@@ -1444,3 +1444,28 @@ register (see **KVMI_CONTROL_EVENTS**).
 
 ``kvmi_event``, the MSR number, the old value and the new value are
 sent to the introspector. The *CONTINUE* action will set the ``new_val``.
+
+8. KVMI_EVENT_XSETBV
+--------------------
+
+:Architectures: x86
+:Versions: >= 1
+:Actions: CONTINUE, CRASH
+:Parameters:
+
+::
+
+	struct kvmi_event;
+
+:Returns:
+
+::
+
+	struct kvmi_vcpu_hdr;
+	struct kvmi_event_reply;
+
+This event is sent when the extended control register XCR0 is going
+to be changed and the introspection has been enabled for this event
+(see *KVMI_CONTROL_EVENTS*).
+
+``kvmi_event`` is sent to the introspector.

@@ -15,6 +15,7 @@ bool kvmi_msr_event(struct kvm_vcpu *vcpu, struct msr_data *msr);
 bool kvmi_monitored_msr(struct kvm_vcpu *vcpu, u32 msr);
 bool kvmi_cr_event(struct kvm_vcpu *vcpu, unsigned int cr,
 		   unsigned long old_value, unsigned long *new_value);
+void kvmi_xsetbv_event(struct kvm_vcpu *vcpu);
 
 #else /* CONFIG_KVM_INTROSPECTION */
 

@@ -35,6 +36,10 @@ static inline bool kvmi_cr_event(struct kvm_vcpu *vcpu, unsigned int cr,
 	return true;
 }
 
+static inline void kvmi_xsetbv_event(struct kvm_vcpu *vcpu)
+{
+}
+
 #endif /* CONFIG_KVM_INTROSPECTION */
 
 #endif /* _ASM_X86_KVMI_HOST_H */

@@ -389,6 +389,45 @@ bool kvmi_cr_event(struct kvm_vcpu *vcpu, unsigned int cr,
 	return ret;
 }
 
+static u32 kvmi_send_xsetbv(struct kvm_vcpu *vcpu)
+{
+	int err, action;
+
+	err = kvmi_send_event(vcpu, KVMI_EVENT_XSETBV, NULL, 0,
+			      NULL, 0, &action);
+	if (err)
+		return KVMI_EVENT_ACTION_CONTINUE;
+
+	return action;
+}
+
+static void __kvmi_xsetbv_event(struct kvm_vcpu *vcpu)
+{
+	u32 action;
+
+	action = kvmi_send_xsetbv(vcpu);
+	switch (action) {
+	case KVMI_EVENT_ACTION_CONTINUE:
+		break;
+	default:
+		kvmi_handle_common_event_actions(vcpu, action, "XSETBV");
+	}
+}
+
+void kvmi_xsetbv_event(struct kvm_vcpu *vcpu)
+{
+	struct kvmi *ikvm;
+
+	ikvm = kvmi_get(vcpu->kvm);
+	if (!ikvm)
+		return;
+
+	if (is_event_enabled(vcpu, KVMI_EVENT_XSETBV))
+		__kvmi_xsetbv_event(vcpu);
+
+	kvmi_put(vcpu->kvm);
+}
+
 bool kvmi_arch_pf_event(struct kvm_vcpu *vcpu, gpa_t gpa, gva_t gva,
 			u8 access)
 {

@@ -868,6 +868,11 @@ static int __kvm_set_xcr(struct kvm_vcpu *vcpu, u32 index, u64 xcr)
 
 int kvm_set_xcr(struct kvm_vcpu *vcpu, u32 index, u64 xcr)
 {
+#ifdef CONFIG_KVM_INTROSPECTION
+	if (xcr != vcpu->arch.xcr0)
+		kvmi_xsetbv_event(vcpu);
+#endif /* CONFIG_KVM_INTROSPECTION */
+
 	if (kvm_x86_ops->get_cpl(vcpu) != 0 ||
 	    __kvm_set_xcr(vcpu, index, xcr)) {
 		kvm_inject_gp(vcpu, 0);