From: Josh Poimboeuf jpoimboe@kernel.org
[ Upstream commit 0fe4aeea9c01baabecc8c3afc7889c809d939bc2 ]
When booting with retbleed=auto, if the kernel wasn't built with CONFIG_CC_HAS_RETURN_THUNK, the mitigation falls back to IBPB. Make sure a warning is printed in that case. The IBPB fallback check is done twice, but it really only needs to be done once.
Signed-off-by: Josh Poimboeuf jpoimboe@kernel.org Signed-off-by: Borislav Petkov bp@suse.de Signed-off-by: Sasha Levin sashal@kernel.org --- arch/x86/kernel/cpu/bugs.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c index d4a18649ce9f..c59db48472dc 100644 --- a/arch/x86/kernel/cpu/bugs.c +++ b/arch/x86/kernel/cpu/bugs.c @@ -871,8 +871,9 @@ static void __init retbleed_select_mitigation(void) retbleed_mitigation = RETBLEED_MITIGATION_UNRET;
/* - * The Intel mitigation (IBRS) was already selected in - * spectre_v2_select_mitigation(). + * The Intel mitigation (IBRS or eIBRS) was already selected in + * spectre_v2_select_mitigation(). 'retbleed_mitigation' will + * be set accordingly below. */
break;