[mirror_ubuntu-artful-kernel.git] / drivers / lguest / core.c

/*P:400 This contains run_guest() which actually calls into the Host<->Guest
 * Switcher and analyzes the return, such as determining if the Guest wants the
 * Host to do something.  This file also contains useful helper routines, and a
 * couple of non-obvious setup and teardown pieces which were implemented after
 * days of debugging pain. :*/
#include <linux/module.h>
#include <linux/stringify.h>
#include <linux/stddef.h>
#include <linux/io.h>
#include <linux/mm.h>
#include <linux/vmalloc.h>
#include <linux/cpu.h>
#include <linux/freezer.h>
#include <linux/highmem.h>
#include <asm/paravirt.h>
#include <asm/pgtable.h>
#include <asm/uaccess.h>
#include <asm/poll.h>
#include <asm/asm-offsets.h>
#include "lg.h"


static struct vm_struct *switcher_vma;
static struct page **switcher_page;

/* This One Big lock protects all inter-guest data structures. */
DEFINE_MUTEX(lguest_lock);

/*H:010 We need to set up the Switcher at a high virtual address.  Remember the
 * Switcher is a few hundred bytes of assembler code which actually changes the
 * CPU to run the Guest, and then changes back to the Host when a trap or
 * interrupt happens.
 *
 * The Switcher code must be at the same virtual address in the Guest as the
 * Host since it will be running as the switchover occurs.
 *
 * Trying to map memory at a particular address is an unusual thing to do, so
 * it's not a simple one-liner. */
static __init int map_switcher(void)
{
	int i, err;
	struct page **pagep;

	/*
	 * Map the Switcher in to high memory.
	 *
	 * It turns out that if we choose the address 0xFFC00000 (4MB under the
	 * top virtual address), it makes setting up the page tables really
	 * easy.
	 */

	/* We allocate an array of "struct page"s.  map_vm_area() wants the
	 * pages in this form, rather than just an array of pointers. */
	switcher_page = kmalloc(sizeof(switcher_page[0])*TOTAL_SWITCHER_PAGES,
				GFP_KERNEL);
	if (!switcher_page) {
		err = -ENOMEM;
		goto out;
	}

	/* Now we actually allocate the pages.  The Guest will see these pages,
	 * so we make sure they're zeroed. */
	for (i = 0; i < TOTAL_SWITCHER_PAGES; i++) {
		unsigned long addr = get_zeroed_page(GFP_KERNEL);
		if (!addr) {
			err = -ENOMEM;
			goto free_some_pages;
		}
		switcher_page[i] = virt_to_page(addr);
	}

	/* First we check that the Switcher won't overlap the fixmap area at
	 * the top of memory.  It's currently nowhere near, but it could have
	 * very strange effects if it ever happened. */
	if (SWITCHER_ADDR + (TOTAL_SWITCHER_PAGES+1)*PAGE_SIZE > FIXADDR_START){
		err = -ENOMEM;
		printk("lguest: mapping switcher would thwack fixmap\n");
		goto free_pages;
	}

	/* Now we reserve the "virtual memory area" we want: 0xFFC00000
	 * (SWITCHER_ADDR).  We might not get it in theory, but in practice
	 * it's worked so far.  The end address needs +1 because __get_vm_area
	 * allocates an extra guard page, so we need space for that. */
	switcher_vma = __get_vm_area(TOTAL_SWITCHER_PAGES * PAGE_SIZE,
				     VM_ALLOC, SWITCHER_ADDR, SWITCHER_ADDR
				     + (TOTAL_SWITCHER_PAGES+1) * PAGE_SIZE);
	if (!switcher_vma) {
		err = -ENOMEM;
		printk("lguest: could not map switcher pages high\n");
		goto free_pages;
	}

	/* This code actually sets up the pages we've allocated to appear at
	 * SWITCHER_ADDR.  map_vm_area() takes the vma we allocated above, the
	 * kind of pages we're mapping (kernel pages), and a pointer to our
	 * array of struct pages.  It increments that pointer, but we don't
	 * care. */
	pagep = switcher_page;
	err = map_vm_area(switcher_vma, PAGE_KERNEL, &pagep);
	if (err) {
		printk("lguest: map_vm_area failed: %i\n", err);
		goto free_vma;
	}

	/* Now the Switcher is mapped at the right address, we can't fail!
	 * Copy in the compiled-in Switcher code (from <arch>_switcher.S). */
	memcpy(switcher_vma->addr, start_switcher_text,
	       end_switcher_text - start_switcher_text);

	printk(KERN_INFO "lguest: mapped switcher at %p\n",
	       switcher_vma->addr);
	/* And we succeeded... */
	return 0;

free_vma:
	vunmap(switcher_vma->addr);
free_pages:
	i = TOTAL_SWITCHER_PAGES;
free_some_pages:
	for (--i; i >= 0; i--)
		__free_pages(switcher_page[i], 0);
	kfree(switcher_page);
out:
	return err;
}
/*:*/

/* Cleaning up the mapping when the module is unloaded is almost...
 * too easy. */
static void unmap_switcher(void)
{
	unsigned int i;

	/* vunmap() undoes *both* map_vm_area() and __get_vm_area(). */
	vunmap(switcher_vma->addr);
	/* Now we just need to free the pages we copied the switcher into */
	for (i = 0; i < TOTAL_SWITCHER_PAGES; i++)
		__free_pages(switcher_page[i], 0);
}

/*H:032
 * Dealing With Guest Memory.
 *
 * Before we go too much further into the Host, we need to grok the routines
 * we use to deal with Guest memory.
 *
 * When the Guest gives us (what it thinks is) a physical address, we can use
 * the normal copy_from_user() & copy_to_user() on the corresponding place in
 * the memory region allocated by the Launcher.
 *
 * But we can't trust the Guest: it might be trying to access the Launcher
 * code.  We have to check that the range is below the pfn_limit the Launcher
 * gave us.  We have to make sure that addr + len doesn't give us a false
 * positive by overflowing, too. */
int lguest_address_ok(const struct lguest *lg,
		      unsigned long addr, unsigned long len)
{
	return (addr+len) / PAGE_SIZE < lg->pfn_limit && (addr+len >= addr);
}

/* This routine copies memory from the Guest.  Here we can see how useful the
 * kill_lguest() routine we met in the Launcher can be: we return a random
 * value (all zeroes) instead of needing to return an error. */
void __lgread(struct lg_cpu *cpu, void *b, unsigned long addr, unsigned bytes)
{
	if (!lguest_address_ok(cpu->lg, addr, bytes)
	    || copy_from_user(b, cpu->lg->mem_base + addr, bytes) != 0) {
		/* copy_from_user should do this, but as we rely on it... */
		memset(b, 0, bytes);
		kill_guest(cpu, "bad read address %#lx len %u", addr, bytes);
	}
}

/* This is the write (copy into guest) version. */
void __lgwrite(struct lg_cpu *cpu, unsigned long addr, const void *b,
	       unsigned bytes)
{
	if (!lguest_address_ok(cpu->lg, addr, bytes)
	    || copy_to_user(cpu->lg->mem_base + addr, b, bytes) != 0)
		kill_guest(cpu, "bad write address %#lx len %u", addr, bytes);
}
/*:*/

/*H:030 Let's jump straight to the the main loop which runs the Guest.
 * Remember, this is called by the Launcher reading /dev/lguest, and we keep
 * going around and around until something interesting happens. */
int run_guest(struct lg_cpu *cpu, unsigned long __user *user)
{
	/* We stop running once the Guest is dead. */
	while (!cpu->lg->dead) {
		/* First we run any hypercalls the Guest wants done. */
		if (cpu->hcall)
			do_hypercalls(cpu);

		/* It's possible the Guest did a NOTIFY hypercall to the
		 * Launcher, in which case we return from the read() now. */
		if (cpu->pending_notify) {
			if (put_user(cpu->pending_notify, user))
				return -EFAULT;
			return sizeof(cpu->pending_notify);
		}

		/* Check for signals */
		if (signal_pending(current))
			return -ERESTARTSYS;

		/* If Waker set break_out, return to Launcher. */
		if (cpu->break_out)
			return -EAGAIN;

		/* Check if there are any interrupts which can be delivered
		 * now: if so, this sets up the hander to be executed when we
		 * next run the Guest. */
		maybe_do_interrupt(cpu);

		/* All long-lived kernel loops need to check with this horrible
		 * thing called the freezer.  If the Host is trying to suspend,
		 * it stops us. */
		try_to_freeze();

		/* Just make absolutely sure the Guest is still alive.  One of
		 * those hypercalls could have been fatal, for example. */
		if (cpu->lg->dead)
			break;

		/* If the Guest asked to be stopped, we sleep.  The Guest's
		 * clock timer or LHCALL_BREAK from the Waker will wake us. */
		if (cpu->halted) {
			set_current_state(TASK_INTERRUPTIBLE);
			schedule();
			continue;
		}

		/* OK, now we're ready to jump into the Guest.  First we put up
		 * the "Do Not Disturb" sign: */
		local_irq_disable();

		/* Actually run the Guest until something happens. */
		lguest_arch_run_guest(cpu);

		/* Now we're ready to be interrupted or moved to other CPUs */
		local_irq_enable();

		/* Now we deal with whatever happened to the Guest. */
		lguest_arch_handle_trap(cpu);
	}

	if (cpu->lg->dead == ERR_PTR(-ERESTART))
		return -ERESTART;
	/* The Guest is dead => "No such file or directory" */
	return -ENOENT;
}

/*H:000
 * Welcome to the Host!
 *
 * By this point your brain has been tickled by the Guest code and numbed by
 * the Launcher code; prepare for it to be stretched by the Host code.  This is
 * the heart.  Let's begin at the initialization routine for the Host's lg
 * module.
 */
static int __init init(void)
{
	int err;

	/* Lguest can't run under Xen, VMI or itself.  It does Tricky Stuff. */
	if (paravirt_enabled()) {
		printk("lguest is afraid of being a guest\n");
		return -EPERM;
	}

	/* First we put the Switcher up in very high virtual memory. */
	err = map_switcher();
	if (err)
		goto out;

	/* Now we set up the pagetable implementation for the Guests. */
	err = init_pagetables(switcher_page, SHARED_SWITCHER_PAGES);
	if (err)
		goto unmap;

	/* We might need to reserve an interrupt vector. */
	err = init_interrupts();
	if (err)
		goto free_pgtables;

	/* /dev/lguest needs to be registered. */
	err = lguest_device_init();
	if (err)
		goto free_interrupts;

	/* Finally we do some architecture-specific setup. */
	lguest_arch_host_init();

	/* All good! */
	return 0;

free_interrupts:
	free_interrupts();
free_pgtables:
	free_pagetables();
unmap:
	unmap_switcher();
out:
	return err;
}

/* Cleaning up is just the same code, backwards.  With a little French. */
static void __exit fini(void)
{
	lguest_device_remove();
	free_interrupts();
	free_pagetables();
	unmap_switcher();

	lguest_arch_host_fini();
}
/*:*/

/* The Host side of lguest can be a module.  This is a nice way for people to
 * play with it.  */
module_init(init);
module_exit(fini);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Rusty Russell <rusty@rustcorp.com.au>");
Commit	Line	Data
f938d2c8 RR	1	/*P:400 This contains run_guest() which actually calls into the Host<->Guest
	2	* Switcher and analyzes the return, such as determining if the Guest wants the
	3	* Host to do something. This file also contains useful helper routines, and a
	4	* couple of non-obvious setup and teardown pieces which were implemented after
	5	* days of debugging pain. :*/
d7e28ffe RR	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>
625efab1	14	#include <linux/highmem.h>
d7e28ffe	15	#include <asm/paravirt.h>
d7e28ffe RR	16	#include <asm/pgtable.h>
	17	#include <asm/uaccess.h>
	18	#include <asm/poll.h>
d7e28ffe	19	#include <asm/asm-offsets.h>
d7e28ffe RR	20	#include "lg.h"
d7e28ffe RR	21
d7e28ffe RR	22
	23	static struct vm_struct *switcher_vma;
	24	static struct page **switcher_page;
	25
d7e28ffe RR	26	/* This One Big lock protects all inter-guest data structures. */
d7e28ffe RR	27	DEFINE_MUTEX(lguest_lock);
d7e28ffe	28
bff672e6 RR	29	/*H:010 We need to set up the Switcher at a high virtual address. Remember the
	30	* Switcher is a few hundred bytes of assembler code which actually changes the
	31	* CPU to run the Guest, and then changes back to the Host when a trap or
	32	* interrupt happens.
	33	*
	34	* The Switcher code must be at the same virtual address in the Guest as the
	35	* Host since it will be running as the switchover occurs.
	36	*
	37	* Trying to map memory at a particular address is an unusual thing to do, so
625efab1	38	* it's not a simple one-liner. */
d7e28ffe RR	39	static __init int map_switcher(void)
	40	{
	41	int i, err;
	42	struct page **pagep;
	43
bff672e6 RR	44	/*
	45	* Map the Switcher in to high memory.
	46	*
	47	* It turns out that if we choose the address 0xFFC00000 (4MB under the
	48	* top virtual address), it makes setting up the page tables really
	49	* easy.
	50	*/
	51
	52	/* We allocate an array of "struct page"s. map_vm_area() wants the
	53	* pages in this form, rather than just an array of pointers. */
d7e28ffe RR	54	switcher_page = kmalloc(sizeof(switcher_page[0])*TOTAL_SWITCHER_PAGES,
	55	GFP_KERNEL);
	56	if (!switcher_page) {
	57	err = -ENOMEM;
	58	goto out;
	59	}
	60
bff672e6 RR	61	/* Now we actually allocate the pages. The Guest will see these pages,
bff672e6 RR	62	* so we make sure they're zeroed. */
d7e28ffe RR	63	for (i = 0; i < TOTAL_SWITCHER_PAGES; i++) {
	64	unsigned long addr = get_zeroed_page(GFP_KERNEL);
	65	if (!addr) {
	66	err = -ENOMEM;
	67	goto free_some_pages;
	68	}
	69	switcher_page[i] = virt_to_page(addr);
	70	}
	71
f14ae652 RR	72	/* First we check that the Switcher won't overlap the fixmap area at
	73	* the top of memory. It's currently nowhere near, but it could have
	74	* very strange effects if it ever happened. */
	75	if (SWITCHER_ADDR + (TOTAL_SWITCHER_PAGES+1)*PAGE_SIZE > FIXADDR_START){
	76	err = -ENOMEM;
	77	printk("lguest: mapping switcher would thwack fixmap\n");
	78	goto free_pages;
	79	}
	80
bff672e6 RR	81	/* Now we reserve the "virtual memory area" we want: 0xFFC00000
bff672e6 RR	82	* (SWITCHER_ADDR). We might not get it in theory, but in practice
f14ae652 RR	83	* it's worked so far. The end address needs +1 because __get_vm_area
f14ae652 RR	84	* allocates an extra guard page, so we need space for that. */
d7e28ffe	85	switcher_vma = __get_vm_area(TOTAL_SWITCHER_PAGES * PAGE_SIZE,
f14ae652 RR	86	VM_ALLOC, SWITCHER_ADDR, SWITCHER_ADDR
f14ae652 RR	87	+ (TOTAL_SWITCHER_PAGES+1) * PAGE_SIZE);
d7e28ffe RR	88	if (!switcher_vma) {
	89	err = -ENOMEM;
	90	printk("lguest: could not map switcher pages high\n");
	91	goto free_pages;
	92	}
	93
bff672e6 RR	94	/* This code actually sets up the pages we've allocated to appear at
	95	* SWITCHER_ADDR. map_vm_area() takes the vma we allocated above, the
	96	* kind of pages we're mapping (kernel pages), and a pointer to our
	97	* array of struct pages. It increments that pointer, but we don't
	98	* care. */
d7e28ffe RR	99	pagep = switcher_page;
	100	err = map_vm_area(switcher_vma, PAGE_KERNEL, &pagep);
	101	if (err) {
	102	printk("lguest: map_vm_area failed: %i\n", err);
	103	goto free_vma;
	104	}
bff672e6	105
625efab1 JS	106	/* Now the Switcher is mapped at the right address, we can't fail!
625efab1 JS	107	* Copy in the compiled-in Switcher code (from <arch>_switcher.S). */
d7e28ffe RR	108	memcpy(switcher_vma->addr, start_switcher_text,
	109	end_switcher_text - start_switcher_text);
	110
d7e28ffe RR	111	printk(KERN_INFO "lguest: mapped switcher at %p\n",
d7e28ffe RR	112	switcher_vma->addr);
bff672e6	113	/* And we succeeded... */
d7e28ffe RR	114	return 0;
	115
	116	free_vma:
	117	vunmap(switcher_vma->addr);
	118	free_pages:
	119	i = TOTAL_SWITCHER_PAGES;
	120	free_some_pages:
	121	for (--i; i >= 0; i--)
	122	__free_pages(switcher_page[i], 0);
	123	kfree(switcher_page);
	124	out:
	125	return err;
	126	}
bff672e6	127	/:/
d7e28ffe	128
bff672e6 RR	129	/* Cleaning up the mapping when the module is unloaded is almost...
bff672e6 RR	130	* too easy. */
d7e28ffe RR	131	static void unmap_switcher(void)
	132	{
	133	unsigned int i;
	134
bff672e6	135	/* vunmap() undoes both map_vm_area() and __get_vm_area(). */
d7e28ffe	136	vunmap(switcher_vma->addr);
bff672e6	137	/* Now we just need to free the pages we copied the switcher into */
d7e28ffe RR	138	for (i = 0; i < TOTAL_SWITCHER_PAGES; i++)
	139	__free_pages(switcher_page[i], 0);
	140	}
	141
e1e72965	142	/*H:032
dde79789 RR	143	* Dealing With Guest Memory.
dde79789 RR	144	*
e1e72965 RR	145	* Before we go too much further into the Host, we need to grok the routines
	146	* we use to deal with Guest memory.
	147	*
dde79789	148	* When the Guest gives us (what it thinks is) a physical address, we can use
3c6b5bfa RR	149	* the normal copy_from_user() & copy_to_user() on the corresponding place in
3c6b5bfa RR	150	* the memory region allocated by the Launcher.
dde79789 RR	151	*
	152	* But we can't trust the Guest: it might be trying to access the Launcher
	153	* code. We have to check that the range is below the pfn_limit the Launcher
	154	* gave us. We have to make sure that addr + len doesn't give us a false
	155	* positive by overflowing, too. */
d7e28ffe RR	156	int lguest_address_ok(const struct lguest *lg,
	157	unsigned long addr, unsigned long len)
	158	{
	159	return (addr+len) / PAGE_SIZE < lg->pfn_limit && (addr+len >= addr);
	160	}
	161
2d37f94a RR	162	/* This routine copies memory from the Guest. Here we can see how useful the
	163	* kill_lguest() routine we met in the Launcher can be: we return a random
	164	* value (all zeroes) instead of needing to return an error. */
382ac6b3	165	void __lgread(struct lg_cpu cpu, void b, unsigned long addr, unsigned bytes)
d7e28ffe	166	{
382ac6b3 GOC	167	if (!lguest_address_ok(cpu->lg, addr, bytes)
382ac6b3 GOC	168	\|\| copy_from_user(b, cpu->lg->mem_base + addr, bytes) != 0) {
d7e28ffe RR	169	/* copy_from_user should do this, but as we rely on it... */
d7e28ffe RR	170	memset(b, 0, bytes);
382ac6b3	171	kill_guest(cpu, "bad read address %#lx len %u", addr, bytes);
d7e28ffe RR	172	}
	173	}
	174
2d37f94a	175	/* This is the write (copy into guest) version. */
382ac6b3	176	void __lgwrite(struct lg_cpu cpu, unsigned long addr, const void b,
2d37f94a	177	unsigned bytes)
d7e28ffe	178	{
382ac6b3 GOC	179	if (!lguest_address_ok(cpu->lg, addr, bytes)
	180	\|\| copy_to_user(cpu->lg->mem_base + addr, b, bytes) != 0)
	181	kill_guest(cpu, "bad write address %#lx len %u", addr, bytes);
d7e28ffe	182	}
2d37f94a	183	/:/
d7e28ffe	184
bff672e6 RR	185	/*H:030 Let's jump straight to the the main loop which runs the Guest.
	186	* Remember, this is called by the Launcher reading /dev/lguest, and we keep
	187	* going around and around until something interesting happens. */
d0953d42	188	int run_guest(struct lg_cpu cpu, unsigned long __user user)
d7e28ffe	189	{
bff672e6	190	/* We stop running once the Guest is dead. */
382ac6b3	191	while (!cpu->lg->dead) {
cc6d4fbc	192	/* First we run any hypercalls the Guest wants done. */
73044f05 GOC	193	if (cpu->hcall)
73044f05 GOC	194	do_hypercalls(cpu);
cc6d4fbc	195
15045275	196	/* It's possible the Guest did a NOTIFY hypercall to the
bff672e6	197	* Launcher, in which case we return from the read() now. */
5e232f4f GOC	198	if (cpu->pending_notify) {
5e232f4f GOC	199	if (put_user(cpu->pending_notify, user))
d7e28ffe	200	return -EFAULT;
5e232f4f	201	return sizeof(cpu->pending_notify);
d7e28ffe RR	202	}
d7e28ffe RR	203
bff672e6	204	/* Check for signals */
d7e28ffe RR	205	if (signal_pending(current))
	206	return -ERESTARTSYS;
	207
	208	/* If Waker set break_out, return to Launcher. */
66686c2a	209	if (cpu->break_out)
d7e28ffe RR	210	return -EAGAIN;
d7e28ffe RR	211
bff672e6 RR	212	/* Check if there are any interrupts which can be delivered
	213	* now: if so, this sets up the hander to be executed when we
	214	* next run the Guest. */
177e449d	215	maybe_do_interrupt(cpu);
d7e28ffe	216
bff672e6 RR	217	/* All long-lived kernel loops need to check with this horrible
	218	* thing called the freezer. If the Host is trying to suspend,
	219	* it stops us. */
d7e28ffe RR	220	try_to_freeze();
d7e28ffe RR	221
bff672e6 RR	222	/* Just make absolutely sure the Guest is still alive. One of
bff672e6 RR	223	* those hypercalls could have been fatal, for example. */
382ac6b3	224	if (cpu->lg->dead)
d7e28ffe RR	225	break;
d7e28ffe RR	226
bff672e6 RR	227	/* If the Guest asked to be stopped, we sleep. The Guest's
bff672e6 RR	228	* clock timer or LHCALL_BREAK from the Waker will wake us. */
66686c2a	229	if (cpu->halted) {
d7e28ffe RR	230	set_current_state(TASK_INTERRUPTIBLE);
	231	schedule();
	232	continue;
	233	}
	234
bff672e6 RR	235	/* OK, now we're ready to jump into the Guest. First we put up
bff672e6 RR	236	* the "Do Not Disturb" sign: */
d7e28ffe RR	237	local_irq_disable();
d7e28ffe RR	238
625efab1	239	/* Actually run the Guest until something happens. */
d0953d42	240	lguest_arch_run_guest(cpu);
bff672e6 RR	241
bff672e6 RR	242	/* Now we're ready to be interrupted or moved to other CPUs */
d7e28ffe RR	243	local_irq_enable();
d7e28ffe RR	244
625efab1	245	/* Now we deal with whatever happened to the Guest. */
73044f05	246	lguest_arch_handle_trap(cpu);
d7e28ffe	247	}
625efab1	248
382ac6b3	249	if (cpu->lg->dead == ERR_PTR(-ERESTART))
ec04b13f	250	return -ERESTART;
bff672e6	251	/* The Guest is dead => "No such file or directory" */
d7e28ffe RR	252	return -ENOENT;
	253	}
	254
bff672e6 RR	255	/*H:000
	256	* Welcome to the Host!
	257	*
	258	* By this point your brain has been tickled by the Guest code and numbed by
	259	* the Launcher code; prepare for it to be stretched by the Host code. This is
	260	* the heart. Let's begin at the initialization routine for the Host's lg
	261	* module.
	262	*/
d7e28ffe RR	263	static int __init init(void)
	264	{
	265	int err;
	266
bff672e6	267	/* Lguest can't run under Xen, VMI or itself. It does Tricky Stuff. */
d7e28ffe	268	if (paravirt_enabled()) {
5c55841d	269	printk("lguest is afraid of being a guest\n");
d7e28ffe RR	270	return -EPERM;
	271	}
	272
bff672e6	273	/* First we put the Switcher up in very high virtual memory. */
d7e28ffe RR	274	err = map_switcher();
d7e28ffe RR	275	if (err)
c18acd73	276	goto out;
d7e28ffe	277
bff672e6	278	/* Now we set up the pagetable implementation for the Guests. */
d7e28ffe	279	err = init_pagetables(switcher_page, SHARED_SWITCHER_PAGES);
c18acd73 RR	280	if (err)
c18acd73 RR	281	goto unmap;
bff672e6	282
c18acd73 RR	283	/* We might need to reserve an interrupt vector. */
	284	err = init_interrupts();
	285	if (err)
	286	goto free_pgtables;
	287
bff672e6	288	/* /dev/lguest needs to be registered. */
d7e28ffe	289	err = lguest_device_init();
c18acd73 RR	290	if (err)
c18acd73 RR	291	goto free_interrupts;
bff672e6	292
625efab1 JS	293	/* Finally we do some architecture-specific setup. */
625efab1 JS	294	lguest_arch_host_init();
bff672e6 RR	295
bff672e6 RR	296	/* All good! */
d7e28ffe	297	return 0;
c18acd73 RR	298
	299	free_interrupts:
	300	free_interrupts();
	301	free_pgtables:
	302	free_pagetables();
	303	unmap:
	304	unmap_switcher();
	305	out:
	306	return err;
d7e28ffe RR	307	}
d7e28ffe RR	308
bff672e6	309	/* Cleaning up is just the same code, backwards. With a little French. */
d7e28ffe RR	310	static void __exit fini(void)
	311	{
	312	lguest_device_remove();
c18acd73	313	free_interrupts();
d7e28ffe RR	314	free_pagetables();
d7e28ffe RR	315	unmap_switcher();
bff672e6	316
625efab1	317	lguest_arch_host_fini();
d7e28ffe	318	}
625efab1	319	/:/
d7e28ffe	320
bff672e6 RR	321	/* The Host side of lguest can be a module. This is a nice way for people to
bff672e6 RR	322	* play with it. */
d7e28ffe RR	323	module_init(init);
	324	module_exit(fini);
	325	MODULE_LICENSE("GPL");
	326	MODULE_AUTHOR("Rusty Russell <rusty@rustcorp.com.au>");