linux/drivers/kvm/mmu.c
Avi Kivity 6b8d0f9b18 KVM: Fix off-by-one when writing to a nonpae guest pde
Nonpae guest pdes are shadowed by two pae ptes, so we double the offset
twice: once to account for the pte size difference, and once because we
need to shadow pdes for a single guest pde.

But when writing to the upper guest pde we also need to truncate the
lower bits, otherwise the multiply shifts these bits into the pde index
and causes an access to the wrong shadow pde.  If we're at the end of the
page (accessing the very last guest pde) we can even overflow into the
next host page and oops.

Signed-off-by: Avi Kivity <avi@qumranet.com>
2007-04-19 18:39:26 +03:00

1477 lines
35 KiB
C

/*
* Kernel-based Virtual Machine driver for Linux
*
* This module enables machines with Intel VT-x extensions to run virtual
* machines without emulation or binary translation.
*
* MMU support
*
* Copyright (C) 2006 Qumranet, Inc.
*
* Authors:
* Yaniv Kamay <yaniv@qumranet.com>
* Avi Kivity <avi@qumranet.com>
*
* This work is licensed under the terms of the GNU GPL, version 2. See
* the COPYING file in the top-level directory.
*
*/
#include <linux/types.h>
#include <linux/string.h>
#include <asm/page.h>
#include <linux/mm.h>
#include <linux/highmem.h>
#include <linux/module.h>
#include "vmx.h"
#include "kvm.h"
#undef MMU_DEBUG
#undef AUDIT
#ifdef AUDIT
static void kvm_mmu_audit(struct kvm_vcpu *vcpu, const char *msg);
#else
static void kvm_mmu_audit(struct kvm_vcpu *vcpu, const char *msg) {}
#endif
#ifdef MMU_DEBUG
#define pgprintk(x...) do { if (dbg) printk(x); } while (0)
#define rmap_printk(x...) do { if (dbg) printk(x); } while (0)
#else
#define pgprintk(x...) do { } while (0)
#define rmap_printk(x...) do { } while (0)
#endif
#if defined(MMU_DEBUG) || defined(AUDIT)
static int dbg = 1;
#endif
#define ASSERT(x) \
if (!(x)) { \
printk(KERN_WARNING "assertion failed %s:%d: %s\n", \
__FILE__, __LINE__, #x); \
}
#define PT64_PT_BITS 9
#define PT64_ENT_PER_PAGE (1 << PT64_PT_BITS)
#define PT32_PT_BITS 10
#define PT32_ENT_PER_PAGE (1 << PT32_PT_BITS)
#define PT_WRITABLE_SHIFT 1
#define PT_PRESENT_MASK (1ULL << 0)
#define PT_WRITABLE_MASK (1ULL << PT_WRITABLE_SHIFT)
#define PT_USER_MASK (1ULL << 2)
#define PT_PWT_MASK (1ULL << 3)
#define PT_PCD_MASK (1ULL << 4)
#define PT_ACCESSED_MASK (1ULL << 5)
#define PT_DIRTY_MASK (1ULL << 6)
#define PT_PAGE_SIZE_MASK (1ULL << 7)
#define PT_PAT_MASK (1ULL << 7)
#define PT_GLOBAL_MASK (1ULL << 8)
#define PT64_NX_MASK (1ULL << 63)
#define PT_PAT_SHIFT 7
#define PT_DIR_PAT_SHIFT 12
#define PT_DIR_PAT_MASK (1ULL << PT_DIR_PAT_SHIFT)
#define PT32_DIR_PSE36_SIZE 4
#define PT32_DIR_PSE36_SHIFT 13
#define PT32_DIR_PSE36_MASK (((1ULL << PT32_DIR_PSE36_SIZE) - 1) << PT32_DIR_PSE36_SHIFT)
#define PT32_PTE_COPY_MASK \
(PT_PRESENT_MASK | PT_ACCESSED_MASK | PT_DIRTY_MASK | PT_GLOBAL_MASK)
#define PT64_PTE_COPY_MASK (PT64_NX_MASK | PT32_PTE_COPY_MASK)
#define PT_FIRST_AVAIL_BITS_SHIFT 9
#define PT64_SECOND_AVAIL_BITS_SHIFT 52
#define PT_SHADOW_PS_MARK (1ULL << PT_FIRST_AVAIL_BITS_SHIFT)
#define PT_SHADOW_IO_MARK (1ULL << PT_FIRST_AVAIL_BITS_SHIFT)
#define PT_SHADOW_WRITABLE_SHIFT (PT_FIRST_AVAIL_BITS_SHIFT + 1)
#define PT_SHADOW_WRITABLE_MASK (1ULL << PT_SHADOW_WRITABLE_SHIFT)
#define PT_SHADOW_USER_SHIFT (PT_SHADOW_WRITABLE_SHIFT + 1)
#define PT_SHADOW_USER_MASK (1ULL << (PT_SHADOW_USER_SHIFT))
#define PT_SHADOW_BITS_OFFSET (PT_SHADOW_WRITABLE_SHIFT - PT_WRITABLE_SHIFT)
#define VALID_PAGE(x) ((x) != INVALID_PAGE)
#define PT64_LEVEL_BITS 9
#define PT64_LEVEL_SHIFT(level) \
( PAGE_SHIFT + (level - 1) * PT64_LEVEL_BITS )
#define PT64_LEVEL_MASK(level) \
(((1ULL << PT64_LEVEL_BITS) - 1) << PT64_LEVEL_SHIFT(level))
#define PT64_INDEX(address, level)\
(((address) >> PT64_LEVEL_SHIFT(level)) & ((1 << PT64_LEVEL_BITS) - 1))
#define PT32_LEVEL_BITS 10
#define PT32_LEVEL_SHIFT(level) \
( PAGE_SHIFT + (level - 1) * PT32_LEVEL_BITS )
#define PT32_LEVEL_MASK(level) \
(((1ULL << PT32_LEVEL_BITS) - 1) << PT32_LEVEL_SHIFT(level))
#define PT32_INDEX(address, level)\
(((address) >> PT32_LEVEL_SHIFT(level)) & ((1 << PT32_LEVEL_BITS) - 1))
#define PT64_BASE_ADDR_MASK (((1ULL << 52) - 1) & ~(u64)(PAGE_SIZE-1))
#define PT64_DIR_BASE_ADDR_MASK \
(PT64_BASE_ADDR_MASK & ~((1ULL << (PAGE_SHIFT + PT64_LEVEL_BITS)) - 1))
#define PT32_BASE_ADDR_MASK PAGE_MASK
#define PT32_DIR_BASE_ADDR_MASK \
(PAGE_MASK & ~((1ULL << (PAGE_SHIFT + PT32_LEVEL_BITS)) - 1))
#define PFERR_PRESENT_MASK (1U << 0)
#define PFERR_WRITE_MASK (1U << 1)
#define PFERR_USER_MASK (1U << 2)
#define PFERR_FETCH_MASK (1U << 4)
#define PT64_ROOT_LEVEL 4
#define PT32_ROOT_LEVEL 2
#define PT32E_ROOT_LEVEL 3
#define PT_DIRECTORY_LEVEL 2
#define PT_PAGE_TABLE_LEVEL 1
#define RMAP_EXT 4
struct kvm_rmap_desc {
u64 *shadow_ptes[RMAP_EXT];
struct kvm_rmap_desc *more;
};
static int is_write_protection(struct kvm_vcpu *vcpu)
{
return vcpu->cr0 & CR0_WP_MASK;
}
static int is_cpuid_PSE36(void)
{
return 1;
}
static int is_nx(struct kvm_vcpu *vcpu)
{
return vcpu->shadow_efer & EFER_NX;
}
static int is_present_pte(unsigned long pte)
{
return pte & PT_PRESENT_MASK;
}
static int is_writeble_pte(unsigned long pte)
{
return pte & PT_WRITABLE_MASK;
}
static int is_io_pte(unsigned long pte)
{
return pte & PT_SHADOW_IO_MARK;
}
static int is_rmap_pte(u64 pte)
{
return (pte & (PT_WRITABLE_MASK | PT_PRESENT_MASK))
== (PT_WRITABLE_MASK | PT_PRESENT_MASK);
}
static int mmu_topup_memory_cache(struct kvm_mmu_memory_cache *cache,
size_t objsize, int min)
{
void *obj;
if (cache->nobjs >= min)
return 0;
while (cache->nobjs < ARRAY_SIZE(cache->objects)) {
obj = kzalloc(objsize, GFP_NOWAIT);
if (!obj)
return -ENOMEM;
cache->objects[cache->nobjs++] = obj;
}
return 0;
}
static void mmu_free_memory_cache(struct kvm_mmu_memory_cache *mc)
{
while (mc->nobjs)
kfree(mc->objects[--mc->nobjs]);
}
static int mmu_topup_memory_caches(struct kvm_vcpu *vcpu)
{
int r;
r = mmu_topup_memory_cache(&vcpu->mmu_pte_chain_cache,
sizeof(struct kvm_pte_chain), 4);
if (r)
goto out;
r = mmu_topup_memory_cache(&vcpu->mmu_rmap_desc_cache,
sizeof(struct kvm_rmap_desc), 1);
out:
return r;
}
static void mmu_free_memory_caches(struct kvm_vcpu *vcpu)
{
mmu_free_memory_cache(&vcpu->mmu_pte_chain_cache);
mmu_free_memory_cache(&vcpu->mmu_rmap_desc_cache);
}
static void *mmu_memory_cache_alloc(struct kvm_mmu_memory_cache *mc,
size_t size)
{
void *p;
BUG_ON(!mc->nobjs);
p = mc->objects[--mc->nobjs];
memset(p, 0, size);
return p;
}
static void mmu_memory_cache_free(struct kvm_mmu_memory_cache *mc, void *obj)
{
if (mc->nobjs < KVM_NR_MEM_OBJS)
mc->objects[mc->nobjs++] = obj;
else
kfree(obj);
}
static struct kvm_pte_chain *mmu_alloc_pte_chain(struct kvm_vcpu *vcpu)
{
return mmu_memory_cache_alloc(&vcpu->mmu_pte_chain_cache,
sizeof(struct kvm_pte_chain));
}
static void mmu_free_pte_chain(struct kvm_vcpu *vcpu,
struct kvm_pte_chain *pc)
{
mmu_memory_cache_free(&vcpu->mmu_pte_chain_cache, pc);
}
static struct kvm_rmap_desc *mmu_alloc_rmap_desc(struct kvm_vcpu *vcpu)
{
return mmu_memory_cache_alloc(&vcpu->mmu_rmap_desc_cache,
sizeof(struct kvm_rmap_desc));
}
static void mmu_free_rmap_desc(struct kvm_vcpu *vcpu,
struct kvm_rmap_desc *rd)
{
mmu_memory_cache_free(&vcpu->mmu_rmap_desc_cache, rd);
}
/*
* Reverse mapping data structures:
*
* If page->private bit zero is zero, then page->private points to the
* shadow page table entry that points to page_address(page).
*
* If page->private bit zero is one, (then page->private & ~1) points
* to a struct kvm_rmap_desc containing more mappings.
*/
static void rmap_add(struct kvm_vcpu *vcpu, u64 *spte)
{
struct page *page;
struct kvm_rmap_desc *desc;
int i;
if (!is_rmap_pte(*spte))
return;
page = pfn_to_page((*spte & PT64_BASE_ADDR_MASK) >> PAGE_SHIFT);
if (!page_private(page)) {
rmap_printk("rmap_add: %p %llx 0->1\n", spte, *spte);
set_page_private(page,(unsigned long)spte);
} else if (!(page_private(page) & 1)) {
rmap_printk("rmap_add: %p %llx 1->many\n", spte, *spte);
desc = mmu_alloc_rmap_desc(vcpu);
desc->shadow_ptes[0] = (u64 *)page_private(page);
desc->shadow_ptes[1] = spte;
set_page_private(page,(unsigned long)desc | 1);
} else {
rmap_printk("rmap_add: %p %llx many->many\n", spte, *spte);
desc = (struct kvm_rmap_desc *)(page_private(page) & ~1ul);
while (desc->shadow_ptes[RMAP_EXT-1] && desc->more)
desc = desc->more;
if (desc->shadow_ptes[RMAP_EXT-1]) {
desc->more = mmu_alloc_rmap_desc(vcpu);
desc = desc->more;
}
for (i = 0; desc->shadow_ptes[i]; ++i)
;
desc->shadow_ptes[i] = spte;
}
}
static void rmap_desc_remove_entry(struct kvm_vcpu *vcpu,
struct page *page,
struct kvm_rmap_desc *desc,
int i,
struct kvm_rmap_desc *prev_desc)
{
int j;
for (j = RMAP_EXT - 1; !desc->shadow_ptes[j] && j > i; --j)
;
desc->shadow_ptes[i] = desc->shadow_ptes[j];
desc->shadow_ptes[j] = NULL;
if (j != 0)
return;
if (!prev_desc && !desc->more)
set_page_private(page,(unsigned long)desc->shadow_ptes[0]);
else
if (prev_desc)
prev_desc->more = desc->more;
else
set_page_private(page,(unsigned long)desc->more | 1);
mmu_free_rmap_desc(vcpu, desc);
}
static void rmap_remove(struct kvm_vcpu *vcpu, u64 *spte)
{
struct page *page;
struct kvm_rmap_desc *desc;
struct kvm_rmap_desc *prev_desc;
int i;
if (!is_rmap_pte(*spte))
return;
page = pfn_to_page((*spte & PT64_BASE_ADDR_MASK) >> PAGE_SHIFT);
if (!page_private(page)) {
printk(KERN_ERR "rmap_remove: %p %llx 0->BUG\n", spte, *spte);
BUG();
} else if (!(page_private(page) & 1)) {
rmap_printk("rmap_remove: %p %llx 1->0\n", spte, *spte);
if ((u64 *)page_private(page) != spte) {
printk(KERN_ERR "rmap_remove: %p %llx 1->BUG\n",
spte, *spte);
BUG();
}
set_page_private(page,0);
} else {
rmap_printk("rmap_remove: %p %llx many->many\n", spte, *spte);
desc = (struct kvm_rmap_desc *)(page_private(page) & ~1ul);
prev_desc = NULL;
while (desc) {
for (i = 0; i < RMAP_EXT && desc->shadow_ptes[i]; ++i)
if (desc->shadow_ptes[i] == spte) {
rmap_desc_remove_entry(vcpu, page,
desc, i,
prev_desc);
return;
}
prev_desc = desc;
desc = desc->more;
}
BUG();
}
}
static void rmap_write_protect(struct kvm_vcpu *vcpu, u64 gfn)
{
struct kvm *kvm = vcpu->kvm;
struct page *page;
struct kvm_memory_slot *slot;
struct kvm_rmap_desc *desc;
u64 *spte;
slot = gfn_to_memslot(kvm, gfn);
BUG_ON(!slot);
page = gfn_to_page(slot, gfn);
while (page_private(page)) {
if (!(page_private(page) & 1))
spte = (u64 *)page_private(page);
else {
desc = (struct kvm_rmap_desc *)(page_private(page) & ~1ul);
spte = desc->shadow_ptes[0];
}
BUG_ON(!spte);
BUG_ON((*spte & PT64_BASE_ADDR_MASK) >> PAGE_SHIFT
!= page_to_pfn(page));
BUG_ON(!(*spte & PT_PRESENT_MASK));
BUG_ON(!(*spte & PT_WRITABLE_MASK));
rmap_printk("rmap_write_protect: spte %p %llx\n", spte, *spte);
rmap_remove(vcpu, spte);
kvm_arch_ops->tlb_flush(vcpu);
*spte &= ~(u64)PT_WRITABLE_MASK;
}
}
static int is_empty_shadow_page(hpa_t page_hpa)
{
u64 *pos;
u64 *end;
for (pos = __va(page_hpa), end = pos + PAGE_SIZE / sizeof(u64);
pos != end; pos++)
if (*pos != 0) {
printk(KERN_ERR "%s: %p %llx\n", __FUNCTION__,
pos, *pos);
return 0;
}
return 1;
}
static void kvm_mmu_free_page(struct kvm_vcpu *vcpu, hpa_t page_hpa)
{
struct kvm_mmu_page *page_head = page_header(page_hpa);
ASSERT(is_empty_shadow_page(page_hpa));
list_del(&page_head->link);
page_head->page_hpa = page_hpa;
list_add(&page_head->link, &vcpu->free_pages);
++vcpu->kvm->n_free_mmu_pages;
}
static unsigned kvm_page_table_hashfn(gfn_t gfn)
{
return gfn;
}
static struct kvm_mmu_page *kvm_mmu_alloc_page(struct kvm_vcpu *vcpu,
u64 *parent_pte)
{
struct kvm_mmu_page *page;
if (list_empty(&vcpu->free_pages))
return NULL;
page = list_entry(vcpu->free_pages.next, struct kvm_mmu_page, link);
list_del(&page->link);
list_add(&page->link, &vcpu->kvm->active_mmu_pages);
ASSERT(is_empty_shadow_page(page->page_hpa));
page->slot_bitmap = 0;
page->global = 1;
page->multimapped = 0;
page->parent_pte = parent_pte;
--vcpu->kvm->n_free_mmu_pages;
return page;
}
static void mmu_page_add_parent_pte(struct kvm_vcpu *vcpu,
struct kvm_mmu_page *page, u64 *parent_pte)
{
struct kvm_pte_chain *pte_chain;
struct hlist_node *node;
int i;
if (!parent_pte)
return;
if (!page->multimapped) {
u64 *old = page->parent_pte;
if (!old) {
page->parent_pte = parent_pte;
return;
}
page->multimapped = 1;
pte_chain = mmu_alloc_pte_chain(vcpu);
INIT_HLIST_HEAD(&page->parent_ptes);
hlist_add_head(&pte_chain->link, &page->parent_ptes);
pte_chain->parent_ptes[0] = old;
}
hlist_for_each_entry(pte_chain, node, &page->parent_ptes, link) {
if (pte_chain->parent_ptes[NR_PTE_CHAIN_ENTRIES-1])
continue;
for (i = 0; i < NR_PTE_CHAIN_ENTRIES; ++i)
if (!pte_chain->parent_ptes[i]) {
pte_chain->parent_ptes[i] = parent_pte;
return;
}
}
pte_chain = mmu_alloc_pte_chain(vcpu);
BUG_ON(!pte_chain);
hlist_add_head(&pte_chain->link, &page->parent_ptes);
pte_chain->parent_ptes[0] = parent_pte;
}
static void mmu_page_remove_parent_pte(struct kvm_vcpu *vcpu,
struct kvm_mmu_page *page,
u64 *parent_pte)
{
struct kvm_pte_chain *pte_chain;
struct hlist_node *node;
int i;
if (!page->multimapped) {
BUG_ON(page->parent_pte != parent_pte);
page->parent_pte = NULL;
return;
}
hlist_for_each_entry(pte_chain, node, &page->parent_ptes, link)
for (i = 0; i < NR_PTE_CHAIN_ENTRIES; ++i) {
if (!pte_chain->parent_ptes[i])
break;
if (pte_chain->parent_ptes[i] != parent_pte)
continue;
while (i + 1 < NR_PTE_CHAIN_ENTRIES
&& pte_chain->parent_ptes[i + 1]) {
pte_chain->parent_ptes[i]
= pte_chain->parent_ptes[i + 1];
++i;
}
pte_chain->parent_ptes[i] = NULL;
if (i == 0) {
hlist_del(&pte_chain->link);
mmu_free_pte_chain(vcpu, pte_chain);
if (hlist_empty(&page->parent_ptes)) {
page->multimapped = 0;
page->parent_pte = NULL;
}
}
return;
}
BUG();
}
static struct kvm_mmu_page *kvm_mmu_lookup_page(struct kvm_vcpu *vcpu,
gfn_t gfn)
{
unsigned index;
struct hlist_head *bucket;
struct kvm_mmu_page *page;
struct hlist_node *node;
pgprintk("%s: looking for gfn %lx\n", __FUNCTION__, gfn);
index = kvm_page_table_hashfn(gfn) % KVM_NUM_MMU_PAGES;
bucket = &vcpu->kvm->mmu_page_hash[index];
hlist_for_each_entry(page, node, bucket, hash_link)
if (page->gfn == gfn && !page->role.metaphysical) {
pgprintk("%s: found role %x\n",
__FUNCTION__, page->role.word);
return page;
}
return NULL;
}
static struct kvm_mmu_page *kvm_mmu_get_page(struct kvm_vcpu *vcpu,
gfn_t gfn,
gva_t gaddr,
unsigned level,
int metaphysical,
u64 *parent_pte)
{
union kvm_mmu_page_role role;
unsigned index;
unsigned quadrant;
struct hlist_head *bucket;
struct kvm_mmu_page *page;
struct hlist_node *node;
role.word = 0;
role.glevels = vcpu->mmu.root_level;
role.level = level;
role.metaphysical = metaphysical;
if (vcpu->mmu.root_level <= PT32_ROOT_LEVEL) {
quadrant = gaddr >> (PAGE_SHIFT + (PT64_PT_BITS * level));
quadrant &= (1 << ((PT32_PT_BITS - PT64_PT_BITS) * level)) - 1;
role.quadrant = quadrant;
}
pgprintk("%s: looking gfn %lx role %x\n", __FUNCTION__,
gfn, role.word);
index = kvm_page_table_hashfn(gfn) % KVM_NUM_MMU_PAGES;
bucket = &vcpu->kvm->mmu_page_hash[index];
hlist_for_each_entry(page, node, bucket, hash_link)
if (page->gfn == gfn && page->role.word == role.word) {
mmu_page_add_parent_pte(vcpu, page, parent_pte);
pgprintk("%s: found\n", __FUNCTION__);
return page;
}
page = kvm_mmu_alloc_page(vcpu, parent_pte);
if (!page)
return page;
pgprintk("%s: adding gfn %lx role %x\n", __FUNCTION__, gfn, role.word);
page->gfn = gfn;
page->role = role;
hlist_add_head(&page->hash_link, bucket);
if (!metaphysical)
rmap_write_protect(vcpu, gfn);
return page;
}
static void kvm_mmu_page_unlink_children(struct kvm_vcpu *vcpu,
struct kvm_mmu_page *page)
{
unsigned i;
u64 *pt;
u64 ent;
pt = __va(page->page_hpa);
if (page->role.level == PT_PAGE_TABLE_LEVEL) {
for (i = 0; i < PT64_ENT_PER_PAGE; ++i) {
if (pt[i] & PT_PRESENT_MASK)
rmap_remove(vcpu, &pt[i]);
pt[i] = 0;
}
kvm_arch_ops->tlb_flush(vcpu);
return;
}
for (i = 0; i < PT64_ENT_PER_PAGE; ++i) {
ent = pt[i];
pt[i] = 0;
if (!(ent & PT_PRESENT_MASK))
continue;
ent &= PT64_BASE_ADDR_MASK;
mmu_page_remove_parent_pte(vcpu, page_header(ent), &pt[i]);
}
}
static void kvm_mmu_put_page(struct kvm_vcpu *vcpu,
struct kvm_mmu_page *page,
u64 *parent_pte)
{
mmu_page_remove_parent_pte(vcpu, page, parent_pte);
}
static void kvm_mmu_zap_page(struct kvm_vcpu *vcpu,
struct kvm_mmu_page *page)
{
u64 *parent_pte;
while (page->multimapped || page->parent_pte) {
if (!page->multimapped)
parent_pte = page->parent_pte;
else {
struct kvm_pte_chain *chain;
chain = container_of(page->parent_ptes.first,
struct kvm_pte_chain, link);
parent_pte = chain->parent_ptes[0];
}
BUG_ON(!parent_pte);
kvm_mmu_put_page(vcpu, page, parent_pte);
*parent_pte = 0;
}
kvm_mmu_page_unlink_children(vcpu, page);
if (!page->root_count) {
hlist_del(&page->hash_link);
kvm_mmu_free_page(vcpu, page->page_hpa);
} else {
list_del(&page->link);
list_add(&page->link, &vcpu->kvm->active_mmu_pages);
}
}
static int kvm_mmu_unprotect_page(struct kvm_vcpu *vcpu, gfn_t gfn)
{
unsigned index;
struct hlist_head *bucket;
struct kvm_mmu_page *page;
struct hlist_node *node, *n;
int r;
pgprintk("%s: looking for gfn %lx\n", __FUNCTION__, gfn);
r = 0;
index = kvm_page_table_hashfn(gfn) % KVM_NUM_MMU_PAGES;
bucket = &vcpu->kvm->mmu_page_hash[index];
hlist_for_each_entry_safe(page, node, n, bucket, hash_link)
if (page->gfn == gfn && !page->role.metaphysical) {
pgprintk("%s: gfn %lx role %x\n", __FUNCTION__, gfn,
page->role.word);
kvm_mmu_zap_page(vcpu, page);
r = 1;
}
return r;
}
static void page_header_update_slot(struct kvm *kvm, void *pte, gpa_t gpa)
{
int slot = memslot_id(kvm, gfn_to_memslot(kvm, gpa >> PAGE_SHIFT));
struct kvm_mmu_page *page_head = page_header(__pa(pte));
__set_bit(slot, &page_head->slot_bitmap);
}
hpa_t safe_gpa_to_hpa(struct kvm_vcpu *vcpu, gpa_t gpa)
{
hpa_t hpa = gpa_to_hpa(vcpu, gpa);
return is_error_hpa(hpa) ? bad_page_address | (gpa & ~PAGE_MASK): hpa;
}
hpa_t gpa_to_hpa(struct kvm_vcpu *vcpu, gpa_t gpa)
{
struct kvm_memory_slot *slot;
struct page *page;
ASSERT((gpa & HPA_ERR_MASK) == 0);
slot = gfn_to_memslot(vcpu->kvm, gpa >> PAGE_SHIFT);
if (!slot)
return gpa | HPA_ERR_MASK;
page = gfn_to_page(slot, gpa >> PAGE_SHIFT);
return ((hpa_t)page_to_pfn(page) << PAGE_SHIFT)
| (gpa & (PAGE_SIZE-1));
}
hpa_t gva_to_hpa(struct kvm_vcpu *vcpu, gva_t gva)
{
gpa_t gpa = vcpu->mmu.gva_to_gpa(vcpu, gva);
if (gpa == UNMAPPED_GVA)
return UNMAPPED_GVA;
return gpa_to_hpa(vcpu, gpa);
}
static void nonpaging_new_cr3(struct kvm_vcpu *vcpu)
{
}
static int nonpaging_map(struct kvm_vcpu *vcpu, gva_t v, hpa_t p)
{
int level = PT32E_ROOT_LEVEL;
hpa_t table_addr = vcpu->mmu.root_hpa;
for (; ; level--) {
u32 index = PT64_INDEX(v, level);
u64 *table;
u64 pte;
ASSERT(VALID_PAGE(table_addr));
table = __va(table_addr);
if (level == 1) {
pte = table[index];
if (is_present_pte(pte) && is_writeble_pte(pte))
return 0;
mark_page_dirty(vcpu->kvm, v >> PAGE_SHIFT);
page_header_update_slot(vcpu->kvm, table, v);
table[index] = p | PT_PRESENT_MASK | PT_WRITABLE_MASK |
PT_USER_MASK;
rmap_add(vcpu, &table[index]);
return 0;
}
if (table[index] == 0) {
struct kvm_mmu_page *new_table;
gfn_t pseudo_gfn;
pseudo_gfn = (v & PT64_DIR_BASE_ADDR_MASK)
>> PAGE_SHIFT;
new_table = kvm_mmu_get_page(vcpu, pseudo_gfn,
v, level - 1,
1, &table[index]);
if (!new_table) {
pgprintk("nonpaging_map: ENOMEM\n");
return -ENOMEM;
}
table[index] = new_table->page_hpa | PT_PRESENT_MASK
| PT_WRITABLE_MASK | PT_USER_MASK;
}
table_addr = table[index] & PT64_BASE_ADDR_MASK;
}
}
static void mmu_free_roots(struct kvm_vcpu *vcpu)
{
int i;
struct kvm_mmu_page *page;
#ifdef CONFIG_X86_64
if (vcpu->mmu.shadow_root_level == PT64_ROOT_LEVEL) {
hpa_t root = vcpu->mmu.root_hpa;
ASSERT(VALID_PAGE(root));
page = page_header(root);
--page->root_count;
vcpu->mmu.root_hpa = INVALID_PAGE;
return;
}
#endif
for (i = 0; i < 4; ++i) {
hpa_t root = vcpu->mmu.pae_root[i];
ASSERT(VALID_PAGE(root));
root &= PT64_BASE_ADDR_MASK;
page = page_header(root);
--page->root_count;
vcpu->mmu.pae_root[i] = INVALID_PAGE;
}
vcpu->mmu.root_hpa = INVALID_PAGE;
}
static void mmu_alloc_roots(struct kvm_vcpu *vcpu)
{
int i;
gfn_t root_gfn;
struct kvm_mmu_page *page;
root_gfn = vcpu->cr3 >> PAGE_SHIFT;
#ifdef CONFIG_X86_64
if (vcpu->mmu.shadow_root_level == PT64_ROOT_LEVEL) {
hpa_t root = vcpu->mmu.root_hpa;
ASSERT(!VALID_PAGE(root));
page = kvm_mmu_get_page(vcpu, root_gfn, 0,
PT64_ROOT_LEVEL, 0, NULL);
root = page->page_hpa;
++page->root_count;
vcpu->mmu.root_hpa = root;
return;
}
#endif
for (i = 0; i < 4; ++i) {
hpa_t root = vcpu->mmu.pae_root[i];
ASSERT(!VALID_PAGE(root));
if (vcpu->mmu.root_level == PT32E_ROOT_LEVEL)
root_gfn = vcpu->pdptrs[i] >> PAGE_SHIFT;
else if (vcpu->mmu.root_level == 0)
root_gfn = 0;
page = kvm_mmu_get_page(vcpu, root_gfn, i << 30,
PT32_ROOT_LEVEL, !is_paging(vcpu),
NULL);
root = page->page_hpa;
++page->root_count;
vcpu->mmu.pae_root[i] = root | PT_PRESENT_MASK;
}
vcpu->mmu.root_hpa = __pa(vcpu->mmu.pae_root);
}
static gpa_t nonpaging_gva_to_gpa(struct kvm_vcpu *vcpu, gva_t vaddr)
{
return vaddr;
}
static int nonpaging_page_fault(struct kvm_vcpu *vcpu, gva_t gva,
u32 error_code)
{
gpa_t addr = gva;
hpa_t paddr;
int r;
r = mmu_topup_memory_caches(vcpu);
if (r)
return r;
ASSERT(vcpu);
ASSERT(VALID_PAGE(vcpu->mmu.root_hpa));
paddr = gpa_to_hpa(vcpu , addr & PT64_BASE_ADDR_MASK);
if (is_error_hpa(paddr))
return 1;
return nonpaging_map(vcpu, addr & PAGE_MASK, paddr);
}
static void nonpaging_free(struct kvm_vcpu *vcpu)
{
mmu_free_roots(vcpu);
}
static int nonpaging_init_context(struct kvm_vcpu *vcpu)
{
struct kvm_mmu *context = &vcpu->mmu;
context->new_cr3 = nonpaging_new_cr3;
context->page_fault = nonpaging_page_fault;
context->gva_to_gpa = nonpaging_gva_to_gpa;
context->free = nonpaging_free;
context->root_level = 0;
context->shadow_root_level = PT32E_ROOT_LEVEL;
mmu_alloc_roots(vcpu);
ASSERT(VALID_PAGE(context->root_hpa));
kvm_arch_ops->set_cr3(vcpu, context->root_hpa);
return 0;
}
static void kvm_mmu_flush_tlb(struct kvm_vcpu *vcpu)
{
++kvm_stat.tlb_flush;
kvm_arch_ops->tlb_flush(vcpu);
}
static void paging_new_cr3(struct kvm_vcpu *vcpu)
{
pgprintk("%s: cr3 %lx\n", __FUNCTION__, vcpu->cr3);
mmu_free_roots(vcpu);
if (unlikely(vcpu->kvm->n_free_mmu_pages < KVM_MIN_FREE_MMU_PAGES))
kvm_mmu_free_some_pages(vcpu);
mmu_alloc_roots(vcpu);
kvm_mmu_flush_tlb(vcpu);
kvm_arch_ops->set_cr3(vcpu, vcpu->mmu.root_hpa);
}
static void mark_pagetable_nonglobal(void *shadow_pte)
{
page_header(__pa(shadow_pte))->global = 0;
}
static inline void set_pte_common(struct kvm_vcpu *vcpu,
u64 *shadow_pte,
gpa_t gaddr,
int dirty,
u64 access_bits,
gfn_t gfn)
{
hpa_t paddr;
*shadow_pte |= access_bits << PT_SHADOW_BITS_OFFSET;
if (!dirty)
access_bits &= ~PT_WRITABLE_MASK;
paddr = gpa_to_hpa(vcpu, gaddr & PT64_BASE_ADDR_MASK);
*shadow_pte |= access_bits;
if (!(*shadow_pte & PT_GLOBAL_MASK))
mark_pagetable_nonglobal(shadow_pte);
if (is_error_hpa(paddr)) {
*shadow_pte |= gaddr;
*shadow_pte |= PT_SHADOW_IO_MARK;
*shadow_pte &= ~PT_PRESENT_MASK;
return;
}
*shadow_pte |= paddr;
if (access_bits & PT_WRITABLE_MASK) {
struct kvm_mmu_page *shadow;
shadow = kvm_mmu_lookup_page(vcpu, gfn);
if (shadow) {
pgprintk("%s: found shadow page for %lx, marking ro\n",
__FUNCTION__, gfn);
access_bits &= ~PT_WRITABLE_MASK;
if (is_writeble_pte(*shadow_pte)) {
*shadow_pte &= ~PT_WRITABLE_MASK;
kvm_arch_ops->tlb_flush(vcpu);
}
}
}
if (access_bits & PT_WRITABLE_MASK)
mark_page_dirty(vcpu->kvm, gaddr >> PAGE_SHIFT);
page_header_update_slot(vcpu->kvm, shadow_pte, gaddr);
rmap_add(vcpu, shadow_pte);
}
static void inject_page_fault(struct kvm_vcpu *vcpu,
u64 addr,
u32 err_code)
{
kvm_arch_ops->inject_page_fault(vcpu, addr, err_code);
}
static inline int fix_read_pf(u64 *shadow_ent)
{
if ((*shadow_ent & PT_SHADOW_USER_MASK) &&
!(*shadow_ent & PT_USER_MASK)) {
/*
* If supervisor write protect is disabled, we shadow kernel
* pages as user pages so we can trap the write access.
*/
*shadow_ent |= PT_USER_MASK;
*shadow_ent &= ~PT_WRITABLE_MASK;
return 1;
}
return 0;
}
static void paging_free(struct kvm_vcpu *vcpu)
{
nonpaging_free(vcpu);
}
#define PTTYPE 64
#include "paging_tmpl.h"
#undef PTTYPE
#define PTTYPE 32
#include "paging_tmpl.h"
#undef PTTYPE
static int paging64_init_context_common(struct kvm_vcpu *vcpu, int level)
{
struct kvm_mmu *context = &vcpu->mmu;
ASSERT(is_pae(vcpu));
context->new_cr3 = paging_new_cr3;
context->page_fault = paging64_page_fault;
context->gva_to_gpa = paging64_gva_to_gpa;
context->free = paging_free;
context->root_level = level;
context->shadow_root_level = level;
mmu_alloc_roots(vcpu);
ASSERT(VALID_PAGE(context->root_hpa));
kvm_arch_ops->set_cr3(vcpu, context->root_hpa |
(vcpu->cr3 & (CR3_PCD_MASK | CR3_WPT_MASK)));
return 0;
}
static int paging64_init_context(struct kvm_vcpu *vcpu)
{
return paging64_init_context_common(vcpu, PT64_ROOT_LEVEL);
}
static int paging32_init_context(struct kvm_vcpu *vcpu)
{
struct kvm_mmu *context = &vcpu->mmu;
context->new_cr3 = paging_new_cr3;
context->page_fault = paging32_page_fault;
context->gva_to_gpa = paging32_gva_to_gpa;
context->free = paging_free;
context->root_level = PT32_ROOT_LEVEL;
context->shadow_root_level = PT32E_ROOT_LEVEL;
mmu_alloc_roots(vcpu);
ASSERT(VALID_PAGE(context->root_hpa));
kvm_arch_ops->set_cr3(vcpu, context->root_hpa |
(vcpu->cr3 & (CR3_PCD_MASK | CR3_WPT_MASK)));
return 0;
}
static int paging32E_init_context(struct kvm_vcpu *vcpu)
{
return paging64_init_context_common(vcpu, PT32E_ROOT_LEVEL);
}
static int init_kvm_mmu(struct kvm_vcpu *vcpu)
{
ASSERT(vcpu);
ASSERT(!VALID_PAGE(vcpu->mmu.root_hpa));
if (!is_paging(vcpu))
return nonpaging_init_context(vcpu);
else if (is_long_mode(vcpu))
return paging64_init_context(vcpu);
else if (is_pae(vcpu))
return paging32E_init_context(vcpu);
else
return paging32_init_context(vcpu);
}
static void destroy_kvm_mmu(struct kvm_vcpu *vcpu)
{
ASSERT(vcpu);
if (VALID_PAGE(vcpu->mmu.root_hpa)) {
vcpu->mmu.free(vcpu);
vcpu->mmu.root_hpa = INVALID_PAGE;
}
}
int kvm_mmu_reset_context(struct kvm_vcpu *vcpu)
{
int r;
destroy_kvm_mmu(vcpu);
r = init_kvm_mmu(vcpu);
if (r < 0)
goto out;
r = mmu_topup_memory_caches(vcpu);
out:
return r;
}
static void mmu_pre_write_zap_pte(struct kvm_vcpu *vcpu,
struct kvm_mmu_page *page,
u64 *spte)
{
u64 pte;
struct kvm_mmu_page *child;
pte = *spte;
if (is_present_pte(pte)) {
if (page->role.level == PT_PAGE_TABLE_LEVEL)
rmap_remove(vcpu, spte);
else {
child = page_header(pte & PT64_BASE_ADDR_MASK);
mmu_page_remove_parent_pte(vcpu, child, spte);
}
}
*spte = 0;
}
void kvm_mmu_pre_write(struct kvm_vcpu *vcpu, gpa_t gpa, int bytes)
{
gfn_t gfn = gpa >> PAGE_SHIFT;
struct kvm_mmu_page *page;
struct hlist_node *node, *n;
struct hlist_head *bucket;
unsigned index;
u64 *spte;
unsigned offset = offset_in_page(gpa);
unsigned pte_size;
unsigned page_offset;
unsigned misaligned;
int level;
int flooded = 0;
int npte;
pgprintk("%s: gpa %llx bytes %d\n", __FUNCTION__, gpa, bytes);
if (gfn == vcpu->last_pt_write_gfn) {
++vcpu->last_pt_write_count;
if (vcpu->last_pt_write_count >= 3)
flooded = 1;
} else {
vcpu->last_pt_write_gfn = gfn;
vcpu->last_pt_write_count = 1;
}
index = kvm_page_table_hashfn(gfn) % KVM_NUM_MMU_PAGES;
bucket = &vcpu->kvm->mmu_page_hash[index];
hlist_for_each_entry_safe(page, node, n, bucket, hash_link) {
if (page->gfn != gfn || page->role.metaphysical)
continue;
pte_size = page->role.glevels == PT32_ROOT_LEVEL ? 4 : 8;
misaligned = (offset ^ (offset + bytes - 1)) & ~(pte_size - 1);
if (misaligned || flooded) {
/*
* Misaligned accesses are too much trouble to fix
* up; also, they usually indicate a page is not used
* as a page table.
*
* If we're seeing too many writes to a page,
* it may no longer be a page table, or we may be
* forking, in which case it is better to unmap the
* page.
*/
pgprintk("misaligned: gpa %llx bytes %d role %x\n",
gpa, bytes, page->role.word);
kvm_mmu_zap_page(vcpu, page);
continue;
}
page_offset = offset;
level = page->role.level;
npte = 1;
if (page->role.glevels == PT32_ROOT_LEVEL) {
page_offset <<= 1; /* 32->64 */
/*
* A 32-bit pde maps 4MB while the shadow pdes map
* only 2MB. So we need to double the offset again
* and zap two pdes instead of one.
*/
if (level == PT32_ROOT_LEVEL) {
page_offset &= ~7; /* kill rounding error */
page_offset <<= 1;
npte = 2;
}
page_offset &= ~PAGE_MASK;
}
spte = __va(page->page_hpa);
spte += page_offset / sizeof(*spte);
while (npte--) {
mmu_pre_write_zap_pte(vcpu, page, spte);
++spte;
}
}
}
void kvm_mmu_post_write(struct kvm_vcpu *vcpu, gpa_t gpa, int bytes)
{
}
int kvm_mmu_unprotect_page_virt(struct kvm_vcpu *vcpu, gva_t gva)
{
gpa_t gpa = vcpu->mmu.gva_to_gpa(vcpu, gva);
return kvm_mmu_unprotect_page(vcpu, gpa >> PAGE_SHIFT);
}
void kvm_mmu_free_some_pages(struct kvm_vcpu *vcpu)
{
while (vcpu->kvm->n_free_mmu_pages < KVM_REFILL_PAGES) {
struct kvm_mmu_page *page;
page = container_of(vcpu->kvm->active_mmu_pages.prev,
struct kvm_mmu_page, link);
kvm_mmu_zap_page(vcpu, page);
}
}
EXPORT_SYMBOL_GPL(kvm_mmu_free_some_pages);
static void free_mmu_pages(struct kvm_vcpu *vcpu)
{
struct kvm_mmu_page *page;
while (!list_empty(&vcpu->kvm->active_mmu_pages)) {
page = container_of(vcpu->kvm->active_mmu_pages.next,
struct kvm_mmu_page, link);
kvm_mmu_zap_page(vcpu, page);
}
while (!list_empty(&vcpu->free_pages)) {
page = list_entry(vcpu->free_pages.next,
struct kvm_mmu_page, link);
list_del(&page->link);
__free_page(pfn_to_page(page->page_hpa >> PAGE_SHIFT));
page->page_hpa = INVALID_PAGE;
}
free_page((unsigned long)vcpu->mmu.pae_root);
}
static int alloc_mmu_pages(struct kvm_vcpu *vcpu)
{
struct page *page;
int i;
ASSERT(vcpu);
for (i = 0; i < KVM_NUM_MMU_PAGES; i++) {
struct kvm_mmu_page *page_header = &vcpu->page_header_buf[i];
INIT_LIST_HEAD(&page_header->link);
if ((page = alloc_page(GFP_KERNEL)) == NULL)
goto error_1;
set_page_private(page, (unsigned long)page_header);
page_header->page_hpa = (hpa_t)page_to_pfn(page) << PAGE_SHIFT;
memset(__va(page_header->page_hpa), 0, PAGE_SIZE);
list_add(&page_header->link, &vcpu->free_pages);
++vcpu->kvm->n_free_mmu_pages;
}
/*
* When emulating 32-bit mode, cr3 is only 32 bits even on x86_64.
* Therefore we need to allocate shadow page tables in the first
* 4GB of memory, which happens to fit the DMA32 zone.
*/
page = alloc_page(GFP_KERNEL | __GFP_DMA32);
if (!page)
goto error_1;
vcpu->mmu.pae_root = page_address(page);
for (i = 0; i < 4; ++i)
vcpu->mmu.pae_root[i] = INVALID_PAGE;
return 0;
error_1:
free_mmu_pages(vcpu);
return -ENOMEM;
}
int kvm_mmu_create(struct kvm_vcpu *vcpu)
{
ASSERT(vcpu);
ASSERT(!VALID_PAGE(vcpu->mmu.root_hpa));
ASSERT(list_empty(&vcpu->free_pages));
return alloc_mmu_pages(vcpu);
}
int kvm_mmu_setup(struct kvm_vcpu *vcpu)
{
ASSERT(vcpu);
ASSERT(!VALID_PAGE(vcpu->mmu.root_hpa));
ASSERT(!list_empty(&vcpu->free_pages));
return init_kvm_mmu(vcpu);
}
void kvm_mmu_destroy(struct kvm_vcpu *vcpu)
{
ASSERT(vcpu);
destroy_kvm_mmu(vcpu);
free_mmu_pages(vcpu);
mmu_free_memory_caches(vcpu);
}
void kvm_mmu_slot_remove_write_access(struct kvm_vcpu *vcpu, int slot)
{
struct kvm *kvm = vcpu->kvm;
struct kvm_mmu_page *page;
list_for_each_entry(page, &kvm->active_mmu_pages, link) {
int i;
u64 *pt;
if (!test_bit(slot, &page->slot_bitmap))
continue;
pt = __va(page->page_hpa);
for (i = 0; i < PT64_ENT_PER_PAGE; ++i)
/* avoid RMW */
if (pt[i] & PT_WRITABLE_MASK) {
rmap_remove(vcpu, &pt[i]);
pt[i] &= ~PT_WRITABLE_MASK;
}
}
}
#ifdef AUDIT
static const char *audit_msg;
static gva_t canonicalize(gva_t gva)
{
#ifdef CONFIG_X86_64
gva = (long long)(gva << 16) >> 16;
#endif
return gva;
}
static void audit_mappings_page(struct kvm_vcpu *vcpu, u64 page_pte,
gva_t va, int level)
{
u64 *pt = __va(page_pte & PT64_BASE_ADDR_MASK);
int i;
gva_t va_delta = 1ul << (PAGE_SHIFT + 9 * (level - 1));
for (i = 0; i < PT64_ENT_PER_PAGE; ++i, va += va_delta) {
u64 ent = pt[i];
if (!ent & PT_PRESENT_MASK)
continue;
va = canonicalize(va);
if (level > 1)
audit_mappings_page(vcpu, ent, va, level - 1);
else {
gpa_t gpa = vcpu->mmu.gva_to_gpa(vcpu, va);
hpa_t hpa = gpa_to_hpa(vcpu, gpa);
if ((ent & PT_PRESENT_MASK)
&& (ent & PT64_BASE_ADDR_MASK) != hpa)
printk(KERN_ERR "audit error: (%s) levels %d"
" gva %lx gpa %llx hpa %llx ent %llx\n",
audit_msg, vcpu->mmu.root_level,
va, gpa, hpa, ent);
}
}
}
static void audit_mappings(struct kvm_vcpu *vcpu)
{
int i;
if (vcpu->mmu.root_level == 4)
audit_mappings_page(vcpu, vcpu->mmu.root_hpa, 0, 4);
else
for (i = 0; i < 4; ++i)
if (vcpu->mmu.pae_root[i] & PT_PRESENT_MASK)
audit_mappings_page(vcpu,
vcpu->mmu.pae_root[i],
i << 30,
2);
}
static int count_rmaps(struct kvm_vcpu *vcpu)
{
int nmaps = 0;
int i, j, k;
for (i = 0; i < KVM_MEMORY_SLOTS; ++i) {
struct kvm_memory_slot *m = &vcpu->kvm->memslots[i];
struct kvm_rmap_desc *d;
for (j = 0; j < m->npages; ++j) {
struct page *page = m->phys_mem[j];
if (!page->private)
continue;
if (!(page->private & 1)) {
++nmaps;
continue;
}
d = (struct kvm_rmap_desc *)(page->private & ~1ul);
while (d) {
for (k = 0; k < RMAP_EXT; ++k)
if (d->shadow_ptes[k])
++nmaps;
else
break;
d = d->more;
}
}
}
return nmaps;
}
static int count_writable_mappings(struct kvm_vcpu *vcpu)
{
int nmaps = 0;
struct kvm_mmu_page *page;
int i;
list_for_each_entry(page, &vcpu->kvm->active_mmu_pages, link) {
u64 *pt = __va(page->page_hpa);
if (page->role.level != PT_PAGE_TABLE_LEVEL)
continue;
for (i = 0; i < PT64_ENT_PER_PAGE; ++i) {
u64 ent = pt[i];
if (!(ent & PT_PRESENT_MASK))
continue;
if (!(ent & PT_WRITABLE_MASK))
continue;
++nmaps;
}
}
return nmaps;
}
static void audit_rmap(struct kvm_vcpu *vcpu)
{
int n_rmap = count_rmaps(vcpu);
int n_actual = count_writable_mappings(vcpu);
if (n_rmap != n_actual)
printk(KERN_ERR "%s: (%s) rmap %d actual %d\n",
__FUNCTION__, audit_msg, n_rmap, n_actual);
}
static void audit_write_protection(struct kvm_vcpu *vcpu)
{
struct kvm_mmu_page *page;
list_for_each_entry(page, &vcpu->kvm->active_mmu_pages, link) {
hfn_t hfn;
struct page *pg;
if (page->role.metaphysical)
continue;
hfn = gpa_to_hpa(vcpu, (gpa_t)page->gfn << PAGE_SHIFT)
>> PAGE_SHIFT;
pg = pfn_to_page(hfn);
if (pg->private)
printk(KERN_ERR "%s: (%s) shadow page has writable"
" mappings: gfn %lx role %x\n",
__FUNCTION__, audit_msg, page->gfn,
page->role.word);
}
}
static void kvm_mmu_audit(struct kvm_vcpu *vcpu, const char *msg)
{
int olddbg = dbg;
dbg = 0;
audit_msg = msg;
audit_rmap(vcpu);
audit_write_protection(vcpu);
audit_mappings(vcpu);
dbg = olddbg;
}
#endif