KVM: MMU: Fix free memory accounting race in mmu_alloc_roots()

Commit Message

Avi Kivity May 10, 2010, 9:09 a.m. UTC

None

Patch

diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 95bee9d..6857a2f 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -2067,6 +2067,7 @@  static int mmu_alloc_roots(struct kvm_vcpu *vcpu)
 			root_gfn = 0;
 		}
 		spin_lock(&vcpu->kvm->mmu_lock);
+		kvm_mmu_free_some_pages(vcpu->kvm);
 		sp = kvm_mmu_get_page(vcpu, root_gfn, 0,
 				      PT64_ROOT_LEVEL, direct,
 				      ACC_ALL, NULL);
@@ -2097,6 +2098,7 @@  static int mmu_alloc_roots(struct kvm_vcpu *vcpu)
 			root_gfn = i << 30;
 		}
 		spin_lock(&vcpu->kvm->mmu_lock);
+		kvm_mmu_free_some_pages(vcpu->kvm);
 		sp = kvm_mmu_get_page(vcpu, root_gfn, i << 30,
 				      PT32_ROOT_LEVEL, direct,
 				      ACC_ALL, NULL);
@@ -2470,9 +2472,6 @@  int kvm_mmu_load(struct kvm_vcpu *vcpu)
 	r = mmu_topup_memory_caches(vcpu);
 	if (r)
 		goto out;
-	spin_lock(&vcpu->kvm->mmu_lock);
-	kvm_mmu_free_some_pages(vcpu);
-	spin_unlock(&vcpu->kvm->mmu_lock);
 	r = mmu_alloc_roots(vcpu);
 	spin_lock(&vcpu->kvm->mmu_lock);
 	mmu_sync_roots(vcpu);