From: Josh Poimboeuf jpoimboe@redhat.com
commit 5c14068f87d04adc73ba3f41c2a303d3c3d1fa12 upstream.
Add MDS to the new 'mitigations=' cmdline option.
Signed-off-by: Josh Poimboeuf jpoimboe@redhat.com Signed-off-by: Thomas Gleixner tglx@linutronix.de [bwh: Backported to 4.4: - Drop the auto,nosmt option, which we can't support - Adjust filenames, context] Signed-off-by: Ben Hutchings ben@decadent.org.uk Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- Documentation/kernel-parameters.txt | 1 + arch/x86/kernel/cpu/bugs.c | 2 +- 2 files changed, 2 insertions(+), 1 deletion(-)
--- a/Documentation/kernel-parameters.txt +++ b/Documentation/kernel-parameters.txt @@ -2187,6 +2187,7 @@ bytes respectively. Such letter suffixes nospectre_v2 [X86] spectre_v2_user=off [X86] spec_store_bypass_disable=off [X86] + mds=off [X86]
auto (default) Mitigate all CPU vulnerabilities, but leave SMT --- a/arch/x86/kernel/cpu/bugs.c +++ b/arch/x86/kernel/cpu/bugs.c @@ -221,7 +221,7 @@ static const char * const mds_strings[]
static void __init mds_select_mitigation(void) { - if (!boot_cpu_has_bug(X86_BUG_MDS)) { + if (!boot_cpu_has_bug(X86_BUG_MDS) || cpu_mitigations_off()) { mds_mitigation = MDS_MITIGATION_OFF; return; }