From a5ce9f2bb665d1d2b31f139a02dbaa2dfbb62fa6 Mon Sep 17 00:00:00 2001 From: Borislav Petkov Date: Mon, 15 Jun 2020 08:51:25 +0200 Subject: [PATCH] x86/speculation: Merge one test in spectre_v2_user_select_mitigation() 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 Cc: Anthony Steinhauser Link: https://lkml.kernel.org/r/20200615065806.GB14668@zn.tnic --- arch/x86/kernel/cpu/bugs.c | 13 ++++--------- 1 file changed, 4 insertions(+), 9 deletions(-) diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c index 0b71970d2d3d2..7beaefa9d198c 100644 --- a/arch/x86/kernel/cpu/bugs.c +++ b/arch/x86/kernel/cpu/bugs.c @@ -763,10 +763,12 @@ spectre_v2_user_select_mitigation(enum spectre_v2_mitigation_cmd v2_cmd) } /* - * 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; /* @@ -778,12 +780,6 @@ spectre_v2_user_select_mitigation(enum spectre_v2_mitigation_cmd v2_cmd) 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: @@ -1270,7 +1266,6 @@ static int ib_prctl_set(struct task_struct *task, unsigned long ctrl) * Indirect branch speculation is always disabled in strict * mode. It can neither be enabled if it was force-disabled * by a previous prctl call. - */ if (spectre_v2_user_ibpb == SPECTRE_V2_USER_STRICT || spectre_v2_user_stibp == SPECTRE_V2_USER_STRICT || -- 2.30.2