diff options
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/ABI/testing/sysfs-bus-thunderbolt | 22 | ||||
| -rw-r--r-- | Documentation/admin-guide/thunderbolt.rst | 23 |
2 files changed, 41 insertions, 4 deletions
diff --git a/Documentation/ABI/testing/sysfs-bus-thunderbolt b/Documentation/ABI/testing/sysfs-bus-thunderbolt index a91b4b24496e..d7f09d011b6d 100644 --- a/Documentation/ABI/testing/sysfs-bus-thunderbolt +++ b/Documentation/ABI/testing/sysfs-bus-thunderbolt @@ -49,6 +49,15 @@ Description: Holds a comma separated list of device unique_ids that If a device is authorized automatically during boot its boot attribute is set to 1. +What: /sys/bus/thunderbolt/devices/.../domainX/deauthorization +Date: May 2021 +KernelVersion: 5.12 +Contact: Mika Westerberg <mika.westerberg@linux.intel.com> +Description: This attribute tells whether the system supports + de-authorization of devices. Value of 1 means user can + de-authorize PCIe tunnel by writing 0 to authorized + attribute under each device. + What: /sys/bus/thunderbolt/devices/.../domainX/iommu_dma_protection Date: Mar 2019 KernelVersion: 4.21 @@ -76,6 +85,8 @@ Description: This attribute holds current Thunderbolt security level usbonly Automatically tunnel USB controller of the connected Thunderbolt dock (and Display Port). All PCIe links downstream of the dock are removed. + nopcie USB4 system where PCIe tunneling is disabled from + the BIOS. ======= ================================================== What: /sys/bus/thunderbolt/devices/.../authorized @@ -84,22 +95,25 @@ KernelVersion: 4.13 Contact: thunderbolt-software@lists.01.org Description: This attribute is used to authorize Thunderbolt devices after they have been connected. If the device is not - authorized, no devices such as PCIe and Display port are - available to the system. + authorized, no PCIe devices are available to the system. Contents of this attribute will be 0 when the device is not yet authorized. 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: == ======================================================== + 0 The device will be de-authorized (only supported if + deauthorization attribute under domain contains 1) 1 The 32 byte hex string is added to the device NVM and the device is authorized. 2 Send a challenge based on the 32 byte hex string. If the diff --git a/Documentation/admin-guide/thunderbolt.rst b/Documentation/admin-guide/thunderbolt.rst index 613cb24c76c7..f18e881373c4 100644 --- a/Documentation/admin-guide/thunderbolt.rst +++ b/Documentation/admin-guide/thunderbolt.rst @@ -47,6 +47,9 @@ be DMA masters and thus read contents of the host memory without CPU and OS knowing about it. There are ways to prevent this by setting up an IOMMU but it is not always available for various reasons. +Some USB4 systems have a BIOS setting to disable PCIe tunneling. This is +treated as another security level (nopcie). + The security levels are as follows: none @@ -77,6 +80,10 @@ The security levels are as follows: Display Port in a dock. All PCIe links downstream of the dock are removed. + nopcie + PCIe tunneling is disabled/forbidden from the BIOS. Available in some + USB4 systems. + The current security level can be read from ``/sys/bus/thunderbolt/devices/domainX/security`` where ``domainX`` is the Thunderbolt domain the host controller manages. There is typically @@ -153,6 +160,22 @@ If the user still wants to connect the device they can either approve the device without a key or write a new key and write 1 to the ``authorized`` file to get the new key stored on the device NVM. +De-authorizing devices +---------------------- +It is possible to de-authorize devices by writing ``0`` to their +``authorized`` attribute. This requires support from the connection +manager implementation and can be checked by reading domain +``deauthorization`` attribute. If it reads ``1`` then the feature is +supported. + +When a device is de-authorized the PCIe tunnel from the parent device +PCIe downstream (or root) port to the device PCIe upstream port is torn +down. This is essentially the same thing as PCIe hot-remove and the PCIe +toplogy in question will not be accessible anymore until the device is +authorized again. If there is storage such as NVMe or similar involved, +there is a risk for data loss if the filesystem on that storage is not +properly shut down. You have been warned! + DMA protection utilizing IOMMU ------------------------------ Recent systems from 2018 and forward with Thunderbolt ports may natively |