KVM: x86: Sync DR7 on KVM_SET_DEBUGREGS

Whenever we change arch.dr7, we also have to call kvm_update_dr7. In
case guest debugging is off, this will synchronize the new state into
hardware.
Signed-off-by: NJan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/x86.c

@@ -2976,6 +2976,7 @@ static int kvm_vcpu_ioctl_x86_set_debugregs(struct kvm_vcpu *vcpu,
 	memcpy(vcpu->arch.db, dbgregs->db, sizeof(vcpu->arch.db));
 	vcpu->arch.dr6 = dbgregs->dr6;
 	vcpu->arch.dr7 = dbgregs->dr7;
+	kvm_update_dr7(vcpu);
 
 	return 0;
 }