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>

1 files changed, 2 insertions, 1 deletions

diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 1249c12e1d5c..28be35c6ff1d 100644
--- 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,