Josh Poimboeuf 27ce8299bc x86/bugs: Don't fill RSB on context switch with eIBRS
User->user Spectre v2 attacks (including RSB) across context switches
are already mitigated by IBPB in cond_mitigation(), if enabled globally
or if either the prev or the next task has opted in to protection.  RSB
filling without IBPB serves no purpose for protecting user space, as
indirect branches are still vulnerable.

User->kernel RSB attacks are mitigated by eIBRS.  In which case the RSB
filling on context switch isn't needed, so remove it.

Suggested-by: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
Reviewed-by: Amit Shah <amit.shah@amd.com>
Reviewed-by: Nikolay Borisov <nik.borisov@suse.com>
Link: https://lore.kernel.org/r/98cdefe42180358efebf78e3b80752850c7a3e1b.1744148254.git.jpoimboe@kernel.org
2025-04-09 12:42:09 +02:00
2024-09-01 20:43:24 -07:00
2025-04-06 10:00:04 -07:00
2022-09-28 09:02:20 +02:00
2025-02-19 14:53:27 -07:00
2025-04-06 13:11:33 -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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