Commit | Line | Data |
---|---|---|
f938d2c8 RR |
1 | /*P:200 This contains all the /dev/lguest code, whereby the userspace launcher |
2 | * controls and communicates with the Guest. For example, the first write will | |
3c6b5bfa RR |
3 | * tell us the Guest's memory layout, pagetable, entry point and kernel address |
4 | * offset. A read will run the Guest until something happens, such as a signal | |
15045275 | 5 | * or the Guest doing a NOTIFY out to the Launcher. :*/ |
d7e28ffe RR |
6 | #include <linux/uaccess.h> |
7 | #include <linux/miscdevice.h> | |
8 | #include <linux/fs.h> | |
9 | #include "lg.h" | |
10 | ||
e1e72965 RR |
11 | /*L:055 When something happens, the Waker process needs a way to stop the |
12 | * kernel running the Guest and return to the Launcher. So the Waker writes | |
13 | * LHREQ_BREAK and the value "1" to /dev/lguest to do this. Once the Launcher | |
14 | * has done whatever needs attention, it writes LHREQ_BREAK and "0" to release | |
15 | * the Waker. */ | |
511801dc | 16 | static int break_guest_out(struct lguest *lg, const unsigned long __user *input) |
d7e28ffe RR |
17 | { |
18 | unsigned long on; | |
19 | ||
e1e72965 | 20 | /* Fetch whether they're turning break on or off. */ |
d7e28ffe RR |
21 | if (get_user(on, input) != 0) |
22 | return -EFAULT; | |
23 | ||
24 | if (on) { | |
25 | lg->break_out = 1; | |
e1e72965 | 26 | /* Pop it out of the Guest (may be running on different CPU) */ |
d7e28ffe RR |
27 | wake_up_process(lg->tsk); |
28 | /* Wait for them to reset it */ | |
29 | return wait_event_interruptible(lg->break_wq, !lg->break_out); | |
30 | } else { | |
31 | lg->break_out = 0; | |
32 | wake_up(&lg->break_wq); | |
33 | return 0; | |
34 | } | |
35 | } | |
36 | ||
dde79789 RR |
37 | /*L:050 Sending an interrupt is done by writing LHREQ_IRQ and an interrupt |
38 | * number to /dev/lguest. */ | |
177e449d | 39 | static int user_send_irq(struct lg_cpu *cpu, const unsigned long __user *input) |
d7e28ffe | 40 | { |
511801dc | 41 | unsigned long irq; |
d7e28ffe RR |
42 | |
43 | if (get_user(irq, input) != 0) | |
44 | return -EFAULT; | |
45 | if (irq >= LGUEST_IRQS) | |
46 | return -EINVAL; | |
dde79789 RR |
47 | /* Next time the Guest runs, the core code will see if it can deliver |
48 | * this interrupt. */ | |
177e449d | 49 | set_bit(irq, cpu->irqs_pending); |
d7e28ffe RR |
50 | return 0; |
51 | } | |
52 | ||
dde79789 RR |
53 | /*L:040 Once our Guest is initialized, the Launcher makes it run by reading |
54 | * from /dev/lguest. */ | |
d7e28ffe RR |
55 | static ssize_t read(struct file *file, char __user *user, size_t size,loff_t*o) |
56 | { | |
57 | struct lguest *lg = file->private_data; | |
d0953d42 GOC |
58 | struct lg_cpu *cpu; |
59 | unsigned int cpu_id = *o; | |
d7e28ffe | 60 | |
dde79789 | 61 | /* You must write LHREQ_INITIALIZE first! */ |
d7e28ffe RR |
62 | if (!lg) |
63 | return -EINVAL; | |
64 | ||
d0953d42 GOC |
65 | /* Watch out for arbitrary vcpu indexes! */ |
66 | if (cpu_id >= lg->nr_cpus) | |
67 | return -EINVAL; | |
68 | ||
69 | cpu = &lg->cpus[cpu_id]; | |
70 | ||
e1e72965 | 71 | /* If you're not the task which owns the Guest, go away. */ |
d7e28ffe RR |
72 | if (current != lg->tsk) |
73 | return -EPERM; | |
74 | ||
dde79789 | 75 | /* If the guest is already dead, we indicate why */ |
d7e28ffe RR |
76 | if (lg->dead) { |
77 | size_t len; | |
78 | ||
dde79789 | 79 | /* lg->dead either contains an error code, or a string. */ |
d7e28ffe RR |
80 | if (IS_ERR(lg->dead)) |
81 | return PTR_ERR(lg->dead); | |
82 | ||
dde79789 | 83 | /* We can only return as much as the buffer they read with. */ |
d7e28ffe RR |
84 | len = min(size, strlen(lg->dead)+1); |
85 | if (copy_to_user(user, lg->dead, len) != 0) | |
86 | return -EFAULT; | |
87 | return len; | |
88 | } | |
89 | ||
15045275 | 90 | /* If we returned from read() last time because the Guest notified, |
dde79789 | 91 | * clear the flag. */ |
15045275 RR |
92 | if (lg->pending_notify) |
93 | lg->pending_notify = 0; | |
d7e28ffe | 94 | |
dde79789 | 95 | /* Run the Guest until something interesting happens. */ |
d0953d42 | 96 | return run_guest(cpu, (unsigned long __user *)user); |
d7e28ffe RR |
97 | } |
98 | ||
4dcc53da GOC |
99 | static int lg_cpu_start(struct lg_cpu *cpu, unsigned id, unsigned long start_ip) |
100 | { | |
101 | if (id >= NR_CPUS) | |
102 | return -EINVAL; | |
103 | ||
104 | cpu->id = id; | |
105 | cpu->lg = container_of((cpu - id), struct lguest, cpus[0]); | |
106 | cpu->lg->nr_cpus++; | |
ad8d8f3b | 107 | init_clockdev(cpu); |
4dcc53da | 108 | |
a53a35a8 GOC |
109 | /* We need a complete page for the Guest registers: they are accessible |
110 | * to the Guest and we can only grant it access to whole pages. */ | |
111 | cpu->regs_page = get_zeroed_page(GFP_KERNEL); | |
112 | if (!cpu->regs_page) | |
113 | return -ENOMEM; | |
114 | ||
115 | /* We actually put the registers at the bottom of the page. */ | |
116 | cpu->regs = (void *)cpu->regs_page + PAGE_SIZE - sizeof(*cpu->regs); | |
117 | ||
118 | /* Now we initialize the Guest's registers, handing it the start | |
119 | * address. */ | |
120 | lguest_arch_setup_regs(cpu, start_ip); | |
121 | ||
4dcc53da GOC |
122 | return 0; |
123 | } | |
124 | ||
47436aa4 | 125 | /*L:020 The initialization write supplies 4 pointer sized (32 or 64 bit) |
511801dc | 126 | * values (in addition to the LHREQ_INITIALIZE value). These are: |
dde79789 | 127 | * |
3c6b5bfa RR |
128 | * base: The start of the Guest-physical memory inside the Launcher memory. |
129 | * | |
dde79789 | 130 | * pfnlimit: The highest (Guest-physical) page number the Guest should be |
e1e72965 RR |
131 | * allowed to access. The Guest memory lives inside the Launcher, so it sets |
132 | * this to ensure the Guest can only reach its own memory. | |
dde79789 RR |
133 | * |
134 | * pgdir: The (Guest-physical) address of the top of the initial Guest | |
135 | * pagetables (which are set up by the Launcher). | |
136 | * | |
137 | * start: The first instruction to execute ("eip" in x86-speak). | |
dde79789 | 138 | */ |
511801dc | 139 | static int initialize(struct file *file, const unsigned long __user *input) |
d7e28ffe | 140 | { |
dde79789 RR |
141 | /* "struct lguest" contains everything we (the Host) know about a |
142 | * Guest. */ | |
d7e28ffe | 143 | struct lguest *lg; |
48245cc0 | 144 | int err; |
47436aa4 | 145 | unsigned long args[4]; |
d7e28ffe | 146 | |
48245cc0 RR |
147 | /* We grab the Big Lguest lock, which protects against multiple |
148 | * simultaneous initializations. */ | |
d7e28ffe | 149 | mutex_lock(&lguest_lock); |
dde79789 | 150 | /* You can't initialize twice! Close the device and start again... */ |
d7e28ffe RR |
151 | if (file->private_data) { |
152 | err = -EBUSY; | |
153 | goto unlock; | |
154 | } | |
155 | ||
156 | if (copy_from_user(args, input, sizeof(args)) != 0) { | |
157 | err = -EFAULT; | |
158 | goto unlock; | |
159 | } | |
160 | ||
48245cc0 RR |
161 | lg = kzalloc(sizeof(*lg), GFP_KERNEL); |
162 | if (!lg) { | |
163 | err = -ENOMEM; | |
d7e28ffe RR |
164 | goto unlock; |
165 | } | |
dde79789 RR |
166 | |
167 | /* Populate the easy fields of our "struct lguest" */ | |
3c6b5bfa RR |
168 | lg->mem_base = (void __user *)(long)args[0]; |
169 | lg->pfn_limit = args[1]; | |
dde79789 | 170 | |
4dcc53da | 171 | /* This is the first cpu */ |
d0953d42 | 172 | err = lg_cpu_start(&lg->cpus[0], 0, args[3]); |
4dcc53da GOC |
173 | if (err) |
174 | goto release_guest; | |
175 | ||
dde79789 RR |
176 | /* Initialize the Guest's shadow page tables, using the toplevel |
177 | * address the Launcher gave us. This allocates memory, so can | |
178 | * fail. */ | |
3c6b5bfa | 179 | err = init_guest_pagetable(lg, args[2]); |
d7e28ffe RR |
180 | if (err) |
181 | goto free_regs; | |
182 | ||
dde79789 RR |
183 | /* We keep a pointer to the Launcher task (ie. current task) for when |
184 | * other Guests want to wake this one (inter-Guest I/O). */ | |
d7e28ffe | 185 | lg->tsk = current; |
dde79789 RR |
186 | /* We need to keep a pointer to the Launcher's memory map, because if |
187 | * the Launcher dies we need to clean it up. If we don't keep a | |
188 | * reference, it is destroyed before close() is called. */ | |
d7e28ffe | 189 | lg->mm = get_task_mm(lg->tsk); |
dde79789 RR |
190 | |
191 | /* Initialize the queue for the waker to wait on */ | |
d7e28ffe | 192 | init_waitqueue_head(&lg->break_wq); |
dde79789 RR |
193 | |
194 | /* We remember which CPU's pages this Guest used last, for optimization | |
195 | * when the same Guest runs on the same CPU twice. */ | |
d7e28ffe | 196 | lg->last_pages = NULL; |
dde79789 RR |
197 | |
198 | /* We keep our "struct lguest" in the file's private_data. */ | |
d7e28ffe RR |
199 | file->private_data = lg; |
200 | ||
201 | mutex_unlock(&lguest_lock); | |
202 | ||
dde79789 | 203 | /* And because this is a write() call, we return the length used. */ |
d7e28ffe RR |
204 | return sizeof(args); |
205 | ||
206 | free_regs: | |
a53a35a8 GOC |
207 | /* FIXME: This should be in free_vcpu */ |
208 | free_page(lg->cpus[0].regs_page); | |
d7e28ffe | 209 | release_guest: |
43054412 | 210 | kfree(lg); |
d7e28ffe RR |
211 | unlock: |
212 | mutex_unlock(&lguest_lock); | |
213 | return err; | |
214 | } | |
215 | ||
dde79789 | 216 | /*L:010 The first operation the Launcher does must be a write. All writes |
e1e72965 | 217 | * start with an unsigned long number: for the first write this must be |
dde79789 | 218 | * LHREQ_INITIALIZE to set up the Guest. After that the Launcher can use |
15045275 | 219 | * writes of other values to send interrupts. */ |
511801dc | 220 | static ssize_t write(struct file *file, const char __user *in, |
d7e28ffe RR |
221 | size_t size, loff_t *off) |
222 | { | |
dde79789 RR |
223 | /* Once the guest is initialized, we hold the "struct lguest" in the |
224 | * file private data. */ | |
d7e28ffe | 225 | struct lguest *lg = file->private_data; |
511801dc JS |
226 | const unsigned long __user *input = (const unsigned long __user *)in; |
227 | unsigned long req; | |
177e449d | 228 | struct lg_cpu *uninitialized_var(cpu); |
7ea07a15 | 229 | unsigned int cpu_id = *off; |
d7e28ffe RR |
230 | |
231 | if (get_user(req, input) != 0) | |
232 | return -EFAULT; | |
511801dc | 233 | input++; |
d7e28ffe | 234 | |
dde79789 | 235 | /* If you haven't initialized, you must do that first. */ |
7ea07a15 GOC |
236 | if (req != LHREQ_INITIALIZE) { |
237 | if (!lg || (cpu_id >= lg->nr_cpus)) | |
238 | return -EINVAL; | |
239 | cpu = &lg->cpus[cpu_id]; | |
240 | if (!cpu) | |
241 | return -EINVAL; | |
242 | } | |
dde79789 RR |
243 | |
244 | /* Once the Guest is dead, all you can do is read() why it died. */ | |
d7e28ffe RR |
245 | if (lg && lg->dead) |
246 | return -ENOENT; | |
247 | ||
248 | /* If you're not the task which owns the Guest, you can only break */ | |
249 | if (lg && current != lg->tsk && req != LHREQ_BREAK) | |
250 | return -EPERM; | |
251 | ||
252 | switch (req) { | |
253 | case LHREQ_INITIALIZE: | |
511801dc | 254 | return initialize(file, input); |
d7e28ffe | 255 | case LHREQ_IRQ: |
177e449d | 256 | return user_send_irq(cpu, input); |
d7e28ffe | 257 | case LHREQ_BREAK: |
511801dc | 258 | return break_guest_out(lg, input); |
d7e28ffe RR |
259 | default: |
260 | return -EINVAL; | |
261 | } | |
262 | } | |
263 | ||
dde79789 RR |
264 | /*L:060 The final piece of interface code is the close() routine. It reverses |
265 | * everything done in initialize(). This is usually called because the | |
266 | * Launcher exited. | |
267 | * | |
268 | * Note that the close routine returns 0 or a negative error number: it can't | |
269 | * really fail, but it can whine. I blame Sun for this wart, and K&R C for | |
270 | * letting them do it. :*/ | |
d7e28ffe RR |
271 | static int close(struct inode *inode, struct file *file) |
272 | { | |
273 | struct lguest *lg = file->private_data; | |
ad8d8f3b | 274 | unsigned int i; |
d7e28ffe | 275 | |
dde79789 | 276 | /* If we never successfully initialized, there's nothing to clean up */ |
d7e28ffe RR |
277 | if (!lg) |
278 | return 0; | |
279 | ||
dde79789 RR |
280 | /* We need the big lock, to protect from inter-guest I/O and other |
281 | * Launchers initializing guests. */ | |
d7e28ffe | 282 | mutex_lock(&lguest_lock); |
a53a35a8 | 283 | for (i = 0; i < lg->nr_cpus; i++) { |
ad8d8f3b GOC |
284 | /* Cancels the hrtimer set via LHCALL_SET_CLOCKEVENT. */ |
285 | hrtimer_cancel(&lg->cpus[i].hrt); | |
a53a35a8 GOC |
286 | /* We can free up the register page we allocated. */ |
287 | free_page(lg->cpus[i].regs_page); | |
288 | } | |
dde79789 | 289 | /* Free up the shadow page tables for the Guest. */ |
d7e28ffe | 290 | free_guest_pagetable(lg); |
dde79789 RR |
291 | /* Now all the memory cleanups are done, it's safe to release the |
292 | * Launcher's memory management structure. */ | |
d7e28ffe | 293 | mmput(lg->mm); |
dde79789 RR |
294 | /* If lg->dead doesn't contain an error code it will be NULL or a |
295 | * kmalloc()ed string, either of which is ok to hand to kfree(). */ | |
d7e28ffe RR |
296 | if (!IS_ERR(lg->dead)) |
297 | kfree(lg->dead); | |
dde79789 RR |
298 | /* We clear the entire structure, which also marks it as free for the |
299 | * next user. */ | |
d7e28ffe | 300 | memset(lg, 0, sizeof(*lg)); |
dde79789 | 301 | /* Release lock and exit. */ |
d7e28ffe | 302 | mutex_unlock(&lguest_lock); |
dde79789 | 303 | |
d7e28ffe RR |
304 | return 0; |
305 | } | |
306 | ||
dde79789 RR |
307 | /*L:000 |
308 | * Welcome to our journey through the Launcher! | |
309 | * | |
310 | * The Launcher is the Host userspace program which sets up, runs and services | |
311 | * the Guest. In fact, many comments in the Drivers which refer to "the Host" | |
312 | * doing things are inaccurate: the Launcher does all the device handling for | |
e1e72965 | 313 | * the Guest, but the Guest can't know that. |
dde79789 RR |
314 | * |
315 | * Just to confuse you: to the Host kernel, the Launcher *is* the Guest and we | |
316 | * shall see more of that later. | |
317 | * | |
318 | * We begin our understanding with the Host kernel interface which the Launcher | |
319 | * uses: reading and writing a character device called /dev/lguest. All the | |
320 | * work happens in the read(), write() and close() routines: */ | |
d7e28ffe RR |
321 | static struct file_operations lguest_fops = { |
322 | .owner = THIS_MODULE, | |
323 | .release = close, | |
324 | .write = write, | |
325 | .read = read, | |
326 | }; | |
dde79789 RR |
327 | |
328 | /* This is a textbook example of a "misc" character device. Populate a "struct | |
329 | * miscdevice" and register it with misc_register(). */ | |
d7e28ffe RR |
330 | static struct miscdevice lguest_dev = { |
331 | .minor = MISC_DYNAMIC_MINOR, | |
332 | .name = "lguest", | |
333 | .fops = &lguest_fops, | |
334 | }; | |
335 | ||
336 | int __init lguest_device_init(void) | |
337 | { | |
338 | return misc_register(&lguest_dev); | |
339 | } | |
340 | ||
341 | void __exit lguest_device_remove(void) | |
342 | { | |
343 | misc_deregister(&lguest_dev); | |
344 | } |