1 files changed, 8 insertions, 2 deletions

diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 913ef4b7939a..b8da6715d08b 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -838,9 +838,15 @@ static int kvm_age_rmapp(struct kvm *kvm, unsigned long *rmapp,
         u64 *spte;
         int young = 0;
 
-        /* always return old for EPT */
+        /*
+         * Emulate the accessed bit for EPT, by checking if this page has
+         * an EPT mapping, and clearing it if it does. On the next access,
+         * a new EPT mapping will be established.
+         * This has some overhead, but not as much as the cost of swapping
+         * out actively used pages or breaking up actively used hugepages.
+         */
         if (!shadow_accessed_mask)
-                return 0;
+                return kvm_unmap_rmapp(kvm, rmapp, data);
 
         spte = rmap_next(kvm, rmapp, NULL);
         while (spte) {