From e8ec1b6e08a2102d8755ccb06fa26d540f26a2fa Mon Sep 17 00:00:00 2001 From: Kim Phillips Date: Tue, 14 Jun 2022 23:15:51 +0200 Subject: x86/bugs: Enable STIBP for JMP2RET For untrained return thunks to be fully effective, STIBP must be enabled or SMT disabled. Co-developed-by: Josh Poimboeuf Signed-off-by: Josh Poimboeuf Signed-off-by: Kim Phillips Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Borislav Petkov --- Documentation/admin-guide/kernel-parameters.txt | 16 +++++++++++----- 1 file changed, 11 insertions(+), 5 deletions(-) (limited to 'Documentation') diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index 529613367e7d..168e164f09eb 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -5201,11 +5201,17 @@ 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. + off - no mitigation + auto - automatically select a migitation + auto,nosmt - automatically select a mitigation, + disabling SMT if necessary for + the full mitigation (only on Zen1 + and older without STIBP). + unret - force enable untrained return thunks, + only effective on AMD f15h-f17h + based systems. + unret,nosmt - like unret, will disable SMT when STIBP + is not available. Selecting 'auto' will choose a mitigation method at run time according to the CPU. -- cgit v1.2.3