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authorMarcelo Tosatti <mtosatti@redhat.com>2009-07-15 15:34:41 -0300
committerAvi Kivity <avi@redhat.com>2009-09-10 08:33:14 +0300
commit6a1ac77110ee3e8d8dfdef8442f3b30b3d83e6a2 (patch)
tree8ca7be75dcdd59b271869b8a002faaf8a4fa8857 /arch/x86
parent3662cb1cd6ed26873ca808f3e16cc54246ad40ca (diff)
KVM: MMU: fix missing locking in alloc_mmu_pages
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>
Diffstat (limited to 'arch/x86')
-rw-r--r--arch/x86/kvm/mmu.c2
1 files changed, 2 insertions, 0 deletions
diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 87c67f449279..86c2551fe136 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