diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index a24da8f..5052acd 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -2097,6 +2097,7 @@
 {
 	struct kvm_mmu_page *sp;
 
+	spin_lock(&kvm->mmu_lock);
 	list_for_each_entry(sp, &kvm->arch.active_mmu_pages, link) {
 		int i;
 		u64 *pt;
@@ -2110,6 +2111,7 @@
 			if (pt[i] & PT_WRITABLE_MASK)
 				pt[i] &= ~PT_WRITABLE_MASK;
 	}
+	spin_unlock(&kvm->mmu_lock);
 }
 
 void kvm_mmu_zap_all(struct kvm *kvm)