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authorJosh Poimboeuf <jpoimboe@redhat.com>2019-11-06 20:26:46 -0600
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2019-11-16 10:27:51 +0100
commitb081576edd675fe37690080eb9093c1779422657 (patch)
parentfaaa0750f5c426102e095b9343b50b868a3a45f0 (diff)
x86/speculation/taa: Fix printing of TAA_MSG_SMT on IBRS_ALL CPUs
commit 012206a822a8b6ac09125bfaa210a95b9eb8f1c1 upstream. 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 <jpoimboe@redhat.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Tyler Hicks <tyhicks@canonical.com> Reviewed-by: Borislav Petkov <bp@suse.de> Signed-off-by: Ben Hutchings <ben@decadent.org.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
1 files changed, 0 insertions, 4 deletions
diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
index df103f7358fe..4c4c62666d06 100644
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -853,10 +853,6 @@ static void update_mds_branch_idle(void)
void arch_smt_update(void)
- /* Enhanced IBRS implies STIBP. No update required. */
- if (spectre_v2_enabled == SPECTRE_V2_IBRS_ENHANCED)
- return;
switch (spectre_v2_user) {