From 012206a822a8b6ac09125bfaa210a95b9eb8f1c1 Mon Sep 17 00:00:00 2001 From: Josh Poimboeuf Date: Wed, 6 Nov 2019 20:26:46 -0600 Subject: [PATCH] x86/speculation/taa: Fix printing of TAA_MSG_SMT on IBRS_ALL CPUs For new IBRS_ALL CPUs, the Enhanced IBRS check at the beginning of cpu_bugs_smt_update() causes the function to return early, unintentionally skipping the MDS and TAA logic. This is not a problem for MDS, because there appears to be no overlap between IBRS_ALL and MDS-affected CPUs. So the MDS mitigation would be disabled and nothing would need to be done in this function anyway. But for TAA, the TAA_MSG_SMT string will never get printed on Cascade Lake and newer. The check is superfluous anyway: when 'spectre_v2_enabled' is SPECTRE_V2_IBRS_ENHANCED, 'spectre_v2_user' is always SPECTRE_V2_USER_NONE, and so the 'spectre_v2_user' switch statement handles it appropriately by doing nothing. So just remove the check. Fixes: 1b42f017415b ("x86/speculation/taa: Add mitigation for TSX Async Abort") Signed-off-by: Josh Poimboeuf Signed-off-by: Thomas Gleixner Reviewed-by: Tyler Hicks Reviewed-by: Borislav Petkov --- arch/x86/kernel/cpu/bugs.c | 4 ---- 1 file changed, 4 deletions(-) diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c index 850005590167..4c7b0fa15a19 100644 --- a/arch/x86/kernel/cpu/bugs.c +++ b/arch/x86/kernel/cpu/bugs.c @@ -886,10 +886,6 @@ static void update_mds_branch_idle(void) void cpu_bugs_smt_update(void) { - /* Enhanced IBRS implies STIBP. No update required. */ - if (spectre_v2_enabled == SPECTRE_V2_IBRS_ENHANCED) - return; - mutex_lock(&spec_ctrl_mutex); switch (spectre_v2_user) { -- 2.20.1