KVM: MMU: make __kvm_mmu_free_some_pages handle empty list

First check if the list is empty before attempting to look at list
entries.

Cc: stable@kernel.org
Signed-off-by: Izik Eidus <ieidus@redhat.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>

diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 1249c12..28be35c 100644 (file)
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -2705,7 +2705,8 @@ EXPORT_SYMBOL_GPL(kvm_mmu_unprotect_page_virt);
 
 void __kvm_mmu_free_some_pages(struct kvm_vcpu *vcpu)
 {
-       while (vcpu->kvm->arch.n_free_mmu_pages < KVM_REFILL_PAGES) {
+       while (vcpu->kvm->arch.n_free_mmu_pages < KVM_REFILL_PAGES &&
+              !list_empty(&vcpu->kvm->arch.active_mmu_pages)) {
                struct kvm_mmu_page *sp;
 
                sp = container_of(vcpu->kvm->arch.active_mmu_pages.prev,