linux/arch/x86/kvm/mmu.c
Avi Kivity e48bb497b9 KVM: MMU: Fix memory leak on guest demand faults
While backporting 72dc67a696, a gfn_to_page()
call was duplicated instead of moved (due to an unrelated patch not being
present in mainline).  This caused a page reference leak, resulting in a
fairly massive memory leak.

Fix by removing the extraneous gfn_to_page() call.

Signed-off-by: Avi Kivity <avi@qumranet.com>
2008-03-25 10:22:17 +02:00

1908 lines
45 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 "vmx.h"
#include "mmu.h"
#include <linux/kvm_host.h>
#include <linux/types.h>
#include <linux/string.h>
#include <linux/mm.h>
#include <linux/highmem.h>
#include <linux/module.h>
#include <linux/swap.h>
#include <asm/page.h>
#include <asm/cmpxchg.h>
#include <asm/io.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
#ifndef MMU_DEBUG
#define ASSERT(x) do { } while (0)
#else
#define ASSERT(x) \
if (!(x)) { \
printk(KERN_WARNING "assertion failed %s:%d: %s\n", \
__FILE__, __LINE__, #x); \
}
#endif
#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_SHIFT 63
#define PT64_NX_MASK (1ULL << PT64_NX_SHIFT)
#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 PT_FIRST_AVAIL_BITS_SHIFT 9
#define PT64_SECOND_AVAIL_BITS_SHIFT 52
#define PT_SHADOW_IO_MARK (1ULL << PT_FIRST_AVAIL_BITS_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 PT64_PERM_MASK (PT_PRESENT_MASK | PT_WRITABLE_MASK | PT_USER_MASK \
| PT64_NX_MASK)
#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
#define ACC_EXEC_MASK 1
#define ACC_WRITE_MASK PT_WRITABLE_MASK
#define ACC_USER_MASK PT_USER_MASK
#define ACC_ALL (ACC_EXEC_MASK | ACC_WRITE_MASK | ACC_USER_MASK)
struct kvm_rmap_desc {
u64 *shadow_ptes[RMAP_EXT];
struct kvm_rmap_desc *more;
};
static struct kmem_cache *pte_chain_cache;
static struct kmem_cache *rmap_desc_cache;
static struct kmem_cache *mmu_page_header_cache;
static u64 __read_mostly shadow_trap_nonpresent_pte;
static u64 __read_mostly shadow_notrap_nonpresent_pte;
void kvm_mmu_set_nonpresent_ptes(u64 trap_pte, u64 notrap_pte)
{
shadow_trap_nonpresent_pte = trap_pte;
shadow_notrap_nonpresent_pte = notrap_pte;
}
EXPORT_SYMBOL_GPL(kvm_mmu_set_nonpresent_ptes);
static int is_write_protection(struct kvm_vcpu *vcpu)
{
return vcpu->arch.cr0 & X86_CR0_WP;
}
static int is_cpuid_PSE36(void)
{
return 1;
}
static int is_nx(struct kvm_vcpu *vcpu)
{
return vcpu->arch.shadow_efer & EFER_NX;
}
static int is_present_pte(unsigned long pte)
{
return pte & PT_PRESENT_MASK;
}
static int is_shadow_present_pte(u64 pte)
{
pte &= ~PT_SHADOW_IO_MARK;
return pte != shadow_trap_nonpresent_pte
&& pte != shadow_notrap_nonpresent_pte;
}
static int is_writeble_pte(unsigned long pte)
{
return pte & PT_WRITABLE_MASK;
}
static int is_dirty_pte(unsigned long pte)
{
return pte & PT_DIRTY_MASK;
}
static int is_io_pte(unsigned long pte)
{
return pte & PT_SHADOW_IO_MARK;
}
static int is_rmap_pte(u64 pte)
{
return is_shadow_present_pte(pte);
}
static gfn_t pse36_gfn_delta(u32 gpte)
{
int shift = 32 - PT32_DIR_PSE36_SHIFT - PAGE_SHIFT;
return (gpte & PT32_DIR_PSE36_MASK) << shift;
}
static void set_shadow_pte(u64 *sptep, u64 spte)
{
#ifdef CONFIG_X86_64
set_64bit((unsigned long *)sptep, spte);
#else
set_64bit((unsigned long long *)sptep, spte);
#endif
}
static int mmu_topup_memory_cache(struct kvm_mmu_memory_cache *cache,
struct kmem_cache *base_cache, int min)
{
void *obj;
if (cache->nobjs >= min)
return 0;
while (cache->nobjs < ARRAY_SIZE(cache->objects)) {
obj = kmem_cache_zalloc(base_cache, GFP_KERNEL);
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_cache_page(struct kvm_mmu_memory_cache *cache,
int min)
{
struct page *page;
if (cache->nobjs >= min)
return 0;
while (cache->nobjs < ARRAY_SIZE(cache->objects)) {
page = alloc_page(GFP_KERNEL);
if (!page)
return -ENOMEM;
set_page_private(page, 0);
cache->objects[cache->nobjs++] = page_address(page);
}
return 0;
}
static void mmu_free_memory_cache_page(struct kvm_mmu_memory_cache *mc)
{
while (mc->nobjs)
free_page((unsigned long)mc->objects[--mc->nobjs]);
}
static int mmu_topup_memory_caches(struct kvm_vcpu *vcpu)
{
int r;
r = mmu_topup_memory_cache(&vcpu->arch.mmu_pte_chain_cache,
pte_chain_cache, 4);
if (r)
goto out;
r = mmu_topup_memory_cache(&vcpu->arch.mmu_rmap_desc_cache,
rmap_desc_cache, 1);
if (r)
goto out;
r = mmu_topup_memory_cache_page(&vcpu->arch.mmu_page_cache, 8);
if (r)
goto out;
r = mmu_topup_memory_cache(&vcpu->arch.mmu_page_header_cache,
mmu_page_header_cache, 4);
out:
return r;
}
static void mmu_free_memory_caches(struct kvm_vcpu *vcpu)
{
mmu_free_memory_cache(&vcpu->arch.mmu_pte_chain_cache);
mmu_free_memory_cache(&vcpu->arch.mmu_rmap_desc_cache);
mmu_free_memory_cache_page(&vcpu->arch.mmu_page_cache);
mmu_free_memory_cache(&vcpu->arch.mmu_page_header_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 struct kvm_pte_chain *mmu_alloc_pte_chain(struct kvm_vcpu *vcpu)
{
return mmu_memory_cache_alloc(&vcpu->arch.mmu_pte_chain_cache,
sizeof(struct kvm_pte_chain));
}
static void mmu_free_pte_chain(struct kvm_pte_chain *pc)
{
kfree(pc);
}
static struct kvm_rmap_desc *mmu_alloc_rmap_desc(struct kvm_vcpu *vcpu)
{
return mmu_memory_cache_alloc(&vcpu->arch.mmu_rmap_desc_cache,
sizeof(struct kvm_rmap_desc));
}
static void mmu_free_rmap_desc(struct kvm_rmap_desc *rd)
{
kfree(rd);
}
/*
* Take gfn and return the reverse mapping to it.
* Note: gfn must be unaliased before this function get called
*/
static unsigned long *gfn_to_rmap(struct kvm *kvm, gfn_t gfn)
{
struct kvm_memory_slot *slot;
slot = gfn_to_memslot(kvm, gfn);
return &slot->rmap[gfn - slot->base_gfn];
}
/*
* Reverse mapping data structures:
*
* If rmapp bit zero is zero, then rmapp point to the shadw page table entry
* that points to page_address(page).
*
* If rmapp bit zero is one, (then rmap & ~1) points to a struct kvm_rmap_desc
* containing more mappings.
*/
static void rmap_add(struct kvm_vcpu *vcpu, u64 *spte, gfn_t gfn)
{
struct kvm_mmu_page *sp;
struct kvm_rmap_desc *desc;
unsigned long *rmapp;
int i;
if (!is_rmap_pte(*spte))
return;
gfn = unalias_gfn(vcpu->kvm, gfn);
sp = page_header(__pa(spte));
sp->gfns[spte - sp->spt] = gfn;
rmapp = gfn_to_rmap(vcpu->kvm, gfn);
if (!*rmapp) {
rmap_printk("rmap_add: %p %llx 0->1\n", spte, *spte);
*rmapp = (unsigned long)spte;
} else if (!(*rmapp & 1)) {
rmap_printk("rmap_add: %p %llx 1->many\n", spte, *spte);
desc = mmu_alloc_rmap_desc(vcpu);
desc->shadow_ptes[0] = (u64 *)*rmapp;
desc->shadow_ptes[1] = spte;
*rmapp = (unsigned long)desc | 1;
} else {
rmap_printk("rmap_add: %p %llx many->many\n", spte, *spte);
desc = (struct kvm_rmap_desc *)(*rmapp & ~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(unsigned long *rmapp,
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)
*rmapp = (unsigned long)desc->shadow_ptes[0];
else
if (prev_desc)
prev_desc->more = desc->more;
else
*rmapp = (unsigned long)desc->more | 1;
mmu_free_rmap_desc(desc);
}
static void rmap_remove(struct kvm *kvm, u64 *spte)
{
struct kvm_rmap_desc *desc;
struct kvm_rmap_desc *prev_desc;
struct kvm_mmu_page *sp;
struct page *page;
unsigned long *rmapp;
int i;
if (!is_rmap_pte(*spte))
return;
sp = page_header(__pa(spte));
page = pfn_to_page((*spte & PT64_BASE_ADDR_MASK) >> PAGE_SHIFT);
mark_page_accessed(page);
if (is_writeble_pte(*spte))
kvm_release_page_dirty(page);
else
kvm_release_page_clean(page);
rmapp = gfn_to_rmap(kvm, sp->gfns[spte - sp->spt]);
if (!*rmapp) {
printk(KERN_ERR "rmap_remove: %p %llx 0->BUG\n", spte, *spte);
BUG();
} else if (!(*rmapp & 1)) {
rmap_printk("rmap_remove: %p %llx 1->0\n", spte, *spte);
if ((u64 *)*rmapp != spte) {
printk(KERN_ERR "rmap_remove: %p %llx 1->BUG\n",
spte, *spte);
BUG();
}
*rmapp = 0;
} else {
rmap_printk("rmap_remove: %p %llx many->many\n", spte, *spte);
desc = (struct kvm_rmap_desc *)(*rmapp & ~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(rmapp,
desc, i,
prev_desc);
return;
}
prev_desc = desc;
desc = desc->more;
}
BUG();
}
}
static u64 *rmap_next(struct kvm *kvm, unsigned long *rmapp, u64 *spte)
{
struct kvm_rmap_desc *desc;
struct kvm_rmap_desc *prev_desc;
u64 *prev_spte;
int i;
if (!*rmapp)
return NULL;
else if (!(*rmapp & 1)) {
if (!spte)
return (u64 *)*rmapp;
return NULL;
}
desc = (struct kvm_rmap_desc *)(*rmapp & ~1ul);
prev_desc = NULL;
prev_spte = NULL;
while (desc) {
for (i = 0; i < RMAP_EXT && desc->shadow_ptes[i]; ++i) {
if (prev_spte == spte)
return desc->shadow_ptes[i];
prev_spte = desc->shadow_ptes[i];
}
desc = desc->more;
}
return NULL;
}
static void rmap_write_protect(struct kvm *kvm, u64 gfn)
{
unsigned long *rmapp;
u64 *spte;
int write_protected = 0;
gfn = unalias_gfn(kvm, gfn);
rmapp = gfn_to_rmap(kvm, gfn);
spte = rmap_next(kvm, rmapp, NULL);
while (spte) {
BUG_ON(!spte);
BUG_ON(!(*spte & PT_PRESENT_MASK));
rmap_printk("rmap_write_protect: spte %p %llx\n", spte, *spte);
if (is_writeble_pte(*spte)) {
set_shadow_pte(spte, *spte & ~PT_WRITABLE_MASK);
write_protected = 1;
}
spte = rmap_next(kvm, rmapp, spte);
}
if (write_protected)
kvm_flush_remote_tlbs(kvm);
}
#ifdef MMU_DEBUG
static int is_empty_shadow_page(u64 *spt)
{
u64 *pos;
u64 *end;
for (pos = spt, end = pos + PAGE_SIZE / sizeof(u64); pos != end; pos++)
if ((*pos & ~PT_SHADOW_IO_MARK) != shadow_trap_nonpresent_pte) {
printk(KERN_ERR "%s: %p %llx\n", __FUNCTION__,
pos, *pos);
return 0;
}
return 1;
}
#endif
static void kvm_mmu_free_page(struct kvm *kvm, struct kvm_mmu_page *sp)
{
ASSERT(is_empty_shadow_page(sp->spt));
list_del(&sp->link);
__free_page(virt_to_page(sp->spt));
__free_page(virt_to_page(sp->gfns));
kfree(sp);
++kvm->arch.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 *sp;
sp = mmu_memory_cache_alloc(&vcpu->arch.mmu_page_header_cache, sizeof *sp);
sp->spt = mmu_memory_cache_alloc(&vcpu->arch.mmu_page_cache, PAGE_SIZE);
sp->gfns = mmu_memory_cache_alloc(&vcpu->arch.mmu_page_cache, PAGE_SIZE);
set_page_private(virt_to_page(sp->spt), (unsigned long)sp);
list_add(&sp->link, &vcpu->kvm->arch.active_mmu_pages);
ASSERT(is_empty_shadow_page(sp->spt));
sp->slot_bitmap = 0;
sp->multimapped = 0;
sp->parent_pte = parent_pte;
--vcpu->kvm->arch.n_free_mmu_pages;
return sp;
}
static void mmu_page_add_parent_pte(struct kvm_vcpu *vcpu,
struct kvm_mmu_page *sp, u64 *parent_pte)
{
struct kvm_pte_chain *pte_chain;
struct hlist_node *node;
int i;
if (!parent_pte)
return;
if (!sp->multimapped) {
u64 *old = sp->parent_pte;
if (!old) {
sp->parent_pte = parent_pte;
return;
}
sp->multimapped = 1;
pte_chain = mmu_alloc_pte_chain(vcpu);
INIT_HLIST_HEAD(&sp->parent_ptes);
hlist_add_head(&pte_chain->link, &sp->parent_ptes);
pte_chain->parent_ptes[0] = old;
}
hlist_for_each_entry(pte_chain, node, &sp->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, &sp->parent_ptes);
pte_chain->parent_ptes[0] = parent_pte;
}
static void mmu_page_remove_parent_pte(struct kvm_mmu_page *sp,
u64 *parent_pte)
{
struct kvm_pte_chain *pte_chain;
struct hlist_node *node;
int i;
if (!sp->multimapped) {
BUG_ON(sp->parent_pte != parent_pte);
sp->parent_pte = NULL;
return;
}
hlist_for_each_entry(pte_chain, node, &sp->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(pte_chain);
if (hlist_empty(&sp->parent_ptes)) {
sp->multimapped = 0;
sp->parent_pte = NULL;
}
}
return;
}
BUG();
}
static struct kvm_mmu_page *kvm_mmu_lookup_page(struct kvm *kvm, gfn_t gfn)
{
unsigned index;
struct hlist_head *bucket;
struct kvm_mmu_page *sp;
struct hlist_node *node;
pgprintk("%s: looking for gfn %lx\n", __FUNCTION__, gfn);
index = kvm_page_table_hashfn(gfn) % KVM_NUM_MMU_PAGES;
bucket = &kvm->arch.mmu_page_hash[index];
hlist_for_each_entry(sp, node, bucket, hash_link)
if (sp->gfn == gfn && !sp->role.metaphysical) {
pgprintk("%s: found role %x\n",
__FUNCTION__, sp->role.word);
return sp;
}
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,
unsigned access,
u64 *parent_pte)
{
union kvm_mmu_page_role role;
unsigned index;
unsigned quadrant;
struct hlist_head *bucket;
struct kvm_mmu_page *sp;
struct hlist_node *node;
role.word = 0;
role.glevels = vcpu->arch.mmu.root_level;
role.level = level;
role.metaphysical = metaphysical;
role.access = access;
if (vcpu->arch.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->arch.mmu_page_hash[index];
hlist_for_each_entry(sp, node, bucket, hash_link)
if (sp->gfn == gfn && sp->role.word == role.word) {
mmu_page_add_parent_pte(vcpu, sp, parent_pte);
pgprintk("%s: found\n", __FUNCTION__);
return sp;
}
++vcpu->kvm->stat.mmu_cache_miss;
sp = kvm_mmu_alloc_page(vcpu, parent_pte);
if (!sp)
return sp;
pgprintk("%s: adding gfn %lx role %x\n", __FUNCTION__, gfn, role.word);
sp->gfn = gfn;
sp->role = role;
hlist_add_head(&sp->hash_link, bucket);
vcpu->arch.mmu.prefetch_page(vcpu, sp);
if (!metaphysical)
rmap_write_protect(vcpu->kvm, gfn);
return sp;
}
static void kvm_mmu_page_unlink_children(struct kvm *kvm,
struct kvm_mmu_page *sp)
{
unsigned i;
u64 *pt;
u64 ent;
pt = sp->spt;
if (sp->role.level == PT_PAGE_TABLE_LEVEL) {
for (i = 0; i < PT64_ENT_PER_PAGE; ++i) {
if (is_shadow_present_pte(pt[i]))
rmap_remove(kvm, &pt[i]);
pt[i] = shadow_trap_nonpresent_pte;
}
kvm_flush_remote_tlbs(kvm);
return;
}
for (i = 0; i < PT64_ENT_PER_PAGE; ++i) {
ent = pt[i];
pt[i] = shadow_trap_nonpresent_pte;
if (!is_shadow_present_pte(ent))
continue;
ent &= PT64_BASE_ADDR_MASK;
mmu_page_remove_parent_pte(page_header(ent), &pt[i]);
}
kvm_flush_remote_tlbs(kvm);
}
static void kvm_mmu_put_page(struct kvm_mmu_page *sp, u64 *parent_pte)
{
mmu_page_remove_parent_pte(sp, parent_pte);
}
static void kvm_mmu_reset_last_pte_updated(struct kvm *kvm)
{
int i;
for (i = 0; i < KVM_MAX_VCPUS; ++i)
if (kvm->vcpus[i])
kvm->vcpus[i]->arch.last_pte_updated = NULL;
}
static void kvm_mmu_zap_page(struct kvm *kvm, struct kvm_mmu_page *sp)
{
u64 *parent_pte;
++kvm->stat.mmu_shadow_zapped;
while (sp->multimapped || sp->parent_pte) {
if (!sp->multimapped)
parent_pte = sp->parent_pte;
else {
struct kvm_pte_chain *chain;
chain = container_of(sp->parent_ptes.first,
struct kvm_pte_chain, link);
parent_pte = chain->parent_ptes[0];
}
BUG_ON(!parent_pte);
kvm_mmu_put_page(sp, parent_pte);
set_shadow_pte(parent_pte, shadow_trap_nonpresent_pte);
}
kvm_mmu_page_unlink_children(kvm, sp);
if (!sp->root_count) {
hlist_del(&sp->hash_link);
kvm_mmu_free_page(kvm, sp);
} else
list_move(&sp->link, &kvm->arch.active_mmu_pages);
kvm_mmu_reset_last_pte_updated(kvm);
}
/*
* Changing the number of mmu pages allocated to the vm
* Note: if kvm_nr_mmu_pages is too small, you will get dead lock
*/
void kvm_mmu_change_mmu_pages(struct kvm *kvm, unsigned int kvm_nr_mmu_pages)
{
/*
* If we set the number of mmu pages to be smaller be than the
* number of actived pages , we must to free some mmu pages before we
* change the value
*/
if ((kvm->arch.n_alloc_mmu_pages - kvm->arch.n_free_mmu_pages) >
kvm_nr_mmu_pages) {
int n_used_mmu_pages = kvm->arch.n_alloc_mmu_pages
- kvm->arch.n_free_mmu_pages;
while (n_used_mmu_pages > kvm_nr_mmu_pages) {
struct kvm_mmu_page *page;
page = container_of(kvm->arch.active_mmu_pages.prev,
struct kvm_mmu_page, link);
kvm_mmu_zap_page(kvm, page);
n_used_mmu_pages--;
}
kvm->arch.n_free_mmu_pages = 0;
}
else
kvm->arch.n_free_mmu_pages += kvm_nr_mmu_pages
- kvm->arch.n_alloc_mmu_pages;
kvm->arch.n_alloc_mmu_pages = kvm_nr_mmu_pages;
}
static int kvm_mmu_unprotect_page(struct kvm *kvm, gfn_t gfn)
{
unsigned index;
struct hlist_head *bucket;
struct kvm_mmu_page *sp;
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 = &kvm->arch.mmu_page_hash[index];
hlist_for_each_entry_safe(sp, node, n, bucket, hash_link)
if (sp->gfn == gfn && !sp->role.metaphysical) {
pgprintk("%s: gfn %lx role %x\n", __FUNCTION__, gfn,
sp->role.word);
kvm_mmu_zap_page(kvm, sp);
r = 1;
}
return r;
}
static void mmu_unshadow(struct kvm *kvm, gfn_t gfn)
{
struct kvm_mmu_page *sp;
while ((sp = kvm_mmu_lookup_page(kvm, gfn)) != NULL) {
pgprintk("%s: zap %lx %x\n", __FUNCTION__, gfn, sp->role.word);
kvm_mmu_zap_page(kvm, sp);
}
}
static void page_header_update_slot(struct kvm *kvm, void *pte, gfn_t gfn)
{
int slot = memslot_id(kvm, gfn_to_memslot(kvm, gfn));
struct kvm_mmu_page *sp = page_header(__pa(pte));
__set_bit(slot, &sp->slot_bitmap);
}
struct page *gva_to_page(struct kvm_vcpu *vcpu, gva_t gva)
{
struct page *page;
gpa_t gpa = vcpu->arch.mmu.gva_to_gpa(vcpu, gva);
if (gpa == UNMAPPED_GVA)
return NULL;
down_read(&current->mm->mmap_sem);
page = gfn_to_page(vcpu->kvm, gpa >> PAGE_SHIFT);
up_read(&current->mm->mmap_sem);
return page;
}
static void mmu_set_spte(struct kvm_vcpu *vcpu, u64 *shadow_pte,
unsigned pt_access, unsigned pte_access,
int user_fault, int write_fault, int dirty,
int *ptwrite, gfn_t gfn, struct page *page)
{
u64 spte;
int was_rmapped = 0;
int was_writeble = is_writeble_pte(*shadow_pte);
hfn_t host_pfn = (*shadow_pte & PT64_BASE_ADDR_MASK) >> PAGE_SHIFT;
pgprintk("%s: spte %llx access %x write_fault %d"
" user_fault %d gfn %lx\n",
__FUNCTION__, *shadow_pte, pt_access,
write_fault, user_fault, gfn);
if (is_rmap_pte(*shadow_pte)) {
if (host_pfn != page_to_pfn(page)) {
pgprintk("hfn old %lx new %lx\n",
host_pfn, page_to_pfn(page));
rmap_remove(vcpu->kvm, shadow_pte);
}
else
was_rmapped = 1;
}
/*
* We don't set the accessed bit, since we sometimes want to see
* whether the guest actually used the pte (in order to detect
* demand paging).
*/
spte = PT_PRESENT_MASK | PT_DIRTY_MASK;
if (!dirty)
pte_access &= ~ACC_WRITE_MASK;
if (!(pte_access & ACC_EXEC_MASK))
spte |= PT64_NX_MASK;
spte |= PT_PRESENT_MASK;
if (pte_access & ACC_USER_MASK)
spte |= PT_USER_MASK;
if (is_error_page(page)) {
set_shadow_pte(shadow_pte,
shadow_trap_nonpresent_pte | PT_SHADOW_IO_MARK);
kvm_release_page_clean(page);
return;
}
spte |= page_to_phys(page);
if ((pte_access & ACC_WRITE_MASK)
|| (write_fault && !is_write_protection(vcpu) && !user_fault)) {
struct kvm_mmu_page *shadow;
spte |= PT_WRITABLE_MASK;
if (user_fault) {
mmu_unshadow(vcpu->kvm, gfn);
goto unshadowed;
}
shadow = kvm_mmu_lookup_page(vcpu->kvm, gfn);
if (shadow) {
pgprintk("%s: found shadow page for %lx, marking ro\n",
__FUNCTION__, gfn);
pte_access &= ~ACC_WRITE_MASK;
if (is_writeble_pte(spte)) {
spte &= ~PT_WRITABLE_MASK;
kvm_x86_ops->tlb_flush(vcpu);
}
if (write_fault)
*ptwrite = 1;
}
}
unshadowed:
if (pte_access & ACC_WRITE_MASK)
mark_page_dirty(vcpu->kvm, gfn);
pgprintk("%s: setting spte %llx\n", __FUNCTION__, spte);
set_shadow_pte(shadow_pte, spte);
page_header_update_slot(vcpu->kvm, shadow_pte, gfn);
if (!was_rmapped) {
rmap_add(vcpu, shadow_pte, gfn);
if (!is_rmap_pte(*shadow_pte))
kvm_release_page_clean(page);
} else {
if (was_writeble)
kvm_release_page_dirty(page);
else
kvm_release_page_clean(page);
}
if (!ptwrite || !*ptwrite)
vcpu->arch.last_pte_updated = shadow_pte;
}
static void nonpaging_new_cr3(struct kvm_vcpu *vcpu)
{
}
static int __nonpaging_map(struct kvm_vcpu *vcpu, gva_t v, int write,
gfn_t gfn, struct page *page)
{
int level = PT32E_ROOT_LEVEL;
hpa_t table_addr = vcpu->arch.mmu.root_hpa;
int pt_write = 0;
for (; ; level--) {
u32 index = PT64_INDEX(v, level);
u64 *table;
ASSERT(VALID_PAGE(table_addr));
table = __va(table_addr);
if (level == 1) {
mmu_set_spte(vcpu, &table[index], ACC_ALL, ACC_ALL,
0, write, 1, &pt_write, gfn, page);
return pt_write || is_io_pte(table[index]);
}
if (table[index] == shadow_trap_nonpresent_pte) {
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, ACC_ALL, &table[index]);
if (!new_table) {
pgprintk("nonpaging_map: ENOMEM\n");
kvm_release_page_clean(page);
return -ENOMEM;
}
table[index] = __pa(new_table->spt) | PT_PRESENT_MASK
| PT_WRITABLE_MASK | PT_USER_MASK;
}
table_addr = table[index] & PT64_BASE_ADDR_MASK;
}
}
static int nonpaging_map(struct kvm_vcpu *vcpu, gva_t v, int write, gfn_t gfn)
{
int r;
struct page *page;
down_read(&vcpu->kvm->slots_lock);
down_read(&current->mm->mmap_sem);
page = gfn_to_page(vcpu->kvm, gfn);
up_read(&current->mm->mmap_sem);
spin_lock(&vcpu->kvm->mmu_lock);
kvm_mmu_free_some_pages(vcpu);
r = __nonpaging_map(vcpu, v, write, gfn, page);
spin_unlock(&vcpu->kvm->mmu_lock);
up_read(&vcpu->kvm->slots_lock);
return r;
}
static void nonpaging_prefetch_page(struct kvm_vcpu *vcpu,
struct kvm_mmu_page *sp)
{
int i;
for (i = 0; i < PT64_ENT_PER_PAGE; ++i)
sp->spt[i] = shadow_trap_nonpresent_pte;
}
static void mmu_free_roots(struct kvm_vcpu *vcpu)
{
int i;
struct kvm_mmu_page *sp;
if (!VALID_PAGE(vcpu->arch.mmu.root_hpa))
return;
spin_lock(&vcpu->kvm->mmu_lock);
#ifdef CONFIG_X86_64
if (vcpu->arch.mmu.shadow_root_level == PT64_ROOT_LEVEL) {
hpa_t root = vcpu->arch.mmu.root_hpa;
sp = page_header(root);
--sp->root_count;
vcpu->arch.mmu.root_hpa = INVALID_PAGE;
spin_unlock(&vcpu->kvm->mmu_lock);
return;
}
#endif
for (i = 0; i < 4; ++i) {
hpa_t root = vcpu->arch.mmu.pae_root[i];
if (root) {
root &= PT64_BASE_ADDR_MASK;
sp = page_header(root);
--sp->root_count;
}
vcpu->arch.mmu.pae_root[i] = INVALID_PAGE;
}
spin_unlock(&vcpu->kvm->mmu_lock);
vcpu->arch.mmu.root_hpa = INVALID_PAGE;
}
static void mmu_alloc_roots(struct kvm_vcpu *vcpu)
{
int i;
gfn_t root_gfn;
struct kvm_mmu_page *sp;
root_gfn = vcpu->arch.cr3 >> PAGE_SHIFT;
#ifdef CONFIG_X86_64
if (vcpu->arch.mmu.shadow_root_level == PT64_ROOT_LEVEL) {
hpa_t root = vcpu->arch.mmu.root_hpa;
ASSERT(!VALID_PAGE(root));
sp = kvm_mmu_get_page(vcpu, root_gfn, 0,
PT64_ROOT_LEVEL, 0, ACC_ALL, NULL);
root = __pa(sp->spt);
++sp->root_count;
vcpu->arch.mmu.root_hpa = root;
return;
}
#endif
for (i = 0; i < 4; ++i) {
hpa_t root = vcpu->arch.mmu.pae_root[i];
ASSERT(!VALID_PAGE(root));
if (vcpu->arch.mmu.root_level == PT32E_ROOT_LEVEL) {
if (!is_present_pte(vcpu->arch.pdptrs[i])) {
vcpu->arch.mmu.pae_root[i] = 0;
continue;
}
root_gfn = vcpu->arch.pdptrs[i] >> PAGE_SHIFT;
} else if (vcpu->arch.mmu.root_level == 0)
root_gfn = 0;
sp = kvm_mmu_get_page(vcpu, root_gfn, i << 30,
PT32_ROOT_LEVEL, !is_paging(vcpu),
ACC_ALL, NULL);
root = __pa(sp->spt);
++sp->root_count;
vcpu->arch.mmu.pae_root[i] = root | PT_PRESENT_MASK;
}
vcpu->arch.mmu.root_hpa = __pa(vcpu->arch.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)
{
gfn_t gfn;
int r;
pgprintk("%s: gva %lx error %x\n", __FUNCTION__, gva, error_code);
r = mmu_topup_memory_caches(vcpu);
if (r)
return r;
ASSERT(vcpu);
ASSERT(VALID_PAGE(vcpu->arch.mmu.root_hpa));
gfn = gva >> PAGE_SHIFT;
return nonpaging_map(vcpu, gva & PAGE_MASK,
error_code & PFERR_WRITE_MASK, gfn);
}
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->arch.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->prefetch_page = nonpaging_prefetch_page;
context->root_level = 0;
context->shadow_root_level = PT32E_ROOT_LEVEL;
context->root_hpa = INVALID_PAGE;
return 0;
}
void kvm_mmu_flush_tlb(struct kvm_vcpu *vcpu)
{
++vcpu->stat.tlb_flush;
kvm_x86_ops->tlb_flush(vcpu);
}
static void paging_new_cr3(struct kvm_vcpu *vcpu)
{
pgprintk("%s: cr3 %lx\n", __FUNCTION__, vcpu->arch.cr3);
mmu_free_roots(vcpu);
}
static void inject_page_fault(struct kvm_vcpu *vcpu,
u64 addr,
u32 err_code)
{
kvm_inject_page_fault(vcpu, addr, err_code);
}
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->arch.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->prefetch_page = paging64_prefetch_page;
context->free = paging_free;
context->root_level = level;
context->shadow_root_level = level;
context->root_hpa = INVALID_PAGE;
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->arch.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->prefetch_page = paging32_prefetch_page;
context->root_level = PT32_ROOT_LEVEL;
context->shadow_root_level = PT32E_ROOT_LEVEL;
context->root_hpa = INVALID_PAGE;
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->arch.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->arch.mmu.root_hpa)) {
vcpu->arch.mmu.free(vcpu);
vcpu->arch.mmu.root_hpa = INVALID_PAGE;
}
}
int kvm_mmu_reset_context(struct kvm_vcpu *vcpu)
{
destroy_kvm_mmu(vcpu);
return init_kvm_mmu(vcpu);
}
EXPORT_SYMBOL_GPL(kvm_mmu_reset_context);
int kvm_mmu_load(struct kvm_vcpu *vcpu)
{
int r;
r = mmu_topup_memory_caches(vcpu);
if (r)
goto out;
spin_lock(&vcpu->kvm->mmu_lock);
kvm_mmu_free_some_pages(vcpu);
mmu_alloc_roots(vcpu);
spin_unlock(&vcpu->kvm->mmu_lock);
kvm_x86_ops->set_cr3(vcpu, vcpu->arch.mmu.root_hpa);
kvm_mmu_flush_tlb(vcpu);
out:
return r;
}
EXPORT_SYMBOL_GPL(kvm_mmu_load);
void kvm_mmu_unload(struct kvm_vcpu *vcpu)
{
mmu_free_roots(vcpu);
}
static void mmu_pte_write_zap_pte(struct kvm_vcpu *vcpu,
struct kvm_mmu_page *sp,
u64 *spte)
{
u64 pte;
struct kvm_mmu_page *child;
pte = *spte;
if (is_shadow_present_pte(pte)) {
if (sp->role.level == PT_PAGE_TABLE_LEVEL)
rmap_remove(vcpu->kvm, spte);
else {
child = page_header(pte & PT64_BASE_ADDR_MASK);
mmu_page_remove_parent_pte(child, spte);
}
}
set_shadow_pte(spte, shadow_trap_nonpresent_pte);
}
static void mmu_pte_write_new_pte(struct kvm_vcpu *vcpu,
struct kvm_mmu_page *sp,
u64 *spte,
const void *new, int bytes,
int offset_in_pte)
{
if (sp->role.level != PT_PAGE_TABLE_LEVEL) {
++vcpu->kvm->stat.mmu_pde_zapped;
return;
}
++vcpu->kvm->stat.mmu_pte_updated;
if (sp->role.glevels == PT32_ROOT_LEVEL)
paging32_update_pte(vcpu, sp, spte, new, bytes, offset_in_pte);
else
paging64_update_pte(vcpu, sp, spte, new, bytes, offset_in_pte);
}
static bool need_remote_flush(u64 old, u64 new)
{
if (!is_shadow_present_pte(old))
return false;
if (!is_shadow_present_pte(new))
return true;
if ((old ^ new) & PT64_BASE_ADDR_MASK)
return true;
old ^= PT64_NX_MASK;
new ^= PT64_NX_MASK;
return (old & ~new & PT64_PERM_MASK) != 0;
}
static void mmu_pte_write_flush_tlb(struct kvm_vcpu *vcpu, u64 old, u64 new)
{
if (need_remote_flush(old, new))
kvm_flush_remote_tlbs(vcpu->kvm);
else
kvm_mmu_flush_tlb(vcpu);
}
static bool last_updated_pte_accessed(struct kvm_vcpu *vcpu)
{
u64 *spte = vcpu->arch.last_pte_updated;
return !!(spte && (*spte & PT_ACCESSED_MASK));
}
static void mmu_guess_page_from_pte_write(struct kvm_vcpu *vcpu, gpa_t gpa,
const u8 *new, int bytes)
{
gfn_t gfn;
int r;
u64 gpte = 0;
struct page *page;
if (bytes != 4 && bytes != 8)
return;
/*
* Assume that the pte write on a page table of the same type
* as the current vcpu paging mode. This is nearly always true
* (might be false while changing modes). Note it is verified later
* by update_pte().
*/
if (is_pae(vcpu)) {
/* Handle a 32-bit guest writing two halves of a 64-bit gpte */
if ((bytes == 4) && (gpa % 4 == 0)) {
r = kvm_read_guest(vcpu->kvm, gpa & ~(u64)7, &gpte, 8);
if (r)
return;
memcpy((void *)&gpte + (gpa % 8), new, 4);
} else if ((bytes == 8) && (gpa % 8 == 0)) {
memcpy((void *)&gpte, new, 8);
}
} else {
if ((bytes == 4) && (gpa % 4 == 0))
memcpy((void *)&gpte, new, 4);
}
if (!is_present_pte(gpte))
return;
gfn = (gpte & PT64_BASE_ADDR_MASK) >> PAGE_SHIFT;
down_read(&current->mm->mmap_sem);
page = gfn_to_page(vcpu->kvm, gfn);
up_read(&current->mm->mmap_sem);
vcpu->arch.update_pte.gfn = gfn;
vcpu->arch.update_pte.page = page;
}
void kvm_mmu_pte_write(struct kvm_vcpu *vcpu, gpa_t gpa,
const u8 *new, int bytes)
{
gfn_t gfn = gpa >> PAGE_SHIFT;
struct kvm_mmu_page *sp;
struct hlist_node *node, *n;
struct hlist_head *bucket;
unsigned index;
u64 entry;
u64 *spte;
unsigned offset = offset_in_page(gpa);
unsigned pte_size;
unsigned page_offset;
unsigned misaligned;
unsigned quadrant;
int level;
int flooded = 0;
int npte;
pgprintk("%s: gpa %llx bytes %d\n", __FUNCTION__, gpa, bytes);
mmu_guess_page_from_pte_write(vcpu, gpa, new, bytes);
spin_lock(&vcpu->kvm->mmu_lock);
kvm_mmu_free_some_pages(vcpu);
++vcpu->kvm->stat.mmu_pte_write;
kvm_mmu_audit(vcpu, "pre pte write");
if (gfn == vcpu->arch.last_pt_write_gfn
&& !last_updated_pte_accessed(vcpu)) {
++vcpu->arch.last_pt_write_count;
if (vcpu->arch.last_pt_write_count >= 3)
flooded = 1;
} else {
vcpu->arch.last_pt_write_gfn = gfn;
vcpu->arch.last_pt_write_count = 1;
vcpu->arch.last_pte_updated = NULL;
}
index = kvm_page_table_hashfn(gfn) % KVM_NUM_MMU_PAGES;
bucket = &vcpu->kvm->arch.mmu_page_hash[index];
hlist_for_each_entry_safe(sp, node, n, bucket, hash_link) {
if (sp->gfn != gfn || sp->role.metaphysical)
continue;
pte_size = sp->role.glevels == PT32_ROOT_LEVEL ? 4 : 8;
misaligned = (offset ^ (offset + bytes - 1)) & ~(pte_size - 1);
misaligned |= bytes < 4;
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, sp->role.word);
kvm_mmu_zap_page(vcpu->kvm, sp);
++vcpu->kvm->stat.mmu_flooded;
continue;
}
page_offset = offset;
level = sp->role.level;
npte = 1;
if (sp->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;
}
quadrant = page_offset >> PAGE_SHIFT;
page_offset &= ~PAGE_MASK;
if (quadrant != sp->role.quadrant)
continue;
}
spte = &sp->spt[page_offset / sizeof(*spte)];
while (npte--) {
entry = *spte;
mmu_pte_write_zap_pte(vcpu, sp, spte);
mmu_pte_write_new_pte(vcpu, sp, spte, new, bytes,
page_offset & (pte_size - 1));
mmu_pte_write_flush_tlb(vcpu, entry, *spte);
++spte;
}
}
kvm_mmu_audit(vcpu, "post pte write");
spin_unlock(&vcpu->kvm->mmu_lock);
if (vcpu->arch.update_pte.page) {
kvm_release_page_clean(vcpu->arch.update_pte.page);
vcpu->arch.update_pte.page = NULL;
}
}
int kvm_mmu_unprotect_page_virt(struct kvm_vcpu *vcpu, gva_t gva)
{
gpa_t gpa;
int r;
down_read(&vcpu->kvm->slots_lock);
gpa = vcpu->arch.mmu.gva_to_gpa(vcpu, gva);
up_read(&vcpu->kvm->slots_lock);
spin_lock(&vcpu->kvm->mmu_lock);
r = kvm_mmu_unprotect_page(vcpu->kvm, gpa >> PAGE_SHIFT);
spin_unlock(&vcpu->kvm->mmu_lock);
return r;
}
void __kvm_mmu_free_some_pages(struct kvm_vcpu *vcpu)
{
while (vcpu->kvm->arch.n_free_mmu_pages < KVM_REFILL_PAGES) {
struct kvm_mmu_page *sp;
sp = container_of(vcpu->kvm->arch.active_mmu_pages.prev,
struct kvm_mmu_page, link);
kvm_mmu_zap_page(vcpu->kvm, sp);
++vcpu->kvm->stat.mmu_recycled;
}
}
int kvm_mmu_page_fault(struct kvm_vcpu *vcpu, gva_t cr2, u32 error_code)
{
int r;
enum emulation_result er;
r = vcpu->arch.mmu.page_fault(vcpu, cr2, error_code);
if (r < 0)
goto out;
if (!r) {
r = 1;
goto out;
}
r = mmu_topup_memory_caches(vcpu);
if (r)
goto out;
er = emulate_instruction(vcpu, vcpu->run, cr2, error_code, 0);
switch (er) {
case EMULATE_DONE:
return 1;
case EMULATE_DO_MMIO:
++vcpu->stat.mmio_exits;
return 0;
case EMULATE_FAIL:
kvm_report_emulation_failure(vcpu, "pagetable");
return 1;
default:
BUG();
}
out:
return r;
}
EXPORT_SYMBOL_GPL(kvm_mmu_page_fault);
static void free_mmu_pages(struct kvm_vcpu *vcpu)
{
struct kvm_mmu_page *sp;
while (!list_empty(&vcpu->kvm->arch.active_mmu_pages)) {
sp = container_of(vcpu->kvm->arch.active_mmu_pages.next,
struct kvm_mmu_page, link);
kvm_mmu_zap_page(vcpu->kvm, sp);
}
free_page((unsigned long)vcpu->arch.mmu.pae_root);
}
static int alloc_mmu_pages(struct kvm_vcpu *vcpu)
{
struct page *page;
int i;
ASSERT(vcpu);
if (vcpu->kvm->arch.n_requested_mmu_pages)
vcpu->kvm->arch.n_free_mmu_pages =
vcpu->kvm->arch.n_requested_mmu_pages;
else
vcpu->kvm->arch.n_free_mmu_pages =
vcpu->kvm->arch.n_alloc_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->arch.mmu.pae_root = page_address(page);
for (i = 0; i < 4; ++i)
vcpu->arch.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->arch.mmu.root_hpa));
return alloc_mmu_pages(vcpu);
}
int kvm_mmu_setup(struct kvm_vcpu *vcpu)
{
ASSERT(vcpu);
ASSERT(!VALID_PAGE(vcpu->arch.mmu.root_hpa));
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 *kvm, int slot)
{
struct kvm_mmu_page *sp;
list_for_each_entry(sp, &kvm->arch.active_mmu_pages, link) {
int i;
u64 *pt;
if (!test_bit(slot, &sp->slot_bitmap))
continue;
pt = sp->spt;
for (i = 0; i < PT64_ENT_PER_PAGE; ++i)
/* avoid RMW */
if (pt[i] & PT_WRITABLE_MASK)
pt[i] &= ~PT_WRITABLE_MASK;
}
}
void kvm_mmu_zap_all(struct kvm *kvm)
{
struct kvm_mmu_page *sp, *node;
spin_lock(&kvm->mmu_lock);
list_for_each_entry_safe(sp, node, &kvm->arch.active_mmu_pages, link)
kvm_mmu_zap_page(kvm, sp);
spin_unlock(&kvm->mmu_lock);
kvm_flush_remote_tlbs(kvm);
}
void kvm_mmu_module_exit(void)
{
if (pte_chain_cache)
kmem_cache_destroy(pte_chain_cache);
if (rmap_desc_cache)
kmem_cache_destroy(rmap_desc_cache);
if (mmu_page_header_cache)
kmem_cache_destroy(mmu_page_header_cache);
}
int kvm_mmu_module_init(void)
{
pte_chain_cache = kmem_cache_create("kvm_pte_chain",
sizeof(struct kvm_pte_chain),
0, 0, NULL);
if (!pte_chain_cache)
goto nomem;
rmap_desc_cache = kmem_cache_create("kvm_rmap_desc",
sizeof(struct kvm_rmap_desc),
0, 0, NULL);
if (!rmap_desc_cache)
goto nomem;
mmu_page_header_cache = kmem_cache_create("kvm_mmu_page_header",
sizeof(struct kvm_mmu_page),
0, 0, NULL);
if (!mmu_page_header_cache)
goto nomem;
return 0;
nomem:
kvm_mmu_module_exit();
return -ENOMEM;
}
/*
* Caculate mmu pages needed for kvm.
*/
unsigned int kvm_mmu_calculate_mmu_pages(struct kvm *kvm)
{
int i;
unsigned int nr_mmu_pages;
unsigned int nr_pages = 0;
for (i = 0; i < kvm->nmemslots; i++)
nr_pages += kvm->memslots[i].npages;
nr_mmu_pages = nr_pages * KVM_PERMILLE_MMU_PAGES / 1000;
nr_mmu_pages = max(nr_mmu_pages,
(unsigned int) KVM_MIN_ALLOC_MMU_PAGES);
return nr_mmu_pages;
}
#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 == shadow_trap_nonpresent_pte)
continue;
va = canonicalize(va);
if (level > 1) {
if (ent == shadow_notrap_nonpresent_pte)
printk(KERN_ERR "audit: (%s) nontrapping pte"
" in nonleaf level: levels %d gva %lx"
" level %d pte %llx\n", audit_msg,
vcpu->arch.mmu.root_level, va, level, ent);
audit_mappings_page(vcpu, ent, va, level - 1);
} else {
gpa_t gpa = vcpu->arch.mmu.gva_to_gpa(vcpu, va);
struct page *page = gpa_to_page(vcpu, gpa);
hpa_t hpa = page_to_phys(page);
if (is_shadow_present_pte(ent)
&& (ent & PT64_BASE_ADDR_MASK) != hpa)
printk(KERN_ERR "xx audit error: (%s) levels %d"
" gva %lx gpa %llx hpa %llx ent %llx %d\n",
audit_msg, vcpu->arch.mmu.root_level,
va, gpa, hpa, ent,
is_shadow_present_pte(ent));
else if (ent == shadow_notrap_nonpresent_pte
&& !is_error_hpa(hpa))
printk(KERN_ERR "audit: (%s) notrap shadow,"
" valid guest gva %lx\n", audit_msg, va);
kvm_release_page_clean(page);
}
}
}
static void audit_mappings(struct kvm_vcpu *vcpu)
{
unsigned i;
if (vcpu->arch.mmu.root_level == 4)
audit_mappings_page(vcpu, vcpu->arch.mmu.root_hpa, 0, 4);
else
for (i = 0; i < 4; ++i)
if (vcpu->arch.mmu.pae_root[i] & PT_PRESENT_MASK)
audit_mappings_page(vcpu,
vcpu->arch.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) {
unsigned long *rmapp = &m->rmap[j];
if (!*rmapp)
continue;
if (!(*rmapp & 1)) {
++nmaps;
continue;
}
d = (struct kvm_rmap_desc *)(*rmapp & ~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 *sp;
int i;
list_for_each_entry(sp, &vcpu->kvm->arch.active_mmu_pages, link) {
u64 *pt = sp->spt;
if (sp->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 *sp;
struct kvm_memory_slot *slot;
unsigned long *rmapp;
gfn_t gfn;
list_for_each_entry(sp, &vcpu->kvm->arch.active_mmu_pages, link) {
if (sp->role.metaphysical)
continue;
slot = gfn_to_memslot(vcpu->kvm, sp->gfn);
gfn = unalias_gfn(vcpu->kvm, sp->gfn);
rmapp = &slot->rmap[gfn - slot->base_gfn];
if (*rmapp)
printk(KERN_ERR "%s: (%s) shadow page has writable"
" mappings: gfn %lx role %x\n",
__FUNCTION__, audit_msg, sp->gfn,
sp->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