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>

1 files changed, 3 insertions, 2 deletions

diff --git a/arch/powerpc/kvm/book3s.c b/arch/powerpc/kvm/book3s.c
index 25da07fd9f77..604af29b71ed 100644
--- a/arch/powerpc/kvm/book3s.c
+++ b/arch/powerpc/kvm/book3s.c
@@ -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);
         }