From: Greg Kroah-Hartman Date: Wed, 27 Nov 2019 10:26:02 +0000 (+0100) Subject: 4.4-stable patches X-Git-Tag: v4.4.204~47 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=350940d8d5e9d2aece1d2191cf149b31b8d71ffc;p=thirdparty%2Fkernel%2Fstable-queue.git 4.4-stable patches added patches: x86-speculation-fix-incorrect-mds-taa-mitigation-status.patch x86-speculation-fix-redundant-mds-mitigation-message.patch --- diff --git a/queue-4.4/series b/queue-4.4/series index bfc628d4205..6abe95bfa2a 100644 --- a/queue-4.4/series +++ b/queue-4.4/series @@ -105,3 +105,5 @@ ocfs2-remove-ocfs2_is_o2cb_active.patch mmc-block-fix-tag-condition-with-packed-writes.patch arc-perf-accommodate-big-endian-cpu.patch x86-insn-fix-awk-regexp-warnings.patch +x86-speculation-fix-incorrect-mds-taa-mitigation-status.patch +x86-speculation-fix-redundant-mds-mitigation-message.patch diff --git a/queue-4.4/x86-speculation-fix-incorrect-mds-taa-mitigation-status.patch b/queue-4.4/x86-speculation-fix-incorrect-mds-taa-mitigation-status.patch new file mode 100644 index 00000000000..ea505535bc0 --- /dev/null +++ b/queue-4.4/x86-speculation-fix-incorrect-mds-taa-mitigation-status.patch @@ -0,0 +1,154 @@ +From 64870ed1b12e235cfca3f6c6da75b542c973ff78 Mon Sep 17 00:00:00 2001 +From: Waiman Long +Date: Fri, 15 Nov 2019 11:14:44 -0500 +Subject: x86/speculation: Fix incorrect MDS/TAA mitigation status + +From: Waiman Long + +commit 64870ed1b12e235cfca3f6c6da75b542c973ff78 upstream. + +For MDS vulnerable processors with TSX support, enabling either MDS or +TAA mitigations will enable the use of VERW to flush internal processor +buffers at the right code path. IOW, they are either both mitigated +or both not. However, if the command line options are inconsistent, +the vulnerabilites sysfs files may not report the mitigation status +correctly. + +For example, with only the "mds=off" option: + + vulnerabilities/mds:Vulnerable; SMT vulnerable + vulnerabilities/tsx_async_abort:Mitigation: Clear CPU buffers; SMT vulnerable + +The mds vulnerabilities file has wrong status in this case. Similarly, +the taa vulnerability file will be wrong with mds mitigation on, but +taa off. + +Change taa_select_mitigation() to sync up the two mitigation status +and have them turned off if both "mds=off" and "tsx_async_abort=off" +are present. + +Update documentation to emphasize the fact that both "mds=off" and +"tsx_async_abort=off" have to be specified together for processors that +are affected by both TAA and MDS to be effective. + + [ bp: Massage and add kernel-parameters.txt change too. ] + +Fixes: 1b42f017415b ("x86/speculation/taa: Add mitigation for TSX Async Abort") +Signed-off-by: Waiman Long +Signed-off-by: Borislav Petkov +Cc: Greg Kroah-Hartman +Cc: "H. Peter Anvin" +Cc: Ingo Molnar +Cc: Jiri Kosina +Cc: Jonathan Corbet +Cc: Josh Poimboeuf +Cc: linux-doc@vger.kernel.org +Cc: Mark Gross +Cc: +Cc: Pawan Gupta +Cc: Peter Zijlstra +Cc: Thomas Gleixner +Cc: Tim Chen +Cc: Tony Luck +Cc: Tyler Hicks +Cc: x86-ml +Link: https://lkml.kernel.org/r/20191115161445.30809-2-longman@redhat.com +Signed-off-by: Greg Kroah-Hartman + +--- + Documentation/hw-vuln/mds.rst | 7 +++++-- + Documentation/hw-vuln/tsx_async_abort.rst | 5 ++++- + Documentation/kernel-parameters.txt | 11 +++++++++++ + arch/x86/kernel/cpu/bugs.c | 17 +++++++++++++++-- + 4 files changed, 35 insertions(+), 5 deletions(-) + +--- a/Documentation/hw-vuln/mds.rst ++++ b/Documentation/hw-vuln/mds.rst +@@ -262,8 +262,11 @@ time with the option "mds=". The valid a + + ============ ============================================================= + +-Not specifying this option is equivalent to "mds=full". +- ++Not specifying this option is equivalent to "mds=full". For processors ++that are affected by both TAA (TSX Asynchronous Abort) and MDS, ++specifying just "mds=off" without an accompanying "tsx_async_abort=off" ++will have no effect as the same mitigation is used for both ++vulnerabilities. + + Mitigation selection guide + -------------------------- +--- a/Documentation/hw-vuln/tsx_async_abort.rst ++++ b/Documentation/hw-vuln/tsx_async_abort.rst +@@ -169,7 +169,10 @@ the option "tsx_async_abort=". The valid + systems will have no effect. + ============ ============================================================= + +-Not specifying this option is equivalent to "tsx_async_abort=full". ++Not specifying this option is equivalent to "tsx_async_abort=full". For ++processors that are affected by both TAA and MDS, specifying just ++"tsx_async_abort=off" without an accompanying "mds=off" will have no ++effect as the same mitigation is used for both vulnerabilities. + + The kernel command line also allows to control the TSX feature using the + parameter "tsx=" on CPUs which support TSX control. MSR_IA32_TSX_CTRL is used +--- a/Documentation/kernel-parameters.txt ++++ b/Documentation/kernel-parameters.txt +@@ -2054,6 +2054,12 @@ bytes respectively. Such letter suffixes + full - Enable MDS mitigation on vulnerable CPUs + off - Unconditionally disable MDS mitigation + ++ On TAA-affected machines, mds=off can be prevented by ++ an active TAA mitigation as both vulnerabilities are ++ mitigated with the same mechanism so in order to disable ++ this mitigation, you need to specify tsx_async_abort=off ++ too. ++ + Not specifying this option is equivalent to + mds=full. + +@@ -4105,6 +4111,11 @@ bytes respectively. Such letter suffixes + + off - Unconditionally disable TAA mitigation + ++ On MDS-affected machines, tsx_async_abort=off can be ++ prevented by an active MDS mitigation as both vulnerabilities ++ are mitigated with the same mechanism so in order to disable ++ this mitigation, you need to specify mds=off too. ++ + Not specifying this option is equivalent to + tsx_async_abort=full. On CPUs which are MDS affected + and deploy MDS mitigation, TAA mitigation is not +--- a/arch/x86/kernel/cpu/bugs.c ++++ b/arch/x86/kernel/cpu/bugs.c +@@ -283,8 +283,12 @@ static void __init taa_select_mitigation + return; + } + +- /* TAA mitigation is turned off on the cmdline (tsx_async_abort=off) */ +- if (taa_mitigation == TAA_MITIGATION_OFF) ++ /* ++ * TAA mitigation via VERW is turned off if both ++ * tsx_async_abort=off and mds=off are specified. ++ */ ++ if (taa_mitigation == TAA_MITIGATION_OFF && ++ mds_mitigation == MDS_MITIGATION_OFF) + goto out; + + if (boot_cpu_has(X86_FEATURE_MD_CLEAR)) +@@ -315,6 +319,15 @@ static void __init taa_select_mitigation + */ + static_branch_enable(&mds_user_clear); + ++ /* ++ * Update MDS mitigation, if necessary, as the mds_user_clear is ++ * now enabled for TAA mitigation. ++ */ ++ if (mds_mitigation == MDS_MITIGATION_OFF && ++ boot_cpu_has_bug(X86_BUG_MDS)) { ++ mds_mitigation = MDS_MITIGATION_FULL; ++ mds_select_mitigation(); ++ } + out: + pr_info("%s\n", taa_strings[taa_mitigation]); + } diff --git a/queue-4.4/x86-speculation-fix-redundant-mds-mitigation-message.patch b/queue-4.4/x86-speculation-fix-redundant-mds-mitigation-message.patch new file mode 100644 index 00000000000..c1c5dfa43e4 --- /dev/null +++ b/queue-4.4/x86-speculation-fix-redundant-mds-mitigation-message.patch @@ -0,0 +1,81 @@ +From cd5a2aa89e847bdda7b62029d94e95488d73f6b2 Mon Sep 17 00:00:00 2001 +From: Waiman Long +Date: Fri, 15 Nov 2019 11:14:45 -0500 +Subject: x86/speculation: Fix redundant MDS mitigation message + +From: Waiman Long + +commit cd5a2aa89e847bdda7b62029d94e95488d73f6b2 upstream. + +Since MDS and TAA mitigations are inter-related for processors that are +affected by both vulnerabilities, the followiing confusing messages can +be printed in the kernel log: + + MDS: Vulnerable + MDS: Mitigation: Clear CPU buffers + +To avoid the first incorrect message, defer the printing of MDS +mitigation after the TAA mitigation selection has been done. However, +that has the side effect of printing TAA mitigation first before MDS +mitigation. + + [ bp: Check box is affected/mitigations are disabled first before + printing and massage. ] + +Suggested-by: Pawan Gupta +Signed-off-by: Waiman Long +Signed-off-by: Borislav Petkov +Cc: Greg Kroah-Hartman +Cc: "H. Peter Anvin" +Cc: Ingo Molnar +Cc: Josh Poimboeuf +Cc: Mark Gross +Cc: Peter Zijlstra +Cc: Thomas Gleixner +Cc: Tim Chen +Cc: Tony Luck +Cc: Tyler Hicks +Cc: x86-ml +Link: https://lkml.kernel.org/r/20191115161445.30809-3-longman@redhat.com +Signed-off-by: Greg Kroah-Hartman + +--- + arch/x86/kernel/cpu/bugs.c | 13 +++++++++++++ + 1 file changed, 13 insertions(+) + +--- a/arch/x86/kernel/cpu/bugs.c ++++ b/arch/x86/kernel/cpu/bugs.c +@@ -37,6 +37,7 @@ static void __init spectre_v2_select_mit + static void __init ssb_select_mitigation(void); + static void __init l1tf_select_mitigation(void); + static void __init mds_select_mitigation(void); ++static void __init mds_print_mitigation(void); + static void __init taa_select_mitigation(void); + + /* The base value of the SPEC_CTRL MSR that always has to be preserved. */ +@@ -99,6 +100,12 @@ void __init check_bugs(void) + mds_select_mitigation(); + taa_select_mitigation(); + ++ /* ++ * As MDS and TAA mitigations are inter-related, print MDS ++ * mitigation until after TAA mitigation selection is done. ++ */ ++ mds_print_mitigation(); ++ + arch_smt_update(); + + #ifdef CONFIG_X86_32 +@@ -224,6 +231,12 @@ static void __init mds_select_mitigation + mds_mitigation = MDS_MITIGATION_OFF; + return; + } ++} ++ ++static void __init mds_print_mitigation(void) ++{ ++ if (!boot_cpu_has_bug(X86_BUG_MDS) || cpu_mitigations_off()) ++ return; + + if (mds_mitigation == MDS_MITIGATION_FULL) { + if (!boot_cpu_has(X86_FEATURE_MD_CLEAR))