On Tue, Jun 09, 2020 at 08:53:49AM -0000, tip-bot2 for Anthony Steinhauser wrote:
@@ -672,23 +665,36 @@ spectre_v2_user_select_mitigation(enum spectre_v2_mitigation_cmd v2_cmd) pr_info("mitigation: Enabling %s Indirect Branch Prediction Barrier\n", static_key_enabled(&switch_mm_always_ibpb) ? "always-on" : "conditional");
spectre_v2_user_ibpb = mode;
- /* If enhanced IBRS is enabled no STIBP required */
- if (spectre_v2_enabled == SPECTRE_V2_IBRS_ENHANCED)
- /*
* If enhanced IBRS is enabled or SMT impossible, STIBP is not* required.*/- if (!smt_possible || spectre_v2_enabled == SPECTRE_V2_IBRS_ENHANCED) return;
/*
* If SMT is not possible or STIBP is not available clear the STIBP* mode.
* At this point, an STIBP mode other than "off" has been set.* If STIBP support is not being forced, check if STIBP always-on* is preferred.*/- if (mode != SPECTRE_V2_USER_STRICT &&
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 (!smt_possible || !boot_cpu_has(X86_FEATURE_STIBP))
- if (!boot_cpu_has(X86_FEATURE_STIBP)) mode = SPECTRE_V2_USER_NONE;
Can we merge this test into the one above? Diff ontop:
--- diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c index 8d57562b1d2c..05b3163e1b8c 100644 --- a/arch/x86/kernel/cpu/bugs.c +++ b/arch/x86/kernel/cpu/bugs.c @@ -673,7 +673,9 @@ spectre_v2_user_select_mitigation(enum spectre_v2_mitigation_cmd v2_cmd) * If 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;
/* @@ -685,12 +687,6 @@ 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: