Rusty Russell | 19f1537 | 2007-10-22 11:24:21 +1000 | [diff] [blame] | 1 | /*P:050 Lguest guests use a very simple method to describe devices. It's a |
Rusty Russell | a6bd8e1 | 2008-03-28 11:05:53 -0500 | [diff] [blame] | 2 | * series of device descriptors contained just above the top of normal Guest |
Rusty Russell | 19f1537 | 2007-10-22 11:24:21 +1000 | [diff] [blame] | 3 | * memory. |
| 4 | * |
| 5 | * We use the standard "virtio" device infrastructure, which provides us with a |
| 6 | * console, a network and a block driver. Each one expects some configuration |
Rusty Russell | a6bd8e1 | 2008-03-28 11:05:53 -0500 | [diff] [blame] | 7 | * information and a "virtqueue" or two to send and receive data. :*/ |
Rusty Russell | 19f1537 | 2007-10-22 11:24:21 +1000 | [diff] [blame] | 8 | #include <linux/init.h> |
| 9 | #include <linux/bootmem.h> |
| 10 | #include <linux/lguest_launcher.h> |
| 11 | #include <linux/virtio.h> |
| 12 | #include <linux/virtio_config.h> |
| 13 | #include <linux/interrupt.h> |
| 14 | #include <linux/virtio_ring.h> |
| 15 | #include <linux/err.h> |
| 16 | #include <asm/io.h> |
| 17 | #include <asm/paravirt.h> |
| 18 | #include <asm/lguest_hcall.h> |
| 19 | |
| 20 | /* The pointer to our (page) of device descriptions. */ |
| 21 | static void *lguest_devices; |
| 22 | |
Rusty Russell | 19f1537 | 2007-10-22 11:24:21 +1000 | [diff] [blame] | 23 | /* For Guests, device memory can be used as normal memory, so we cast away the |
| 24 | * __iomem to quieten sparse. */ |
| 25 | static inline void *lguest_map(unsigned long phys_addr, unsigned long pages) |
| 26 | { |
Rusty Russell | e27810f | 2008-05-30 15:09:40 -0500 | [diff] [blame] | 27 | return (__force void *)ioremap_cache(phys_addr, PAGE_SIZE*pages); |
Rusty Russell | 19f1537 | 2007-10-22 11:24:21 +1000 | [diff] [blame] | 28 | } |
| 29 | |
| 30 | static inline void lguest_unmap(void *addr) |
| 31 | { |
| 32 | iounmap((__force void __iomem *)addr); |
| 33 | } |
| 34 | |
| 35 | /*D:100 Each lguest device is just a virtio device plus a pointer to its entry |
| 36 | * in the lguest_devices page. */ |
| 37 | struct lguest_device { |
| 38 | struct virtio_device vdev; |
| 39 | |
| 40 | /* The entry in the lguest_devices page for this device. */ |
| 41 | struct lguest_device_desc *desc; |
| 42 | }; |
| 43 | |
| 44 | /* Since the virtio infrastructure hands us a pointer to the virtio_device all |
| 45 | * the time, it helps to have a curt macro to get a pointer to the struct |
| 46 | * lguest_device it's enclosed in. */ |
Alexey Dobriyan | 2547844 | 2008-02-08 04:20:14 -0800 | [diff] [blame] | 47 | #define to_lgdev(vd) container_of(vd, struct lguest_device, vdev) |
Rusty Russell | 19f1537 | 2007-10-22 11:24:21 +1000 | [diff] [blame] | 48 | |
| 49 | /*D:130 |
| 50 | * Device configurations |
| 51 | * |
Rusty Russell | a586d4f | 2008-02-04 23:49:56 -0500 | [diff] [blame] | 52 | * The configuration information for a device consists of one or more |
Rusty Russell | a6bd8e1 | 2008-03-28 11:05:53 -0500 | [diff] [blame] | 53 | * virtqueues, a feature bitmap, and some configuration bytes. The |
Rusty Russell | 6e5aa7e | 2008-02-04 23:50:03 -0500 | [diff] [blame] | 54 | * configuration bytes don't really matter to us: the Launcher sets them up, and |
Rusty Russell | a586d4f | 2008-02-04 23:49:56 -0500 | [diff] [blame] | 55 | * the driver will look at them during setup. |
Rusty Russell | 19f1537 | 2007-10-22 11:24:21 +1000 | [diff] [blame] | 56 | * |
Rusty Russell | a586d4f | 2008-02-04 23:49:56 -0500 | [diff] [blame] | 57 | * A convenient routine to return the device's virtqueue config array: |
| 58 | * immediately after the descriptor. */ |
| 59 | static struct lguest_vqconfig *lg_vq(const struct lguest_device_desc *desc) |
| 60 | { |
| 61 | return (void *)(desc + 1); |
| 62 | } |
Rusty Russell | 19f1537 | 2007-10-22 11:24:21 +1000 | [diff] [blame] | 63 | |
Rusty Russell | a586d4f | 2008-02-04 23:49:56 -0500 | [diff] [blame] | 64 | /* The features come immediately after the virtqueues. */ |
| 65 | static u8 *lg_features(const struct lguest_device_desc *desc) |
| 66 | { |
| 67 | return (void *)(lg_vq(desc) + desc->num_vq); |
| 68 | } |
Rusty Russell | 19f1537 | 2007-10-22 11:24:21 +1000 | [diff] [blame] | 69 | |
Rusty Russell | a586d4f | 2008-02-04 23:49:56 -0500 | [diff] [blame] | 70 | /* The config space comes after the two feature bitmasks. */ |
| 71 | static u8 *lg_config(const struct lguest_device_desc *desc) |
| 72 | { |
| 73 | return lg_features(desc) + desc->feature_len * 2; |
| 74 | } |
| 75 | |
| 76 | /* The total size of the config page used by this device (incl. desc) */ |
| 77 | static unsigned desc_size(const struct lguest_device_desc *desc) |
| 78 | { |
| 79 | return sizeof(*desc) |
| 80 | + desc->num_vq * sizeof(struct lguest_vqconfig) |
| 81 | + desc->feature_len * 2 |
| 82 | + desc->config_len; |
| 83 | } |
| 84 | |
Rusty Russell | c45a681 | 2008-05-02 21:50:50 -0500 | [diff] [blame] | 85 | /* This gets the device's feature bits. */ |
| 86 | static u32 lg_get_features(struct virtio_device *vdev) |
Rusty Russell | 19f1537 | 2007-10-22 11:24:21 +1000 | [diff] [blame] | 87 | { |
Rusty Russell | c45a681 | 2008-05-02 21:50:50 -0500 | [diff] [blame] | 88 | unsigned int i; |
| 89 | u32 features = 0; |
Rusty Russell | 19f1537 | 2007-10-22 11:24:21 +1000 | [diff] [blame] | 90 | struct lguest_device_desc *desc = to_lgdev(vdev)->desc; |
Rusty Russell | c45a681 | 2008-05-02 21:50:50 -0500 | [diff] [blame] | 91 | u8 *in_features = lg_features(desc); |
Rusty Russell | 19f1537 | 2007-10-22 11:24:21 +1000 | [diff] [blame] | 92 | |
Rusty Russell | c45a681 | 2008-05-02 21:50:50 -0500 | [diff] [blame] | 93 | /* We do this the slow but generic way. */ |
| 94 | for (i = 0; i < min(desc->feature_len * 8, 32); i++) |
| 95 | if (in_features[i / 8] & (1 << (i % 8))) |
| 96 | features |= (1 << i); |
Rusty Russell | 19f1537 | 2007-10-22 11:24:21 +1000 | [diff] [blame] | 97 | |
Rusty Russell | c45a681 | 2008-05-02 21:50:50 -0500 | [diff] [blame] | 98 | return features; |
| 99 | } |
Rusty Russell | a586d4f | 2008-02-04 23:49:56 -0500 | [diff] [blame] | 100 | |
Rusty Russell | 1dc3e3b | 2008-08-26 00:19:27 -0500 | [diff] [blame] | 101 | /* The virtio core takes the features the Host offers, and copies the |
| 102 | * ones supported by the driver into the vdev->features array. Once |
| 103 | * that's all sorted out, this routine is called so we can tell the |
| 104 | * Host which features we understand and accept. */ |
Rusty Russell | c624896 | 2008-07-25 12:06:07 -0500 | [diff] [blame] | 105 | static void lg_finalize_features(struct virtio_device *vdev) |
Rusty Russell | c45a681 | 2008-05-02 21:50:50 -0500 | [diff] [blame] | 106 | { |
Rusty Russell | c624896 | 2008-07-25 12:06:07 -0500 | [diff] [blame] | 107 | unsigned int i, bits; |
Rusty Russell | c45a681 | 2008-05-02 21:50:50 -0500 | [diff] [blame] | 108 | struct lguest_device_desc *desc = to_lgdev(vdev)->desc; |
| 109 | /* Second half of bitmap is features we accept. */ |
| 110 | u8 *out_features = lg_features(desc) + desc->feature_len; |
| 111 | |
Rusty Russell | e34f872 | 2008-07-25 12:06:13 -0500 | [diff] [blame] | 112 | /* Give virtio_ring a chance to accept features. */ |
| 113 | vring_transport_features(vdev); |
| 114 | |
Rusty Russell | 1dc3e3b | 2008-08-26 00:19:27 -0500 | [diff] [blame] | 115 | /* The vdev->feature array is a Linux bitmask: this isn't the |
| 116 | * same as a the simple array of bits used by lguest devices |
| 117 | * for features. So we do this slow, manual conversion which is |
| 118 | * completely general. */ |
Rusty Russell | c45a681 | 2008-05-02 21:50:50 -0500 | [diff] [blame] | 119 | memset(out_features, 0, desc->feature_len); |
Rusty Russell | c624896 | 2008-07-25 12:06:07 -0500 | [diff] [blame] | 120 | bits = min_t(unsigned, desc->feature_len, sizeof(vdev->features)) * 8; |
| 121 | for (i = 0; i < bits; i++) { |
| 122 | if (test_bit(i, vdev->features)) |
Rusty Russell | c45a681 | 2008-05-02 21:50:50 -0500 | [diff] [blame] | 123 | out_features[i / 8] |= (1 << (i % 8)); |
| 124 | } |
Rusty Russell | 19f1537 | 2007-10-22 11:24:21 +1000 | [diff] [blame] | 125 | } |
| 126 | |
| 127 | /* Once they've found a field, getting a copy of it is easy. */ |
Rusty Russell | a586d4f | 2008-02-04 23:49:56 -0500 | [diff] [blame] | 128 | static void lg_get(struct virtio_device *vdev, unsigned int offset, |
Rusty Russell | 19f1537 | 2007-10-22 11:24:21 +1000 | [diff] [blame] | 129 | void *buf, unsigned len) |
| 130 | { |
Rusty Russell | a586d4f | 2008-02-04 23:49:56 -0500 | [diff] [blame] | 131 | struct lguest_device_desc *desc = to_lgdev(vdev)->desc; |
| 132 | |
| 133 | /* Check they didn't ask for more than the length of the config! */ |
| 134 | BUG_ON(offset + len > desc->config_len); |
| 135 | memcpy(buf, lg_config(desc) + offset, len); |
Rusty Russell | 19f1537 | 2007-10-22 11:24:21 +1000 | [diff] [blame] | 136 | } |
| 137 | |
| 138 | /* Setting the contents is also trivial. */ |
Rusty Russell | a586d4f | 2008-02-04 23:49:56 -0500 | [diff] [blame] | 139 | static void lg_set(struct virtio_device *vdev, unsigned int offset, |
Rusty Russell | 19f1537 | 2007-10-22 11:24:21 +1000 | [diff] [blame] | 140 | const void *buf, unsigned len) |
| 141 | { |
Rusty Russell | a586d4f | 2008-02-04 23:49:56 -0500 | [diff] [blame] | 142 | struct lguest_device_desc *desc = to_lgdev(vdev)->desc; |
| 143 | |
| 144 | /* Check they didn't ask for more than the length of the config! */ |
| 145 | BUG_ON(offset + len > desc->config_len); |
| 146 | memcpy(lg_config(desc) + offset, buf, len); |
Rusty Russell | 19f1537 | 2007-10-22 11:24:21 +1000 | [diff] [blame] | 147 | } |
| 148 | |
| 149 | /* The operations to get and set the status word just access the status field |
| 150 | * of the device descriptor. */ |
| 151 | static u8 lg_get_status(struct virtio_device *vdev) |
| 152 | { |
| 153 | return to_lgdev(vdev)->desc->status; |
| 154 | } |
| 155 | |
Rusty Russell | a007a75 | 2008-05-02 21:50:53 -0500 | [diff] [blame] | 156 | /* To notify on status updates, we (ab)use the NOTIFY hypercall, with the |
| 157 | * descriptor address of the device. A zero status means "reset". */ |
| 158 | static void set_status(struct virtio_device *vdev, u8 status) |
Rusty Russell | 6e5aa7e | 2008-02-04 23:50:03 -0500 | [diff] [blame] | 159 | { |
| 160 | unsigned long offset = (void *)to_lgdev(vdev)->desc - lguest_devices; |
| 161 | |
Rusty Russell | a007a75 | 2008-05-02 21:50:53 -0500 | [diff] [blame] | 162 | /* We set the status. */ |
| 163 | to_lgdev(vdev)->desc->status = status; |
Rusty Russell | 6e5aa7e | 2008-02-04 23:50:03 -0500 | [diff] [blame] | 164 | hcall(LHCALL_NOTIFY, (max_pfn<<PAGE_SHIFT) + offset, 0, 0); |
| 165 | } |
| 166 | |
Rusty Russell | a007a75 | 2008-05-02 21:50:53 -0500 | [diff] [blame] | 167 | static void lg_set_status(struct virtio_device *vdev, u8 status) |
| 168 | { |
| 169 | BUG_ON(!status); |
| 170 | set_status(vdev, status); |
| 171 | } |
| 172 | |
| 173 | static void lg_reset(struct virtio_device *vdev) |
| 174 | { |
| 175 | set_status(vdev, 0); |
| 176 | } |
| 177 | |
Rusty Russell | 19f1537 | 2007-10-22 11:24:21 +1000 | [diff] [blame] | 178 | /* |
| 179 | * Virtqueues |
| 180 | * |
| 181 | * The other piece of infrastructure virtio needs is a "virtqueue": a way of |
| 182 | * the Guest device registering buffers for the other side to read from or |
| 183 | * write into (ie. send and receive buffers). Each device can have multiple |
Rusty Russell | e1e7296 | 2007-10-25 15:02:50 +1000 | [diff] [blame] | 184 | * virtqueues: for example the console driver uses one queue for sending and |
| 185 | * another for receiving. |
Rusty Russell | 19f1537 | 2007-10-22 11:24:21 +1000 | [diff] [blame] | 186 | * |
| 187 | * Fortunately for us, a very fast shared-memory-plus-descriptors virtqueue |
| 188 | * already exists in virtio_ring.c. We just need to connect it up. |
| 189 | * |
| 190 | * We start with the information we need to keep about each virtqueue. |
| 191 | */ |
| 192 | |
| 193 | /*D:140 This is the information we remember about each virtqueue. */ |
| 194 | struct lguest_vq_info |
| 195 | { |
| 196 | /* A copy of the information contained in the device config. */ |
| 197 | struct lguest_vqconfig config; |
| 198 | |
| 199 | /* The address where we mapped the virtio ring, so we can unmap it. */ |
| 200 | void *pages; |
| 201 | }; |
| 202 | |
| 203 | /* When the virtio_ring code wants to prod the Host, it calls us here and we |
Rusty Russell | a6bd8e1 | 2008-03-28 11:05:53 -0500 | [diff] [blame] | 204 | * make a hypercall. We hand the physical address of the virtqueue so the Host |
Rusty Russell | 19f1537 | 2007-10-22 11:24:21 +1000 | [diff] [blame] | 205 | * knows which virtqueue we're talking about. */ |
| 206 | static void lg_notify(struct virtqueue *vq) |
| 207 | { |
| 208 | /* We store our virtqueue information in the "priv" pointer of the |
| 209 | * virtqueue structure. */ |
| 210 | struct lguest_vq_info *lvq = vq->priv; |
| 211 | |
| 212 | hcall(LHCALL_NOTIFY, lvq->config.pfn << PAGE_SHIFT, 0, 0); |
| 213 | } |
| 214 | |
Rusty Russell | 6db6a5f | 2009-03-09 10:06:28 -0600 | [diff] [blame] | 215 | /* An extern declaration inside a C file is bad form. Don't do it. */ |
| 216 | extern void lguest_setup_irq(unsigned int irq); |
| 217 | |
Rusty Russell | 19f1537 | 2007-10-22 11:24:21 +1000 | [diff] [blame] | 218 | /* This routine finds the first virtqueue described in the configuration of |
| 219 | * this device and sets it up. |
| 220 | * |
| 221 | * This is kind of an ugly duckling. It'd be nicer to have a standard |
| 222 | * representation of a virtqueue in the configuration space, but it seems that |
Rusty Russell | e1e7296 | 2007-10-25 15:02:50 +1000 | [diff] [blame] | 223 | * everyone wants to do it differently. The KVM coders want the Guest to |
Rusty Russell | 19f1537 | 2007-10-22 11:24:21 +1000 | [diff] [blame] | 224 | * allocate its own pages and tell the Host where they are, but for lguest it's |
| 225 | * simpler for the Host to simply tell us where the pages are. |
| 226 | * |
Rusty Russell | a6bd8e1 | 2008-03-28 11:05:53 -0500 | [diff] [blame] | 227 | * So we provide drivers with a "find the Nth virtqueue and set it up" |
| 228 | * function. */ |
Rusty Russell | 19f1537 | 2007-10-22 11:24:21 +1000 | [diff] [blame] | 229 | static struct virtqueue *lg_find_vq(struct virtio_device *vdev, |
Rusty Russell | a586d4f | 2008-02-04 23:49:56 -0500 | [diff] [blame] | 230 | unsigned index, |
Rusty Russell | 18445c4 | 2008-02-04 23:49:57 -0500 | [diff] [blame] | 231 | void (*callback)(struct virtqueue *vq)) |
Rusty Russell | 19f1537 | 2007-10-22 11:24:21 +1000 | [diff] [blame] | 232 | { |
Rusty Russell | a586d4f | 2008-02-04 23:49:56 -0500 | [diff] [blame] | 233 | struct lguest_device *ldev = to_lgdev(vdev); |
Rusty Russell | 19f1537 | 2007-10-22 11:24:21 +1000 | [diff] [blame] | 234 | struct lguest_vq_info *lvq; |
| 235 | struct virtqueue *vq; |
Rusty Russell | 19f1537 | 2007-10-22 11:24:21 +1000 | [diff] [blame] | 236 | int err; |
| 237 | |
Rusty Russell | a586d4f | 2008-02-04 23:49:56 -0500 | [diff] [blame] | 238 | /* We must have this many virtqueues. */ |
| 239 | if (index >= ldev->desc->num_vq) |
Rusty Russell | 19f1537 | 2007-10-22 11:24:21 +1000 | [diff] [blame] | 240 | return ERR_PTR(-ENOENT); |
| 241 | |
| 242 | lvq = kmalloc(sizeof(*lvq), GFP_KERNEL); |
| 243 | if (!lvq) |
| 244 | return ERR_PTR(-ENOMEM); |
| 245 | |
Rusty Russell | a586d4f | 2008-02-04 23:49:56 -0500 | [diff] [blame] | 246 | /* Make a copy of the "struct lguest_vqconfig" entry, which sits after |
| 247 | * the descriptor. We need a copy because the config space might not |
| 248 | * be aligned correctly. */ |
| 249 | memcpy(&lvq->config, lg_vq(ldev->desc)+index, sizeof(lvq->config)); |
Rusty Russell | 19f1537 | 2007-10-22 11:24:21 +1000 | [diff] [blame] | 250 | |
Rusty Russell | a586d4f | 2008-02-04 23:49:56 -0500 | [diff] [blame] | 251 | printk("Mapping virtqueue %i addr %lx\n", index, |
| 252 | (unsigned long)lvq->config.pfn << PAGE_SHIFT); |
Rusty Russell | 19f1537 | 2007-10-22 11:24:21 +1000 | [diff] [blame] | 253 | /* Figure out how many pages the ring will take, and map that memory */ |
| 254 | lvq->pages = lguest_map((unsigned long)lvq->config.pfn << PAGE_SHIFT, |
Rusty Russell | 42b36cc | 2007-11-12 13:39:18 +1100 | [diff] [blame] | 255 | DIV_ROUND_UP(vring_size(lvq->config.num, |
Rusty Russell | 2966af7 | 2008-12-30 09:25:58 -0600 | [diff] [blame] | 256 | LGUEST_VRING_ALIGN), |
Rusty Russell | 19f1537 | 2007-10-22 11:24:21 +1000 | [diff] [blame] | 257 | PAGE_SIZE)); |
| 258 | if (!lvq->pages) { |
| 259 | err = -ENOMEM; |
| 260 | goto free_lvq; |
| 261 | } |
| 262 | |
| 263 | /* OK, tell virtio_ring.c to set up a virtqueue now we know its size |
| 264 | * and we've got a pointer to its pages. */ |
Rusty Russell | 87c7d57 | 2008-12-30 09:26:03 -0600 | [diff] [blame] | 265 | vq = vring_new_virtqueue(lvq->config.num, LGUEST_VRING_ALIGN, |
| 266 | vdev, lvq->pages, lg_notify, callback); |
Rusty Russell | 19f1537 | 2007-10-22 11:24:21 +1000 | [diff] [blame] | 267 | if (!vq) { |
| 268 | err = -ENOMEM; |
| 269 | goto unmap; |
| 270 | } |
| 271 | |
Rusty Russell | 6db6a5f | 2009-03-09 10:06:28 -0600 | [diff] [blame] | 272 | /* Make sure the interrupt is allocated. */ |
| 273 | lguest_setup_irq(lvq->config.irq); |
| 274 | |
Rusty Russell | 19f1537 | 2007-10-22 11:24:21 +1000 | [diff] [blame] | 275 | /* Tell the interrupt for this virtqueue to go to the virtio_ring |
| 276 | * interrupt handler. */ |
| 277 | /* FIXME: We used to have a flag for the Host to tell us we could use |
| 278 | * the interrupt as a source of randomness: it'd be nice to have that |
| 279 | * back.. */ |
| 280 | err = request_irq(lvq->config.irq, vring_interrupt, IRQF_SHARED, |
Mark McLoughlin | bda53cd | 2008-12-10 17:45:39 +0000 | [diff] [blame] | 281 | dev_name(&vdev->dev), vq); |
Rusty Russell | 19f1537 | 2007-10-22 11:24:21 +1000 | [diff] [blame] | 282 | if (err) |
| 283 | goto destroy_vring; |
| 284 | |
| 285 | /* Last of all we hook up our 'struct lguest_vq_info" to the |
| 286 | * virtqueue's priv pointer. */ |
| 287 | vq->priv = lvq; |
| 288 | return vq; |
| 289 | |
| 290 | destroy_vring: |
| 291 | vring_del_virtqueue(vq); |
| 292 | unmap: |
| 293 | lguest_unmap(lvq->pages); |
| 294 | free_lvq: |
| 295 | kfree(lvq); |
| 296 | return ERR_PTR(err); |
| 297 | } |
| 298 | /*:*/ |
| 299 | |
| 300 | /* Cleaning up a virtqueue is easy */ |
| 301 | static void lg_del_vq(struct virtqueue *vq) |
| 302 | { |
| 303 | struct lguest_vq_info *lvq = vq->priv; |
| 304 | |
Rusty Russell | 74b2553 | 2007-11-19 11:20:42 -0500 | [diff] [blame] | 305 | /* Release the interrupt */ |
| 306 | free_irq(lvq->config.irq, vq); |
Rusty Russell | 19f1537 | 2007-10-22 11:24:21 +1000 | [diff] [blame] | 307 | /* Tell virtio_ring.c to free the virtqueue. */ |
| 308 | vring_del_virtqueue(vq); |
| 309 | /* Unmap the pages containing the ring. */ |
| 310 | lguest_unmap(lvq->pages); |
| 311 | /* Free our own queue information. */ |
| 312 | kfree(lvq); |
| 313 | } |
| 314 | |
| 315 | /* The ops structure which hooks everything together. */ |
| 316 | static struct virtio_config_ops lguest_config_ops = { |
Rusty Russell | c45a681 | 2008-05-02 21:50:50 -0500 | [diff] [blame] | 317 | .get_features = lg_get_features, |
Rusty Russell | c624896 | 2008-07-25 12:06:07 -0500 | [diff] [blame] | 318 | .finalize_features = lg_finalize_features, |
Rusty Russell | 19f1537 | 2007-10-22 11:24:21 +1000 | [diff] [blame] | 319 | .get = lg_get, |
| 320 | .set = lg_set, |
| 321 | .get_status = lg_get_status, |
| 322 | .set_status = lg_set_status, |
Rusty Russell | 6e5aa7e | 2008-02-04 23:50:03 -0500 | [diff] [blame] | 323 | .reset = lg_reset, |
Rusty Russell | 19f1537 | 2007-10-22 11:24:21 +1000 | [diff] [blame] | 324 | .find_vq = lg_find_vq, |
| 325 | .del_vq = lg_del_vq, |
| 326 | }; |
| 327 | |
| 328 | /* The root device for the lguest virtio devices. This makes them appear as |
| 329 | * /sys/devices/lguest/0,1,2 not /sys/devices/0,1,2. */ |
Mark McLoughlin | ff8561c | 2008-12-15 12:58:28 +0000 | [diff] [blame] | 330 | static struct device *lguest_root; |
Rusty Russell | 19f1537 | 2007-10-22 11:24:21 +1000 | [diff] [blame] | 331 | |
| 332 | /*D:120 This is the core of the lguest bus: actually adding a new device. |
| 333 | * It's a separate function because it's neater that way, and because an |
| 334 | * earlier version of the code supported hotplug and unplug. They were removed |
| 335 | * early on because they were never used. |
| 336 | * |
| 337 | * As Andrew Tridgell says, "Untested code is buggy code". |
| 338 | * |
| 339 | * It's worth reading this carefully: we start with a pointer to the new device |
Rusty Russell | b769f57 | 2008-05-30 15:09:42 -0500 | [diff] [blame] | 340 | * descriptor in the "lguest_devices" page, and the offset into the device |
| 341 | * descriptor page so we can uniquely identify it if things go badly wrong. */ |
| 342 | static void add_lguest_device(struct lguest_device_desc *d, |
| 343 | unsigned int offset) |
Rusty Russell | 19f1537 | 2007-10-22 11:24:21 +1000 | [diff] [blame] | 344 | { |
| 345 | struct lguest_device *ldev; |
| 346 | |
Rusty Russell | e1e7296 | 2007-10-25 15:02:50 +1000 | [diff] [blame] | 347 | /* Start with zeroed memory; Linux's device layer seems to count on |
| 348 | * it. */ |
Rusty Russell | 19f1537 | 2007-10-22 11:24:21 +1000 | [diff] [blame] | 349 | ldev = kzalloc(sizeof(*ldev), GFP_KERNEL); |
| 350 | if (!ldev) { |
Rusty Russell | b769f57 | 2008-05-30 15:09:42 -0500 | [diff] [blame] | 351 | printk(KERN_EMERG "Cannot allocate lguest dev %u type %u\n", |
| 352 | offset, d->type); |
Rusty Russell | 19f1537 | 2007-10-22 11:24:21 +1000 | [diff] [blame] | 353 | return; |
| 354 | } |
| 355 | |
| 356 | /* This devices' parent is the lguest/ dir. */ |
Mark McLoughlin | ff8561c | 2008-12-15 12:58:28 +0000 | [diff] [blame] | 357 | ldev->vdev.dev.parent = lguest_root; |
Rusty Russell | 19f1537 | 2007-10-22 11:24:21 +1000 | [diff] [blame] | 358 | /* We have a unique device index thanks to the dev_index counter. */ |
Rusty Russell | 19f1537 | 2007-10-22 11:24:21 +1000 | [diff] [blame] | 359 | ldev->vdev.id.device = d->type; |
| 360 | /* We have a simple set of routines for querying the device's |
| 361 | * configuration information and setting its status. */ |
| 362 | ldev->vdev.config = &lguest_config_ops; |
| 363 | /* And we remember the device's descriptor for lguest_config_ops. */ |
| 364 | ldev->desc = d; |
| 365 | |
| 366 | /* register_virtio_device() sets up the generic fields for the struct |
| 367 | * virtio_device and calls device_register(). This makes the bus |
| 368 | * infrastructure look for a matching driver. */ |
| 369 | if (register_virtio_device(&ldev->vdev) != 0) { |
Rusty Russell | b769f57 | 2008-05-30 15:09:42 -0500 | [diff] [blame] | 370 | printk(KERN_ERR "Failed to register lguest dev %u type %u\n", |
| 371 | offset, d->type); |
Rusty Russell | 19f1537 | 2007-10-22 11:24:21 +1000 | [diff] [blame] | 372 | kfree(ldev); |
| 373 | } |
| 374 | } |
| 375 | |
| 376 | /*D:110 scan_devices() simply iterates through the device page. The type 0 is |
| 377 | * reserved to mean "end of devices". */ |
| 378 | static void scan_devices(void) |
| 379 | { |
| 380 | unsigned int i; |
| 381 | struct lguest_device_desc *d; |
| 382 | |
| 383 | /* We start at the page beginning, and skip over each entry. */ |
Rusty Russell | a586d4f | 2008-02-04 23:49:56 -0500 | [diff] [blame] | 384 | for (i = 0; i < PAGE_SIZE; i += desc_size(d)) { |
Rusty Russell | 19f1537 | 2007-10-22 11:24:21 +1000 | [diff] [blame] | 385 | d = lguest_devices + i; |
| 386 | |
| 387 | /* Once we hit a zero, stop. */ |
| 388 | if (d->type == 0) |
| 389 | break; |
| 390 | |
Rusty Russell | a586d4f | 2008-02-04 23:49:56 -0500 | [diff] [blame] | 391 | printk("Device at %i has size %u\n", i, desc_size(d)); |
Rusty Russell | b769f57 | 2008-05-30 15:09:42 -0500 | [diff] [blame] | 392 | add_lguest_device(d, i); |
Rusty Russell | 19f1537 | 2007-10-22 11:24:21 +1000 | [diff] [blame] | 393 | } |
| 394 | } |
| 395 | |
| 396 | /*D:105 Fairly early in boot, lguest_devices_init() is called to set up the |
| 397 | * lguest device infrastructure. We check that we are a Guest by checking |
| 398 | * pv_info.name: there are other ways of checking, but this seems most |
| 399 | * obvious to me. |
| 400 | * |
| 401 | * So we can access the "struct lguest_device_desc"s easily, we map that memory |
| 402 | * and store the pointer in the global "lguest_devices". Then we register a |
| 403 | * root device from which all our devices will hang (this seems to be the |
| 404 | * correct sysfs incantation). |
| 405 | * |
| 406 | * Finally we call scan_devices() which adds all the devices found in the |
| 407 | * lguest_devices page. */ |
| 408 | static int __init lguest_devices_init(void) |
| 409 | { |
| 410 | if (strcmp(pv_info.name, "lguest") != 0) |
| 411 | return 0; |
| 412 | |
Mark McLoughlin | ff8561c | 2008-12-15 12:58:28 +0000 | [diff] [blame] | 413 | lguest_root = root_device_register("lguest"); |
| 414 | if (IS_ERR(lguest_root)) |
Rusty Russell | 19f1537 | 2007-10-22 11:24:21 +1000 | [diff] [blame] | 415 | panic("Could not register lguest root"); |
| 416 | |
| 417 | /* Devices are in a single page above top of "normal" mem */ |
| 418 | lguest_devices = lguest_map(max_pfn<<PAGE_SHIFT, 1); |
| 419 | |
| 420 | scan_devices(); |
| 421 | return 0; |
| 422 | } |
| 423 | /* We do this after core stuff, but before the drivers. */ |
| 424 | postcore_initcall(lguest_devices_init); |
| 425 | |
| 426 | /*D:150 At this point in the journey we used to now wade through the lguest |
| 427 | * devices themselves: net, block and console. Since they're all now virtio |
| 428 | * devices rather than lguest-specific, I've decided to ignore them. Mostly, |
| 429 | * they're kind of boring. But this does mean you'll never experience the |
| 430 | * thrill of reading the forbidden love scene buried deep in the block driver. |
| 431 | * |
| 432 | * "make Launcher" beckons, where we answer questions like "Where do Guests |
| 433 | * come from?", and "What do you do when someone asks for optimization?". */ |