The following commit has been merged into the x86/cpu branch of tip: Commit-ID: a5ce9f2bb665d1d2b31f139a02dbaa2dfbb62fa6 Gitweb: https://git.kernel.org/tip/a5ce9f2bb665d1d2b31f139a02dbaa2dfbb62fa6 Author: Borislav Petkov <bp@xxxxxxx> AuthorDate: Mon, 15 Jun 2020 08:51:25 +02:00 Committer: Borislav Petkov <bp@xxxxxxx> CommitterDate: Tue, 16 Jun 2020 23:14:47 +02:00 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 <bp@xxxxxxx> Cc: Anthony Steinhauser <asteinhauser@xxxxxxxxxx> Link: https://lkml.kernel.org/r/20200615065806.GB14668@xxxxxxx --- 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 0b71970..7beaefa 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 ||
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