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KVM: fix the handling of dirty bitmaps to avoid overflows 

Int is not long enough to store the size of a dirty bitmap.

This patch fixes this problem with the introduction of a wrapper
function to calculate the sizes of dirty bitmaps.

Note: in mark_page_dirty(), we have to consider the fact that
  __set_bit() takes the offset as int, not long.

Signed-off-by: Takuya Yoshikawa <yoshikawa.takuya@oss.ntt.co.jp>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
This commit is contained in:
Takuya Yoshikawa 2010-04-12 19:35:35 +09:00 committed by Avi Kivity
parent 77662e0028
commit 87bf6e7de1
5 changed files with 24 additions and 13 deletions
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9
arch/ia64/kvm/kvm-ia64.c
View File

@ -1802,7 +1802,8 @@ static int kvm_ia64_sync_dirty_log(struct kvm *kvm,
{
struct kvm_memory_slot *memslot;
int r, i;
long n, base;
long base;
unsigned long n;
unsigned long *dirty_bitmap = (unsigned long *)(kvm->arch.vm_base +
offsetof(struct kvm_vm_data, kvm_mem_dirty_log));
@ -1815,7 +1816,7 @@ static int kvm_ia64_sync_dirty_log(struct kvm *kvm,
if (!memslot->dirty_bitmap)
goto out;
n = ALIGN(memslot->npages, BITS_PER_LONG) / 8;
n = kvm_dirty_bitmap_bytes(memslot);
base = memslot->base_gfn / BITS_PER_LONG;
for (i = 0; i < n/sizeof(long); ++i) {
@ -1831,7 +1832,7 @@ int kvm_vm_ioctl_get_dirty_log(struct kvm *kvm,
struct kvm_dirty_log *log)
{
int r;
int n;
unsigned long n;
struct kvm_memory_slot *memslot;
int is_dirty = 0;
@ -1850,7 +1851,7 @@ int kvm_vm_ioctl_get_dirty_log(struct kvm *kvm,
if (is_dirty) {
kvm_flush_remote_tlbs(kvm);
memslot = &kvm->memslots->memslots[log->slot];
n = ALIGN(memslot->npages, BITS_PER_LONG) / 8;
n = kvm_dirty_bitmap_bytes(memslot);
memset(memslot->dirty_bitmap, 0, n);
}
r = 0;

5
arch/powerpc/kvm/book3s.c
View File

@ -1004,7 +1004,8 @@ int kvm_vm_ioctl_get_dirty_log(struct kvm *kvm,
struct kvm_vcpu *vcpu;
ulong ga, ga_end;
int is_dirty = 0;
int r, n;
int r;
unsigned long n;
mutex_lock(&kvm->slots_lock);
@ -1022,7 +1023,7 @@ int kvm_vm_ioctl_get_dirty_log(struct kvm *kvm,
kvm_for_each_vcpu(n, vcpu, kvm)
kvmppc_mmu_pte_pflush(vcpu, ga, ga_end);
n = ALIGN(memslot->npages, BITS_PER_LONG) / 8;
n = kvm_dirty_bitmap_bytes(memslot);
memset(memslot->dirty_bitmap, 0, n);
}

5
arch/x86/kvm/x86.c
View File

@ -2612,8 +2612,9 @@ static int kvm_vm_ioctl_reinject(struct kvm *kvm,
int kvm_vm_ioctl_get_dirty_log(struct kvm *kvm,
struct kvm_dirty_log *log)
{
int r, n, i;
int r, i;
struct kvm_memory_slot *memslot;
unsigned long n;
unsigned long is_dirty = 0;
unsigned long *dirty_bitmap = NULL;
@ -2628,7 +2629,7 @@ int kvm_vm_ioctl_get_dirty_log(struct kvm *kvm,
if (!memslot->dirty_bitmap)
goto out;
n = ALIGN(memslot->npages, BITS_PER_LONG) / 8;
n = kvm_dirty_bitmap_bytes(memslot);
r = -ENOMEM;
dirty_bitmap = vmalloc(n);

5
include/linux/kvm_host.h
View File

@ -119,6 +119,11 @@ struct kvm_memory_slot {
int user_alloc;
};
static inline unsigned long kvm_dirty_bitmap_bytes(struct kvm_memory_slot *memslot)
{
return ALIGN(memslot->npages, BITS_PER_LONG) / 8;
}
struct kvm_kernel_irq_routing_entry {
u32 gsi;
u32 type;

13
virt/kvm/kvm_main.c
View File

@ -648,7 +648,7 @@ skip_lpage:
/* Allocate page dirty bitmap if needed */
if ((new.flags & KVM_MEM_LOG_DIRTY_PAGES) && !new.dirty_bitmap) {
unsigned dirty_bytes = ALIGN(npages, BITS_PER_LONG) / 8;
unsigned long dirty_bytes = kvm_dirty_bitmap_bytes(&new);
new.dirty_bitmap = vmalloc(dirty_bytes);
if (!new.dirty_bitmap)
@ -768,7 +768,7 @@ int kvm_get_dirty_log(struct kvm *kvm,
{
struct kvm_memory_slot *memslot;
int r, i;
int n;
unsigned long n;
unsigned long any = 0;
r = -EINVAL;
@ -780,7 +780,7 @@ int kvm_get_dirty_log(struct kvm *kvm,
if (!memslot->dirty_bitmap)
goto out;
n = ALIGN(memslot->npages, BITS_PER_LONG) / 8;
n = kvm_dirty_bitmap_bytes(memslot);
for (i = 0; !any && i < n/sizeof(long); ++i)
any = memslot->dirty_bitmap[i];
@ -1186,10 +1186,13 @@ void mark_page_dirty(struct kvm *kvm, gfn_t gfn)
memslot = gfn_to_memslot_unaliased(kvm, gfn);
if (memslot && memslot->dirty_bitmap) {
unsigned long rel_gfn = gfn - memslot->base_gfn;
unsigned long *p = memslot->dirty_bitmap +
rel_gfn / BITS_PER_LONG;
int offset = rel_gfn % BITS_PER_LONG;
/* avoid RMW */
if (!generic_test_le_bit(rel_gfn, memslot->dirty_bitmap))
generic___set_le_bit(rel_gfn, memslot->dirty_bitmap);
if (!generic_test_le_bit(offset, p))
generic___set_le_bit(offset, p);
}
}