Thomas Gleixner 8f849ff63b x86/microcode: Handle "offline" CPUs correctly
Offline CPUs need to be parked in a safe loop when microcode update is
in progress on the primary CPU. Currently, offline CPUs are parked in
mwait_play_dead(), and for Intel CPUs, its not a safe instruction,
because the MWAIT instruction can be patched in the new microcode update
that can cause instability.

  - Add a new microcode state 'UCODE_OFFLINE' to report status on per-CPU
  basis.
  - Force NMI on the offline CPUs.

Wake up offline CPUs while the update is in progress and then return
them back to mwait_play_dead() after microcode update is complete.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/20231002115903.660850472@linutronix.de
2023-10-24 15:05:55 +02:00
2022-09-28 09:02:20 +02:00
2023-10-15 13:34:39 -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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