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1/*P:400
2 * This contains run_guest() which actually calls into the Host<->Guest
3 * Switcher and analyzes the return, such as determining if the Guest wants the
4 * Host to do something. This file also contains useful helper routines.
5:*/
6#include <linux/module.h>
7#include <linux/stringify.h>
8#include <linux/stddef.h>
9#include <linux/io.h>
10#include <linux/mm.h>
11#include <linux/vmalloc.h>
12#include <linux/cpu.h>
13#include <linux/freezer.h>
14#include <linux/highmem.h>
15#include <linux/slab.h>
16#include <asm/paravirt.h>
17#include <asm/pgtable.h>
18#include <asm/uaccess.h>
19#include <asm/poll.h>
20#include <asm/asm-offsets.h>
21#include "lg.h"
22
23
24static struct vm_struct *switcher_vma;
25static struct page **switcher_page;
26
27/* This One Big lock protects all inter-guest data structures. */
28DEFINE_MUTEX(lguest_lock);
29
30/*H:010
31 * We need to set up the Switcher at a high virtual address. Remember the
32 * Switcher is a few hundred bytes of assembler code which actually changes the
33 * CPU to run the Guest, and then changes back to the Host when a trap or
34 * interrupt happens.
35 *
36 * The Switcher code must be at the same virtual address in the Guest as the
37 * Host since it will be running as the switchover occurs.
38 *
39 * Trying to map memory at a particular address is an unusual thing to do, so
40 * it's not a simple one-liner.
41 */
42static __init int map_switcher(void)
43{
44 int i, err;
45 struct page **pagep;
46
47 /*
48 * Map the Switcher in to high memory.
49 *
50 * It turns out that if we choose the address 0xFFC00000 (4MB under the
51 * top virtual address), it makes setting up the page tables really
52 * easy.
53 */
54
55 /*
56 * We allocate an array of struct page pointers. map_vm_area() wants
57 * this, rather than just an array of pages.
58 */
59 switcher_page = kmalloc(sizeof(switcher_page[0])*TOTAL_SWITCHER_PAGES,
60 GFP_KERNEL);
61 if (!switcher_page) {
62 err = -ENOMEM;
63 goto out;
64 }
65
66 /*
67 * Now we actually allocate the pages. The Guest will see these pages,
68 * so we make sure they're zeroed.
69 */
70 for (i = 0; i < TOTAL_SWITCHER_PAGES; i++) {
71 switcher_page[i] = alloc_page(GFP_KERNEL|__GFP_ZERO);
72 if (!switcher_page[i]) {
73 err = -ENOMEM;
74 goto free_some_pages;
75 }
76 }
77
78 /*
79 * First we check that the Switcher won't overlap the fixmap area at
80 * the top of memory. It's currently nowhere near, but it could have
81 * very strange effects if it ever happened.
82 */
83 if (SWITCHER_ADDR + (TOTAL_SWITCHER_PAGES+1)*PAGE_SIZE > FIXADDR_START){
84 err = -ENOMEM;
85 printk("lguest: mapping switcher would thwack fixmap\n");
86 goto free_pages;
87 }
88
89 /*
90 * Now we reserve the "virtual memory area" we want: 0xFFC00000
91 * (SWITCHER_ADDR). We might not get it in theory, but in practice
92 * it's worked so far. The end address needs +1 because __get_vm_area
93 * allocates an extra guard page, so we need space for that.
94 */
95 switcher_vma = __get_vm_area(TOTAL_SWITCHER_PAGES * PAGE_SIZE,
96 VM_ALLOC, SWITCHER_ADDR, SWITCHER_ADDR
97 + (TOTAL_SWITCHER_PAGES+1) * PAGE_SIZE);
98 if (!switcher_vma) {
99 err = -ENOMEM;
100 printk("lguest: could not map switcher pages high\n");
101 goto free_pages;
102 }
103
104 /*
105 * This code actually sets up the pages we've allocated to appear at
106 * SWITCHER_ADDR. map_vm_area() takes the vma we allocated above, the
107 * kind of pages we're mapping (kernel pages), and a pointer to our
108 * array of struct pages. It increments that pointer, but we don't
109 * care.
110 */
111 pagep = switcher_page;
112 err = map_vm_area(switcher_vma, PAGE_KERNEL_EXEC, &pagep);
113 if (err) {
114 printk("lguest: map_vm_area failed: %i\n", err);
115 goto free_vma;
116 }
117
118 /*
119 * Now the Switcher is mapped at the right address, we can't fail!
120 * Copy in the compiled-in Switcher code (from x86/switcher_32.S).
121 */
122 memcpy(switcher_vma->addr, start_switcher_text,
123 end_switcher_text - start_switcher_text);
124
125 printk(KERN_INFO "lguest: mapped switcher at %p\n",
126 switcher_vma->addr);
127 /* And we succeeded... */
128 return 0;
129
130free_vma:
131 vunmap(switcher_vma->addr);
132free_pages:
133 i = TOTAL_SWITCHER_PAGES;
134free_some_pages:
135 for (--i; i >= 0; i--)
136 __free_pages(switcher_page[i], 0);
137 kfree(switcher_page);
138out:
139 return err;
140}
141/*:*/
142
143/* Cleaning up the mapping when the module is unloaded is almost... too easy. */
144static void unmap_switcher(void)
145{
146 unsigned int i;
147
148 /* vunmap() undoes *both* map_vm_area() and __get_vm_area(). */
149 vunmap(switcher_vma->addr);
150 /* Now we just need to free the pages we copied the switcher into */
151 for (i = 0; i < TOTAL_SWITCHER_PAGES; i++)
152 __free_pages(switcher_page[i], 0);
153 kfree(switcher_page);
154}
155
156/*H:032
157 * Dealing With Guest Memory.
158 *
159 * Before we go too much further into the Host, we need to grok the routines
160 * we use to deal with Guest memory.
161 *
162 * When the Guest gives us (what it thinks is) a physical address, we can use
163 * the normal copy_from_user() & copy_to_user() on the corresponding place in
164 * the memory region allocated by the Launcher.
165 *
166 * But we can't trust the Guest: it might be trying to access the Launcher
167 * code. We have to check that the range is below the pfn_limit the Launcher
168 * gave us. We have to make sure that addr + len doesn't give us a false
169 * positive by overflowing, too.
170 */
171bool lguest_address_ok(const struct lguest *lg,
172 unsigned long addr, unsigned long len)
173{
174 return (addr+len) / PAGE_SIZE < lg->pfn_limit && (addr+len >= addr);
175}
176
177/*
178 * This routine copies memory from the Guest. Here we can see how useful the
179 * kill_lguest() routine we met in the Launcher can be: we return a random
180 * value (all zeroes) instead of needing to return an error.
181 */
182void __lgread(struct lg_cpu *cpu, void *b, unsigned long addr, unsigned bytes)
183{
184 if (!lguest_address_ok(cpu->lg, addr, bytes)
185 || copy_from_user(b, cpu->lg->mem_base + addr, bytes) != 0) {
186 /* copy_from_user should do this, but as we rely on it... */
187 memset(b, 0, bytes);
188 kill_guest(cpu, "bad read address %#lx len %u", addr, bytes);
189 }
190}
191
192/* This is the write (copy into Guest) version. */
193void __lgwrite(struct lg_cpu *cpu, unsigned long addr, const void *b,
194 unsigned bytes)
195{
196 if (!lguest_address_ok(cpu->lg, addr, bytes)
197 || copy_to_user(cpu->lg->mem_base + addr, b, bytes) != 0)
198 kill_guest(cpu, "bad write address %#lx len %u", addr, bytes);
199}
200/*:*/
201
202/*H:030
203 * Let's jump straight to the the main loop which runs the Guest.
204 * Remember, this is called by the Launcher reading /dev/lguest, and we keep
205 * going around and around until something interesting happens.
206 */
207int run_guest(struct lg_cpu *cpu, unsigned long __user *user)
208{
209 /* We stop running once the Guest is dead. */
210 while (!cpu->lg->dead) {
211 unsigned int irq;
212 bool more;
213
214 /* First we run any hypercalls the Guest wants done. */
215 if (cpu->hcall)
216 do_hypercalls(cpu);
217
218 /*
219 * It's possible the Guest did a NOTIFY hypercall to the
220 * Launcher.
221 */
222 if (cpu->pending_notify) {
223 /*
224 * Does it just needs to write to a registered
225 * eventfd (ie. the appropriate virtqueue thread)?
226 */
227 if (!send_notify_to_eventfd(cpu)) {
228 /* OK, we tell the main Laucher. */
229 if (put_user(cpu->pending_notify, user))
230 return -EFAULT;
231 return sizeof(cpu->pending_notify);
232 }
233 }
234
235 /* Check for signals */
236 if (signal_pending(current))
237 return -ERESTARTSYS;
238
239 /*
240 * Check if there are any interrupts which can be delivered now:
241 * if so, this sets up the hander to be executed when we next
242 * run the Guest.
243 */
244 irq = interrupt_pending(cpu, &more);
245 if (irq < LGUEST_IRQS)
246 try_deliver_interrupt(cpu, irq, more);
247
248 /*
249 * All long-lived kernel loops need to check with this horrible
250 * thing called the freezer. If the Host is trying to suspend,
251 * it stops us.
252 */
253 try_to_freeze();
254
255 /*
256 * Just make absolutely sure the Guest is still alive. One of
257 * those hypercalls could have been fatal, for example.
258 */
259 if (cpu->lg->dead)
260 break;
261
262 /*
263 * If the Guest asked to be stopped, we sleep. The Guest's
264 * clock timer will wake us.
265 */
266 if (cpu->halted) {
267 set_current_state(TASK_INTERRUPTIBLE);
268 /*
269 * Just before we sleep, make sure no interrupt snuck in
270 * which we should be doing.
271 */
272 if (interrupt_pending(cpu, &more) < LGUEST_IRQS)
273 set_current_state(TASK_RUNNING);
274 else
275 schedule();
276 continue;
277 }
278
279 /*
280 * OK, now we're ready to jump into the Guest. First we put up
281 * the "Do Not Disturb" sign:
282 */
283 local_irq_disable();
284
285 /* Actually run the Guest until something happens. */
286 lguest_arch_run_guest(cpu);
287
288 /* Now we're ready to be interrupted or moved to other CPUs */
289 local_irq_enable();
290
291 /* Now we deal with whatever happened to the Guest. */
292 lguest_arch_handle_trap(cpu);
293 }
294
295 /* Special case: Guest is 'dead' but wants a reboot. */
296 if (cpu->lg->dead == ERR_PTR(-ERESTART))
297 return -ERESTART;
298
299 /* The Guest is dead => "No such file or directory" */
300 return -ENOENT;
301}
302
303/*H:000
304 * Welcome to the Host!
305 *
306 * By this point your brain has been tickled by the Guest code and numbed by
307 * the Launcher code; prepare for it to be stretched by the Host code. This is
308 * the heart. Let's begin at the initialization routine for the Host's lg
309 * module.
310 */
311static int __init init(void)
312{
313 int err;
314
315 /* Lguest can't run under Xen, VMI or itself. It does Tricky Stuff. */
316 if (paravirt_enabled()) {
317 printk("lguest is afraid of being a guest\n");
318 return -EPERM;
319 }
320
321 /* First we put the Switcher up in very high virtual memory. */
322 err = map_switcher();
323 if (err)
324 goto out;
325
326 /* Now we set up the pagetable implementation for the Guests. */
327 err = init_pagetables(switcher_page, SHARED_SWITCHER_PAGES);
328 if (err)
329 goto unmap;
330
331 /* We might need to reserve an interrupt vector. */
332 err = init_interrupts();
333 if (err)
334 goto free_pgtables;
335
336 /* /dev/lguest needs to be registered. */
337 err = lguest_device_init();
338 if (err)
339 goto free_interrupts;
340
341 /* Finally we do some architecture-specific setup. */
342 lguest_arch_host_init();
343
344 /* All good! */
345 return 0;
346
347free_interrupts:
348 free_interrupts();
349free_pgtables:
350 free_pagetables();
351unmap:
352 unmap_switcher();
353out:
354 return err;
355}
356
357/* Cleaning up is just the same code, backwards. With a little French. */
358static void __exit fini(void)
359{
360 lguest_device_remove();
361 free_interrupts();
362 free_pagetables();
363 unmap_switcher();
364
365 lguest_arch_host_fini();
366}
367/*:*/
368
369/*
370 * The Host side of lguest can be a module. This is a nice way for people to
371 * play with it.
372 */
373module_init(init);
374module_exit(fini);
375MODULE_LICENSE("GPL");
376MODULE_AUTHOR("Rusty Russell <rusty@rustcorp.com.au>");
1/*P:400
2 * This contains run_guest() which actually calls into the Host<->Guest
3 * Switcher and analyzes the return, such as determining if the Guest wants the
4 * Host to do something. This file also contains useful helper routines.
5:*/
6#include <linux/module.h>
7#include <linux/stringify.h>
8#include <linux/stddef.h>
9#include <linux/io.h>
10#include <linux/mm.h>
11#include <linux/vmalloc.h>
12#include <linux/cpu.h>
13#include <linux/freezer.h>
14#include <linux/highmem.h>
15#include <linux/slab.h>
16#include <asm/paravirt.h>
17#include <asm/pgtable.h>
18#include <asm/uaccess.h>
19#include <asm/poll.h>
20#include <asm/asm-offsets.h>
21#include "lg.h"
22
23unsigned long switcher_addr;
24struct page **lg_switcher_pages;
25static struct vm_struct *switcher_text_vma;
26static struct vm_struct *switcher_stacks_vma;
27
28/* This One Big lock protects all inter-guest data structures. */
29DEFINE_MUTEX(lguest_lock);
30
31/*H:010
32 * We need to set up the Switcher at a high virtual address. Remember the
33 * Switcher is a few hundred bytes of assembler code which actually changes the
34 * CPU to run the Guest, and then changes back to the Host when a trap or
35 * interrupt happens.
36 *
37 * The Switcher code must be at the same virtual address in the Guest as the
38 * Host since it will be running as the switchover occurs.
39 *
40 * Trying to map memory at a particular address is an unusual thing to do, so
41 * it's not a simple one-liner.
42 */
43static __init int map_switcher(void)
44{
45 int i, err;
46
47 /*
48 * Map the Switcher in to high memory.
49 *
50 * It turns out that if we choose the address 0xFFC00000 (4MB under the
51 * top virtual address), it makes setting up the page tables really
52 * easy.
53 */
54
55 /* We assume Switcher text fits into a single page. */
56 if (end_switcher_text - start_switcher_text > PAGE_SIZE) {
57 printk(KERN_ERR "lguest: switcher text too large (%zu)\n",
58 end_switcher_text - start_switcher_text);
59 return -EINVAL;
60 }
61
62 /*
63 * We allocate an array of struct page pointers. map_vm_area() wants
64 * this, rather than just an array of pages.
65 */
66 lg_switcher_pages = kmalloc(sizeof(lg_switcher_pages[0])
67 * TOTAL_SWITCHER_PAGES,
68 GFP_KERNEL);
69 if (!lg_switcher_pages) {
70 err = -ENOMEM;
71 goto out;
72 }
73
74 /*
75 * Now we actually allocate the pages. The Guest will see these pages,
76 * so we make sure they're zeroed.
77 */
78 for (i = 0; i < TOTAL_SWITCHER_PAGES; i++) {
79 lg_switcher_pages[i] = alloc_page(GFP_KERNEL|__GFP_ZERO);
80 if (!lg_switcher_pages[i]) {
81 err = -ENOMEM;
82 goto free_some_pages;
83 }
84 }
85
86 /*
87 * Copy in the compiled-in Switcher code (from x86/switcher_32.S).
88 * It goes in the first page, which we map in momentarily.
89 */
90 memcpy(kmap(lg_switcher_pages[0]), start_switcher_text,
91 end_switcher_text - start_switcher_text);
92 kunmap(lg_switcher_pages[0]);
93
94 /*
95 * We place the Switcher underneath the fixmap area, which is the
96 * highest virtual address we can get. This is important, since we
97 * tell the Guest it can't access this memory, so we want its ceiling
98 * as high as possible.
99 */
100 switcher_addr = FIXADDR_START - TOTAL_SWITCHER_PAGES*PAGE_SIZE;
101
102 /*
103 * Now we reserve the "virtual memory area"s we want. We might
104 * not get them in theory, but in practice it's worked so far.
105 *
106 * We want the switcher text to be read-only and executable, and
107 * the stacks to be read-write and non-executable.
108 */
109 switcher_text_vma = __get_vm_area(PAGE_SIZE, VM_ALLOC|VM_NO_GUARD,
110 switcher_addr,
111 switcher_addr + PAGE_SIZE);
112
113 if (!switcher_text_vma) {
114 err = -ENOMEM;
115 printk("lguest: could not map switcher pages high\n");
116 goto free_pages;
117 }
118
119 switcher_stacks_vma = __get_vm_area(SWITCHER_STACK_PAGES * PAGE_SIZE,
120 VM_ALLOC|VM_NO_GUARD,
121 switcher_addr + PAGE_SIZE,
122 switcher_addr + TOTAL_SWITCHER_PAGES * PAGE_SIZE);
123 if (!switcher_stacks_vma) {
124 err = -ENOMEM;
125 printk("lguest: could not map switcher pages high\n");
126 goto free_text_vma;
127 }
128
129 /*
130 * This code actually sets up the pages we've allocated to appear at
131 * switcher_addr. map_vm_area() takes the vma we allocated above, the
132 * kind of pages we're mapping (kernel text pages and kernel writable
133 * pages respectively), and a pointer to our array of struct pages.
134 */
135 err = map_vm_area(switcher_text_vma, PAGE_KERNEL_RX, lg_switcher_pages);
136 if (err) {
137 printk("lguest: text map_vm_area failed: %i\n", err);
138 goto free_vmas;
139 }
140
141 err = map_vm_area(switcher_stacks_vma, PAGE_KERNEL,
142 lg_switcher_pages + SWITCHER_TEXT_PAGES);
143 if (err) {
144 printk("lguest: stacks map_vm_area failed: %i\n", err);
145 goto free_vmas;
146 }
147
148 /*
149 * Now the Switcher is mapped at the right address, we can't fail!
150 */
151 printk(KERN_INFO "lguest: mapped switcher at %p\n",
152 switcher_text_vma->addr);
153 /* And we succeeded... */
154 return 0;
155
156free_vmas:
157 /* Undoes map_vm_area and __get_vm_area */
158 vunmap(switcher_stacks_vma->addr);
159free_text_vma:
160 vunmap(switcher_text_vma->addr);
161free_pages:
162 i = TOTAL_SWITCHER_PAGES;
163free_some_pages:
164 for (--i; i >= 0; i--)
165 __free_pages(lg_switcher_pages[i], 0);
166 kfree(lg_switcher_pages);
167out:
168 return err;
169}
170/*:*/
171
172/* Cleaning up the mapping when the module is unloaded is almost... too easy. */
173static void unmap_switcher(void)
174{
175 unsigned int i;
176
177 /* vunmap() undoes *both* map_vm_area() and __get_vm_area(). */
178 vunmap(switcher_text_vma->addr);
179 vunmap(switcher_stacks_vma->addr);
180 /* Now we just need to free the pages we copied the switcher into */
181 for (i = 0; i < TOTAL_SWITCHER_PAGES; i++)
182 __free_pages(lg_switcher_pages[i], 0);
183 kfree(lg_switcher_pages);
184}
185
186/*H:032
187 * Dealing With Guest Memory.
188 *
189 * Before we go too much further into the Host, we need to grok the routines
190 * we use to deal with Guest memory.
191 *
192 * When the Guest gives us (what it thinks is) a physical address, we can use
193 * the normal copy_from_user() & copy_to_user() on the corresponding place in
194 * the memory region allocated by the Launcher.
195 *
196 * But we can't trust the Guest: it might be trying to access the Launcher
197 * code. We have to check that the range is below the pfn_limit the Launcher
198 * gave us. We have to make sure that addr + len doesn't give us a false
199 * positive by overflowing, too.
200 */
201bool lguest_address_ok(const struct lguest *lg,
202 unsigned long addr, unsigned long len)
203{
204 return addr+len <= lg->pfn_limit * PAGE_SIZE && (addr+len >= addr);
205}
206
207/*
208 * This routine copies memory from the Guest. Here we can see how useful the
209 * kill_lguest() routine we met in the Launcher can be: we return a random
210 * value (all zeroes) instead of needing to return an error.
211 */
212void __lgread(struct lg_cpu *cpu, void *b, unsigned long addr, unsigned bytes)
213{
214 if (!lguest_address_ok(cpu->lg, addr, bytes)
215 || copy_from_user(b, cpu->lg->mem_base + addr, bytes) != 0) {
216 /* copy_from_user should do this, but as we rely on it... */
217 memset(b, 0, bytes);
218 kill_guest(cpu, "bad read address %#lx len %u", addr, bytes);
219 }
220}
221
222/* This is the write (copy into Guest) version. */
223void __lgwrite(struct lg_cpu *cpu, unsigned long addr, const void *b,
224 unsigned bytes)
225{
226 if (!lguest_address_ok(cpu->lg, addr, bytes)
227 || copy_to_user(cpu->lg->mem_base + addr, b, bytes) != 0)
228 kill_guest(cpu, "bad write address %#lx len %u", addr, bytes);
229}
230/*:*/
231
232/*H:030
233 * Let's jump straight to the the main loop which runs the Guest.
234 * Remember, this is called by the Launcher reading /dev/lguest, and we keep
235 * going around and around until something interesting happens.
236 */
237int run_guest(struct lg_cpu *cpu, unsigned long __user *user)
238{
239 /* If the launcher asked for a register with LHREQ_GETREG */
240 if (cpu->reg_read) {
241 if (put_user(*cpu->reg_read, user))
242 return -EFAULT;
243 cpu->reg_read = NULL;
244 return sizeof(*cpu->reg_read);
245 }
246
247 /* We stop running once the Guest is dead. */
248 while (!cpu->lg->dead) {
249 unsigned int irq;
250 bool more;
251
252 /* First we run any hypercalls the Guest wants done. */
253 if (cpu->hcall)
254 do_hypercalls(cpu);
255
256 /* Do we have to tell the Launcher about a trap? */
257 if (cpu->pending.trap) {
258 if (copy_to_user(user, &cpu->pending,
259 sizeof(cpu->pending)))
260 return -EFAULT;
261 return sizeof(cpu->pending);
262 }
263
264 /*
265 * All long-lived kernel loops need to check with this horrible
266 * thing called the freezer. If the Host is trying to suspend,
267 * it stops us.
268 */
269 try_to_freeze();
270
271 /* Check for signals */
272 if (signal_pending(current))
273 return -ERESTARTSYS;
274
275 /*
276 * Check if there are any interrupts which can be delivered now:
277 * if so, this sets up the hander to be executed when we next
278 * run the Guest.
279 */
280 irq = interrupt_pending(cpu, &more);
281 if (irq < LGUEST_IRQS)
282 try_deliver_interrupt(cpu, irq, more);
283
284 /*
285 * Just make absolutely sure the Guest is still alive. One of
286 * those hypercalls could have been fatal, for example.
287 */
288 if (cpu->lg->dead)
289 break;
290
291 /*
292 * If the Guest asked to be stopped, we sleep. The Guest's
293 * clock timer will wake us.
294 */
295 if (cpu->halted) {
296 set_current_state(TASK_INTERRUPTIBLE);
297 /*
298 * Just before we sleep, make sure no interrupt snuck in
299 * which we should be doing.
300 */
301 if (interrupt_pending(cpu, &more) < LGUEST_IRQS)
302 set_current_state(TASK_RUNNING);
303 else
304 schedule();
305 continue;
306 }
307
308 /*
309 * OK, now we're ready to jump into the Guest. First we put up
310 * the "Do Not Disturb" sign:
311 */
312 local_irq_disable();
313
314 /* Actually run the Guest until something happens. */
315 lguest_arch_run_guest(cpu);
316
317 /* Now we're ready to be interrupted or moved to other CPUs */
318 local_irq_enable();
319
320 /* Now we deal with whatever happened to the Guest. */
321 lguest_arch_handle_trap(cpu);
322 }
323
324 /* Special case: Guest is 'dead' but wants a reboot. */
325 if (cpu->lg->dead == ERR_PTR(-ERESTART))
326 return -ERESTART;
327
328 /* The Guest is dead => "No such file or directory" */
329 return -ENOENT;
330}
331
332/*H:000
333 * Welcome to the Host!
334 *
335 * By this point your brain has been tickled by the Guest code and numbed by
336 * the Launcher code; prepare for it to be stretched by the Host code. This is
337 * the heart. Let's begin at the initialization routine for the Host's lg
338 * module.
339 */
340static int __init init(void)
341{
342 int err;
343
344 /* Lguest can't run under Xen, VMI or itself. It does Tricky Stuff. */
345 if (get_kernel_rpl() != 0) {
346 printk("lguest is afraid of being a guest\n");
347 return -EPERM;
348 }
349
350 /* First we put the Switcher up in very high virtual memory. */
351 err = map_switcher();
352 if (err)
353 goto out;
354
355 /* We might need to reserve an interrupt vector. */
356 err = init_interrupts();
357 if (err)
358 goto unmap;
359
360 /* /dev/lguest needs to be registered. */
361 err = lguest_device_init();
362 if (err)
363 goto free_interrupts;
364
365 /* Finally we do some architecture-specific setup. */
366 lguest_arch_host_init();
367
368 /* All good! */
369 return 0;
370
371free_interrupts:
372 free_interrupts();
373unmap:
374 unmap_switcher();
375out:
376 return err;
377}
378
379/* Cleaning up is just the same code, backwards. With a little French. */
380static void __exit fini(void)
381{
382 lguest_device_remove();
383 free_interrupts();
384 unmap_switcher();
385
386 lguest_arch_host_fini();
387}
388/*:*/
389
390/*
391 * The Host side of lguest can be a module. This is a nice way for people to
392 * play with it.
393 */
394module_init(init);
395module_exit(fini);
396MODULE_LICENSE("GPL");
397MODULE_AUTHOR("Rusty Russell <rusty@rustcorp.com.au>");