7cae7849fc
PCIe Address Translation Services (ATS) provides a mechanism for a device to provide an on-device caching translation agent (device IOTLB). We already have a means to disable support for this feature via the pci=noats option. For untrusted and externally facing devices, we not only disable ATS support for the device, but we use Access Control Services (ACS) Transaction Blocking to actively prevent devices from sending TLPs with non-default AT field values. Extend pci=noats to also make use of PCI_ACS_TB so that not only is ATS disabled at the device, but blocked at the downstream ports. This provides a means to further lock-down ATS for cases such as device assignment, where it may not be the hardware configuration of the device that makes it untrusted, but the driver running on the device. Link: https://lore.kernel.org/r/162404966325.2362347.12176138291577486015.stgit@omen Signed-off-by: Alex Williamson <alex.williamson@redhat.com> Signed-off-by: Bjorn Helgaas <bhelgaas@google.com> Cc: Rajat Jain <rajatja@google.com>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.