From: Waiman Long longman@redhat.com
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 pawan.kumar.gupta@linux.intel.com Signed-off-by: Waiman Long longman@redhat.com Signed-off-by: Borislav Petkov bp@suse.de Cc: Greg Kroah-Hartman gregkh@linuxfoundation.org Cc: "H. Peter Anvin" hpa@zytor.com Cc: Ingo Molnar mingo@redhat.com Cc: Josh Poimboeuf jpoimboe@redhat.com Cc: Mark Gross mgross@linux.intel.com Cc: Peter Zijlstra peterz@infradead.org Cc: Thomas Gleixner tglx@linutronix.de Cc: Tim Chen tim.c.chen@linux.intel.com Cc: Tony Luck tony.luck@intel.com Cc: Tyler Hicks tyhicks@canonical.com Cc: x86-ml x86@kernel.org Link: https://lkml.kernel.org/r/20191115161445.30809-3-longman@redhat.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- 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 @@ -39,6 +39,7 @@ 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. */ @@ -108,6 +109,12 @@ 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 @@ -245,6 +252,12 @@ static void __init mds_select_mitigation (mds_nosmt || cpu_mitigations_auto_nosmt())) cpu_smt_disable(false); } +} + +static void __init mds_print_mitigation(void) +{ + if (!boot_cpu_has_bug(X86_BUG_MDS) || cpu_mitigations_off()) + return;
pr_info("%s\n", mds_strings[mds_mitigation]); }