x86/bugs: Add AMD retbleed= boot parameter

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Add the "retbleed=<value>" boot parameter to select a mitigation for
RETBleed. Possible values are "off", "auto" and "unret"
(JMP2RET mitigation). The default value is "auto".

Currently, "retbleed=auto" will select the unret mitigation on
AMD and Hygon and no mitigation on Intel (JMP2RET is not effective on
Intel).

  [peterz: rebase; add hygon]
  [jpoimboe: cleanups]

Signed-off-by: Alexandre Chartre <alexandre.chartre@oracle.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Borislav Petkov <bp@suse.de>

...

This commit is contained in:

Alexandre Chartre 2022-06-14 23:15:50 +02:00 • committed by Borislav Petkov

parent 6b80b59b35

commit 7fbf47c7ce

3 changed files with 125 additions and 1 deletions

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15

Documentation/admin-guide/kernel-parameters.txt

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3

arch/x86/Kconfig

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108

arch/x86/kernel/cpu/bugs.c

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