Kevin Loughlin 07f99c3fbe x86/lib: Add WBNOINVD helper functions
In line with WBINVD usage, add WBNOINVD helper functions.  Explicitly fall
back to WBINVD (via alternative()) if WBNOINVD isn't supported even though
the instruction itself is backwards compatible (WBNOINVD is WBINVD with an
ignored REP prefix), so that disabling X86_FEATURE_WBNOINVD behaves as one
would expect, e.g. in case there's a hardware issue that affects WBNOINVD.

Opportunistically, add comments explaining the architectural behavior of
WBINVD and WBNOINVD, and provide hints and pointers to uarch-specific
behavior.

Note, alternative() ensures compatibility with early boot code as needed.

  [ bp: Massage, fix typos, make export _GPL. ]

Signed-off-by: Kevin Loughlin <kevinloughlin@google.com>
Co-developed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Tom Lendacky <thomas.lendacky@amd.com>
Reviewed-by: Kai Huang <kai.huang@intel.com>
Acked-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/20250522233733.3176144-4-seanjc@google.com
2025-07-10 13:23:10 +02:00
2022-09-28 09:02:20 +02:00
2025-06-21 07:34:28 -07:00
2025-02-19 14:53:27 -07:00
2025-07-06 14:10:26 -07:00
2024-03-18 03:36:32 -06:00

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 reStructuredText 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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