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Date: Sun, 23 Aug 2009 14:56:28 +0300 From: Avi Kivity <avi@...hat.com> To: kvm@...r.kernel.org Cc: linux-kernel@...r.kernel.org Subject: [PATCH 29/46] KVM: MMU: fix missing locking in alloc_mmu_pages From: Marcelo Tosatti <mtosatti@...hat.com> 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@...hat.com> --- arch/x86/kvm/mmu.c | 2 ++ 1 files changed, 2 insertions(+), 0 deletions(-) diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c index 87c67f4..86c2551 100644 --- a/arch/x86/kvm/mmu.c +++ b/arch/x86/kvm/mmu.c @@ -2728,12 +2728,14 @@ static int alloc_mmu_pages(struct kvm_vcpu *vcpu) 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 -- 1.6.4.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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