blob: d0a1d8a45c815e347e249beaff4855455e1e708c [file] [log] [blame]
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 */
Heinz Graalfs46f9c2b2013-10-29 09:38:50 +1030232static bool lg_notify(struct virtqueue *vq)
Rusty Russell19f15372007-10-22 11:24:21 +1000233{
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);
Heinz Graalfs46f9c2b2013-10-29 09:38:50 +1030241 return true;
Rusty Russell19f15372007-10-22 11:24:21 +1000242}
243
Rusty Russell6db6a5f2009-03-09 10:06:28 -0600244/* An extern declaration inside a C file is bad form. Don't do it. */
Stratos Psomadakisb6c96c02012-01-12 15:44:47 +1030245extern int lguest_setup_irq(unsigned int irq);
Rusty Russell6db6a5f2009-03-09 10:06:28 -0600246
Rusty Russell2e04ef72009-07-30 16:03:45 -0600247/*
Rusty Russella91d74a2009-07-30 16:03:45 -0600248 * This routine finds the Nth virtqueue described in the configuration of
Rusty Russell19f15372007-10-22 11:24:21 +1000249 * this device and sets it up.
250 *
251 * This is kind of an ugly duckling. It'd be nicer to have a standard
252 * representation of a virtqueue in the configuration space, but it seems that
Rusty Russelle1e72962007-10-25 15:02:50 +1000253 * everyone wants to do it differently. The KVM coders want the Guest to
Rusty Russell19f15372007-10-22 11:24:21 +1000254 * allocate its own pages and tell the Host where they are, but for lguest it's
255 * simpler for the Host to simply tell us where the pages are.
Rusty Russell2e04ef72009-07-30 16:03:45 -0600256 */
Rusty Russell19f15372007-10-22 11:24:21 +1000257static struct virtqueue *lg_find_vq(struct virtio_device *vdev,
Rusty Russella586d4f2008-02-04 23:49:56 -0500258 unsigned index,
Rusty Russell9499f5e2009-06-12 22:16:35 -0600259 void (*callback)(struct virtqueue *vq),
260 const char *name)
Rusty Russell19f15372007-10-22 11:24:21 +1000261{
Rusty Russella586d4f2008-02-04 23:49:56 -0500262 struct lguest_device *ldev = to_lgdev(vdev);
Rusty Russell19f15372007-10-22 11:24:21 +1000263 struct lguest_vq_info *lvq;
264 struct virtqueue *vq;
Rusty Russell19f15372007-10-22 11:24:21 +1000265 int err;
266
Michael S. Tsirkin6457f1262012-09-05 21:47:45 +0300267 if (!name)
268 return NULL;
269
Rusty Russella586d4f2008-02-04 23:49:56 -0500270 /* We must have this many virtqueues. */
271 if (index >= ldev->desc->num_vq)
Rusty Russell19f15372007-10-22 11:24:21 +1000272 return ERR_PTR(-ENOENT);
273
274 lvq = kmalloc(sizeof(*lvq), GFP_KERNEL);
275 if (!lvq)
276 return ERR_PTR(-ENOMEM);
277
Rusty Russell2e04ef72009-07-30 16:03:45 -0600278 /*
279 * Make a copy of the "struct lguest_vqconfig" entry, which sits after
Rusty Russella586d4f2008-02-04 23:49:56 -0500280 * the descriptor. We need a copy because the config space might not
Rusty Russell2e04ef72009-07-30 16:03:45 -0600281 * be aligned correctly.
282 */
Rusty Russella586d4f2008-02-04 23:49:56 -0500283 memcpy(&lvq->config, lg_vq(ldev->desc)+index, sizeof(lvq->config));
Rusty Russell19f15372007-10-22 11:24:21 +1000284
Rusty Russella586d4f2008-02-04 23:49:56 -0500285 printk("Mapping virtqueue %i addr %lx\n", index,
286 (unsigned long)lvq->config.pfn << PAGE_SHIFT);
Rusty Russell19f15372007-10-22 11:24:21 +1000287 /* Figure out how many pages the ring will take, and map that memory */
288 lvq->pages = lguest_map((unsigned long)lvq->config.pfn << PAGE_SHIFT,
Rusty Russell42b36cc2007-11-12 13:39:18 +1100289 DIV_ROUND_UP(vring_size(lvq->config.num,
Rusty Russell2966af72008-12-30 09:25:58 -0600290 LGUEST_VRING_ALIGN),
Rusty Russell19f15372007-10-22 11:24:21 +1000291 PAGE_SIZE));
292 if (!lvq->pages) {
293 err = -ENOMEM;
294 goto free_lvq;
295 }
296
Rusty Russell2e04ef72009-07-30 16:03:45 -0600297 /*
298 * OK, tell virtio_ring.c to set up a virtqueue now we know its size
Rusty Russell7b21e342012-01-12 15:44:42 +1030299 * and we've got a pointer to its pages. Note that we set weak_barriers
300 * to 'true': the host just a(nother) SMP CPU, so we only need inter-cpu
301 * barriers.
Rusty Russell2e04ef72009-07-30 16:03:45 -0600302 */
Jason Wang17bb6d42012-08-28 13:54:13 +0200303 vq = vring_new_virtqueue(index, lvq->config.num, LGUEST_VRING_ALIGN, vdev,
Rusty Russell7b21e342012-01-12 15:44:42 +1030304 true, lvq->pages, lg_notify, callback, name);
Rusty Russell19f15372007-10-22 11:24:21 +1000305 if (!vq) {
306 err = -ENOMEM;
307 goto unmap;
308 }
309
Rusty Russell6db6a5f2009-03-09 10:06:28 -0600310 /* Make sure the interrupt is allocated. */
Stratos Psomadakisb6c96c02012-01-12 15:44:47 +1030311 err = lguest_setup_irq(lvq->config.irq);
312 if (err)
313 goto destroy_vring;
Rusty Russell6db6a5f2009-03-09 10:06:28 -0600314
Rusty Russell2e04ef72009-07-30 16:03:45 -0600315 /*
316 * Tell the interrupt for this virtqueue to go to the virtio_ring
317 * interrupt handler.
318 *
319 * FIXME: We used to have a flag for the Host to tell us we could use
Rusty Russell19f15372007-10-22 11:24:21 +1000320 * the interrupt as a source of randomness: it'd be nice to have that
Rusty Russell2e04ef72009-07-30 16:03:45 -0600321 * back.
322 */
Rusty Russell19f15372007-10-22 11:24:21 +1000323 err = request_irq(lvq->config.irq, vring_interrupt, IRQF_SHARED,
Mark McLoughlinbda53cd2008-12-10 17:45:39 +0000324 dev_name(&vdev->dev), vq);
Rusty Russell19f15372007-10-22 11:24:21 +1000325 if (err)
Stratos Psomadakisb6c96c02012-01-12 15:44:47 +1030326 goto free_desc;
Rusty Russell19f15372007-10-22 11:24:21 +1000327
Rusty Russell2e04ef72009-07-30 16:03:45 -0600328 /*
329 * Last of all we hook up our 'struct lguest_vq_info" to the
330 * virtqueue's priv pointer.
331 */
Rusty Russell19f15372007-10-22 11:24:21 +1000332 vq->priv = lvq;
333 return vq;
334
Stratos Psomadakisb6c96c02012-01-12 15:44:47 +1030335free_desc:
336 irq_free_desc(lvq->config.irq);
Rusty Russell19f15372007-10-22 11:24:21 +1000337destroy_vring:
338 vring_del_virtqueue(vq);
339unmap:
340 lguest_unmap(lvq->pages);
341free_lvq:
342 kfree(lvq);
343 return ERR_PTR(err);
344}
345/*:*/
346
347/* Cleaning up a virtqueue is easy */
348static void lg_del_vq(struct virtqueue *vq)
349{
350 struct lguest_vq_info *lvq = vq->priv;
351
Rusty Russell74b25532007-11-19 11:20:42 -0500352 /* Release the interrupt */
353 free_irq(lvq->config.irq, vq);
Rusty Russell19f15372007-10-22 11:24:21 +1000354 /* Tell virtio_ring.c to free the virtqueue. */
355 vring_del_virtqueue(vq);
356 /* Unmap the pages containing the ring. */
357 lguest_unmap(lvq->pages);
358 /* Free our own queue information. */
359 kfree(lvq);
360}
361
Michael S. Tsirkind2a7ddd2009-06-12 22:16:36 -0600362static void lg_del_vqs(struct virtio_device *vdev)
363{
364 struct virtqueue *vq, *n;
365
366 list_for_each_entry_safe(vq, n, &vdev->vqs, list)
367 lg_del_vq(vq);
368}
369
370static int lg_find_vqs(struct virtio_device *vdev, unsigned nvqs,
371 struct virtqueue *vqs[],
372 vq_callback_t *callbacks[],
373 const char *names[])
374{
375 struct lguest_device *ldev = to_lgdev(vdev);
376 int i;
377
378 /* We must have this many virtqueues. */
379 if (nvqs > ldev->desc->num_vq)
380 return -ENOENT;
381
382 for (i = 0; i < nvqs; ++i) {
383 vqs[i] = lg_find_vq(vdev, i, callbacks[i], names[i]);
384 if (IS_ERR(vqs[i]))
385 goto error;
386 }
387 return 0;
388
389error:
390 lg_del_vqs(vdev);
391 return PTR_ERR(vqs[i]);
392}
393
Rick Jones66846042011-11-14 14:17:08 +0000394static const char *lg_bus_name(struct virtio_device *vdev)
395{
396 return "";
397}
398
Rusty Russell19f15372007-10-22 11:24:21 +1000399/* The ops structure which hooks everything together. */
Stephen Hemminger93503932013-02-10 15:57:38 +1030400static const struct virtio_config_ops lguest_config_ops = {
Rusty Russellc45a6812008-05-02 21:50:50 -0500401 .get_features = lg_get_features,
Rusty Russellc6248962008-07-25 12:06:07 -0500402 .finalize_features = lg_finalize_features,
Rusty Russell19f15372007-10-22 11:24:21 +1000403 .get = lg_get,
404 .set = lg_set,
405 .get_status = lg_get_status,
406 .set_status = lg_set_status,
Rusty Russell6e5aa7e2008-02-04 23:50:03 -0500407 .reset = lg_reset,
Michael S. Tsirkind2a7ddd2009-06-12 22:16:36 -0600408 .find_vqs = lg_find_vqs,
409 .del_vqs = lg_del_vqs,
Rick Jones66846042011-11-14 14:17:08 +0000410 .bus_name = lg_bus_name,
Rusty Russell19f15372007-10-22 11:24:21 +1000411};
412
Rusty Russell2e04ef72009-07-30 16:03:45 -0600413/*
414 * The root device for the lguest virtio devices. This makes them appear as
415 * /sys/devices/lguest/0,1,2 not /sys/devices/0,1,2.
416 */
Mark McLoughlinff8561c2008-12-15 12:58:28 +0000417static struct device *lguest_root;
Rusty Russell19f15372007-10-22 11:24:21 +1000418
Rusty Russell2e04ef72009-07-30 16:03:45 -0600419/*D:120
420 * This is the core of the lguest bus: actually adding a new device.
Rusty Russell19f15372007-10-22 11:24:21 +1000421 * It's a separate function because it's neater that way, and because an
422 * earlier version of the code supported hotplug and unplug. They were removed
423 * early on because they were never used.
424 *
425 * As Andrew Tridgell says, "Untested code is buggy code".
426 *
427 * It's worth reading this carefully: we start with a pointer to the new device
Rusty Russellb769f572008-05-30 15:09:42 -0500428 * descriptor in the "lguest_devices" page, and the offset into the device
Rusty Russell2e04ef72009-07-30 16:03:45 -0600429 * descriptor page so we can uniquely identify it if things go badly wrong.
430 */
Rusty Russellb769f572008-05-30 15:09:42 -0500431static void add_lguest_device(struct lguest_device_desc *d,
432 unsigned int offset)
Rusty Russell19f15372007-10-22 11:24:21 +1000433{
434 struct lguest_device *ldev;
435
Rusty Russell2e04ef72009-07-30 16:03:45 -0600436 /* Start with zeroed memory; Linux's device layer counts on it. */
Rusty Russell19f15372007-10-22 11:24:21 +1000437 ldev = kzalloc(sizeof(*ldev), GFP_KERNEL);
438 if (!ldev) {
Rusty Russellb769f572008-05-30 15:09:42 -0500439 printk(KERN_EMERG "Cannot allocate lguest dev %u type %u\n",
440 offset, d->type);
Rusty Russell19f15372007-10-22 11:24:21 +1000441 return;
442 }
443
444 /* This devices' parent is the lguest/ dir. */
Mark McLoughlinff8561c2008-12-15 12:58:28 +0000445 ldev->vdev.dev.parent = lguest_root;
Rusty Russella91d74a2009-07-30 16:03:45 -0600446 /*
447 * The device type comes straight from the descriptor. There's also a
448 * device vendor field in the virtio_device struct, which we leave as
449 * 0.
450 */
Rusty Russell19f15372007-10-22 11:24:21 +1000451 ldev->vdev.id.device = d->type;
Rusty Russell2e04ef72009-07-30 16:03:45 -0600452 /*
453 * We have a simple set of routines for querying the device's
454 * configuration information and setting its status.
455 */
Rusty Russell19f15372007-10-22 11:24:21 +1000456 ldev->vdev.config = &lguest_config_ops;
457 /* And we remember the device's descriptor for lguest_config_ops. */
458 ldev->desc = d;
459
Rusty Russell2e04ef72009-07-30 16:03:45 -0600460 /*
461 * register_virtio_device() sets up the generic fields for the struct
Rusty Russell19f15372007-10-22 11:24:21 +1000462 * virtio_device and calls device_register(). This makes the bus
Rusty Russell2e04ef72009-07-30 16:03:45 -0600463 * infrastructure look for a matching driver.
464 */
Rusty Russell19f15372007-10-22 11:24:21 +1000465 if (register_virtio_device(&ldev->vdev) != 0) {
Rusty Russellb769f572008-05-30 15:09:42 -0500466 printk(KERN_ERR "Failed to register lguest dev %u type %u\n",
467 offset, d->type);
Rusty Russell19f15372007-10-22 11:24:21 +1000468 kfree(ldev);
469 }
470}
471
Rusty Russell2e04ef72009-07-30 16:03:45 -0600472/*D:110
473 * scan_devices() simply iterates through the device page. The type 0 is
474 * reserved to mean "end of devices".
475 */
Rusty Russell19f15372007-10-22 11:24:21 +1000476static void scan_devices(void)
477{
478 unsigned int i;
479 struct lguest_device_desc *d;
480
481 /* We start at the page beginning, and skip over each entry. */
Rusty Russella586d4f2008-02-04 23:49:56 -0500482 for (i = 0; i < PAGE_SIZE; i += desc_size(d)) {
Rusty Russell19f15372007-10-22 11:24:21 +1000483 d = lguest_devices + i;
484
485 /* Once we hit a zero, stop. */
486 if (d->type == 0)
487 break;
488
Rusty Russella586d4f2008-02-04 23:49:56 -0500489 printk("Device at %i has size %u\n", i, desc_size(d));
Rusty Russellb769f572008-05-30 15:09:42 -0500490 add_lguest_device(d, i);
Rusty Russell19f15372007-10-22 11:24:21 +1000491 }
492}
493
Rusty Russell2e04ef72009-07-30 16:03:45 -0600494/*D:105
495 * Fairly early in boot, lguest_devices_init() is called to set up the
Rusty Russell19f15372007-10-22 11:24:21 +1000496 * lguest device infrastructure. We check that we are a Guest by checking
497 * pv_info.name: there are other ways of checking, but this seems most
498 * obvious to me.
499 *
500 * So we can access the "struct lguest_device_desc"s easily, we map that memory
501 * and store the pointer in the global "lguest_devices". Then we register a
502 * root device from which all our devices will hang (this seems to be the
503 * correct sysfs incantation).
504 *
505 * Finally we call scan_devices() which adds all the devices found in the
Rusty Russell2e04ef72009-07-30 16:03:45 -0600506 * lguest_devices page.
507 */
Rusty Russell19f15372007-10-22 11:24:21 +1000508static int __init lguest_devices_init(void)
509{
510 if (strcmp(pv_info.name, "lguest") != 0)
511 return 0;
512
Mark McLoughlinff8561c2008-12-15 12:58:28 +0000513 lguest_root = root_device_register("lguest");
514 if (IS_ERR(lguest_root))
Rusty Russell19f15372007-10-22 11:24:21 +1000515 panic("Could not register lguest root");
516
517 /* Devices are in a single page above top of "normal" mem */
518 lguest_devices = lguest_map(max_pfn<<PAGE_SHIFT, 1);
519
520 scan_devices();
521 return 0;
522}
523/* We do this after core stuff, but before the drivers. */
524postcore_initcall(lguest_devices_init);
525
Rusty Russell2e04ef72009-07-30 16:03:45 -0600526/*D:150
527 * At this point in the journey we used to now wade through the lguest
Rusty Russell19f15372007-10-22 11:24:21 +1000528 * devices themselves: net, block and console. Since they're all now virtio
529 * devices rather than lguest-specific, I've decided to ignore them. Mostly,
530 * they're kind of boring. But this does mean you'll never experience the
531 * thrill of reading the forbidden love scene buried deep in the block driver.
532 *
533 * "make Launcher" beckons, where we answer questions like "Where do Guests
Rusty Russell2e04ef72009-07-30 16:03:45 -0600534 * come from?", and "What do you do when someone asks for optimization?".
535 */