Andy Lutomirski 229b969b3d x86/apic: Initialize TPR to block interrupts 16-31
The APIC, per spec, is fundamentally confused and thinks that interrupt
vectors 16-31 are valid.  This makes no sense -- the CPU reserves vectors
0-31 for exceptions (faults, traps, etc).  Obviously, no device should
actually produce an interrupt with vector 16-31, but robustness can be
improved by setting the APIC TPR class to 1, which will prevent delivery of
an interrupt with a vector below 32.

Note: This is *not* intended as a security measure against attackers who
control malicious hardware.  Any PCI or similar hardware that can be
controlled by an attacker MUST be behind a functional IOMMU that remaps
interrupts.  The purpose of this change is to reduce the chance that a
certain class of device malfunctions crashes the kernel in hard-to-debug
ways.

Suggested-by: Andrew Cooper <andrew.cooper3@citrix.com>
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/dc04a9f8b234d7b0956a8d2560b8945bcd9c4bf7.1563117760.git.luto@kernel.org
2019-07-22 10:12:32 +02:00
2019-06-18 14:37:27 +01:00
2019-07-19 12:22:04 -07:00
2019-07-21 14:05:38 -07:00

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.
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