To establish performance characteristics of a CXL device when used via a particular CXL topology (root ports, switches, end points) it is necessary to set the appropriate link speed and width in the PCI Express capability structure. Provide x-speed and x-link properties for this. Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com> Message-Id: <20240916173518.1843023-6-Jonathan.Cameron@huawei.com> Reviewed-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>