From: Borislav Petkov bp@suse.de
commit a5ce9f2bb665d1d2b31f139a02dbaa2dfbb62fa6 upstream.
Merge the test whether the CPU supports STIBP into the test which determines whether STIBP is required. Thus try to simplify what is already an insane logic.
Remove a superfluous newline in a comment, while at it.
Signed-off-by: Borislav Petkov bp@suse.de Cc: Anthony Steinhauser asteinhauser@google.com Link: https://lkml.kernel.org/r/20200615065806.GB14668@zn.tnic [fllinden@amazon.com: fixed contextual conflict (comment) for 4.19] Signed-off-by: Frank van der Linden fllinden@amazon.com Signed-off-by: Ben Hutchings ben@decadent.org.uk Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/x86/kernel/cpu/bugs.c | 13 ++++--------- 1 file changed, 4 insertions(+), 9 deletions(-)
--- a/arch/x86/kernel/cpu/bugs.c +++ b/arch/x86/kernel/cpu/bugs.c @@ -755,10 +755,12 @@ spectre_v2_user_select_mitigation(enum s }
/* - * If enhanced IBRS is enabled or SMT impossible, STIBP is not + * If no STIBP, enhanced IBRS is enabled or SMT impossible, STIBP is not * required. */ - if (!smt_possible || spectre_v2_enabled == SPECTRE_V2_IBRS_ENHANCED) + if (!boot_cpu_has(X86_FEATURE_STIBP) || + !smt_possible || + spectre_v2_enabled == SPECTRE_V2_IBRS_ENHANCED) return;
/* @@ -770,12 +772,6 @@ spectre_v2_user_select_mitigation(enum s boot_cpu_has(X86_FEATURE_AMD_STIBP_ALWAYS_ON)) mode = SPECTRE_V2_USER_STRICT_PREFERRED;
- /* - * If STIBP is not available, clear the STIBP mode. - */ - if (!boot_cpu_has(X86_FEATURE_STIBP)) - mode = SPECTRE_V2_USER_NONE; - spectre_v2_user_stibp = mode;
set_mode: @@ -1254,7 +1250,6 @@ static int ib_prctl_set(struct task_stru if (spectre_v2_user_ibpb == SPECTRE_V2_USER_NONE && spectre_v2_user_stibp == SPECTRE_V2_USER_NONE) return 0; - /* * With strict mode for both IBPB and STIBP, the instruction * code paths avoid checking this task flag and instead,