Loading...
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>");
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 <linux/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>");