kvm: memslots: track id_to_index changes during the insertion sort

This completes the optimization from the previous patch, by
removing the KVM_MEM_SLOTS_NUM-iteration loop from insert_memslot.

Reviewed-by: Igor Mammedov <imammedo@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index c0c2202..eae07f9 100644 (file)
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -677,31 +677,31 @@ static int kvm_create_dirty_bitmap(struct kvm_memory_slot *memslot)
 static void insert_memslot(struct kvm_memslots *slots,
                           struct kvm_memory_slot *new)
 {
-       int i = slots->id_to_index[new->id];
-       struct kvm_memory_slot *old = id_to_memslot(slots, new->id);
+       int id = new->id;
+       int i = slots->id_to_index[id];
        struct kvm_memory_slot *mslots = slots->memslots;
 
-       if (new->npages == old->npages) {
-               *old = *new;
-               return;
-       }
-
-       while (1) {
-               if (i < (KVM_MEM_SLOTS_NUM - 1) &&
-                       new->npages < mslots[i + 1].npages) {
-                       mslots[i] = mslots[i + 1];
-                       i++;
-               } else if (i > 0 && new->npages > mslots[i - 1].npages) {
-                       mslots[i] = mslots[i - 1];
-                       i--;
+       WARN_ON(mslots[i].id != id);
+       if (new->npages != mslots[i].npages) {
+               if (new->npages < mslots[i].npages) {
+                       while (i < KVM_MEM_SLOTS_NUM - 1 &&
+                              new->npages < mslots[i + 1].npages) {
+                               mslots[i] = mslots[i + 1];
+                               slots->id_to_index[mslots[i].id] = i;
+                               i++;
+                       }
                } else {
-                       mslots[i] = *new;
-                       break;
+                       while (i > 0 &&
+                              new->npages > mslots[i - 1].npages) {
+                               mslots[i] = mslots[i - 1];
+                               slots->id_to_index[mslots[i].id] = i;
+                               i--;
+                       }
                }
        }
 
-       for (i = 0; i < KVM_MEM_SLOTS_NUM; i++)
-               slots->id_to_index[slots->memslots[i].id] = i;
+       mslots[i] = *new;
+       slots->id_to_index[mslots[i].id] = i;
 }
 
 static void update_memslots(struct kvm_memslots *slots,