Messages in this thread Patch in this message |  | | | Date | Thu, 01 Oct 2009 16:31:27 -0700 | | From | Greg KH <> | | Subject | [patch 11/30] KVM: MMU: fix missing locking in alloc_mmu_pages |
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2.6.30-stable review patch. If anyone has any objections, please let us know.
------------------ From: Marcelo Tosatti <mtosatti@redhat.com> (cherry picked from commit 6a1ac77110ee3e8d8dfdef8442f3b30b3d83e6a2)
n_requested_mmu_pages/n_free_mmu_pages are used by kvm_mmu_change_mmu_pages to calculate the number of pages to zap.
alloc_mmu_pages, called from the vcpu initialization path, modifies this variables without proper locking, which can result in a negative value in kvm_mmu_change_mmu_pages (say, with cpu hotplug).
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de> --- arch/x86/kvm/mmu.c | 2 ++ 1 file changed, 2 insertions(+) --- a/arch/x86/kvm/mmu.c +++ b/arch/x86/kvm/mmu.c @@ -2692,12 +2692,14 @@ static int alloc_mmu_pages(struct kvm_vc ASSERT(vcpu); + spin_lock(&vcpu->kvm->mmu_lock); if (vcpu->kvm->arch.n_requested_mmu_pages) vcpu->kvm->arch.n_free_mmu_pages = vcpu->kvm->arch.n_requested_mmu_pages; else vcpu->kvm->arch.n_free_mmu_pages = vcpu->kvm->arch.n_alloc_mmu_pages; + spin_unlock(&vcpu->kvm->mmu_lock); /* * When emulating 32-bit mode, cr3 is only 32 bits even on x86_64. * Therefore we need to allocate shadow page tables in the first
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