KVM: page track: add notifier support

[cascardo/linux.git] / arch / x86 / kvm / page_track.c

diff --git a/arch/x86/kvm/page_track.c b/arch/x86/kvm/page_track.c
index f127f6d..11f7643 100644 (file)
--- a/arch/x86/kvm/page_track.c
+++ b/arch/x86/kvm/page_track.c
@@ -150,3 +150,73 @@ bool kvm_page_track_is_active(struct kvm_vcpu *vcpu, gfn_t gfn,
 
        return !!ACCESS_ONCE(slot->arch.gfn_track[mode][index]);
 }
+
+void kvm_page_track_init(struct kvm *kvm)
+{
+       struct kvm_page_track_notifier_head *head;
+
+       head = &kvm->arch.track_notifier_head;
+       init_srcu_struct(&head->track_srcu);
+       INIT_HLIST_HEAD(&head->track_notifier_list);
+}
+
+/*
+ * register the notifier so that event interception for the tracked guest
+ * pages can be received.
+ */
+void
+kvm_page_track_register_notifier(struct kvm *kvm,
+                                struct kvm_page_track_notifier_node *n)
+{
+       struct kvm_page_track_notifier_head *head;
+
+       head = &kvm->arch.track_notifier_head;
+
+       spin_lock(&kvm->mmu_lock);
+       hlist_add_head_rcu(&n->node, &head->track_notifier_list);
+       spin_unlock(&kvm->mmu_lock);
+}
+
+/*
+ * stop receiving the event interception. It is the opposed operation of
+ * kvm_page_track_register_notifier().
+ */
+void
+kvm_page_track_unregister_notifier(struct kvm *kvm,
+                                  struct kvm_page_track_notifier_node *n)
+{
+       struct kvm_page_track_notifier_head *head;
+
+       head = &kvm->arch.track_notifier_head;
+
+       spin_lock(&kvm->mmu_lock);
+       hlist_del_rcu(&n->node);
+       spin_unlock(&kvm->mmu_lock);
+       synchronize_srcu(&head->track_srcu);
+}
+
+/*
+ * Notify the node that write access is intercepted and write emulation is
+ * finished at this time.
+ *
+ * The node should figure out if the written page is the one that node is
+ * interested in by itself.
+ */
+void kvm_page_track_write(struct kvm_vcpu *vcpu, gpa_t gpa, const u8 *new,
+                         int bytes)
+{
+       struct kvm_page_track_notifier_head *head;
+       struct kvm_page_track_notifier_node *n;
+       int idx;
+
+       head = &vcpu->kvm->arch.track_notifier_head;
+
+       if (hlist_empty(&head->track_notifier_list))
+               return;
+
+       idx = srcu_read_lock(&head->track_srcu);
+       hlist_for_each_entry_rcu(n, &head->track_notifier_list, node)
+               if (n->track_write)
+                       n->track_write(vcpu, gpa, new, bytes);
+       srcu_read_unlock(&head->track_srcu, idx);
+}