On Tue, Jan 5, 2021 at 11:28 AM Mika Westerberg
<mika.westerberg@xxxxxxxxxxxxxxx> wrote:
>
> In some cases it is useful to be able de-authorize devices. For example
> if user logs out the userspace can have a policy that disconnects PCIe
> devices until logged in again. This is only possible for software based
> connection manager as it directly controls the tunnels.
>
> For this reason make the authorized attribute accept writing 0 which
> makes the software connection manager to tear down the corresponding
> PCIe tunnel. Userspace can check if this is supported by reading a new
> domain attribute deauthorization, that holds 1 in that case.
What a great feature! Thanks for implementing it.
BTW, is there any general way to disable the device operations before such a
disconnection? The user has a way to stop removable disks, for example, but
maybe other devices need additional precaution from the user (eGPU?).
> Possible values are supported:
>
> - == ===========================================
> + == ===================================================
> + 0 The device will be de-authorized (only supported if
> + deauthorization attribute under domain contains 1)
> 1 The device will be authorized and connected
> - == ===========================================
> + == ===================================================
>
> When key attribute contains 32 byte hex string the possible
> values are:
As 0 is available for 'secure' security level too, you may want to reflect it in
the documentation here somehow.
> +static int disapprove_switch(struct device *dev, void *data)
Maybe it's better to mark `data` as `__maybe_unused`?
> +{
> + struct tb_switch *sw;
> +
> + sw = tb_to_switch(dev);
> + if (sw && sw->authorized) {
> + int ret;
> +
> + /* First children */
> + ret = device_for_each_child_reverse(&sw->dev, NULL, disapprove_switch);
> + if (ret)
> + return ret;
> +
> + ret = tb_domain_disapprove_switch(sw->tb, sw);
> + if (ret)
> + return ret;
> +
> + sw->authorized = 0;
> + kobject_uevent(&sw->dev.kobj, KOBJ_CHANGE);
> + }
> +
> + return 0;
> +}
> +
