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x86/speculation/taa: Fix printing of TAA_MSG_SMT on IBRS_ALL CPUs

This commit is contained in:
Salvatore Bonaccorso 2019-11-08 00:14:08 +01:00
parent 37baed7166
commit be004c1b69
3 changed files with 51 additions and 0 deletions
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1
debian/changelog vendored
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@ -10,6 +10,7 @@ linux (4.19.67-2+deb10u2) UNRELEASED; urgency=medium
- x86/tsx: Add "auto" option to the tsx= cmdline parameter
- x86/speculation/taa: Add documentation for TSX Async Abort
- x86/tsx: Add config options to set tsx=on|off|auto
- x86/speculation/taa: Fix printing of TAA_MSG_SMT on IBRS_ALL CPUs
TSX is now disabled by default; see
Documentation/admin-guide/hw-vuln/tsx_async_abort.rst
* [x86] KVM: Add mitigation for Machine Check Error on Page Size Change

49
debian/patches/bugfix/x86/taa/0010-x86-speculation-taa-Fix-printing-of-TAA_MSG_SMT-on-I.patch vendored Normal file
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@ -0,0 +1,49 @@
From: Josh Poimboeuf <jpoimboe@redhat.com>
Date: Wed, 6 Nov 2019 20:26:46 -0600
Subject: x86/speculation/taa: Fix printing of TAA_MSG_SMT on IBRS_ALL CPUs
Origin: https://git.kernel.org/linus/012206a822a8b6ac09125bfaa210a95b9eb8f1c1
Bug-Debian-Security: https://security-tracker.debian.org/tracker/CVE-2019-11135
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>
---
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 8237b86ba6dc..10d11586f805 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 arch_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) {
--
2.24.0

1
debian/patches/series vendored
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@ -267,6 +267,7 @@ bugfix/x86/taa/0006-kvm-x86-Export-MDS_NO-0-to-guests-when-TSX-is-enable.patch
bugfix/x86/taa/0007-x86-tsx-Add-auto-option-to-the-tsx-cmdline-parameter.patch
bugfix/x86/taa/0008-x86-speculation-taa-Add-documentation-for-TSX-Async-.patch
bugfix/x86/taa/0009-x86-tsx-Add-config-options-to-set-tsx-on-off-auto.patch
bugfix/x86/taa/0010-x86-speculation-taa-Fix-printing-of-TAA_MSG_SMT-on-I.patch
bugfix/x86/itlb_multihit/0010-KVM-x86-adjust-kvm_mmu_page-member-to-save-8-bytes.patch
bugfix/x86/itlb_multihit/0011-kvm-Convert-kvm_lock-to-a-mutex.patch
bugfix/x86/itlb_multihit/0012-kvm-x86-Do-not-release-the-page-inside-mmu_set_spte.patch