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linux/drivers/kvm/mmu.c
Ingo Molnar 8018c27b26 [PATCH] kvm: fix GFP_KERNEL allocation in atomic section in kvm_dev_ioctl_create_vcpu() 
fix an GFP_KERNEL allocation in atomic section: kvm_dev_ioctl_create_vcpu()
called kvm_mmu_init(), which calls alloc_pages(), while holding the vcpu.

The fix is to set up the MMU state in two phases: kvm_mmu_create() and
kvm_mmu_setup().

(NOTE: free_vcpus does an kvm_mmu_destroy() call so there's no need for any
extra teardown branch on allocation/init failure here.)

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Cc: Avi Kivity <avi@qumranet.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-12-30 10:56:44 -08:00

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/*
* 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"
#define pgprintk(x...) do { } while (0)
#define ASSERT(x) \
if (!(x)) { \
printk(KERN_WARNING "assertion failed %s:%d: %s\n", \
__FILE__, __LINE__, #x); \
}
#define PT64_ENT_PER_PAGE 512
#define PT32_ENT_PER_PAGE 1024
#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) & PAGE_MASK)
#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 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
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_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 void kvm_mmu_free_page(struct kvm_vcpu *vcpu, hpa_t page_hpa)
{
struct kvm_mmu_page *page_head = page_header(page_hpa);
list_del(&page_head->link);
page_head->page_hpa = page_hpa;
list_add(&page_head->link, &vcpu->free_pages);
}
static int is_empty_shadow_page(hpa_t page_hpa)
{
u32 *pos;
u32 *end;
for (pos = __va(page_hpa), end = pos + PAGE_SIZE / sizeof(u32);
pos != end; pos++)
if (*pos != 0)
return 0;
return 1;
}
static hpa_t kvm_mmu_alloc_page(struct kvm_vcpu *vcpu, u64 *parent_pte)
{
struct kvm_mmu_page *page;
if (list_empty(&vcpu->free_pages))
return INVALID_PAGE;
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->parent_pte = parent_pte;
return page->page_hpa;
}
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 release_pt_page_64(struct kvm_vcpu *vcpu, hpa_t page_hpa,
int level)
{
ASSERT(vcpu);
ASSERT(VALID_PAGE(page_hpa));
ASSERT(level <= PT64_ROOT_LEVEL && level > 0);
if (level == 1)
memset(__va(page_hpa), 0, PAGE_SIZE);
else {
u64 *pos;
u64 *end;
for (pos = __va(page_hpa), end = pos + PT64_ENT_PER_PAGE;
pos != end; pos++) {
u64 current_ent = *pos;
*pos = 0;
if (is_present_pte(current_ent))
release_pt_page_64(vcpu,
current_ent &
PT64_BASE_ADDR_MASK,
level - 1);
}
}
kvm_mmu_free_page(vcpu, page_hpa);
}
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;
ASSERT(VALID_PAGE(table_addr));
table = __va(table_addr);
if (level == 1) {
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;
return 0;
}
if (table[index] == 0) {
hpa_t new_table = kvm_mmu_alloc_page(vcpu,
&table[index]);
if (!VALID_PAGE(new_table)) {
pgprintk("nonpaging_map: ENOMEM\n");
return -ENOMEM;
}
if (level == PT32E_ROOT_LEVEL)
table[index] = new_table | PT_PRESENT_MASK;
else
table[index] = new_table | PT_PRESENT_MASK |
PT_WRITABLE_MASK | PT_USER_MASK;
}
table_addr = table[index] & PT64_BASE_ADDR_MASK;
}
}
static void nonpaging_flush(struct kvm_vcpu *vcpu)
{
hpa_t root = vcpu->mmu.root_hpa;
++kvm_stat.tlb_flush;
pgprintk("nonpaging_flush\n");
ASSERT(VALID_PAGE(root));
release_pt_page_64(vcpu, root, vcpu->mmu.shadow_root_level);
root = kvm_mmu_alloc_page(vcpu, NULL);
ASSERT(VALID_PAGE(root));
vcpu->mmu.root_hpa = root;
if (is_paging(vcpu))
root |= (vcpu->cr3 & (CR3_PCD_MASK | CR3_WPT_MASK));
kvm_arch_ops->set_cr3(vcpu, root);
kvm_arch_ops->tlb_flush(vcpu);
}
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)
{
int ret;
gpa_t addr = gva;
ASSERT(vcpu);
ASSERT(VALID_PAGE(vcpu->mmu.root_hpa));
for (;;) {
hpa_t paddr;
paddr = gpa_to_hpa(vcpu , addr & PT64_BASE_ADDR_MASK);
if (is_error_hpa(paddr))
return 1;
ret = nonpaging_map(vcpu, addr & PAGE_MASK, paddr);
if (ret) {
nonpaging_flush(vcpu);
continue;
}
break;
}
return ret;
}
static void nonpaging_inval_page(struct kvm_vcpu *vcpu, gva_t addr)
{
}
static void nonpaging_free(struct kvm_vcpu *vcpu)
{
hpa_t root;
ASSERT(vcpu);
root = vcpu->mmu.root_hpa;
if (VALID_PAGE(root))
release_pt_page_64(vcpu, root, vcpu->mmu.shadow_root_level);
vcpu->mmu.root_hpa = INVALID_PAGE;
}
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->inval_page = nonpaging_inval_page;
context->gva_to_gpa = nonpaging_gva_to_gpa;
context->free = nonpaging_free;
context->root_level = PT32E_ROOT_LEVEL;
context->shadow_root_level = PT32E_ROOT_LEVEL;
context->root_hpa = kvm_mmu_alloc_page(vcpu, NULL);
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)
{
struct kvm_mmu_page *page, *npage;
list_for_each_entry_safe(page, npage, &vcpu->kvm->active_mmu_pages,
link) {
if (page->global)
continue;
if (!page->parent_pte)
continue;
*page->parent_pte = 0;
release_pt_page_64(vcpu, page->page_hpa, 1);
}
++kvm_stat.tlb_flush;
kvm_arch_ops->tlb_flush(vcpu);
}
static void paging_new_cr3(struct kvm_vcpu *vcpu)
{
kvm_mmu_flush_tlb(vcpu);
}
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)
{
hpa_t paddr;
*shadow_pte |= access_bits << PT_SHADOW_BITS_OFFSET;
if (!dirty)
access_bits &= ~PT_WRITABLE_MASK;
if (access_bits & PT_WRITABLE_MASK)
mark_page_dirty(vcpu->kvm, gaddr >> PAGE_SHIFT);
*shadow_pte |= access_bits;
paddr = gpa_to_hpa(vcpu, gaddr & PT64_BASE_ADDR_MASK);
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;
} else {
*shadow_pte |= paddr;
page_header_update_slot(vcpu->kvm, shadow_pte, gaddr);
}
}
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 int may_access(u64 pte, int write, int user)
{
if (user && !(pte & PT_USER_MASK))
return 0;
if (write && !(pte & PT_WRITABLE_MASK))
return 0;
return 1;
}
/*
* Remove a shadow pte.
*/
static void paging_inval_page(struct kvm_vcpu *vcpu, gva_t addr)
{
hpa_t page_addr = vcpu->mmu.root_hpa;
int level = vcpu->mmu.shadow_root_level;
++kvm_stat.invlpg;
for (; ; level--) {
u32 index = PT64_INDEX(addr, level);
u64 *table = __va(page_addr);
if (level == PT_PAGE_TABLE_LEVEL ) {
table[index] = 0;
return;
}
if (!is_present_pte(table[index]))
return;
page_addr = table[index] & PT64_BASE_ADDR_MASK;
if (level == PT_DIRECTORY_LEVEL &&
(table[index] & PT_SHADOW_PS_MARK)) {
table[index] = 0;
release_pt_page_64(vcpu, page_addr, PT_PAGE_TABLE_LEVEL);
kvm_arch_ops->tlb_flush(vcpu);
return;
}
}
}
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(struct kvm_vcpu *vcpu)
{
struct kvm_mmu *context = &vcpu->mmu;
ASSERT(is_pae(vcpu));
context->new_cr3 = paging_new_cr3;
context->page_fault = paging64_page_fault;
context->inval_page = paging_inval_page;
context->gva_to_gpa = paging64_gva_to_gpa;
context->free = paging_free;
context->root_level = PT64_ROOT_LEVEL;
context->shadow_root_level = PT64_ROOT_LEVEL;
context->root_hpa = kvm_mmu_alloc_page(vcpu, NULL);
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 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->inval_page = paging_inval_page;
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 = kvm_mmu_alloc_page(vcpu, NULL);
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)
{
int ret;
if ((ret = paging64_init_context(vcpu)))
return ret;
vcpu->mmu.root_level = PT32E_ROOT_LEVEL;
vcpu->mmu.shadow_root_level = PT32E_ROOT_LEVEL;
return 0;
}
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);
}
static void free_mmu_pages(struct kvm_vcpu *vcpu)
{
while (!list_empty(&vcpu->free_pages)) {
struct kvm_mmu_page *page;
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;
}
}
static int alloc_mmu_pages(struct kvm_vcpu *vcpu)
{
int i;
ASSERT(vcpu);
for (i = 0; i < KVM_NUM_MMU_PAGES; i++) {
struct page *page;
struct kvm_mmu_page *page_header = &vcpu->page_header_buf[i];
INIT_LIST_HEAD(&page_header->link);
if ((page = alloc_page(GFP_KVM_MMU)) == NULL)
goto error_1;
page->private = (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);
}
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);
}
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 = __va(page->page_hpa);
for (i = 0; i < PT64_ENT_PER_PAGE; ++i)
/* avoid RMW */
if (pt[i] & PT_WRITABLE_MASK)
pt[i] &= ~PT_WRITABLE_MASK;
}
}
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