[deliverable/linux.git] / drivers / lguest / page_tables.c

/* Shadow page table operations.
 * Copyright (C) Rusty Russell IBM Corporation 2006.
 * GPL v2 and any later version */
#include <linux/mm.h>
#include <linux/types.h>
#include <linux/spinlock.h>
#include <linux/random.h>
#include <linux/percpu.h>
#include <asm/tlbflush.h>
#include "lg.h"

#define PTES_PER_PAGE_SHIFT 10
#define PTES_PER_PAGE (1 << PTES_PER_PAGE_SHIFT)
#define SWITCHER_PGD_INDEX (PTES_PER_PAGE - 1)

static DEFINE_PER_CPU(spte_t *, switcher_pte_pages);
#define switcher_pte_page(cpu) per_cpu(switcher_pte_pages, cpu)

static unsigned vaddr_to_pgd_index(unsigned long vaddr)
{
	return vaddr >> (PAGE_SHIFT + PTES_PER_PAGE_SHIFT);
}

/* These access the shadow versions (ie. the ones used by the CPU). */
static spgd_t *spgd_addr(struct lguest *lg, u32 i, unsigned long vaddr)
{
	unsigned int index = vaddr_to_pgd_index(vaddr);

	if (index >= SWITCHER_PGD_INDEX) {
		kill_guest(lg, "attempt to access switcher pages");
		index = 0;
	}
	return &lg->pgdirs[i].pgdir[index];
}

static spte_t *spte_addr(struct lguest *lg, spgd_t spgd, unsigned long vaddr)
{
	spte_t *page = __va(spgd.pfn << PAGE_SHIFT);
	BUG_ON(!(spgd.flags & _PAGE_PRESENT));
	return &page[(vaddr >> PAGE_SHIFT) % PTES_PER_PAGE];
}

/* These access the guest versions. */
static unsigned long gpgd_addr(struct lguest *lg, unsigned long vaddr)
{
	unsigned int index = vaddr >> (PAGE_SHIFT + PTES_PER_PAGE_SHIFT);
	return lg->pgdirs[lg->pgdidx].cr3 + index * sizeof(gpgd_t);
}

static unsigned long gpte_addr(struct lguest *lg,
			       gpgd_t gpgd, unsigned long vaddr)
{
	unsigned long gpage = gpgd.pfn << PAGE_SHIFT;
	BUG_ON(!(gpgd.flags & _PAGE_PRESENT));
	return gpage + ((vaddr>>PAGE_SHIFT) % PTES_PER_PAGE) * sizeof(gpte_t);
}

/* Do a virtual -> physical mapping on a user page. */
static unsigned long get_pfn(unsigned long virtpfn, int write)
{
	struct page *page;
	unsigned long ret = -1UL;

	down_read(&current->mm->mmap_sem);
	if (get_user_pages(current, current->mm, virtpfn << PAGE_SHIFT,
			   1, write, 1, &page, NULL) == 1)
		ret = page_to_pfn(page);
	up_read(&current->mm->mmap_sem);
	return ret;
}

static spte_t gpte_to_spte(struct lguest *lg, gpte_t gpte, int write)
{
	spte_t spte;
	unsigned long pfn;

	/* We ignore the global flag. */
	spte.flags = (gpte.flags & ~_PAGE_GLOBAL);
	pfn = get_pfn(gpte.pfn, write);
	if (pfn == -1UL) {
		kill_guest(lg, "failed to get page %u", gpte.pfn);
		/* Must not put_page() bogus page on cleanup. */
		spte.flags = 0;
	}
	spte.pfn = pfn;
	return spte;
}

static void release_pte(spte_t pte)
{
	if (pte.flags & _PAGE_PRESENT)
		put_page(pfn_to_page(pte.pfn));
}

static void check_gpte(struct lguest *lg, gpte_t gpte)
{
	if ((gpte.flags & (_PAGE_PWT|_PAGE_PSE)) || gpte.pfn >= lg->pfn_limit)
		kill_guest(lg, "bad page table entry");
}

static void check_gpgd(struct lguest *lg, gpgd_t gpgd)
{
	if ((gpgd.flags & ~_PAGE_TABLE) || gpgd.pfn >= lg->pfn_limit)
		kill_guest(lg, "bad page directory entry");
}

/* FIXME: We hold reference to pages, which prevents them from being
   swapped.  It'd be nice to have a callback when Linux wants to swap out. */

/* We fault pages in, which allows us to update accessed/dirty bits.
 * Return true if we got page. */
int demand_page(struct lguest *lg, unsigned long vaddr, int errcode)
{
	gpgd_t gpgd;
	spgd_t *spgd;
	unsigned long gpte_ptr;
	gpte_t gpte;
	spte_t *spte;

	gpgd = mkgpgd(lgread_u32(lg, gpgd_addr(lg, vaddr)));
	if (!(gpgd.flags & _PAGE_PRESENT))
		return 0;

	spgd = spgd_addr(lg, lg->pgdidx, vaddr);
	if (!(spgd->flags & _PAGE_PRESENT)) {
		/* Get a page of PTEs for them. */
		unsigned long ptepage = get_zeroed_page(GFP_KERNEL);
		/* FIXME: Steal from self in this case? */
		if (!ptepage) {
			kill_guest(lg, "out of memory allocating pte page");
			return 0;
		}
		check_gpgd(lg, gpgd);
		spgd->raw.val = (__pa(ptepage) | gpgd.flags);
	}

	gpte_ptr = gpte_addr(lg, gpgd, vaddr);
	gpte = mkgpte(lgread_u32(lg, gpte_ptr));

	/* No page? */
	if (!(gpte.flags & _PAGE_PRESENT))
		return 0;

	/* Write to read-only page? */
	if ((errcode & 2) && !(gpte.flags & _PAGE_RW))
		return 0;

	/* User access to a non-user page? */
	if ((errcode & 4) && !(gpte.flags & _PAGE_USER))
		return 0;

	check_gpte(lg, gpte);
	gpte.flags |= _PAGE_ACCESSED;
	if (errcode & 2)
		gpte.flags |= _PAGE_DIRTY;

	/* We're done with the old pte. */
	spte = spte_addr(lg, *spgd, vaddr);
	release_pte(*spte);

	/* We don't make it writable if this isn't a write: later
	 * write will fault so we can set dirty bit in guest. */
	if (gpte.flags & _PAGE_DIRTY)
		*spte = gpte_to_spte(lg, gpte, 1);
	else {
		gpte_t ro_gpte = gpte;
		ro_gpte.flags &= ~_PAGE_RW;
		*spte = gpte_to_spte(lg, ro_gpte, 0);
	}

	/* Now we update dirty/accessed on guest. */
	lgwrite_u32(lg, gpte_ptr, gpte.raw.val);
	return 1;
}

/* This is much faster than the full demand_page logic. */
static int page_writable(struct lguest *lg, unsigned long vaddr)
{
	spgd_t *spgd;
	unsigned long flags;

	spgd = spgd_addr(lg, lg->pgdidx, vaddr);
	if (!(spgd->flags & _PAGE_PRESENT))
		return 0;

	flags = spte_addr(lg, *spgd, vaddr)->flags;
	return (flags & (_PAGE_PRESENT|_PAGE_RW)) == (_PAGE_PRESENT|_PAGE_RW);
}

void pin_page(struct lguest *lg, unsigned long vaddr)
{
	if (!page_writable(lg, vaddr) && !demand_page(lg, vaddr, 2))
		kill_guest(lg, "bad stack page %#lx", vaddr);
}

static void release_pgd(struct lguest *lg, spgd_t *spgd)
{
	if (spgd->flags & _PAGE_PRESENT) {
		unsigned int i;
		spte_t *ptepage = __va(spgd->pfn << PAGE_SHIFT);
		for (i = 0; i < PTES_PER_PAGE; i++)
			release_pte(ptepage[i]);
		free_page((long)ptepage);
		spgd->raw.val = 0;
	}
}

static void flush_user_mappings(struct lguest *lg, int idx)
{
	unsigned int i;
	for (i = 0; i < vaddr_to_pgd_index(lg->page_offset); i++)
		release_pgd(lg, lg->pgdirs[idx].pgdir + i);
}

void guest_pagetable_flush_user(struct lguest *lg)
{
	flush_user_mappings(lg, lg->pgdidx);
}

static unsigned int find_pgdir(struct lguest *lg, unsigned long pgtable)
{
	unsigned int i;
	for (i = 0; i < ARRAY_SIZE(lg->pgdirs); i++)
		if (lg->pgdirs[i].cr3 == pgtable)
			break;
	return i;
}

static unsigned int new_pgdir(struct lguest *lg,
			      unsigned long cr3,
			      int *blank_pgdir)
{
	unsigned int next;

	next = random32() % ARRAY_SIZE(lg->pgdirs);
	if (!lg->pgdirs[next].pgdir) {
		lg->pgdirs[next].pgdir = (spgd_t *)get_zeroed_page(GFP_KERNEL);
		if (!lg->pgdirs[next].pgdir)
			next = lg->pgdidx;
		else
			/* There are no mappings: you'll need to re-pin */
			*blank_pgdir = 1;
	}
	lg->pgdirs[next].cr3 = cr3;
	/* Release all the non-kernel mappings. */
	flush_user_mappings(lg, next);

	return next;
}

void guest_new_pagetable(struct lguest *lg, unsigned long pgtable)
{
	int newpgdir, repin = 0;

	newpgdir = find_pgdir(lg, pgtable);
	if (newpgdir == ARRAY_SIZE(lg->pgdirs))
		newpgdir = new_pgdir(lg, pgtable, &repin);
	lg->pgdidx = newpgdir;
	if (repin)
		pin_stack_pages(lg);
}

static void release_all_pagetables(struct lguest *lg)
{
	unsigned int i, j;

	for (i = 0; i < ARRAY_SIZE(lg->pgdirs); i++)
		if (lg->pgdirs[i].pgdir)
			for (j = 0; j < SWITCHER_PGD_INDEX; j++)
				release_pgd(lg, lg->pgdirs[i].pgdir + j);
}

void guest_pagetable_clear_all(struct lguest *lg)
{
	release_all_pagetables(lg);
	pin_stack_pages(lg);
}

static void do_set_pte(struct lguest *lg, int idx,
		       unsigned long vaddr, gpte_t gpte)
{
	spgd_t *spgd = spgd_addr(lg, idx, vaddr);
	if (spgd->flags & _PAGE_PRESENT) {
		spte_t *spte = spte_addr(lg, *spgd, vaddr);
		release_pte(*spte);
		if (gpte.flags & (_PAGE_DIRTY | _PAGE_ACCESSED)) {
			check_gpte(lg, gpte);
			*spte = gpte_to_spte(lg, gpte, gpte.flags&_PAGE_DIRTY);
		} else
			spte->raw.val = 0;
	}
}

void guest_set_pte(struct lguest *lg,
		   unsigned long cr3, unsigned long vaddr, gpte_t gpte)
{
	/* Kernel mappings must be changed on all top levels. */
	if (vaddr >= lg->page_offset) {
		unsigned int i;
		for (i = 0; i < ARRAY_SIZE(lg->pgdirs); i++)
			if (lg->pgdirs[i].pgdir)
				do_set_pte(lg, i, vaddr, gpte);
	} else {
		int pgdir = find_pgdir(lg, cr3);
		if (pgdir != ARRAY_SIZE(lg->pgdirs))
			do_set_pte(lg, pgdir, vaddr, gpte);
	}
}

void guest_set_pmd(struct lguest *lg, unsigned long cr3, u32 idx)
{
	int pgdir;

	if (idx >= SWITCHER_PGD_INDEX)
		return;

	pgdir = find_pgdir(lg, cr3);
	if (pgdir < ARRAY_SIZE(lg->pgdirs))
		release_pgd(lg, lg->pgdirs[pgdir].pgdir + idx);
}

int init_guest_pagetable(struct lguest *lg, unsigned long pgtable)
{
	/* We assume this in flush_user_mappings, so check now */
	if (vaddr_to_pgd_index(lg->page_offset) >= SWITCHER_PGD_INDEX)
		return -EINVAL;
	lg->pgdidx = 0;
	lg->pgdirs[lg->pgdidx].cr3 = pgtable;
	lg->pgdirs[lg->pgdidx].pgdir = (spgd_t*)get_zeroed_page(GFP_KERNEL);
	if (!lg->pgdirs[lg->pgdidx].pgdir)
		return -ENOMEM;
	return 0;
}

void free_guest_pagetable(struct lguest *lg)
{
	unsigned int i;

	release_all_pagetables(lg);
	for (i = 0; i < ARRAY_SIZE(lg->pgdirs); i++)
		free_page((long)lg->pgdirs[i].pgdir);
}

/* Caller must be preempt-safe */
void map_switcher_in_guest(struct lguest *lg, struct lguest_pages *pages)
{
	spte_t *switcher_pte_page = __get_cpu_var(switcher_pte_pages);
	spgd_t switcher_pgd;
	spte_t regs_pte;

	/* Since switcher less that 4MB, we simply mug top pte page. */
	switcher_pgd.pfn = __pa(switcher_pte_page) >> PAGE_SHIFT;
	switcher_pgd.flags = _PAGE_KERNEL;
	lg->pgdirs[lg->pgdidx].pgdir[SWITCHER_PGD_INDEX] = switcher_pgd;

	/* Map our regs page over stack page. */
	regs_pte.pfn = __pa(lg->regs_page) >> PAGE_SHIFT;
	regs_pte.flags = _PAGE_KERNEL;
	switcher_pte_page[(unsigned long)pages/PAGE_SIZE%PTES_PER_PAGE]
		= regs_pte;
}

static void free_switcher_pte_pages(void)
{
	unsigned int i;

	for_each_possible_cpu(i)
		free_page((long)switcher_pte_page(i));
}

static __init void populate_switcher_pte_page(unsigned int cpu,
					      struct page *switcher_page[],
					      unsigned int pages)
{
	unsigned int i;
	spte_t *pte = switcher_pte_page(cpu);

	for (i = 0; i < pages; i++) {
		pte[i].pfn = page_to_pfn(switcher_page[i]);
		pte[i].flags = _PAGE_PRESENT|_PAGE_ACCESSED;
	}

	/* We only map this CPU's pages, so guest can't see others. */
	i = pages + cpu*2;

	/* First page (regs) is rw, second (state) is ro. */
	pte[i].pfn = page_to_pfn(switcher_page[i]);
	pte[i].flags = _PAGE_PRESENT|_PAGE_ACCESSED|_PAGE_RW;
	pte[i+1].pfn = page_to_pfn(switcher_page[i+1]);
	pte[i+1].flags = _PAGE_PRESENT|_PAGE_ACCESSED;
}

__init int init_pagetables(struct page **switcher_page, unsigned int pages)
{
	unsigned int i;

	for_each_possible_cpu(i) {
		switcher_pte_page(i) = (spte_t *)get_zeroed_page(GFP_KERNEL);
		if (!switcher_pte_page(i)) {
			free_switcher_pte_pages();
			return -ENOMEM;
		}
		populate_switcher_pte_page(i, switcher_page, pages);
	}
	return 0;
}

void free_pagetables(void)
{
	free_switcher_pte_pages();
}
Commit	Line	Data
d7e28ffe RR	1	/* Shadow page table operations.
	2	* Copyright (C) Rusty Russell IBM Corporation 2006.
	3	* GPL v2 and any later version */
	4	#include <linux/mm.h>
	5	#include <linux/types.h>
	6	#include <linux/spinlock.h>
	7	#include <linux/random.h>
	8	#include <linux/percpu.h>
	9	#include <asm/tlbflush.h>
	10	#include "lg.h"
	11
	12	#define PTES_PER_PAGE_SHIFT 10
	13	#define PTES_PER_PAGE (1 << PTES_PER_PAGE_SHIFT)
	14	#define SWITCHER_PGD_INDEX (PTES_PER_PAGE - 1)
	15
	16	static DEFINE_PER_CPU(spte_t *, switcher_pte_pages);
	17	#define switcher_pte_page(cpu) per_cpu(switcher_pte_pages, cpu)
	18
	19	static unsigned vaddr_to_pgd_index(unsigned long vaddr)
	20	{
	21	return vaddr >> (PAGE_SHIFT + PTES_PER_PAGE_SHIFT);
	22	}
	23
	24	/* These access the shadow versions (ie. the ones used by the CPU). */
	25	static spgd_t spgd_addr(struct lguest lg, u32 i, unsigned long vaddr)
	26	{
	27	unsigned int index = vaddr_to_pgd_index(vaddr);
	28
	29	if (index >= SWITCHER_PGD_INDEX) {
	30	kill_guest(lg, "attempt to access switcher pages");
	31	index = 0;
	32	}
	33	return &lg->pgdirs[i].pgdir[index];
	34	}
	35
	36	static spte_t spte_addr(struct lguest lg, spgd_t spgd, unsigned long vaddr)
	37	{
	38	spte_t *page = __va(spgd.pfn << PAGE_SHIFT);
	39	BUG_ON(!(spgd.flags & _PAGE_PRESENT));
	40	return &page[(vaddr >> PAGE_SHIFT) % PTES_PER_PAGE];
	41	}
	42
	43	/* These access the guest versions. */
	44	static unsigned long gpgd_addr(struct lguest *lg, unsigned long vaddr)
	45	{
	46	unsigned int index = vaddr >> (PAGE_SHIFT + PTES_PER_PAGE_SHIFT);
	47	return lg->pgdirs[lg->pgdidx].cr3 + index * sizeof(gpgd_t);
	48	}
	49
	50	static unsigned long gpte_addr(struct lguest *lg,
	51	gpgd_t gpgd, unsigned long vaddr)
	52	{
	53	unsigned long gpage = gpgd.pfn << PAGE_SHIFT;
	54	BUG_ON(!(gpgd.flags & _PAGE_PRESENT));
	55	return gpage + ((vaddr>>PAGE_SHIFT) % PTES_PER_PAGE) * sizeof(gpte_t);
	56	}
	57
	58	/* Do a virtual -> physical mapping on a user page. */
	59	static unsigned long get_pfn(unsigned long virtpfn, int write)
	60	{
	61	struct page *page;
	62	unsigned long ret = -1UL;
	63
	64	down_read(&current->mm->mmap_sem);
65	if (get_user_pages(current, current->mm, virtpfn << PAGE_SHIFT,
66	1, write, 1, &page, NULL) == 1)
67	ret = page_to_pfn(page);
68	up_read(&current->mm->mmap_sem);
69	return ret;
70	}
71
72	static spte_t gpte_to_spte(struct lguest *lg, gpte_t gpte, int write)
73	{
74	spte_t spte;
75	unsigned long pfn;
76
77	/* We ignore the global flag. */
78	spte.flags = (gpte.flags & ~_PAGE_GLOBAL);
79	pfn = get_pfn(gpte.pfn, write);
80	if (pfn == -1UL) {
81	kill_guest(lg, "failed to get page %u", gpte.pfn);
82	/* Must not put_page() bogus page on cleanup. */
83	spte.flags = 0;
84	}
85	spte.pfn = pfn;
86	return spte;
87	}
88
89	static void release_pte(spte_t pte)
90	{
91	if (pte.flags & _PAGE_PRESENT)
92	put_page(pfn_to_page(pte.pfn));
93	}
94
95	static void check_gpte(struct lguest *lg, gpte_t gpte)
96	{
97	if ((gpte.flags & (_PAGE_PWT\|_PAGE_PSE)) \|\| gpte.pfn >= lg->pfn_limit)
98	kill_guest(lg, "bad page table entry");
99	}
100
101	static void check_gpgd(struct lguest *lg, gpgd_t gpgd)
102	{
103	if ((gpgd.flags & ~_PAGE_TABLE) \|\| gpgd.pfn >= lg->pfn_limit)
104	kill_guest(lg, "bad page directory entry");
105	}
106
107	/* FIXME: We hold reference to pages, which prevents them from being
108	swapped. It'd be nice to have a callback when Linux wants to swap out. */
109
110	/* We fault pages in, which allows us to update accessed/dirty bits.
111	* Return true if we got page. */
112	int demand_page(struct lguest *lg, unsigned long vaddr, int errcode)
113	{
114	gpgd_t gpgd;
115	spgd_t *spgd;
116	unsigned long gpte_ptr;
117	gpte_t gpte;
118	spte_t *spte;
119
120	gpgd = mkgpgd(lgread_u32(lg, gpgd_addr(lg, vaddr)));
121	if (!(gpgd.flags & _PAGE_PRESENT))
122	return 0;
123
124	spgd = spgd_addr(lg, lg->pgdidx, vaddr);
125	if (!(spgd->flags & _PAGE_PRESENT)) {
126	/* Get a page of PTEs for them. */
127	unsigned long ptepage = get_zeroed_page(GFP_KERNEL);
128	/* FIXME: Steal from self in this case? */
129	if (!ptepage) {
130	kill_guest(lg, "out of memory allocating pte page");
131	return 0;
132	}
133	check_gpgd(lg, gpgd);
134	spgd->raw.val = (__pa(ptepage) \| gpgd.flags);
135	}
136
137	gpte_ptr = gpte_addr(lg, gpgd, vaddr);
138	gpte = mkgpte(lgread_u32(lg, gpte_ptr));
139
140	/* No page? */
141	if (!(gpte.flags & _PAGE_PRESENT))
142	return 0;
143
144	/* Write to read-only page? */
145	if ((errcode & 2) && !(gpte.flags & _PAGE_RW))
146	return 0;
147
148	/* User access to a non-user page? */
149	if ((errcode & 4) && !(gpte.flags & _PAGE_USER))
150	return 0;
151
152	check_gpte(lg, gpte);
153	gpte.flags \|= _PAGE_ACCESSED;
154	if (errcode & 2)
155	gpte.flags \|= _PAGE_DIRTY;
156
157	/* We're done with the old pte. */
158	spte = spte_addr(lg, *spgd, vaddr);
159	release_pte(*spte);
160
161	/* We don't make it writable if this isn't a write: later
162	* write will fault so we can set dirty bit in guest. */
163	if (gpte.flags & _PAGE_DIRTY)
164	*spte = gpte_to_spte(lg, gpte, 1);
165	else {
166	gpte_t ro_gpte = gpte;
167	ro_gpte.flags &= ~_PAGE_RW;
168	*spte = gpte_to_spte(lg, ro_gpte, 0);
169	}
170
171	/* Now we update dirty/accessed on guest. */
172	lgwrite_u32(lg, gpte_ptr, gpte.raw.val);
173	return 1;
174	}
175
176	/* This is much faster than the full demand_page logic. */
177	static int page_writable(struct lguest *lg, unsigned long vaddr)
178	{
179	spgd_t *spgd;
180	unsigned long flags;
181
182	spgd = spgd_addr(lg, lg->pgdidx, vaddr);
183	if (!(spgd->flags & _PAGE_PRESENT))
184	return 0;
185
186	flags = spte_addr(lg, *spgd, vaddr)->flags;
187	return (flags & (_PAGE_PRESENT\|_PAGE_RW)) == (_PAGE_PRESENT\|_PAGE_RW);
188	}
189
190	void pin_page(struct lguest *lg, unsigned long vaddr)
191	{
192	if (!page_writable(lg, vaddr) && !demand_page(lg, vaddr, 2))
193	kill_guest(lg, "bad stack page %#lx", vaddr);
194	}
195
196	static void release_pgd(struct lguest lg, spgd_t spgd)
197	{
198	if (spgd->flags & _PAGE_PRESENT) {
199	unsigned int i;
200	spte_t *ptepage = __va(spgd->pfn << PAGE_SHIFT);
201	for (i = 0; i < PTES_PER_PAGE; i++)
202	release_pte(ptepage[i]);
203	free_page((long)ptepage);
204	spgd->raw.val = 0;
205	}
206	}
207
208	static void flush_user_mappings(struct lguest *lg, int idx)
209	{
210	unsigned int i;
211	for (i = 0; i < vaddr_to_pgd_index(lg->page_offset); i++)
212	release_pgd(lg, lg->pgdirs[idx].pgdir + i);
213	}
214
215	void guest_pagetable_flush_user(struct lguest *lg)
216	{
217	flush_user_mappings(lg, lg->pgdidx);
218	}
219
220	static unsigned int find_pgdir(struct lguest *lg, unsigned long pgtable)
221	{
222	unsigned int i;
223	for (i = 0; i < ARRAY_SIZE(lg->pgdirs); i++)
224	if (lg->pgdirs[i].cr3 == pgtable)
225	break;
226	return i;
227	}
228
229	static unsigned int new_pgdir(struct lguest *lg,
230	unsigned long cr3,
231	int *blank_pgdir)
232	{
233	unsigned int next;
234
235	next = random32() % ARRAY_SIZE(lg->pgdirs);
236	if (!lg->pgdirs[next].pgdir) {
237	lg->pgdirs[next].pgdir = (spgd_t *)get_zeroed_page(GFP_KERNEL);
238	if (!lg->pgdirs[next].pgdir)
239	next = lg->pgdidx;
240	else
241	/* There are no mappings: you'll need to re-pin */
242	*blank_pgdir = 1;
243	}
244	lg->pgdirs[next].cr3 = cr3;
245	/* Release all the non-kernel mappings. */
246	flush_user_mappings(lg, next);
247
248	return next;
249	}
250
251	void guest_new_pagetable(struct lguest *lg, unsigned long pgtable)
252	{
253	int newpgdir, repin = 0;
254
255	newpgdir = find_pgdir(lg, pgtable);
256	if (newpgdir == ARRAY_SIZE(lg->pgdirs))
257	newpgdir = new_pgdir(lg, pgtable, &repin);
258	lg->pgdidx = newpgdir;
259	if (repin)
260	pin_stack_pages(lg);
261	}
262
263	static void release_all_pagetables(struct lguest *lg)
264	{
265	unsigned int i, j;
266
267	for (i = 0; i < ARRAY_SIZE(lg->pgdirs); i++)
268	if (lg->pgdirs[i].pgdir)
269	for (j = 0; j < SWITCHER_PGD_INDEX; j++)
270	release_pgd(lg, lg->pgdirs[i].pgdir + j);
271	}
272
273	void guest_pagetable_clear_all(struct lguest *lg)
274	{
275	release_all_pagetables(lg);
276	pin_stack_pages(lg);
277	}
278
279	static void do_set_pte(struct lguest *lg, int idx,
280	unsigned long vaddr, gpte_t gpte)
281	{
282	spgd_t *spgd = spgd_addr(lg, idx, vaddr);
283	if (spgd->flags & _PAGE_PRESENT) {
284	spte_t spte = spte_addr(lg, spgd, vaddr);
285	release_pte(*spte);
286	if (gpte.flags & (_PAGE_DIRTY \| _PAGE_ACCESSED)) {
287	check_gpte(lg, gpte);
288	*spte = gpte_to_spte(lg, gpte, gpte.flags&_PAGE_DIRTY);
289	} else
290	spte->raw.val = 0;
291	}
292	}
293
294	void guest_set_pte(struct lguest *lg,
295	unsigned long cr3, unsigned long vaddr, gpte_t gpte)
296	{
297	/* Kernel mappings must be changed on all top levels. */
298	if (vaddr >= lg->page_offset) {
299	unsigned int i;
300	for (i = 0; i < ARRAY_SIZE(lg->pgdirs); i++)
301	if (lg->pgdirs[i].pgdir)
302	do_set_pte(lg, i, vaddr, gpte);
303	} else {
304	int pgdir = find_pgdir(lg, cr3);
305	if (pgdir != ARRAY_SIZE(lg->pgdirs))
306	do_set_pte(lg, pgdir, vaddr, gpte);
307	}
308	}
309
310	void guest_set_pmd(struct lguest *lg, unsigned long cr3, u32 idx)
311	{
312	int pgdir;
313
314	if (idx >= SWITCHER_PGD_INDEX)
315	return;
316
317	pgdir = find_pgdir(lg, cr3);
318	if (pgdir < ARRAY_SIZE(lg->pgdirs))
319	release_pgd(lg, lg->pgdirs[pgdir].pgdir + idx);
320	}
321
322	int init_guest_pagetable(struct lguest *lg, unsigned long pgtable)
323	{
324	/* We assume this in flush_user_mappings, so check now */
325	if (vaddr_to_pgd_index(lg->page_offset) >= SWITCHER_PGD_INDEX)
326	return -EINVAL;
327	lg->pgdidx = 0;
328	lg->pgdirs[lg->pgdidx].cr3 = pgtable;
329	lg->pgdirs[lg->pgdidx].pgdir = (spgd_t*)get_zeroed_page(GFP_KERNEL);
330	if (!lg->pgdirs[lg->pgdidx].pgdir)
331	return -ENOMEM;
332	return 0;
333	}
334
335	void free_guest_pagetable(struct lguest *lg)
336	{
337	unsigned int i;
338
339	release_all_pagetables(lg);
340	for (i = 0; i < ARRAY_SIZE(lg->pgdirs); i++)
341	free_page((long)lg->pgdirs[i].pgdir);
342	}
343
344	/* Caller must be preempt-safe */
345	void map_switcher_in_guest(struct lguest lg, struct lguest_pages pages)
346	{
347	spte_t *switcher_pte_page = __get_cpu_var(switcher_pte_pages);
348	spgd_t switcher_pgd;
349	spte_t regs_pte;
350
351	/* Since switcher less that 4MB, we simply mug top pte page. */
352	switcher_pgd.pfn = __pa(switcher_pte_page) >> PAGE_SHIFT;
353	switcher_pgd.flags = _PAGE_KERNEL;
354	lg->pgdirs[lg->pgdidx].pgdir[SWITCHER_PGD_INDEX] = switcher_pgd;
355
356	/* Map our regs page over stack page. */
357	regs_pte.pfn = __pa(lg->regs_page) >> PAGE_SHIFT;
358	regs_pte.flags = _PAGE_KERNEL;
359	switcher_pte_page[(unsigned long)pages/PAGE_SIZE%PTES_PER_PAGE]
360	= regs_pte;
361	}
362
363	static void free_switcher_pte_pages(void)
364	{
365	unsigned int i;
366
367	for_each_possible_cpu(i)
368	free_page((long)switcher_pte_page(i));
369	}
370
371	static __init void populate_switcher_pte_page(unsigned int cpu,
372	struct page *switcher_page[],
373	unsigned int pages)
374	{
375	unsigned int i;
376	spte_t *pte = switcher_pte_page(cpu);
377
378	for (i = 0; i < pages; i++) {
379	pte[i].pfn = page_to_pfn(switcher_page[i]);
380	pte[i].flags = _PAGE_PRESENT\|_PAGE_ACCESSED;
381	}
382
383	/* We only map this CPU's pages, so guest can't see others. */
384	i = pages + cpu*2;
385
386	/* First page (regs) is rw, second (state) is ro. */
387	pte[i].pfn = page_to_pfn(switcher_page[i]);
388	pte[i].flags = _PAGE_PRESENT\|_PAGE_ACCESSED\|_PAGE_RW;
389	pte[i+1].pfn = page_to_pfn(switcher_page[i+1]);
390	pte[i+1].flags = _PAGE_PRESENT\|_PAGE_ACCESSED;
391	}
392
393	__init int init_pagetables(struct page **switcher_page, unsigned int pages)
394	{
395	unsigned int i;
396
397	for_each_possible_cpu(i) {
398	switcher_pte_page(i) = (spte_t *)get_zeroed_page(GFP_KERNEL);
399	if (!switcher_pte_page(i)) {
400	free_switcher_pte_pages();
401	return -ENOMEM;
402	}
403	populate_switcher_pte_page(i, switcher_page, pages);
404	}
405	return 0;
406	}
407
408	void free_pagetables(void)
409	{
410	free_switcher_pte_pages();
411	}