linux/drivers/kvm/mmu.c
Avi Kivity 2e3e5882dc KVM: MMU: Don't do GFP_NOWAIT allocations
Before preempt notifiers, kvm needed to allocate memory with GFP_NOWAIT so
as not to have to enable preemption and take a heavyweight exit.  On oom, we'd
fall back to a GFP_KERNEL allocation.

With preemption notifiers, we can do a GFP_KERNEL allocation, and perform
the heavyweight exit only if the kernel decides to put us to sleep.

Signed-off-by: Avi Kivity <avi@qumranet.com>
2007-10-13 10:18:27 +02:00

1498 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 "vmx.h"
#include "kvm.h"
#include <linux/types.h>
#include <linux/string.h>
#include <linux/mm.h>
#include <linux/highmem.h>
#include <linux/module.h>
#include <asm/page.h>
#include <asm/cmpxchg.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_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 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 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 struct kmem_cache *pte_chain_cache;
static struct kmem_cache *rmap_desc_cache;
static struct kmem_cache *mmu_page_header_cache;
static int is_write_protection(struct kvm_vcpu *vcpu)
{
return vcpu->cr0 & X86_CR0_WP;
}
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 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;
kvm_mmu_free_some_pages(vcpu);
r = mmu_topup_memory_cache(&vcpu->mmu_pte_chain_cache,
pte_chain_cache, 4);
if (r)
goto out;
r = mmu_topup_memory_cache(&vcpu->mmu_rmap_desc_cache,
rmap_desc_cache, 1);
if (r)
goto out;
r = mmu_topup_memory_cache_page(&vcpu->mmu_page_cache, 4);
if (r)
goto out;
r = mmu_topup_memory_cache(&vcpu->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->mmu_pte_chain_cache);
mmu_free_memory_cache(&vcpu->mmu_rmap_desc_cache);
mmu_free_memory_cache_page(&vcpu->mmu_page_cache);
mmu_free_memory_cache(&vcpu->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->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->mmu_rmap_desc_cache,
sizeof(struct kvm_rmap_desc));
}
static void mmu_free_rmap_desc(struct kvm_rmap_desc *rd)
{
kfree(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 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(desc);
}
static void rmap_remove(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(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_rmap_desc *desc;
u64 *spte;
page = gfn_to_page(kvm, gfn);
BUG_ON(!page);
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(spte);
set_shadow_pte(spte, *spte & ~PT_WRITABLE_MASK);
kvm_flush_remote_tlbs(vcpu->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 != 0) {
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 *page_head)
{
ASSERT(is_empty_shadow_page(page_head->spt));
list_del(&page_head->link);
__free_page(virt_to_page(page_head->spt));
kfree(page_head);
++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 (!vcpu->kvm->n_free_mmu_pages)
return NULL;
page = mmu_memory_cache_alloc(&vcpu->mmu_page_header_cache,
sizeof *page);
page->spt = mmu_memory_cache_alloc(&vcpu->mmu_page_cache, PAGE_SIZE);
set_page_private(virt_to_page(page->spt), (unsigned long)page);
list_add(&page->link, &vcpu->kvm->active_mmu_pages);
ASSERT(is_empty_shadow_page(page->spt));
page->slot_bitmap = 0;
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_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(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,
unsigned hugepage_access,
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;
role.hugepage_access = hugepage_access;
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 *kvm,
struct kvm_mmu_page *page)
{
unsigned i;
u64 *pt;
u64 ent;
pt = page->spt;
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(&pt[i]);
pt[i] = 0;
}
kvm_flush_remote_tlbs(kvm);
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(page_header(ent), &pt[i]);
}
kvm_flush_remote_tlbs(kvm);
}
static void kvm_mmu_put_page(struct kvm_mmu_page *page,
u64 *parent_pte)
{
mmu_page_remove_parent_pte(page, parent_pte);
}
static void kvm_mmu_zap_page(struct kvm *kvm,
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(page, parent_pte);
set_shadow_pte(parent_pte, 0);
}
kvm_mmu_page_unlink_children(kvm, page);
if (!page->root_count) {
hlist_del(&page->hash_link);
kvm_mmu_free_page(kvm, page);
} else
list_move(&page->link, &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->kvm, page);
r = 1;
}
return r;
}
static void mmu_unshadow(struct kvm_vcpu *vcpu, gfn_t gfn)
{
struct kvm_mmu_page *page;
while ((page = kvm_mmu_lookup_page(vcpu, gfn)) != NULL) {
pgprintk("%s: zap %lx %x\n",
__FUNCTION__, gfn, page->role.word);
kvm_mmu_zap_page(vcpu->kvm, page);
}
}
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 page *page;
ASSERT((gpa & HPA_ERR_MASK) == 0);
page = gfn_to_page(vcpu->kvm, gpa >> PAGE_SHIFT);
if (!page)
return gpa | HPA_ERR_MASK;
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);
}
struct page *gva_to_page(struct kvm_vcpu *vcpu, gva_t gva)
{
gpa_t gpa = vcpu->mmu.gva_to_gpa(vcpu, gva);
if (gpa == UNMAPPED_GVA)
return NULL;
return pfn_to_page(gpa_to_hpa(vcpu, gpa) >> PAGE_SHIFT);
}
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, 0, &table[index]);
if (!new_table) {
pgprintk("nonpaging_map: ENOMEM\n");
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 void mmu_free_roots(struct kvm_vcpu *vcpu)
{
int i;
struct kvm_mmu_page *page;
if (!VALID_PAGE(vcpu->mmu.root_hpa))
return;
#ifdef CONFIG_X86_64
if (vcpu->mmu.shadow_root_level == PT64_ROOT_LEVEL) {
hpa_t root = vcpu->mmu.root_hpa;
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];
if (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, 0, NULL);
root = __pa(page->spt);
++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) {
if (!is_present_pte(vcpu->pdptrs[i])) {
vcpu->mmu.pae_root[i] = 0;
continue;
}
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),
0, NULL);
root = __pa(page->spt);
++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;
context->root_hpa = INVALID_PAGE;
return 0;
}
static 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->cr3);
mmu_free_roots(vcpu);
}
static void inject_page_fault(struct kvm_vcpu *vcpu,
u64 addr,
u32 err_code)
{
kvm_x86_ops->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->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;
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->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;
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->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)
{
destroy_kvm_mmu(vcpu);
return init_kvm_mmu(vcpu);
}
int kvm_mmu_load(struct kvm_vcpu *vcpu)
{
int r;
mutex_lock(&vcpu->kvm->lock);
r = mmu_topup_memory_caches(vcpu);
if (r)
goto out;
mmu_alloc_roots(vcpu);
kvm_x86_ops->set_cr3(vcpu, vcpu->mmu.root_hpa);
kvm_mmu_flush_tlb(vcpu);
out:
mutex_unlock(&vcpu->kvm->lock);
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 *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(spte);
else {
child = page_header(pte & PT64_BASE_ADDR_MASK);
mmu_page_remove_parent_pte(child, spte);
}
}
*spte = 0;
kvm_flush_remote_tlbs(vcpu->kvm);
}
static void mmu_pte_write_new_pte(struct kvm_vcpu *vcpu,
struct kvm_mmu_page *page,
u64 *spte,
const void *new, int bytes)
{
if (page->role.level != PT_PAGE_TABLE_LEVEL)
return;
if (page->role.glevels == PT32_ROOT_LEVEL)
paging32_update_pte(vcpu, page, spte, new, bytes);
else
paging64_update_pte(vcpu, page, spte, new, bytes);
}
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 *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;
unsigned quadrant;
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);
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, page->role.word);
kvm_mmu_zap_page(vcpu->kvm, 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;
}
quadrant = page_offset >> PAGE_SHIFT;
page_offset &= ~PAGE_MASK;
if (quadrant != page->role.quadrant)
continue;
}
spte = &page->spt[page_offset / sizeof(*spte)];
while (npte--) {
mmu_pte_write_zap_pte(vcpu, page, spte);
mmu_pte_write_new_pte(vcpu, page, spte, new, bytes);
++spte;
}
}
}
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->kvm, page);
}
}
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->kvm, 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);
vcpu->kvm->n_free_mmu_pages = KVM_NUM_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));
return alloc_mmu_pages(vcpu);
}
int kvm_mmu_setup(struct kvm_vcpu *vcpu)
{
ASSERT(vcpu);
ASSERT(!VALID_PAGE(vcpu->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 *page;
list_for_each_entry(page, &kvm->active_mmu_pages, link) {
int i;
u64 *pt;
if (!test_bit(slot, &page->slot_bitmap))
continue;
pt = page->spt;
for (i = 0; i < PT64_ENT_PER_PAGE; ++i)
/* avoid RMW */
if (pt[i] & PT_WRITABLE_MASK) {
rmap_remove(&pt[i]);
pt[i] &= ~PT_WRITABLE_MASK;
}
}
}
void kvm_mmu_zap_all(struct kvm *kvm)
{
struct kvm_mmu_page *page, *node;
list_for_each_entry_safe(page, node, &kvm->active_mmu_pages, link)
kvm_mmu_zap_page(kvm, page);
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;
}
#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)
{
unsigned 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 = page->spt;
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