From 7fbf47c7ce50b38a64576b150e7011ae73d54669 Mon Sep 17 00:00:00 2001 From: Alexandre Chartre Date: Tue, 14 Jun 2022 23:15:50 +0200 Subject: x86/bugs: Add AMD retbleed= boot parameter Add the "retbleed=" 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 Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Borislav Petkov Reviewed-by: Josh Poimboeuf Signed-off-by: Borislav Petkov --- Documentation/admin-guide/kernel-parameters.txt | 15 +++++++++++++++ 1 file changed, 15 insertions(+) (limited to 'Documentation') diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index 2522b11e593f..529613367e7d 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -5197,6 +5197,21 @@ retain_initrd [RAM] Keep initrd memory after extraction + retbleed= [X86] Control mitigation of RETBleed (Arbitrary + Speculative Code Execution with Return Instructions) + vulnerability. + + off - unconditionally disable + auto - automatically select a migitation + unret - force enable untrained return thunks, + only effective on AMD Zen {1,2} + based systems. + + Selecting 'auto' will choose a mitigation method at run + time according to the CPU. + + Not specifying this option is equivalent to retbleed=auto. + rfkill.default_state= 0 "airplane mode". All wifi, bluetooth, wimax, gps, fm, etc. communication is blocked by default. -- cgit v1.2.3