9d40b85bb4
AMD Zen 2 introduces a new RDPRU instruction which is used to give access to some processor registers that are typically only accessible when the privilege level is zero. ECX is used as the implicit register to specify which register to read. RDPRU places the specified register’s value into EDX:EAX. For example, the RDPRU instruction can be used to read MPERF and APERF at CPL > 0. Add the feature bit so it is visible in /proc/cpuinfo. Details are available in the AMD64 Architecture Programmer’s Manual: https://www.amd.com/system/files/TechDocs/24594.pdf Signed-off-by: Babu Moger <babu.moger@amd.com> Signed-off-by: Borislav Petkov <bp@suse.de> Cc: Aaron Lewis <aaronlewis@google.com> Cc: ak@linux.intel.com Cc: Fenghua Yu <fenghua.yu@intel.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: "Peter Zijlstra (Intel)" <peterz@infradead.org> Cc: robert.hu@linux.intel.com Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Thomas Hellstrom <thellstrom@vmware.com> Cc: x86-ml <x86@kernel.org> Link: https://lkml.kernel.org/r/20191007204839.5727.10803.stgit@localhost.localdomain
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.