KVM: x86/mmu: Skip invalid pages during zapping iff root_count is zero
Do not skip invalid shadow pages when zapping obsolete pages if the
pages' root_count has reached zero, in which case the page can be
immediately zapped and freed.
Update the comment accordingly.
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 5f08640..5269aa0 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -5693,11 +5693,12 @@ static void kvm_zap_obsolete_pages(struct kvm *kvm)
break;
/*
- * Since we are reversely walking the list and the invalid
- * list will be moved to the head, skip the invalid page
- * can help us to avoid the infinity list walking.
+ * Skip invalid pages with a non-zero root count, zapping pages
+ * with a non-zero root count will never succeed, i.e. the page
+ * will get thrown back on active_mmu_pages and we'll get stuck
+ * in an infinite loop.
*/
- if (sp->role.invalid)
+ if (sp->role.invalid && sp->root_count)
continue;
/*