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| author | Marcelo Tosatti <mtosatti@redhat.com> | 2009-07-22 13:05:49 -0300 |
|---|---|---|
| committer | Avi Kivity <avi@redhat.com> | 2009-08-05 13:59:43 +0300 |
| commit | 025dbbf36a7680bffe54d9dcbf0a8bc01a7cbd10 (patch) | |
| tree | 17ae3afc86e2cbd71101b136933432928e60b7b7 | |
| parent | 4b656b1202498184a0ecef86b3b89ff613b9c6ab (diff) | |
| download | kernel-crypto-025dbbf36a7680bffe54d9dcbf0a8bc01a7cbd10.tar.gz kernel-crypto-025dbbf36a7680bffe54d9dcbf0a8bc01a7cbd10.tar.xz kernel-crypto-025dbbf36a7680bffe54d9dcbf0a8bc01a7cbd10.zip | |
KVM: MMU: handle n_free_mmu_pages > n_alloc_mmu_pages in kvm_mmu_change_mmu_pages
kvm_mmu_change_mmu_pages mishandles the case where n_alloc_mmu_pages is
smaller then n_free_mmu_pages, by not checking if the result of
the subtraction is negative.
Its a valid condition which can happen if a large number of pages has
been recently freed.
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
| -rw-r--r-- | arch/x86/kvm/mmu.c | 15 |
1 files changed, 8 insertions, 7 deletions
diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c index 7030b5f911b..49a10d00830 100644 --- a/arch/x86/kvm/mmu.c +++ b/arch/x86/kvm/mmu.c @@ -1407,24 +1407,25 @@ static int kvm_mmu_zap_page(struct kvm *kvm, struct kvm_mmu_page *sp) */ void kvm_mmu_change_mmu_pages(struct kvm *kvm, unsigned int kvm_nr_mmu_pages) { + int used_pages; + + used_pages = kvm->arch.n_alloc_mmu_pages - kvm->arch.n_free_mmu_pages; + used_pages = max(0, used_pages); + /* * If we set the number of mmu pages to be smaller be than the * number of actived pages , we must to free some mmu pages before we * change the value */ - if ((kvm->arch.n_alloc_mmu_pages - kvm->arch.n_free_mmu_pages) > - kvm_nr_mmu_pages) { - int n_used_mmu_pages = kvm->arch.n_alloc_mmu_pages - - kvm->arch.n_free_mmu_pages; - - while (n_used_mmu_pages > kvm_nr_mmu_pages) { + if (used_pages > kvm_nr_mmu_pages) { + while (used_pages > kvm_nr_mmu_pages) { struct kvm_mmu_page *page; page = container_of(kvm->arch.active_mmu_pages.prev, struct kvm_mmu_page, link); kvm_mmu_zap_page(kvm, page); - n_used_mmu_pages--; + used_pages--; } kvm->arch.n_free_mmu_pages = 0; } |