72009-07-30 16:03:45 -0600112/*
Rusty Russell3c3ed482011-07-22 14:39:49 +0930113 * To notify on reset or feature finalization, we (ab)use the NOTIFY
114 * hypercall, with the descriptor address of the device.
115 */
116static 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
123/*
Rusty Russell2e04ef72009-07-30 16:03:45 -0600124 * 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 */
Rusty Russellc6248962008-07-25 12:06:07 -0500129static void lg_finalize_features(struct virtio_device *vdev)
Rusty Russellc45a6812008-05-02 21:50:50 -0500130{
Rusty Russellc6248962008-07-25 12:06:07 -0500131 unsigned int i, bits;
Rusty Russellc45a6812008-05-02 21:50:50 -0500132 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
Rusty Russelle34f8722008-07-25 12:06:13 -0500136 /* Give virtio_ring a chance to accept features. */
137 vring_transport_features(vdev);
138
Rusty Russell2e04ef72009-07-30 16:03:45 -0600139 /*
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.
143 */
Rusty Russellc45a6812008-05-02 21:50:50 -0500144 memset(out_features, 0, desc->feature_len);
Rusty Russellc6248962008-07-25 12:06:07 -0500145 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))
Rusty Russellc45a6812008-05-02 21:50:50 -0500148 out_features[i / 8] |= (1 << (i % 8));
149 }
Rusty Russell3c3ed482011-07-22 14:39:49 +0930150
151 /* Tell Host we've finished with this device's feature negotiation */
152 status_notify(vdev);
Rusty Russell19f15372007-10-22 11:24:21 +1000153}
154
155/* Once they've found a field, getting a copy of it is easy. */
Rusty Russella586d4f2008-02-04 23:49:56 -0500156static void lg_get(struct virtio_device *vdev, unsigned int offset,
Rusty Russell19f15372007-10-22 11:24:21 +1000157 void *buf, unsigned len)
158{
Rusty Russella586d4f2008-02-04 23:49:56 -0500159 struct lguest_device_desc *desc = to_lgdev(vdev)->desc;
160
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);
Rusty Russell19f15372007-10-22 11:24:21 +1000164}
165
166/* Setting the contents is also trivial. */
Rusty Russella586d4f2008-02-04 23:49:56 -0500167static void lg_set(struct virtio_device *vdev, unsigned int offset,
Rusty Russell19f15372007-10-22 11:24:21 +1000168 const void *buf, unsigned len)
169{
Rusty Russella586d4f2008-02-04 23:49:56 -0500170 struct lguest_device_desc *desc = to_lgdev(vdev)->desc;
171
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);
Rusty Russell19f15372007-10-22 11:24:21 +1000175}
176
Rusty Russell2e04ef72009-07-30 16:03:45 -0600177/*
178 * The operations to get and set the status word just access the status field
179 * of the device descriptor.
180 */
Rusty Russell19f15372007-10-22 11:24:21 +1000181static u8 lg_get_status(struct virtio_device *vdev)
182{
183 return to_lgdev(vdev)->desc->status;
184}
185
Rusty Russella007a752008-05-02 21:50:53 -0500186static void lg_set_status(struct virtio_device *vdev, u8 status)
187{
188 BUG_ON(!status);
Rusty Russell3c3ed482011-07-22 14:39:49 +0930189 to_lgdev(vdev)->desc->status = status;
190
191 /* Tell Host immediately if we failed. */
192 if (status & VIRTIO_CONFIG_S_FAILED)
193 status_notify(vdev);
Rusty Russella007a752008-05-02 21:50:53 -0500194}
195
196static void lg_reset(struct virtio_device *vdev)
197{
Rusty Russell3c3ed482011-07-22 14:39:49 +0930198 /* 0 status means "reset" */
199 to_lgdev(vdev)->desc->status = 0;
200 status_notify(vdev);
Rusty Russella007a752008-05-02 21:50:53 -0500201}
202
Rusty Russell19f15372007-10-22 11:24:21 +1000203/*
204 * Virtqueues
205 *
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
Rusty Russelle1e72962007-10-25 15:02:50 +1000209 * virtqueues: for example the console driver uses one queue for sending and
210 * another for receiving.
Rusty Russell19f15372007-10-22 11:24:21 +1000211 *
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.
214 *
215 * We start with the information we need to keep about each virtqueue.
216 */
217
218/*D:140 This is the information we remember about each virtqueue. */
Rusty Russell1842f232009-07-30 16:03:46 -0600219struct lguest_vq_info {
Rusty Russell19f15372007-10-22 11:24:21 +1000220 /* A copy of the information contained in the device config. */
221 struct lguest_vqconfig config;
222
223 /* The address where we mapped the virtio ring, so we can unmap it. */
224 void *pages;
225};
226
Rusty Russell2e04ef72009-07-30 16:03:45 -0600227/*
228 * When the virtio_ring code wants to prod the Host, it calls us here and we
Rusty Russella6bd8e12008-03-28 11:05:53 -0500229 * make a hypercall. We hand the physical address of the virtqueue so the Host
Rusty Russell2e04ef72009-07-30 16:03:45 -0600230 * knows which virtqueue we're talking about.
231 */
Rusty Russell19f15372007-10-22 11:24:21 +1000232static void lg_notify(struct virtqueue *vq)
233{
Rusty Russell2e04ef72009-07-30 16:03:45 -0600234 /*
235 * We store our virtqueue information in the "priv" pointer of the
236 * virtqueue structure.
237 */
Rusty Russell19f15372007-10-22 11:24:21 +1000238 struct lguest_vq_info *lvq = vq->priv;
239
Rusty Russell091ebf02010-04-14 21:43:54 -0600240 hcall(LHCALL_NOTIFY, lvq->config.pfn << PAGE_SHIFT, 0, 0, 0);
Rusty Russell19f15372007-10-22 11:24:21 +1000241}
242
Rusty Russell6db6a5f2009-03-09 10:06:28 -0600243/* An extern declaration inside a C file is bad form. Don't do it. */
Stratos Psomadakisb6c96c02012-01-12 15:44:47 +1030244extern int lguest_setup_irq(unsigned int irq);
Rusty Russell6db6a5f2009-03-09 10:06:28 -0600245
Rusty Russell2e04ef72009-07-30 16:03:45 -0600246/*
Rusty Russella91d74a2009-07-30 16:03:45 -0600247 * This routine finds the Nth virtqueue described in the configuration of
Rusty Russell19f15372007-10-22 11:24:21 +1000248 * this device and sets it up.
249 *
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
Rusty Russelle1e72962007-10-25 15:02:50 +1000252 * everyone wants to do it differently. The KVM coders want the Guest to
Rusty Russell19f15372007-10-22 11:24:21 +1000253 * 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.
Rusty Russell2e04ef72009-07-30 16:03:45 -0600255 */
Rusty Russell19f15372007-10-22 11:24:21 +1000256static struct virtqueue *lg_find_vq(struct virtio_device *vdev,
Rusty Russella586d4f2008-02-04 23:49:56 -0500257 unsigned index,
Rusty Russell9499f5e2009-06-12 22:16:35 -0600258 void (*callback)(struct virtqueue *vq),
259 const char *name)
Rusty Russell19f15372007-10-22 11:24:21 +1000260{
Rusty Russella586d4f2008-02-04 23:49:56 -0500261 struct lguest_device *ldev = to_lgdev(vdev);
Rusty Russell19f15372007-10-22 11:24:21 +1000262 struct lguest_vq_info *lvq;
263 struct virtqueue *vq;
Rusty Russell19f15372007-10-22 11:24:21 +1000264 int err;
265
Michael S. Tsirkin6457f122012-09-05 21:47:45 +0300266 if (!name)
267 return NULL;
268
Rusty Russella586d4f2008-02-04 23:49:56 -0500269 /* We must have this many virtqueues. */
270 if (index >= ldev->desc->num_vq)
Rusty Russell19f15372007-10-22 11:24:21 +1000271 return ERR_PTR(-ENOENT);
272
273 lvq = kmalloc(sizeof(*lvq), GFP_KERNEL);
274 if (!lvq)
275 return ERR_PTR(-ENOMEM);
276
Rusty Russell2e04ef72009-07-30 16:03:45 -0600277 /*
278 * Make a copy of the "struct lguest_vqconfig" entry, which sits after
Rusty Russella586d4f2008-02-04 23:49:56 -0500279 * the descriptor. We need a copy because the config space might not
Rusty Russell2e04ef72009-07-30 16:03:45 -0600280 * be aligned correctly.
281 */
Rusty Russella586d4f2008-02-04 23:49:56 -0500282 memcpy(&lvq->config, lg_vq(ldev->desc)+index, sizeof(lvq->config));
Rusty Russell19f15372007-10-22 11:24:21 +1000283
Rusty Russella586d4f2008-02-04 23:49:56 -0500284 printk("Mapping virtqueue %i addr %lx\n", index,
285 (unsigned long)lvq->config.pfn << PAGE_SHIFT);
Rusty Russell19f15372007-10-22 11:24:21 +1000286 /* Figure out how many pages the ring will take, and map that memory */
287 lvq->pages = lguest_map((unsigned long)lvq->config.pfn << PAGE_SHIFT,
Rusty Russell42b36cc2007-11-12 13:39:18 +1100288 DIV_ROUND_UP(vring_size(lvq->config.num,
Rusty Russell2966af72008-12-30 09:25:58 -0600289 LGUEST_VRING_ALIGN),
Rusty Russell19f15372007-10-22 11:24:21 +1000290 PAGE_SIZE));
291 if (!lvq->pages) {
292 err = -ENOMEM;
293 goto free_lvq;
294 }
295
Rusty Russell2e04ef72009-07-30 16:03:45 -0600296 /*
297 * OK, tell virtio_ring.c to set up a virtqueue now we know its size
Rusty Russell7b21e342012-01-12 15:44:42 +1030298 * and we've got a pointer to its pages. Note that we set weak_barriers
299 * to 'true': the host just a(nother) SMP CPU, so we only need inter-cpu
300 * barriers.
Rusty Russell2e04ef72009-07-30 16:03:45 -0600301 */
Jason Wang17bb6d42012-08-28 13:54:13 +0200302 vq = vring_new_virtqueue(index, lvq->config.num, LGUEST_VRING_ALIGN, vdev,
Rusty Russell7b21e342012-01-12 15:44:42 +1030303 true, lvq->pages, lg_notify, callback, name);
Rusty Russell19f15372007-10-22 11:24:21 +1000304 if (!vq) {
305 err = -ENOMEM;
306 goto unmap;
307 }
308
Rusty Russell6db6a5f2009-03-09 10:06:28 -0600309 /* Make sure the interrupt is allocated. */
Stratos Psomadakisb6c96c02012-01-12 15:44:47 +1030310 err = lguest_setup_irq(lvq->config.irq);
311 if (err)
312 goto destroy_vring;
Rusty Russell6db6a5f2009-03-09 10:06:28 -0600313
Rusty Russell2e04ef72009-07-30 16:03:45 -0600314 /*
315 * Tell the interrupt for this virtqueue to go to the virtio_ring
316 * interrupt handler.
317 *
318 * FIXME: We used to have a flag for the Host to tell us we could use
Rusty Russell19f15372007-10-22 11:24:21 +1000319 * the interrupt as a source of randomness: it'd be nice to have that
Rusty Russell2e04ef72009-07-30 16:03:45 -0600320 * back.
321 */
Rusty Russell19f15372007-10-22 11:24:21 +1000322 err = request_irq(lvq->config.irq, vring_interrupt, IRQF_SHARED,
Mark McLoughlinbda53cd2008-12-10 17:45:39 +0000323 dev_name(&vdev->dev), vq);
Rusty Russell19f15372007-10-22 11:24:21 +1000324 if (err)
Stratos Psomadakisb6c96c02012-01-12 15:44:47 +1030325 goto free_desc;
Rusty Russell19f15372007-10-22 11:24:21 +1000326
Rusty Russell2e04ef72009-07-30 16:03:45 -0600327 /*
328 * Last of all we hook up our 'struct lguest_vq_info" to the
329 * virtqueue's priv pointer.
330 */
Rusty Russell19f15372007-10-22 11:24:21 +1000331 vq->priv = lvq;
332 return vq;
333
Stratos Psomadakisb6c96c02012-01-12 15:44:47 +1030334free_desc:
335 irq_free_desc(lvq->config.irq);
Rusty Russell19f15372007-10-22 11:24:21 +1000336destroy_vring:
337 vring_del_virtqueue(vq);
338unmap:
339 lguest_unmap(lvq->pages);
340free_lvq:
341 kfree(lvq);
342 return ERR_PTR(err);
343}
344/*:*/
345
346/* Cleaning up a virtqueue is easy */
347static void lg_del_vq(struct virtqueue *vq)
348{
349 struct lguest_vq_info *lvq = vq->priv;
350
Rusty Russell74b25532007-11-19 11:20:42 -0500351 /* Release the interrupt */
352 free_irq(lvq->config.irq, vq);
Rusty Russell19f15372007-10-22 11:24:21 +1000353 /* Tell virtio_ring.c to free the virtqueue. */
354 vring_del_virtqueue(vq);
355 /* Unmap the pages containing the ring. */
356 lguest_unmap(lvq->pages);
357 /* Free our own queue information. */
358 kfree(lvq);
359}
360
Michael S. Tsirkind2a7ddd2009-06-12 22:16:36 -0600361static void lg_del_vqs(struct virtio_device *vdev)
362{
363 struct virtqueue *vq, *n;
364
365 list_for_each_entry_safe(vq, n, &vdev->vqs, list)
366 lg_del_vq(vq);
367}
368
369static int lg_find_vqs(struct virtio_device *vdev, unsigned nvqs,
370 struct virtqueue *vqs[],
371 vq_callback_t *callbacks[],
372 const char *names[])
373{
374 struct lguest_device *ldev = to_lgdev(vdev);
375 int i;
376
377 /* We must have this many virtqueues. */
378 if (nvqs > ldev->desc->num_vq)
379 return -ENOENT;
380
381 for (i = 0; i < nvqs; ++i) {
382 vqs[i] = lg_find_vq(vdev, i, callbacks[i], names[i]);
383 if (IS_ERR(vqs[i]))
384 goto error;
385 }
386 return 0;
387
388error:
389 lg_del_vqs(vdev);
390 return PTR_ERR(vqs[i]);
391}
392
Rick Jones66846042011-11-14 14:17:08 +0000393static const char *lg_bus_name(struct virtio_device *vdev)
394{
395 return "";
396}
397
Rusty Russell19f15372007-10-22 11:24:21 +1000398/* The ops structure which hooks everything together. */
Stephen Hemminger93503932013-02-10 15:57:38 +1030399static const struct virtio_config_ops lguest_config_ops = {
Rusty Russellc45a6812008-05-02 21:50:50 -0500400 .get_features = lg_get_features,
Rusty Russellc6248962008-07-25 12:06:07 -0500401 .finalize_features = lg_finalize_features,
Rusty Russell19f15372007-10-22 11:24:21 +1000402 .get = lg_get,
403 .set = lg_set,
404 .get_status = lg_get_status,
405 .set_status = lg_set_status,
Rusty Russell6e5aa7e2008-02-04 23:50:03 -0500406 .reset = lg_reset,
Michael S. Tsirkind2a7ddd2009-06-12 22:16:36 -0600407 .find_vqs = lg_find_vqs,
408 .del_vqs = lg_del_vqs,
Rick Jones66846042011-11-14 14:17:08 +0000409 .bus_name = lg_bus_name,
Rusty Russell19f15372007-10-22 11:24:21 +1000410};
411
Rusty Russell2e04ef72009-07-30 16:03:45 -0600412/*
413 * The root device for the lguest virtio devices. This makes them appear as
414 * /sys/devices/lguest/0,1,2 not /sys/devices/0,1,2.
415 */
Mark McLoughlinff8561c2008-12-15 12:58:28 +0000416static struct device *lguest_root;
Rusty Russell19f15372007-10-22 11:24:21 +1000417
Rusty Russell2e04ef72009-07-30 16:03:45 -0600418/*D:120
419 * This is the core of the lguest bus: actually adding a new device.
Rusty Russell19f15372007-10-22 11:24:21 +1000420 * It's a separate function because it's neater that way, and because an
421 * earlier version of the code supported hotplug and unplug. They were removed
422 * early on because they were never used.
423 *
424 * As Andrew Tridgell says, "Untested code is buggy code".
425 *
426 * It's worth reading this carefully: we start with a pointer to the new device
Rusty Russellb769f572008-05-30 15:09:42 -0500427 * descriptor in the "lguest_devices" page, and the offset into the device
Rusty Russell2e04ef72009-07-30 16:03:45 -0600428 * descriptor page so we can uniquely identify it if things go badly wrong.
429 */
Rusty Russellb769f572008-05-30 15:09:42 -0500430static void add_lguest_device(struct lguest_device_desc *d,
431 unsigned int offset)
Rusty Russell19f15372007-10-22 11:24:21 +1000432{
433 struct lguest_device *ldev;
434
Rusty Russell2e04ef72009-07-30 16:03:45 -0600435 /* Start with zeroed memory; Linux's device layer counts on it. */
Rusty Russell19f15372007-10-22 11:24:21 +1000436 ldev = kzalloc(sizeof(*ldev), GFP_KERNEL);
437 if (!ldev) {
Rusty Russellb769f572008-05-30 15:09:42 -0500438 printk(KERN_EMERG "Cannot allocate lguest dev %u type %u\n",
439 offset, d->type);
Rusty Russell19f15372007-10-22 11:24:21 +1000440 return;
441 }
442
443 /* This devices' parent is the lguest/ dir. */
Mark McLoughlinff8561c2008-12-15 12:58:28 +0000444 ldev->vdev.dev.parent = lguest_root;
Rusty Russella91d74a2009-07-30 16:03:45 -0600445 /*
446 * The device type comes straight from the descriptor. There's also a
447 * device vendor field in the virtio_device struct, which we leave as
448 * 0.
449 */
Rusty Russell19f15372007-10-22 11:24:21 +1000450 ldev->vdev.id.device = d->type;
Rusty Russell2e04ef72009-07-30 16:03:45 -0600451 /*
452 * We have a simple set of routines for querying the device's
453 * configuration information and setting its status.
454 */
Rusty Russell19f15372007-10-22 11:24:21 +1000455 ldev->vdev.config = &lguest_config_ops;
456 /* And we remember the device's descriptor for lguest_config_ops. */
457 ldev->desc = d;
458
Rusty Russell2e04ef72009-07-30 16:03:45 -0600459 /*
460 * register_virtio_device() sets up the generic fields for the struct
Rusty Russell19f15372007-10-22 11:24:21 +1000461 * virtio_device and calls device_register(). This makes the bus
Rusty Russell2e04ef72009-07-30 16:03:45 -0600462 * infrastructure look for a matching driver.
463 */
Rusty Russell19f15372007-10-22 11:24:21 +1000464 if (register_virtio_device(&ldev->vdev) != 0) {
Rusty Russellb769f572008-05-30 15:09:42 -0500465 printk(KERN_ERR "Failed to register lguest dev %u type %u\n",
466 offset, d->type);
Rusty Russell19f15372007-10-22 11:24:21 +1000467 kfree(ldev);
468 }
469}
470
Rusty Russell2e04ef72009-07-30 16:03:45 -0600471/*D:110
472 * scan_devices() simply iterates through the device page. The type 0 is
473 * reserved to mean "end of devices".
474 */
Rusty Russell19f15372007-10-22 11:24:21 +1000475static void scan_devices(void)
476{
477 unsigned int i;
478 struct lguest_device_desc *d;
479
480 /* We start at the page beginning, and skip over each entry. */
Rusty Russella586d4f2008-02-04 23:49:56 -0500481 for (i = 0; i < PAGE_SIZE; i += desc_size(d)) {
Rusty Russell19f15372007-10-22 11:24:21 +1000482 d = lguest_devices + i;
483
484 /* Once we hit a zero, stop. */
485 if (d->type == 0)
486 break;
487
Rusty Russella586d4f2008-02-04 23:49:56 -0500488 printk("Device at %i has size %u\n", i, desc_size(d));
Rusty Russellb769f572008-05-30 15:09:42 -0500489 add_lguest_device(d, i);
Rusty Russell19f15372007-10-22 11:24:21 +1000490 }
491}
492
Rusty Russell2e04ef72009-07-30 16:03:45 -0600493/*D:105
494 * Fairly early in boot, lguest_devices_init() is called to set up the
Rusty Russell19f15372007-10-22 11:24:21 +1000495 * lguest device infrastructure. We check that we are a Guest by checking
496 * pv_info.name: there are other ways of checking, but this seems most
497 * obvious to me.
498 *
499 * So we can access the "struct lguest_device_desc"s easily, we map that memory
500 * and store the pointer in the global "lguest_devices". Then we register a
501 * root device from which all our devices will hang (this seems to be the
502 * correct sysfs incantation).
503 *
504 * Finally we call scan_devices() which adds all the devices found in the
Rusty Russell2e04ef72009-07-30 16:03:45 -0600505 * lguest_devices page.
506 */
Rusty Russell19f15372007-10-22 11:24:21 +1000507static int __init lguest_devices_init(void)
508{
509 if (strcmp(pv_info.name, "lguest") != 0)
510 return 0;
511
Mark McLoughlinff8561c2008-12-15 12:58:28 +0000512 lguest_root = root_device_register("lguest");
513 if (IS_ERR(lguest_root))
Rusty Russell19f15372007-10-22 11:24:21 +1000514 panic("Could not register lguest root");
515
516 /* Devices are in a single page above top of "normal" mem */
517 lguest_devices = lguest_map(max_pfn<<PAGE_SHIFT, 1);
518
519 scan_devices();
520 return 0;
521}
522/* We do this after core stuff, but before the drivers. */
523postcore_initcall(lguest_devices_init);
524
Rusty Russell2e04ef72009-07-30 16:03:45 -0600525/*D:150
526 * At this point in the journey we used to now wade through the lguest
Rusty Russell19f15372007-10-22 11:24:21 +1000527 * devices themselves: net, block and console. Since they're all now virtio
528 * devices rather than lguest-specific, I've decided to ignore them. Mostly,
529 * they're kind of boring. But this does mean you'll never experience the
530 * thrill of reading the forbidden love scene buried deep in the block driver.
531 *
532 * "make Launcher" beckons, where we answer questions like "Where do Guests
Rusty Russell2e04ef72009-07-30 16:03:45 -0600533 * come from?", and "What do you do when someone asks for optimization?".
534 */