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| author | Takuya Yoshikawa <yoshikawa.takuya@oss.ntt.co.jp> | 2010-04-12 19:35:35 +0900 |
|---|---|---|
| committer | Avi Kivity <avi@redhat.com> | 2010-04-20 13:06:55 +0300 |
| commit | 87bf6e7de1134f48681fd2ce4b7c1ec45458cb6d (patch) | |
| tree | ae8ce63cecab98c036c0d76422de42cf78e042f4 /virt | |
| parent | 77662e0028c7c63e34257fda03ff9625c59d939d (diff) | |
| download | lwn-87bf6e7de1134f48681fd2ce4b7c1ec45458cb6d.tar.gz lwn-87bf6e7de1134f48681fd2ce4b7c1ec45458cb6d.zip | |
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>
Diffstat (limited to 'virt')
| -rw-r--r-- | virt/kvm/kvm_main.c | 13 |
1 files changed, 8 insertions, 5 deletions
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 5a0cd194dce0..364daacafb58 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -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); } } |