50 lines
1.8 KiB
Diff
50 lines
1.8 KiB
Diff
From: Josh Poimboeuf <jpoimboe@redhat.com>
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Date: Wed, 6 Nov 2019 20:26:46 -0600
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Subject: x86/speculation/taa: Fix printing of TAA_MSG_SMT on IBRS_ALL CPUs
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Origin: https://git.kernel.org/linus/012206a822a8b6ac09125bfaa210a95b9eb8f1c1
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Bug-Debian-Security: https://security-tracker.debian.org/tracker/CVE-2019-11135
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For new IBRS_ALL CPUs, the Enhanced IBRS check at the beginning of
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cpu_bugs_smt_update() causes the function to return early, unintentionally
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skipping the MDS and TAA logic.
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This is not a problem for MDS, because there appears to be no overlap
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between IBRS_ALL and MDS-affected CPUs. So the MDS mitigation would be
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disabled and nothing would need to be done in this function anyway.
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But for TAA, the TAA_MSG_SMT string will never get printed on Cascade
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Lake and newer.
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The check is superfluous anyway: when 'spectre_v2_enabled' is
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SPECTRE_V2_IBRS_ENHANCED, 'spectre_v2_user' is always
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SPECTRE_V2_USER_NONE, and so the 'spectre_v2_user' switch statement
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handles it appropriately by doing nothing. So just remove the check.
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Fixes: 1b42f017415b ("x86/speculation/taa: Add mitigation for TSX Async Abort")
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Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
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Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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Reviewed-by: Tyler Hicks <tyhicks@canonical.com>
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Reviewed-by: Borislav Petkov <bp@suse.de>
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---
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arch/x86/kernel/cpu/bugs.c | 4 ----
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1 file changed, 4 deletions(-)
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diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
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index 8237b86ba6dc..10d11586f805 100644
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--- a/arch/x86/kernel/cpu/bugs.c
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+++ b/arch/x86/kernel/cpu/bugs.c
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@@ -886,10 +886,6 @@ static void update_mds_branch_idle(void)
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void arch_smt_update(void)
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{
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- /* Enhanced IBRS implies STIBP. No update required. */
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- if (spectre_v2_enabled == SPECTRE_V2_IBRS_ENHANCED)
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- return;
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-
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mutex_lock(&spec_ctrl_mutex);
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switch (spectre_v2_user) {
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--
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2.24.0
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